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E0340 – Elaboration of porous mullite-based materials via SHS reaction

In order to produce cheaper mullite from kaolinitic clays we worked on the opportunity to use self-propagating high-temperature synthesis (SHS) reaction to obtain this phase. Two ways were explored during the combustion of metals mixed with the clay. The first one concerns the nature of the combustion gas (air or pure oxygen) which was tested on mixtures of clay and metal powders. The second one showed the influence of magnesium addition in clay/Al mixture. Results conclude that to obtain porous mullite at low-cost by SHS process the best conditions are the addition of magnesium powder and combustion in oxygen gas. Because a SHS reaction is always quicker, we compared this process with the traditional reactive sintering in order to explain the structure and the microstructure of the SHS products.
A. Esharghawi, C. Penot, F. Nardou, Ceramics International 36 (2010) 231–239

E0332 – Polymorphism of new rubidium magnesium monophosphate

Novel phase RbMgPO4, synthesized by solid state reaction, sustains phase transitions at 169 and 184 °C. The medium (?)- and high- (?) temperature forms (orthorhombic, respectively Pna21 and Pnma, Z=4) are typical stuffed tridymites but the ambient form (?) exhibits an unusual three-fold Pna21 superstructure that results from the change of coordination of one third of the Mg atoms. Cell parameters are as follows: for ?: a=26.535(1) Å, b=9.2926(3) Å, c=5.3368(2) Å; for ?: a=8.7938(3) Å, b=9.3698(3) Å, c=5.3956(1) Å; for ?: a=8.7907(3) Å, b=5.4059(1) Å, c=9.3949(3) Å.
Rajia Ait Benhamou, Gilles Wallez, Pascal Loiseau, Bruno Viana, Mohamed Elaatmani, Mohamed Daoud, Abdelwahed Zegzouti, Journal of Solid State Chemistry 183 (2010) 2082–2086

E0320 – Challenges in the crystal growth of Li2CuO2 and LiMnPO4

Single crystals of a potential battery material, LiMnPO4, and the spin ladder compound Li2CuO2 are grown under elevated gas pressure in a newly designed vertical floating zone facility with optical heating. Lithium vaporization and its reaction with gases in the growth chamber are principal challenges of the growth process. By applying high argon pressure of 40 bar during Travelling Solvent Floating Zone growth of LiMnPO4 the vaporization was reduced by orders of magnitude. The optical radiation, penetrating the transparent melt, affects the crystal/melt interface curvature during the growth. The growth direction was recognized to be decisive for changing the interface curvature from concave to convex and enabling efficient grain selection. By using an Ar/O2 gas mixture in crystal growth of Li2CuO2 the direct exchange between oxygen in the atmosphere and the floating zone, the oxygen content of the melt and finally the quality of Li2CuO2 crystals are controlled
Nadja Wizent, Günter Behr, Wolfgang Löser, Bernd Büchner, Rüdiger Klingeler, Journal ofCrystal Growth 318 (2011) 995–999

E0298 – Study of physical and mechanical applications on ceramics of the lateritic and alluvial clayey mixtures of the Yaoundé region (Cameroon)

Ceramic products were prepared by mixing lateritic and alluvial clayey materials of Yaoundé (Cameroon) in the humid tropical region, with 20, 50 and 80 wt.% of alluvial clay respectively in lateritic clay. Samples were grounded and sieved and powders obtained were shaped by uniaxial pressing of wet granules and fired under low temperatures between 350 and 1050 °C. Open porosity, bulk density and flexural strength were the principal properties characterised. Results indicates that a maximum of 80 wt.% of alluvial clayey material must be added to lateritic clays of Yaoundé, to obtain weakly porous ceramics and to attain the bulk density ranging from 1.56 to 1.97 g/m3 and a flexural strength of 6–19.85 MPa would be equivalent alluvial clay ceramics. But ceramics with lesser amount of alluvial clayey materials also have interesting flexural strengths in the range of 5–16 MPa, thus higher than porous lateritic clay ceramics.
G.F. Ngon Ngon, R. Yongue Fouateu, G.L. Lecomte Nana, D.L. Bitom, P. Bilong, G. Lecomte, Construction and Building Materials 31 (2012) 294–299

E0290 – Apatite-structured compounds: Synthesis and high-temperature investigation

The phase transitions and thermal expansion of apatite-structured compounds with the general formula MII5(AVO4)3L (MII = Ca, Sr, Cd, Ba, Pb; AV = P, V, Cr, Mn; L = OH, F, Cl, Br, I) have been studied by high-temperature X-ray diffraction and differential thermal analysis. Polymorphic transition nature was explained on the basis of the structure data. Connection between thermal stability and peculiarities of thermal expansion, which were explained in assumption of composition and structure of apatites was ascertained.
Alexander V. Knyazev, Nikolai G. Chernorukov, Evgeny N. Bulanov, Materials Chemistry and Physics 132 (2012) 773– 781

E0288 – Correlation between structure and photoluminescence of the europium doped glaserite-type phosphate Na2SrMg(PO4)2

A new phosphate Na2SrMg(PO4)2 has been synthesized and investigated by X-ray diffraction, DTA, 31P NMR spectroscopy and photoluminescence measurements. This compound crystallizes in the space group P21/a of the monoclinic system with the cell parameters: a = 9.158(1) Å, b = 5.267(1) Å, c = 13.498 (1) Å, ? = 90.01(1)° and four formula units per cell. Its structure is closely related to that of the mineral glaserite K3Na(SO4)2 and thus it can be described by the general formula XY2M(TO4)2. The X, Y, M and T sites are fully occupied by Sr2+, Na+, Mg2+ and P5+ cations, respectively. The anionic framework is consisted by the stacking along the [001] direction of two kinds of alternating [MgP2O84?]? mixed layers parallel to the (a, b) plane and resulting from a corner-sharing between MgO6 octahedra and PO4 tetrahedra. The Sr2+ cations are located within the interlayer space, while those Na+ are found in large cavities bounded to the layers. The DTA analysis showed a congruent melting of this compound at 1374 K. The 31P NMR spectroscopy confirmed the presence of two distinct phosphors sites in the structure. Optical studies were performed on the Na2SrMg(PO4)2 compound doped with Eu3+ and Eu2+. The trivalent europium was used as a local probe, replacing strontium and sodium, what gives complementary and consistent results to the crystallographic analyses. The divalent europium was used to analyze preliminary the potentiality for this compound to be integrated as phosphor in Light Emitting Diode (LED).
Amal Boukhris, Mourad Hidouri, Benoit Glorieux, Mongi Ben Amara, Materials Chemistry and Physics 137 (2012) 26-33

E0246 – Sintering of tricalcium phosphate–fluorapatite composites by addition of alumina

The effect of alumina (Al2O3) addition on the densification of tricalcium phosphate–26.52 wt% fluorapatite composites was investigated. The sintering behaviour was investigated using X-ray diffraction, scanning electron microscopy and by analysis using 31P and 27Al nuclear magnetic resonance. The composites sintering alumina additives have been tested in order to enhance their sinterability. When small amount of Al2O3 was added, densification of the tricalcium phosphate–26.52 wt% fluorapatite composites was markedly enhanced. The densification of the pure tricalcium phosphate–26.52 wt% fluorapatite composites was about 87%, whereas it reached 91% with 2.5 wt% Al2O3 at 1300 8C. High temperatures were not very efficient conditions. About 1400 8C, grain growth becomes important and induces an intragranular porosity which is responsible for decrease in density. The 31P and 27Al MAS-NMR analysis of tricalcium phosphate–26.52 wt% fluorapatite composites sintered with Al2O3 additives reveals the presence of tetrahedral P and octahedral Al sites.
Foued Ben Ayed, Jamel Bouaziz, Ceramics International 34 (2008) 1885–1892

E0243 – Estimation of Liquidus Temperatures for Multicomponent Silicates from Activation Energies for Viscous Flow

This article considers the viscous-flow phenomenon in molten silicate melts in the vicinity of their liquidus temperatures. An agglomeration of ionic species occurs in the liquid slag with decreasing temperatures and results in an increase in the viscosity and the activation energy for viscous flow. The latter was found to be nonlinear, increasing rapidly as the temperature is approached wherein a solid phase is likely to separate from the liquid. The second derivative of the activation energy for viscous flow with respect to temperature was found to show a discontinuity in the vicinity of the liquidus temperature. This has been verified in the case of viscous flow for both pure water and CaOSiO2 melts. Experimental data for the viscosities of complex silicate melts and mold fluxes have also demonstrated the occurrence of a discontinuity in the second-derivative function, which is in accordance with the liquidus temperature as determined by differential thermal analysis (DTA). Thus, the second derivative offers a useful way of estimating the liquidus temperatures of multicomponent silicates, which are often difficult to determine due to supercooling effects.
S. Seetharaman, S. Sridhar, Du Sichen, K.C. Mills, Metallurgical and Materials Transactions B, Volume 31B, February 2000—111

E0231 – Thermodynamic properties of pentalead tris(vanadate) chloride

In the present work the temperature dependences of pentalead tris(vanadate) chloride heat capacity have been measured for the first time in the range from 7 to 350 K. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity Cp ? (T), enthalpy H?(T)?H?(0), entropy S?(T)?S?(0) and Gibbs function G?(T)?H?(0), for the range from T?0 to 350 K. The differential scanning calorimetry in temperature interval 298–1473K was applied to measure temperatures of phase transition and melting of compound under study. The high-temperature X-ray diffraction in range 298–1073K was used for the determining thermal expansion coefficients.
A.V. Knyazev, E.N. Bulanov, N.N. Smirnova, N.Yu. Kuznetsova, I.A. Letyanina, E.D. Pryamova, Thermochimica Acta 515 (2011) 79–83

E0222 – Isomorphism and phase diagram of Pb5(PO4)3F–Pb5(PO4)3Cl system

Compounds of composition Pb5(PO4)3FxCl1?x (0 ? x ? 1), which are synthetic analogues of minerals pyromorphite, flourapatite, and endlichite, were synthesized for the first time by high-temperature solid phase reactions. X-ray diffraction and IR spectroscopy were used to determine the structure of the compounds and revealed complete miscibility in the solid phase of the Pb5(PO4)3F–Pb5(PO4)3Cl binary system. Adiabatic reaction calorimetry was used to measure standard enthalpies of mixing and formation and show that the regular solutions model is applicable to the Pb5(PO4)3F–Pb5(PO4)3Cl system. Differential thermal analysis in tandem with high-temperature X-ray diffraction were used to study the phase diagram and characterize phase transitions.
A.V. Knyazev, N.G. Chernorukov, E.N. Bulanov, Thermochimica Acta 513 (2011) 112–118

E0220 – Phase diagram of apatite system Ca10(PO4)6Cl2–Pb10(PO4)6Cl2

Compounds in Ca10(PO4)6Cl2–Pb10(PO4)6Cl2 system were synthesized by solid state reaction. It was ascertained using DTA and X-ray diffraction methods that in the investigated system there are two fields because of the formation a compound with formula Ca7Pb3(PO4)6Cl2. The first area is the Pb10(PO4)6Cl2–Ca7Pb3(PO4)6Cl2 which is characterized by unbounded mixing of components. The second Ca7Pb3(PO4)6Cl2–Ca10(PO4)6Cl2 area has complicated character due to presence of decomposition processes. In spite of the presence of the one nature polymorphic transitions of Ca10(PO4)6Cl2 and Pb10(PO4)6Cl2 the same effects on all solid solutions were not observed
A.V. Knyazev, N.G. Chernorukov, E.N. Bulanov, Thermochimica Acta ,526 (2011) 72–77

E0202 – Two new lithium uranyl tungstates Li2(UO2)(WO4)2 and Li2(UO2)4(WO4)4O with framework based on the uranophane sheet anion topology

Two new lithium uranyl tangstates Li2(UO2)(WO4)2 and Li2(UO2)4(WO4)4O have been prepared by high-temperature solid state reactions of Li2CO3, U3O8 and WO3. For each compound, the crystal structure was determined by single crystal X-ray diffraction data, usinga Brucker diffractometer, equipped with a SMART CCD detector and MoKalpha radiation. The crystal structures were solved at room temperature by direct methods followed by Fourier difference techniques, and refined by a least square procedure on the basis of F2 for all independent reflections, to R1 = 0.035 for 65 refined parameters and 807 reflections with I>2?(I) for Li2(UO2)(WO4)2 and to R1 = 0.051 for 153 refined parameters and 1766 reflections with I>2?(I) for Li2(UO2)4(WO4)4O. The crystal structure of Li2(UO2)(WO4)2 is formed by perovskite sheets of WO6 octahedra, one octahedron thickness, connected together by (UO5) infinite chains, and creating tunnels parallel to the c-axis. The lithium atoms are localized in the tunnels. The structure can be deduced from that of UMO5 (M = Mo, V, Nb) compounds by the replacement of half U atoms by Li. The crystal structure of Li2(UO2)4(WO4)4O consists of UO7 pentagonal bipyramids, UO6 tetragonal bipyramids and WO6 distorted octahedra linked together to form a three-dimensional framework creating paralleled channels filled with lithium cations. The structure can also be described by the stackingof layers with the uranophane sheet anion topology similar to those obtained in UMO5 (M = Mo, V, Nb, Sb) compounds with an ordered population of pentagons by U and Li and of squares by U and W. The measured conductivities are comparable to those of the better Li+ ion conductor solid electrolytes such as Lisicon or Li-balumina. Crystallographic data: Li2(UO2)(WO4)2, orthorhombic symmetry, space group Pbcn and unit cell parameters a = 7.9372(15)Å, b = 12.786(2)Å , c = 7.4249(14)Å , ?cal = 6.87(2) g/cm3, ?mes = 6.89(1) g/cm3 and Z = 4. Li2(UO2)4(WO4)4O, monoclinic symmetry, space group C2=c and unit cell parameters a = 14.019(4)Å , b = 6.3116(17)Å , c = 22.296(6)Å , beta = 98.86(3)° , ?cal = 7.16(2) g/cm3, ?mes = 7.25(3) g/cm3 and Z = 4.
S. Obbade, S. Yagoubi, C. Dion, M. Saadi, and F. Abraham, Journal of Solid State Chemistry 177 (2004) 1681-1694

E0201 – Synthesis, crystal structure and electrical characterization of Cs4[(UO2)2(V2O7)O2], a uranyl divanadate with chains of corner-sharing uranyl square bipyramids

A new cesium uranyl vanadate Cs4[(UO2)2(V2O7)O2] has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. It crystallizes in the orthorhombic symmetry with space group Pmmn and following cell parameters: a = 8.4828(15) Å, b = 13.426(2) Å and c = 7.1366(13) Å, V = 812.8(3) Å3, Z = 2 with ?mes = 5.39(2) g/cm3 and ?cal = 5.38(1) g/cm3. A full-matrix least-squares refinement on the basis of F2 yielded R1 = 0.027 and wR2 = 0.066 for 62 parameters with 636 independent reflections with I>2?(I) collected on a BRUKER AXS diffractometer with MoKa radiation and a charge-coupled device detector. The crystal structure is characterized by [(UO2)2(V2O7)O2]4- corrugated layers parallel to (001). The layers are built up from distorted (UO2)O4 octahedra and divanadate V2O7 units resulting from two VO4 tetrahedra sharing corner. The distorted uranyl octahedra (UO2)O4 are linked by corners to form infinite [UO5)]4- chains parallel to the a-axis. These chains are linked together by symmetrical divanadate units sharing two corners with each chain, the two last corners being oriented towards the same interlayer. The cohesion of the structure is assured by interlayer Cs+ ions. Their mobility within the interlayer space gives rise to a cationic conductivity with an important jump between 635°C and 680°C. Cs4[(UO2)2(V2O7)O2] is readily decomposed by water at 60°C to form the Cs-carnotite analog Cs2(UO2)2(V2O8) compound.
S. Obbade, C. Dion, M. Saadi, and F. Abraham, Journal of Solid State Chemistry 177 (2004) 1567-1574

E0200 – Study on the effects of volatiles on BBO crystal growth

beta-BaB2O4 (BBO) crystals were grown from high-temperature borate solutions by the top seeded growth method (TSGM) using NaF as a flux. During the crystal growth, volatiles were found to cause defects in BBO crystals. The component of volatiles was investigated to be sodium fluoride (NaF) by X-ray diffraction. Optical microscope and electron microscope were used to identify inclusions in BBO crystals. Two mechanisms for the formation of inclusions caused by the volatilization of NaF were discussed and the inclusion free BBO crystals with 70mm in diameter and 20mm in thickness were obtained.
Zijie Xu, Journal of Crystal Growth 265 (2004) 553-557

E0198 – Luminescence emission spectra in the temperature range of the structural phase transitions of Na2SO4

The spectral properties of Na2SO4 have been studied by means of infrared stimulated luminescence (IRSL), thermoluminescence (TL) and radioluminescence (RL) in the range of 200-800 nm. The observed changes in the RL emission spectra after an annealing treatment (400°C for 1 h) could be linked to thermal phase transformations and alkali self-diffusion through the lattice of this salt. Despite the complexity of the luminescence spectra structure, five emission bands peaked at 330, 345, 385, 460 and 630 nm could be distinguished. The UV-blue TL emission of this material exhibits a maximum peaked at 230°C which is well correlated with the differential thermal analysis (DTA) and can be associated with the thermal transformation of the orthorhombic sodium sulphate (Na2SO4) V (thenardite) phase into Na2SO4 III, II and I phases. Taking into account the observed changes on the structural phase transition by X-ray diffraction (XRD) from 16°C onwards, this material does not show satisfactory features for radiation dosimetry, but could be employed for temperature calibration of TL readers.
V. Correcher, J. Garcia-Guinea, P. Lopez-Arce, J.M. Gomez-Ros, Spectrochimica Acta Part A 60 (2004) 1431-1438

E0197 – A novel open-framework with non-crossing channels in the uranyl vanadates A(UO2)4(VO4)3 (A=Li, Na)

A new sodium uranyl vanadate Na(UO2)4(VO4)3 has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. It crystallizes in the tetragonal symmetry with space group I41/amd and following cell parameters: a = 7.2267(4) Å and c = 34.079(4) Å , V = 1779.8(2) Å3, Z = 4 with ?mes = 5.36(3) g/cm3 and ?cal = 5.40(2) g/cm3. A full-matrix least-squares refinement on the basis of F2 yielded R1 = 0.028 and wR2 = 0.056 for 52 parameters with 474 independent reflections with I>2?(I) collected on a BRUKER AXS diffractometer with MoKalpha radiation and a CCD detector. The crystal structure is characterized by [(UO2)2(VO4)] sheets parallel to (001) formed by corner-shared UO6 distorted octahedra and V(2)O4 tetrahedra, connected by V(1)O4 tetrahedra to [UO5]4- chains of edge-shared UO7 pentagonal bipyramids alternately parallel to the a- and b-axis. The resulting three-dimensional framework creates mono-dimensional channels running down the a- and b-axis formed by face-shared oxygen octahedra half occupied by Na. The powder of Li analog compound Li(UO2)4(VO4)3 has been synthesized by solid-state reaction. The two compounds exhibit high mobility of the alkaline ions within the two-dimensional network of non-intersecting channels.
S. Obbade, C. Dion, M. Rivenet, M. Saadi, and F. Abraham, Journal of Solid State Chemistry 177 (2004) 2058-2067

E0189 – A reinvestigation of the crystal structure of alpha-Pb2BiVO6

A previously reported beta phase for Pb2BiVO6 has been characterized as a stable phase, and the phase transitions alpha --> beta and beta --> delta were identified in the mother phase as well as in Pb2BiV(1-x)MxO(6-y) solid solutions (M = Cr, Mn); the high temperature form delta-Pb2BiVO6 eventually decomposes at 480°C to a mixture of PbBiVO5 and Pb4BiVO8 before showing recombination at 650°C. The related substituted compositions behave the same way. The crystal structure of alpha-Pb2BiVO6 (I) is monoclinic, P21/n, a = 7.717(3) Å, b = 5.845(3) Å, c = 29.081(8) Å, beta = 94.27(1)°, Z = 8. Oxygen atoms are in tetrahedral interstices formed by four Bi and Pb atoms. These tetrahedra articulate by Bi-Pb edge sharing in two dimensions parallel to the b axis to form infinite chains. Mixed O(V Bi Pb)4 tetrahedra bridge the O(Bi Pb)4 ribbons by edge sharing to complete the three-dimensional articulation of the structure. alpha-Pb2BiV(1-x)MnxO(6-y) (x = 0.06) (II) is monoclinic, P21/m, a = 7.684(3) Å, b = 5.822(3) Å, c = 14.708(6) Å, beta = 100.92(1)°, Z = 4. Tetrahedral units of O(2Bi 2Pb) are also present in (II). They form dimers O2Bi4Pb4 by Bi-Bi edge sharing. The dimers form a chain along the b axis by sharing Bi-Pb edges. Two independent MO4 tetrahedra (M = V, Mn) are present in which one has V/Mn mixed occupancy. Both tetrahedra show statistical disorder by rotation around a V-O apex. The disordered tetrahedral oxygen atoms are part of the coordination sphere of Bi and Pb. The matrix {-1 0 0, 0 - 10, 1 0 2} relates the structures and unit cells of [I], and [II].
O. Labidi, J.P. Wignacourt, P. Roussel, M. Drache, P. Conflant, H. Steinfink, Solid State Sciences 6 (2004) 783--790

E0186 – Phase equilibria in the Bi2TeO5-Bi2SeO5 system and a high temperature neutron powder diffraction study of Bi2SeO5

Phase equilibria in the Bi2TeO5-Bi2SeO5 system were studied by X-ray, DTA and second harmonic generation (SHG). The samples were synthesized by solid state reactions of the Bi, Te and Se oxides. The phase diagram is interpreted as a quasibinary peritectic one with wide ranges of solid solutions on the basis of both compounds. The SHG study showed Bi2SeO5 to undergo a phase transition at about 250°C. Neutron diffraction (25-650°C) showed no major changes in the structure of Bi2SeO5 at high temperatures. However, the analysis of the oxygen atom thermal factors and site occupancies suggested that the mechanism of the phase transformation is an order-disorder transition involving reorientation of the SeO3 group.
O.A. Dityatyev, P. Smidt, S.Yu. Stefanovich, P. Lightfoot, V.A. Dolgikh, H. Opperman, Solid State Sciences 6 (2004) 915-922

E0185 – Characteristics of Pb[(Zn1/3Nb2/3)0.955Ti0.045]O3 single crystals versus growth method

Relaxor-based piezoelectric 0.955Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 (PZN-4.5PT) single crystals were grown by two methods: the flux method and the modified Bridgman method from a flux of Pb3O4 in sealed platinum crucibles at about 1200°C with a cooling rate of 0.8-1°C/h for flux method and a translation rate of 0.4-0.6 mm/h for MB method. A dedicated oven suitable for two methods has been specially built. The ratio PZN-PT/Flux was 40/60 mol % for the two methods. In this paper, some characteristics of the crystals obtained by flux and modified Bridgmann method such as the lattice parameters and the melting point are compared. The dielectric properties of the grown PZN-4.5PT crystals have been measured as a function of temperature at various frequencies. The phase transition from the tetragonal P4mm to cubic phase takes place at 166°C for the crystals grown by Bridgmann modified method and Flux method.
A. Benayad, D. Kobor, L. Lebrun, B. Guiffard, D. Guyomar, Journal of Crystal Growth 270 (2004) 137-144

E0182 – Pb(UO2)(V2O7), a novel lead uranyl divanadate

A new lead uranyl divanadate, PbUO2(V2O7), has been synthesized by high temperature solid-state reaction and its crystal structure was solved by direct methods using single-crystal X-ray diffraction data. It crystallizes in the monoclinic system with space group P21/n and following cell parameters: a=6.9212(9) Å , b=9.6523(13) Å , c=11.7881(16) Å , beta=91.74(1)°, V=787.01(2) Å3, Z=4, pmes=5.82(3), pcal=5.83(1) g/cm3. A full-matrix least-squares refinement on the basis of F2 yielded R1=0.029 and wR2=0.064 for 2136 independent reflections with I>2?(I) collected with a Bruker AXS diffractometer (MoKalpha radiation). The crystal structure of PbUO2(V2O7) consists of a tri-dimensional framework resulting from the association of V2O7 divanadate units formed by two VO4 tetrahedra sharing corner and UO7 uranyl pentagonal bipyramids and creating one-dimensional elliptic channels occupied by the Pb2+ ions. In PbUO2(V2O7), infinite ribbons of four pentagons wide are formed which can be deduced from the sheets with Uranophane type anion-topology that occurs, for example, in the uranyl divanadate (UO2)2(V2O7), by replacement of half-U atoms of the edge-shared UO7 pentagonal bipyramids by Pb atoms. Infrared spectroscopy was investigated at room temperature in the frequency range 400-4000 cm-1, showing some characteristic bands of uranyl ion and of VO4 tetrahedra.
S. Obbade , C. Dion, M. Saadi, S. Yagoubi, F. Abraham, Journal of Solid State Chemistry 177 (2004) 3909-3917

E0180 – Floating zone growth and characterization of Pr5Si3 single crystals

Pr5Si3 single crystals have been grown by the floating zone technique with optical heating. The crystals are crack-free, 6mm in diameter and 40-60mm in length. Pr5Si3 crystallizes with the tetragonal Cr5B3 crystal structure type (space group: I4/mcm) and with lattice parameters a = b = 7.8172(7) Å and c = 13.816(3) Å. Single crystal XRD data have been refined based on the Cr5B3 structure. The electrical resistivity of Pr5Si3 single crystals exhibit metallic behavior with an anomaly at TC = 43.5(1.0)K corresponding to a ferromagnetic ordering transition, which was confirmed by magneticsusc eptibility measurements.
D. Souptel, A. Leithe-Jasper, W. Löser, W. Schnelle, H. Borrmann, Günter Behr, Journal of Crystal Growth 273 (2004) 311-319

E0169 – Growth and characterization of a new nonlinear optical crystal Ca5(BO3)3F

A new nonlinear optical crystal calcium fluoroborate (Ca5(BO3)3F) has been grown successfully using LiF as a flux for the first time. Phase diagram of the pseudobinary Ca5(BO3)3F-LiF system within the composition range from 10 to 60wt% LiF was investigated by Xray powder diffraction and differential thermal analysis. Our experiments demonstrated that the composition of LiF from 15 to 35wt% was beneficial to the growth of Ca5(BO3)3F crystals in Ca5(BO3)3F-LiF system. Transmission spectrum was recorded from 185 to 3000 nm, which showed that the UV cutoff for Ca5(BO3)3F crystal was about 190 nm. Second-harmonic generation efficiency was measured from Kurtz's powder technique, which indicated that Ca5(BO3)3F could be phase matchable, and second-harmonic generation efficiency of Ca5(BO3)3F was about two times as large as that of KDP. Ca5(BO3)3F has potential application as a nonlinear optical material in UV region.
G. Chen, Y. Wu, P. Fu, Journal of Crystal Growth 292 (2006) 449-453

E0162 – Synthesis and characterization of alpha-GaPO4 single crystals grown by the flux method

Hexagonal gallium orthophosphate crystals with sizes of 6 x 4 x 1mm3 have been obtained by spontaneous nucleation using the slow cooling method from X2O-3MoO3 fluxes with X = Li, K. Infrared transmission measurements revealed samples without significant hydroxyl groups and thermal analyses have pointed out the total reversibility state of the phase transition alpha-quartz GaPO42 <-> beta-cristobalite GaPO4.
M. Beaurain, P. Armand , P. Papet, Journal of Crystal Growth 294 (2006) 396-400

E0159 – Mineralogical, crystallographic and morphological characteristics of natural kaolins from the Ivory Coast (West Africa)

Thirteen clay samples from four deposits in the Ivory Coast (West Africa) were studied using X-ray diffraction, thermogravimetric analysis and chemical analysis. Mineralogical, crystallographic and morphological characteristics of these samples are given. Kaolinite is the principal mineral but other minerals are present in small quantities: illite, quartz, anatase and iron oxides (oxides and oxyhydroxides). The crystallographic, morphological and surface characteristics are influenced by the presence of these impurities. In particular, the presence of iron oxides was associated with reduced structural ordering and thermal stability of kaolinite and increased specific surface area. These clays could be used in the ceramics industry to make tiles and bricks, and also in agronomy as supports for chemical fertilizers or for environmental protection by immobilising potentially toxic waste products.
J. Sei, F. Morato, G. Kra, S. Staunton, H. Quiquampoix, J.C. Jumas, J. Olivier-Fourcade, Journal of African Earth Sciences 46 (2006) 245-252

E0152 – Hydrothermal synthesis and characterization of a new zinc phosphate [Zn2.5(HPO4)2(PO4)][C6H10N2].5H2O

A new two-dimensional zinc phosphate, [Zn2.5(HPO4)2(PO4)][C6N2H10].5H2O (denoted in the following as ZnP-2AMP), with alternating inorganic and organic layers has been synthesized hydrothermally using 2-aminomethylpyridine (2AMP) as the structure-directing agent. This compound represents the first structure with a Zn/P ratio of 5/6. The structure of this compound, determined by single crystal X-ray diffraction, consists of anionic parallel [Zn2.5(HPO4)2(PO4)(H2O)2]2 sheets built up from ZnO4, ZnO2(H2O)4, PO4 and HPO4, alternating with thick slabs of organic molecules (C6H10N2)2+ and water molecules, the octahedral ZnO2(H2O)4 being enclosed in each [4^6 8^2 12^2] cage. The organic cations are linked to the anionic sheets through hydrogen bonds. Solid-state 13C and 31P MAS NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the partial attribution of phosphorus and carbon signals to the independent crystallographic sites and to the various atoms of the organic groups. Additional characterization of the compound has also been performed by IR spectroscopy and TG-DTA analyses.
R. Kefi, C. Ben Nasr, F. Lefebvre, M. Rzaigui, Polyhedron 25 (2006) 2953-2958

E0131 – Evidence for the nucleation and epitaxial growth of Zn phyllosilicate on montmorillonite

Zinc uptake in suspensions (63.7 g L 1) ofMX80montmorillonite was investigated at pH4.0 and 7.3, a total Zn concentration ([Zn]total) of 500 lM, and dissolved Si concentrations ([Si]aq) of 70 and 500 lMin 0.5 MNaCl, by kinetics experiments and polarized extended Xray absorption fine structure (P-EXAFS) spectroscopy. Differential thermogravimetric analysis verified the cis-vacant character of the montmorillonite. No Zn uptake occurred at pH 4.0, confirming that cation exchange was hampered by the high ionic strength of the suspension. At pH 7.3 and low [Si]aq ( 70 lM), Zn uptake occurred rapidly during the first hour of reaction, and then leveled off to 50 lmol/g montmorillonite at 168 h. The uptake rate is consistent with Zn sorption on pH-dependent edge sites. At pH 7.3 and high [Si]aq ( 500 lM), the initial sorption rate was similar, but Zn sorption continued, reaching 130 lmol/g at 168 h, and was paralleled by Si uptake with a Si/Zn uptake ratio of 1.51(10), suggesting formation of a Zn (hydrous) silicate. P-EXAFS data indicated that the first oxygen coordination shell of sorbed Zn is split into two subshells at 1.97(2) and 2.08(3)-2.12(2) Å for all EXAFS samples. These two distances are assigned to a mixture of tetrahedral (IVZn) and octahedral (VIZn) Zn complexes. The proportion of IVZn was lower in the high [Si]aq samples and decreased with reaction time. Al low [Si]aq and 216 h of reaction, nearest cationic shells of 0.6(4) Al in the film plane and 0.5(4) Si out of the film plane were detected at 3.00(2) and 3.21(2) Å , respectively, and were interpreted as the formation of IVZn and VIZn mononuclear complexes at the edges of montmorillonite platelets, in structural continuity to the (Al, Mg) octahedral sheets. At high [Si]aq, in-plane Zn and Al and out-of-plane Si neighbors were detected at 4 h, indicating the formation of Zn phyllosilicate nuclei at the layer edges. At 313 h, Zn-Al pairs were no longer detected, and Zn atoms were surrounded on average by 3.4(5) in-plane Zn at 3.10(1) Å and 1.7(9) out-of-plane Si at 3.30(2) Å , supporting the precipitation of a Zn phyllosilicate. Thus, dioctahedral Al phyllosilicate may act as a nucleating surface for the heterogeneous formation of trioctahedral Zn phyllosilicate at [Si]aq relevant to natural systems.
M.L. Schlegel, A. Manceau, Geochimica et Cosmochimica Acta 70 (2006) 901-917

E0115 – Thermodynamic study of the solid-liquid equilibria in the MPO3-Cu(PO3)2 systems

Thermodynamic exploration of solid-liquid equilibria of the MIPO3-Cu(PO3)2 (with MI=Li, Na, K, Rb, Cs, Ag, Tl) systems is carried out with a semi-empirical equation of the liquidus curves. The enthalpies of fusion of pure polyphosphates and some intermediate compounds were determined from DTA curves. The temperature, enthalpy and entropy of fusion are calculated for each solid phase with the exception of silver polyphosphate and the intermediate compound Cs4Cu(PO3)6 which have very limited crystallization fields. The calculated values of the melting enthalpies are approximately equal to the measured ones. The melting enthalpy of Cu(PO3)2 calculated from different binary systems shows a wide variation in the obtained values, 35-54 kJ mol-1. The experimental value is 33.65 kJ mol-1. The calculated temperatures and compositions in most binary systems are in good agreement with experimental determinations.
C. Marhag, D.B. Hassen-Chehimi, H. Said, Journal of Thermal Analysis and Calorimetry 76 (2004) 417-428

E0114 – Thermodynamique des mélanges binaires LiPO3-Pb(PO3)2. Diagramme de phases et étude thermodynamique du liquide

Study of solid-liquid phase diagram of LiPO3-Pb(PO3)2 binary system, in certain calcination conditions, shows the existence of several metastable phasis. When heated at a temperature of 723 K the binary mixtures lead uncompletely to a defined compound Pb2Li(PO3). On heating these ternary solid mixtures, three eutectic reactions have been observed: (1) LiPO3+Pb(PO3)2Liquid at a temperature of 793 K (2) LiPO3+Pb2Li(PO3)5Liquid at a temperature of 843 K (3) Pb2Li(PO3)5+Pb(PO3)2Liquid at a temperature of 891 K The metastable liquid phase appears in the system at temperature of 793 K. DTA experiments performed on the binary LiPO3-Pb(PO3)2 mixtures, show a superposition of two diagrams. The first one is metastable and the second represents the stable equilibrium phase diagram. Measurements of liquid enthalpy of binary LiPO3-Pb(PO3)2 system at temperature of 979.65 K were reported. The corresponding values were very small and so the binary system can be considered as athermal. Assuming an ideal behaviour, the liquidus curves in the metastable diagram were calculated and the eutectic reaction (LiPO3-Pb(PO3)2Liquid) was confirmed at 793 K.
C. Marhag, H. Said, P. Satre, C. Favotto, J. Rogez, Journal of Thermal Analysis and Calorimetry 74 (2003) 275-285

E0112 – Thermal and structural studies of sodium borosilicate glasses containing thorium oxide

K. Sreejith, V. Sudarsan, R. Mishra, C.G.S. Pillai, Thermans (2002) 280-282

E0111 – Etude du systeme LiPO3-Pr(PO3)3 données sur LiPr(PO3)4

The LiPO3-Pr(PO3)3 system was studied by micro-differential thermal analysis. The only new compound observed in the system was LiPr(PO3)4, melting incongruently at 1246 K. An eutectic appears at 926 K. Crystallographic data and powder diagram of the new compound are given. LiPr(PO3)4 crystallizes in the C2/c monoclinic system with unit cell: a=16.428(6), b=7.054(3), c=9.747(4) , =126°31(3), V=910.2 3, Z=4. The IR and Raman spectra of this compound are given.
M. Ferid, B. Piriou and M. Trabelsi-Ayedi, Journal of Thermal Analysis and Calorimetry 53 (1998) 227-234

E0110 – Thermodynamic study of the solid-liquid equilibria in the systems MPO3-Pr(PO3)3 (M=Na, Rb, Cs or Ag)

A previously established equation of a stoichiometric phase liquidus curve was applied to determination of the phase diagrams of the systems MIPO3-Pr(PO3)3 (with MI=Na, Rb, Cs or Ag). The temperature, enthalpy and entropy of fusion were calculated for each solid phase with the exception of silver polyphosphate, the crystallization field of which was very limited. The enthalpy of fusion of the polyphosphate Pr(PO3)3 was determined from the DTA curve. The melting enthalpy of Pr(PO3)3 calculated from the different binary systems was approximately equal to the measured value. The calculated temperatures and compositions were in good agreement with those determined experimentally.
D. Ben Hassen-Chehimi, N. Kbir-Ariguib and M. Trabelsi-Ayedi, Journal of Thermal Analysis and Calorimetry 53 (1998) 871-882

E0103 – Influence of different amounts of hematite seedings on the temperature of phase transformation of transition aluminas into corundum

Corundum (alpha-Al2O3) is the only stable oxide in the aluminium-oxygen system and is characterized by its high mechanical and chemical stability. But there are some problems in producing very fine corundum powders. Usually alpha-Al2O3 is obtained from transition aluminas at temperatures in the range of 1100-1200°C. At this temperatures the dispersity of the corundum formed is reduced due to the start of grain growth processes. That is the reason for our investigations in preparing alpha-Al2O3 at lower temperatures. Therefore aluminium-secondary-butoxide was hydrolysed in water and seeded with different amounts of hematite. The dried powders were investigated for instance by using differential thermal analysis. A nearly linear relation between seeding amount and transformation temperature was found. The formation temperature of corundum was decreased by seeding with 10 wt% hematite from about 1100 to 970°C.
Th. Oberbach, C. Günther, G. Werner, G. Tomandl and G. Wolf, Thermochimica Acta 271 (1996) 155-162

E0097 – Phase transitions of Li2ZrO3 and Li4SiO4 at high temperature

T. Tatsuya, M. Tsuneo, JSCTA 104-105

E0093 – Melting of forsterite and spinel, with implications for the glass transition of Mg2SiO4 liquid

P. Richet, F. Leclerc, L. Benoist, Geophysical Research Letters 20 (1993) 1675-1678

E0083 – Polymorphism of Ca3SiO4Cl2 – DTA studies

The studies of calcium chlorosilicate Ca3SiO4Cl2 phase transition by DTA and high temperature calorimetry have been carried out. The temperature of transition as well as heat transition have been elucidated.
K. Miskiewicz and M. Pyzalski, Cement and Concrete Research 18 (1988) 819-822

E0082 – The dehydroxylation of aluminium hydroxides and the kinetics of alpha-Al2O3 formation

Studies were made of the dehydroxylation of several aluminium hydroxide modifications and the kinetics of alpha-Al2O3 formation. The investigated samples differed in both mineral composition and the level of alkali admixtures. It was found that the rate of formation and the quantity of alpha-Al2O3 depend mainly on the purity of the aluminium hydroxides, while the transition forms of alumina depend on the initial type of the aluminium hydroxide.
M. Pyzalski and M. Wojcik, Journal of Thermal Analysis 36 (1990) 2147-2151

E0081 – DTA studies of 12CaO,7Al2O3 polymorphism

The polymorphism of 12CaO.7AI203 has been studied by means of a Setaram G-24 thermoanalyser and by X-ray diffraction using a Philips diffractometer. Thermal treatment was carried out at 1.3 Pa as well as in air atmosphere.
M. Pyzalski, Z. Konik, J. Iwanciw and A. Stock, Journal of Thermal Analysis 32 (1987) 1727-1729

E0074 – Untersuchungen zum thermischen verhalten von NH4Al(SO4)2.12H2O

H-H. Emons, R. Naumann, K. Köhnke, Z. Anorg. Allg. Chem. 577 (1989) 83-92

B3263 – High-pressure phase relations in the system CaAl4Si2O11–NaAl3Si3O11 with implication for Na-rich CAS phase in shocked Martian meteorites

High-pressure phase relations in the system NaAl3Si3O11–CaAl4Si2O11 were examined at 13–23 GPa and 1600–1900 °C, using a multianvil apparatus. A Ca-aluminosilicate with CaAl4Si2O11 composition, designated CAS phase, is stable above about 13 GPa at 1600 °C. In the system NaAl3Si3O11–CaAl4Si2O11, the CAS phase dissolving NaAl3Si3O11 component coexists with jadeite, corundum and stishovite below 22 GPa, above which the CAS phase coexists with Na-rich calcium ferrite, corundum and stishovite. At 1600 °C, the solubility of NaAl3Si3O11 component in the CAS solid solution increases with increasing pressure up to about 50 mol% at about 22 GPa, above which the solubility decreases with pressure. The maximum solubility of NaAl3Si3O11 component in the CAS phase increases with temperature up to around 70 mol% at 1900 °C at 22 GPa. The dissociation of NaAlSi2O6 jadeite to NaAlSiO4 calcium ferrite plus stishovite occurs at about 22 GPa. Lattice parameters of the CAS phase with the hexagonal Ba-ferrite structure change with increase of the NaAl3Si3O11 component: a-axis decreases and c-axis slightly increases, resulting in decrease of molar volume. Enthalpies of the CAS solid solutions were measured by high-temperature drop-solution calorimetry techniques. The results show that enthalpy of hypothetical NaAl3Si3O11 CAS phase is much higher than the mixture of NaAlSi2O6 jadeite, corundum and stishovite and is close to that of the mixture of NaAlSiO4 calcium ferrite, corundum and stishovite. When we adopt the Na:Ca ratio of 75:25 of the natural Na-rich CAS phase in a shocked Martian meteorite, Zagami, the phase relations determined above suggest that the natural CAS phase crystallized from melt at pressure around 22 GPa and temperature close to or higher than 2000–2200 °C. The inferred P, T conditions are consistent with those estimated using other high-pressure minerals in the shocked meteorite.
M. Akaogi, M. Haraguchi, K. Nakanishi, H. Ajiro, H. Kojitani, Earth and Planetary Science Letters 289 (2010) 503–508

B3247 – K3YB6O12: A new nonlinear optical crystal with a short UV cutoff edge

A new non-centrosymmetric borate, K3YB6O12, has been synthesized by solid state reaction techniques, and a K3YB6O12 crystal with dimensions of ?40 mm × 30 mm × 10 mm was successfully grown by the top-seeded solution growth method using a K2O–B2O3–KBF4 flux. K3YB6O12 crystallizes in the trigonal space group R32 with cell parameters of a = 13.2202(19) Å, c = 30.281(6) Å, and Z = 15. In the structure of K3YB6O12, B5O10 groups are bridged by Y3O12 chains and discrete YO6 octahedra via corner-sharing, constructing columns packed side by side in a hexagonal motif along the c-axis to form a three-dimensional framework. The three-dimensional framework affords one-dimensional tunnels of 8-membered rings along the b-axis which are occupied by K atoms. K3YB6O12 melts incongruently at 941 °C, and exhibits a short UV cutoff edge at 195 nm. The second harmonic generation effect of K3YB6O12 is weaker than that of KH2PO4
Sangen Zhao, Guochun Zhang, Jiyong Yao, Yicheng Wu, Materials Research Bulletin 47 (2012) 3810–3813

B3245 – Preparation, structure, and photoluminescence properties of new layered borates KBaRE(B3O6)2 (RE ¼ Y, Eu, and Tb)

A series of potassium barium rare earth borates, KBaRE(B3O6)2 (RE = Y, Eu, and Tb), have been synthesized with solid state reaction techniques. Single crystals of the first member of the series, KBaY(B3O6)2, have been grown via spontaneous crystallization. Single crystal X-ray diffraction results show that KBaY(B3O6)2 belongs to the trigonal system, space group R with cell parameters of a = 7.1677(10) Å, c = 17.588(4) Å, and Z = 3. The nearly planar B3O6 groups serve as the fundamental building units, which are distributed layer upon layer along the c axis. Regular YO6 octahedra and irregular Ba/KO9 polyhedra alternately locate between the B3O6 layers and form YO6 and Ba/KO9 polyhedra layers, respectively. DSC analysis shows that the melting point of KBaY(B3O6)2 is 989 °C, and the X-ray powder diffraction pattern of melted KBaY(B3O6)2 crystal confirms that it melts incongruently. The photoluminescence properties of KBaEu(B3O6)2 and KBaTb(B3O6)2 under UV excitation have also been investigated.
Sangen Zhao, Jiyong Yao, Erpan Zhang, Guochun Zhang, Jianxiu Zhang, Peizhen Fu, Yicheng Wu, Solid State Sciences 14 (2012) 305-310

B3233 – Phase diagram of the TbBr3–CsBr binary system. Thermodynamic and transport properties of the Cs3TbBr6 compound

Phase equilibria in the TbBr3–CsBr binary system were established from Differential Scanning Calorimetry (DSC) measurements. This binary system is characterized by three compounds, namely Cs3TbBr6, Cs3Tb2Br9 and CsTb2Br7, and two eutectics located at the TbBr3 mole fraction, x=0.095 (865 K) and x=0.552 (808 K), respectively. Cs3TbBr6 undergoes a solid–solid phase transition at 728 K and melts congruently at 1083 K with the related enthalpies 8.4 and 60.6 kJ mol?1, respectively. Cs3Tb2Br9, decomposes peritectically at 879 K, whereas CsTb2Br9 forms from Cs3Tb2Br9 and TbBr3 at 776 K and melts incongruently at 846 K. It undergoes also a solid–solid phase transition at 805 K, temperature very close to that (808 K) of the Cs3Tb2Br9–CsTb2Br7 eutectic. Separate investigations of the thermodynamic and transport properties were performed on the Cs3TbBr6 compound. These heat capacity and electrical conductivity experimental results suggest an order–disorder mechanism in the alkali metal cation sublattice whereas the TbBr6 octahedra, forming the anionic sublattice, retain their normal lattice positions. Compatibility of the experimental data was tested by the CALPHAD method. The entropy of mixing and Gibbs energies of formation of solid compounds were calculated. The temperature range of Cs3TbBr6 existence was discussed.
Leszek Rycerz, Ida Chojnacka, Jan Kapala, Marcelle Gaune-Escard, CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 37 (2012) 108–115

B3196 – The energetics of nanophase calcite

Calcium carbonate (CaCO3) is an important component of the near-surface environment. Understanding the nature of its precipitation is important for a variety of environmental processes, as well as for the geologic sequestration of anthropogenic carbon dioxide. Calcite is the most thermodynamically stable bulk polymorph, but energy crossovers may exist that could favor the precipitation of vaterite or aragonite with decreasing particle size. The purpose of this study is to determine the surface energy of calcite, which is the first step towards understanding the effect of particle size on thermodynamic stability in the calcium carbonate system. The enthalpies of five well-characterized calcite samples (four nanophase and one bulk) were measured by acid solution isothermal and water adsorption calorimetric techniques. From the calorimetric data, the surface energies of calcite were determined to be 1.48 ± 0.21 and 1.87 ± 0.16 J/m2 for hydrous and anhydrous surfaces. These values are similar to those measured for many oxides but larger than predicted from computational models for idealized calcite surfaces. The surfaces of synthetic CaCO3 particles contain a range of planes and defect structures, which may give rise to the difference between the experimental and modeled values.
Tori Z. Forbes, A.V. Radha, Alexandra Navrotsky, Geochimica et Cosmochimica Acta 75 (2011) 7893–7905

B3189 – Interactions between silica sand and sodium silicate solution during consolidation process

This work is based on the knowledge of the consolidation of silica sand with an alkaline solution in order to determine the mechanisms that occur during the drying of sand and various alkaline solution mixtures. The investigations concern effects of sand distribution size, dilution of sodium silicate solutions and drying temperature of the mixtures on consolidation behaviour. The thermal analysis performed on fresh mixtures show a release of free-water from diluted silicate solution during the consolidation. SEM observations and compressive strength tests results indicate that interactions between sodium silicate binder and silica sand depend on drying temperature. Consequently two consolidation mechanisms are proposed: at low drying temperature (70 °C), sodium silicate acts as a thin layer of glue covering sand grains and bind them to each other, while at high temperature (150 °C), dissolution–precipitation reaction occurred in the mixture consolidating more strongly the granular system. The increase of Si/Na molar ratio in a sodium silicate solution containing silica sand is in accordance with the proposed mechanism.
S. Lucas, M.T. Tognonvi, J-L. Gelet, J. Soro, S. Rossignol, Journal of Non-Crystalline Solids 357 (2011) 1310–1318

B3179 – High-temperature thermal and X-ray diffraction studies, and room-temperature spectroscopic investigation of some inorganic pigments

Inorganic Cr- and Mn-containing pigments of different structural types were investigated by high-temperature and spectroscopic methods. The differential scanning calorimetry in the temperature interval 298–1723 K was applied to measure temperatures of phase transition and melting of the studied compounds. High-temperature X-ray diffraction in the range 298–1173 K was used for the determination of the thermal expansion coefficients for the first time. Factor group analysis was used to predict general vibration modes of pigments and determine the activity of these vibrations in Raman and IR spectra, the Assignment of bands in Raman, IR and diffuse reflectance spectra was undertaken
A.V. Knyazev, M. Maczka, E.N. Bulanov, M. Ptak, S.S. Belopolskaya, Dyes and Pigments 91 (2011) 286-293

B3168 – Large SiO2-substituted GeO2 single-crystals with the ?-quartz structure

Colorless, transparent SiO2-substituted GeO2 single-crystals with the ?-quartz-like structure have been grown by spontaneous nucleation using the slow-cooling method from K2O–3MoO3 flux. The cell parameter values as well as the semi-quantitative chemical analyses confirm the presence of Si-content in the as-grown crystals. Their thermal behavior was studied by means of differential scanning calorimetry and high-temperature X-ray diffraction. The high stability of the ?-quartz-like structure as a function of temperature was confirmed up to 1000 °C. The structural parameter data have been used to estimate the lattice and volume thermal expansion coefficients from room temperature up to 1000 °C.
Pascale Armand, Simon Clément, Denis Balitsky, Adrien Lignie, Philippe Papet, Journal of Crystal Growth 316 (2011) 153–157

B3133 – Phase transitions in hydrothermal K2HPO4 solutions

A 0.1 M potassium phosphate (K2HPO4) solution was reacted in a flow-through cell pressurized to 22 MPa. Reduced light transmission through the cell windows was observed at a setpoint temperature ?400 °C, along with a decrease in effluent conductivity, but with no effect on flow. These observations suggest solution separation at ?360 °C, with accumulation of a salt-concentrated liquid in the cell body and transition of a dilute liquid to a supercritical fluid at temperature >374 °C. High-pressure differential scanning calorimetry experiments confirm an onset temperature of 354 °C with an endothermic transition at 377 °C and 22 MPa. For apparent density, ? = 150–500 kg/m3, the average transition temperature for 0.1 M solutions, 375 ± 5 °C, is slightly elevated relative to that of water at 371 ± 4 °C. Highest deviation for 1.0 M solutions, 365 ± 15 °C, is attributed to increased K2HPO4 hydrolysis and polymerization reactions
Ashaki A. Rouff, Stefan Rabe, Frédéric Vogel, J. of Supercritical Fluids 57 (2011) 207–212

B3120 – Evaporation kinetics of volatile liquids and release kinetics of water from a smectite clay: Comparison between experiments and finite element calculations

Numerical calculations of the evaporation kinetics of bulk volatile liquids and of water from smectite clay granules are compared with experimental results. The weight loss of the volatiles is analyzed by thermogravimetry and differential calorimetry. Under the thermodynamic conditions of the experiments, finite element calculations are in good agreement with the experimental data, and an approximate semi-analytical model is developed in order to explain the dependence of the rate of evaporation on the temperature, the chemical species and the carrier gas flow rate. The initial rate of evaporation of water from the clay granule is close to that for bulk water. Its decrease with time is determined mainly by changes in the gas/condensed phase partition given by the equilibrium desorption isotherm, with little limitations due to internal diffusion effects for the present experimental conditions. Its temperature dependence could also be approximately described by an Arrhenius-type equation derived from the semi-analytical model. Further analysis of the experimental measurements reveals steps in the heat of vaporization of water as a function of water concentration, that could be related to the equilibrium desorption isotherm.
Pascal Clausen, Brigitte Watzke, Eric Hughes, Christopher J.G. Plummer, Jan-Anders E. Månson, International Journal of Engineering Science 49 (2011) 1125–1140

B3116 – Heat capacity and thermodynamic properties of germanium disulfide at temperatures from T = (2 to 1240) K

The heat capacity of polycrystalline germanium disulfide ?-GeS2 has been measured by relaxation calorimetry, adiabatic calorimetry, DSC and heat flux calorimetry from T = (2 to 1240) K. Values of the molar heat capacity, standard molar entropy and standard molar enthalpy are 66.191 J · K?1 · mol?1, 87.935 J · K?1 · mol?1 and 12.642 kJ · mol?1. The temperature of fusion and its enthalpy change are 1116 K and 23 kJ · mol?1, respectively. The thermodynamic functions of ?-GeS2 were calculated over the range (2 to 1240) K
Jirí Málek, Takefumi Mitsuhashi, Naoki Ohashi, Yuki Taniguchi, Hitoshi Kawaji, Tooru Atake, J. Chem. Thermodynamics 43 (2011) 405–409

B3070 – Electrical conductivity of new zinc phosphate glass/metal composites

Zinc phosphate–glass/metal composites have been successfully prepared. Glass with composition of 45 mol% ZnO–55 mol% P2O5 (ZP) has been filled with metallic powders (nickel and cobalt). The glass matrix thermal stability has been assessed by differential thermal analysis technique. The morphology has been examined by scanning electronic microscopy, showing almost homogenous composites. Comparison between the measured and calculated densities as a function of metallic content exhibits a good coherence and allows the estimation of porosity inside the composites. X-ray diffraction analysis has revealed that the ZP-matrix phase is amorphous when the temperature treatment is below the glass transition temperature Tg. However, the principal peaks observed in the case of the composites have been assigned to the metallic crystals of nickel or cobalt fillers. It has been found that the phosphate glass phase is not affected by the growing of the metallic network. The electronic conductivity measurements versus filler volume fraction have been investigated for the first time on phosphate–glass/metal composites. This study has shown the occurrence of a conducting transition at around 30% filler volume fraction. The obtained result has been interpreted on the basis of the statistical percolation theory frame.
A. Maaroufi, O. Oabi, G. Pinto, M. Ouchetto, R. Benavente, J.M. Pereña, Journal of Non-Crystalline Solids 358 (2012) 2764–2770

B3040 – Synthesis, structure, physical properties, and electronic structure of KGaSe2

The ternary gallium selenide KGaSe2 has been synthesized by solid-state reactions and good quality crystal has been obtained. KGaSe2 crystallizes in the monoclinic space group C2/c with cell dimensions of a = 10.878(2) Å, b = 10.872(2) Å, c = 15.380(3) Å, and ? = 100.18(3)°. In the structure, adamantane like [Ga4Se10]8? units are connected by common corners forming two-dimensional [GaSe2]? layers which are separated by K+ cations. KGaSe2 exhibits congruent-melting behavior at around 965 °C. It is transparent in the range of 0.47-20.0 ?m and has a band gap of 2.60(2) eV. From a band structure calculation, KGaSe2 is a direct-gap semiconductor. The band gap is mainly determined by the [GaSe2]? layer.
Kai Feng, Dajiang Mei, Lei Bai, Zheshuai Lin, Jiyong Yao, Yicheng Wu, Solid State Sciences 14 (2012) 1152-1156

B3030 – Heat capacities of hydrous silicate glasses and liquids

Differential scanning calorimetry measurements made at atmospheric pressure from300 K to about 100 K above the glass transition temperature (Tg) are reported for two new series of hydrated aluminosilicate glasses and supercooled liquids forwater contents between 0 and 7.3 mol%. The compositions are synthetic iron-free analogs of tephrite and foidite lava compositions, and are depolymerized (NBO/T=0.8 and 1.5, respectively). In all cases, water exerts a marked depressing effect on Tg, in close agreementwith the results of viscosity experiments on the same samples. For glasses, the partialmolar heat capacity of water previously published for polymerized compositions (Bouhifd et al., 2006) reproduces the present data within the combined uncertainties of the experimental and model values. For the hydrous silicate glasses, the partial molar heat capacity ofwater can be thus considered as independent of composition, and insensitive to structural factors above room temperature. However, for hydrous liquids the existing data suggest two different coefficients for polymerized and depolymerized melts. In depolymerized liquids, the partial molar heat capacity of water (CpH2O) (is about 237±40 J/mol K, which is nearly three times higher than that previously determined for polymerized hydrous liquids CpH2O (?85 J/mol K for three hydrous melts with 0
M.A. Bouhifd, A.G. Whittington, A.C. Withers, P. Richet, Chemical Geology (2012)

B3020 – Silica–paraffin and kaolin–paraffin dispersions: Use of rheological and calorimetric methods to investigate the nature of their dispersed microstructure units

The yield stress and enthalpy of the wetting of silica–paraffin and kaolin–paraffin dispersions were measured as a function of the volumetric concentration ? of the dispersed colloidal powders after having performed a careful analysis of their macro–meso microstructure. The evolution and stability of the corresponding microstructure units is strongly linked to the shape of the ?0 versus ? and ?H versus ? curves. The percolation threshold and values are fairly equal for each dispersion. These values were observed to be 9% and 18% for silica–paraffin and kaolin–paraffin dispersions, respectively. Two different paths of microstructural evolution were identified for the silica–paraffin and the kaolin–paraffin dispersions with respect to particle shape and size. The stability of the silica–paraffin microstructure units was greater than that corresponding to the kaolin–paraffin ones.
Dario T. Beruto, Alberto Lagazzo, Rodolfo Botter, Colloids and Surfaces A: Physicochem. Eng. Aspects 396 (2012) 153– 160

B2984 – Quick method for determination of equilibrium temperature of calcium carbonate dissociation

A quick method for determination of equilibrium temperature of high temperature reactions, which is inexpensive and suitable for small industrial laboratories, is reported. Reaction of high temperature dissociation of calcium carbonate is used as example for quick method application. The method is based on calorimetric measurement, Hess Law, and thermodynamic calculations. The calibrated calorimeter is used to determine enthalpy change for reactions CaCO3(s) ? HCl(l), Ca(s) ? 2HCl(l), and CaO(s) ? 2HCl(l). By application of Hess’s energy cycle, enthalpies of formation of calcium carbonate and calcium oxide were determined. Acquired results were used to calculate enthalpy change for carbonate dissociation reaction. Calculated enthalpy change value was used for free energy change in dependence of temperature and also for equilibrium constant in dependence of temperature calculation using equations derived from basic thermodynamic equations. Using this method, equilibrium temperature for calcium carbonate dissociation reaction is found to be equal to 1154.14 K, which confirms accuracy of the method.
Barbara Odak, Tihomir Kosor, J Therm Anal Calorim (2012) 110, 991–996

B2976 – Molar heat capacity and thermodynamic properties of Lu(C5H9NO4)(C3H4N2)6(ClO4)3 5HClO4 10H2O

A complex of Lutetium perchloric acid coordinated with L-glutaminic acid (C5H9NO4) and imidazole (C3H4N2), Lu(C5H9NO4)(C3H4N2)6(ClO4)3 5HClO4 10H2O was synthesized and characterized. Thermodynamic properties of the complex were studiedwith an adiabatic calorimeter (AC) from 80 to 390 K and differential scanning calorimetry (DSC) from 100 to 300 K. Two thermal abnormalities were discovered at 220.34 and 248.47 K, which were deduced to be phase transitions. One was interpreted as a freezing-in phenomenon of the reorientational motion of ClO4- ions and the other was attributed to the orientational order/disorder process of ClO4- ions. The low-temperature molar heat capacities were measured by AC and the thermodynamic functions [HT - H298.15] and [ST - S298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior of the complex was studied by thermogravimetric analysis and DSC.
X.-C. Lv, Z.-C. Tan, X.-H. Gao, P. Chen, J Therm Anal Calorim, 2012

B2971 – Effect of storage time on the pressure oxidation enthalpy of pyrite

The information on heat of oxidation–reduction reactions is important for the heat balance and optimization of the autoclave design in the hydrometallurgical industry in ore processing. Pyrite (FeS2) is a gangue mineral that presents with nickel-containing pentlandite, and copper-containing chalcopyrite minerals. The presence of pyrite impacts to the overall heat of leaching process. This study has been performed on a differential scanning calorimeter (DSC80, Setaram) with a commercial mixing cell to study the thermal behaviour of pure pyrite FeS2 (Valdenegrillos, Spain) mineral particles during oxidative pressure leaching at 150 °C and partial oxygen pressure of 3.4 MPa.A calorimetric method for determining the enthalpy of leaching of sulphide minerals at high temperatures and oxygen pressures has been used to evaluate the enthalpies of oxidation of freshly ground pyrite and pyrite stored for a year in contact with air (stored pyrite) under conditions relevant to pressure oxidation operations. Ground pyrite stored over time has long since been known to result in greater heat evolution during oxidative leaching. A likely mechanism for this phenomenon was uncovered: formation of ferrous sulphate and sulphuric acid during storage in contact with air influencing greater heat evolution at the outset of the reaction. Two mass loss steps on TG curve of stored pyrite, attributed to the elimination of atmospheric moisture andH2Omolecule from FeSO4 H2O, is absent on TGcurve of freshly ground pyrite.
I. V. Bylina, S. C. Mojumdar, V. G. Papangela, J Therm Anal Calorim (2012) 108, 829–835

B2963 – Instrumentation and calibration of the Calvet calorimeter. Enthalpy of solution of PrBr3 at standard conditions

The original Calvet calorimeter, made from aluminum block, were instrumented. The cells for the solution calorimetry measurement have been projected and constructed. The calibration of calorimeter was performed by measurement of the dependence of reference material on temperature and the influence of mechanical events on thermograms. The enthalpies of solution in water and 0.01 M HCl were investigated for chlorides and bromides of alkali metals (Na Cs), PrBr3 and Rb3PrBr6. The enthalpies of solution of alkali halides have been compared to the reference data obtained for infinite solution. The decomposition of Rb3PrBr6 at temperatures lower than 399 K has been stated. The enthalpy of solution PrBr3 at 298.15 K has been determined.
Beata Salamon, Jan Kapa?a, Marcelle Gaune-Escard, J Therm Anal Calorim (2012) 108, 421–424

B2962 – Heat capacity and thermodynamic properties of tellurites Yb2(TeO3)3, Dy2(TeO3)3 and Er2(TeO3)3

The experimental results obtained for the specific molar heat capacity of the tellurites Yb2(TeO3)3, Dy2(TeO3)3 and Er2(TeO3)3 are processed by the least squares method. The temperature dependence of the specific molar heat capacity derived is used to determine the thermodynamic properties: entropy, enthalpy and Gibbs function of the tellurites Yb2(TeO3)3, Dy2(TeO3)3 and Er2(TeO3)3.
Lubka Atanasov, Ginka Baikusheva-Dimitrova, J Therm Anal Calorim (2012) 107, 809–812

B2942 – Thermodynamic properties and dissociation of SrLaAlO4

The enthalpy of solution of SrLaA1O4 in the 2PbO · B2O3 melt at 973 K was measured using a hightemperature Cal vet microcalorimeter. The enthalpies of formation of SrLaA1O4 from the constituent oxides and constituent elements at 298.15 K were determined to be -97.7 ±5.5 and -2422.9 ±5.6 kJ/mol, respectively. The partial pressures of the vapor species over molten SrLaA1O4 at Tm = 1923 K were evaluated. The equilibrium oxygen pressure at 1923 K was found to be 5.05 × 10-3 Pa
A. V. Novoselov, L. P. Ogorodova, G. V. Zimina, A. Pajaczkowska, Inorganic Materials, February 2000, Volume 36, Issue 2, pp 180-182

B2941 – The thermodynamic characteristics of natural iron-lithium micas

A thermochemical study of natural lithium micas, iron-containing polylithionite and lepidolite, was performed on a high-temperature heat-flux Calvet microcalorimeter (Setaram, France). Melt solution calorimetry was used to measure the enthalpies of mineral formation from the elements ?f H°el (298.15 K), ?5989.3 ± 9.6 and ?5981.3 ± 6.3 kJ/mol, respectively. The drop method was used to determine the enthalpy increments heating of the micas over the temperature interval 444–973 K. The equations for the temperature dependences of the heat capacities and enthalpies of Fe-polylithionite and Fe-lepidolite were obtained. The S° (298.15 K) and ?f G°el (298.15 K) values were estimated. The thermodynamic functions of the micas were calculated over the temperature range 298.15–1000 K.
L. P. Ogorodova, I. A. Kiseleva, L. V. Mel’chakova, T. N. Shuriga

B2940 – Enthalpy of Formation for Natural Paulingite Zeolite

Natural paulingite zeolite of the composition (K4.48Na0.56Ca2.95Ba0.87Mg0.06)[Al11.04Fe 0.04 3+ Si30.49O84] · 35.25H2O (Vinariská Hora, Czechia) was studied calorimetrically on a high-temperature Tian-Calvet microcalorimeter. Enthalpies of formation from oxides (?1969 ± 128 kJ/mol) and elements (?52393 ± 132 kJ/mol) were determined for this mineral by melt dissolution calorimetry. The obtained experimental results and the literature data were used to calculate the Gibbs free energy of formation from elements
L. P. Ogorodova, L. V. Mel’chakova, I. A. Kiseleva, Russian Journal of Physical Chemistry A, 2008, Vol. 82, No. 1, pp. 138–139

B2939 – Enthalpy of Formation of Talc Mg3[Si4O10](OH)2 According to Dissolution Calorimetry

A thermochemical study of natural talc was performed by high-temperature melt dissolution calorimetry on a Tian–Calvet calorimeter. Based on the total values of the increment in enthalpy upon heating the sample from room temperature to 973 K, and of the dissolution enthalpy at 973 K measured in this work for talc and gibbsite (along with those determined for tremolite, brucite, and their corresponding oxides), the enthalpy of formation was calculated for talc composed of elements, Mg3[Si4O10](OH)2, at 298.15 K.
L. P. Ogorodova, I. A. Kiseleva, Russian Journal of Physical Chemistry A, 2011, Vol. 85, No. 9, pp. 1489–1491

B2938 – The Thermodynamic Properties of Natural Margarite

Thermal, IR spectroscopic, and thermochemical studies of natural brittle mica, margarite Ca1.00Na0.10Mg0.02Al3.89 Si2.03Ti0.01O10(OH)1.74F0.26, were performed. The enthalpy of formation of natural margarite from the elements (–6269 ± 12 kJ/mol) was determined by melt solution calorimetry on a high-temperature heat-conducting Calvet microcalorimeter (Setaram, France). Enthalpy growth over the temperature range 298.15–973 K was determined by the drop method
L. P. Ogorodova, M. F. Vigasina, L. V. Mel’chakova, Russian Journal of Physical Chemistry A, 2009, Vol. 83, No. 13, pp. 2204–2207

B2937 – The Enthalpies of Formation of Natural and Synthetic Nanotubular Chrysotile

The thermochemical properties of natural chrysotile–asbestos and synthetic nanotubular chrysotile were studied on a high-temperature heat conducting Tian–Calvet microcalorimeter. The enthalpies of their formation from the elements at 298.15 K were determined by melt solution calorimetry at 973 K. The ?f(298.15K) value obtained for natural chrysotile–asbestos was close to that reported in the literature. The enthalpy of formation of synthetic nanotubular chrysotile was determined for the first time. The relation between the microstructural features of nanotubes and calorimetric data is discussed.
L. P. Ogorodova, I. A. Kiseleva, E. N. Korytkova, V. V. Gusarov, Russian Journal of Physical Chemistry, 2006, Vol. 80, No. 7, pp. 1021–1024

B2933 – Calorimetric study on high-pressure transitions in KAlSi3O8

KAlSi3O8 sanidine dissociates into a mixture of K2Si4O9 wadeite, Al2SiO5 kyanite and SiO2 coesite, which further recombine into KAlSi3O8 hollandite with increasing pressure. Enthalpies of KAlSi3O8 sanidine and hollandite, K2Si4O9 wadeite and Al2SiO5 kyanite were measured by high-temperature solution calorimetry. Using the data, enthalpies of transitions at 298 K were obtained as 65.1 ± 7.4 kJ mol)1 for sanidine fi wadeite + kyanite + coesite and 99.3 ± 3.6 kJ mol)1 for wadeite + kyanite + coesite fi hollandite. The isobaric heat capacity of KAlSi3O8 hollandite was measured at 160–700 K by differential scanning calorimetry, and was also calculated using the Kieffer model. Combination of both the results yielded a heat-capacity equation of KAlSi3O8 hollandite above 298 K as Cp = 3.896x102–1.823x103T(-0.5)–1.293x107T -2 +1.631x109T-3 (Cp in J mol)1 K)1, T in K). The equilibrium transition boundaries were calculated using these new data on the transition enthalpies and heat capacity. The calculated transition boundaries are in general agreement with the phase relations experimentally determined previously. The calculated boundary for wadeite+kyanite+coesite fi hollandite intersects with the coesite–stishovite transition boundary, resulting in a stability field of the assemblage of wadeite + kyanite + stishovite below about 1273 K at about 8 GPa. Some phase–equilibrium experiments in the present study confirmed that sanidine transforms directly to wadeite + kyanite + coesite at 1373 Kat about 6.3 GPa, without an intervening stability field of KAlSiO4 kalsilite+coesite which was previously suggested. The transition boundaries in KAlSi3O8 determined in this study put some constraints on the stability range of KAlSi3O8 hollandite in the mantle and that of sanidine inclusions in kimberlitic diamonds.
M. Akaogi, N. Kamii, A. Kishi, H. Kojitani, Phys Chem Minerals (2004) 31: 85–91

B2875 – Thermodynamic Properties and Decomposition of Lithium Hexafluoroarsenate, LiAsF6

The heat capacity of lithium hexafluoroarsenate is determined in the temperature range 50–750 K by adiabatic and differential scanning calorimetry techniques. The thermodynamic properties of LiAsF6 under standard conditions are evaluated: C p 0(298.15 K) = 162.5 ± 0.3 J/(K mol), S 0(298.15 K) = 173.4 ± 0.4 J/(K mol), ?0(298.15 K) = 81.69 ± 0.20 J/(K mol), and H 0(298.15 K) – H 0(0) = 27340 ± 60 J/mol. The C p(T) curve is found to contain a lambda-type anomaly with a peak at 535.0 ± 0.5 K, which is due to the structural transformation from the low-temperature, rhombohedral phase to the high-temperature, cubic phase. The enthalpy and entropy of this transformation are 5.29 ± 0.27 kJ/mol and 10.30 ± 0.53 J/(K mol), respectively. The thermal decomposition of LiAsF6 is studied. It is found that LiAsF6 decomposes in the range 715–820 K. The heat of decomposition, determined in the range 765–820 K using a sealed crucible and equal to the internal energy change ?U r(T), is 31.64 ± 0.08 kJ/mol.
K. S. Gavrichev, G. A. Sharpataya, V. E. Gorbunov, L. N. Golushina, V. N. Plakhotnik, I. V. Goncharova, V. M. Gurevich, Inorganic Materials February 2003, Volume 39, Issue 2, pp 175-182

B2869 – SO2 oxidation catalyst model systems characterized by thermal methods

The molten salts M2S2O7 and MHSO4, the binary molten salt Systems M2S2O7-MHSO4 and the molten salt-gas systems M2S2O7 V2O5 and M2S2O7-M2SO4 V2O5 (M = Na, K, Rb, Cs) in O-2, SO2 and At atmospheres have been investigated by thermal methods like calorimetry, Differential Enthalpic Analysis (DEA) and Differential Scanning Calorimetry (DSC). Fundamental thermodynamic data like temperatures and molar heats of solid-solid transition and fusion, phase diagrams, heat capacities of solids and liquids, heat of mixing and heats of complex formation have been obtained and the results are discussed in relation to the mechanism Of SO2 oxidation by V2O5 based industrial catalysts.
G. Hatem, Kim Michael Eriksen, M. Gaune-Escard, Rasmus Fehrmann, Topics in Catalysis, Vol. 19, N° 3-4, May 2002

B2851 – Mechanochemical synthesis and characterization of nanocrystalline BiSe, Bi2Se3 semiconductors

Mechanochemical synthesis of bismuth selenides (BiSe, Bi2Se3) was performed by high-energy milling of bismuth and selenium powders in a planetary ball mill. The particle size distribution and the specific surface area of Bi/Se and 2Bi/3Se powder mixtures were analysed at increasing milling time. The products were characterized by X-ray diffraction, differential scanning calorimetry and transmission electron microscopy. The presence of bismuth selenide phases was observed after only 1 min of milling and full conversion into hexagonal BiSe phase (nevskite) and rhombohedral Bi2Se3 phase (paraguanajuatite) was reached after 10 min of milling. The nanocrystalline nature of both mechanochemically synthesised bismuth selenides was confirmed and their optical band gap energies were obtained on the basis of the recorded absorption spectra in UV–Vis spectral region.
Marcela Achimovicova, Francisco Jose Gotor, Concepcion Real, Nina Daneu, J Mater Sci, Mater Electron (2012) 23,1844–1850

B2848 – Phases of the K2TaF7–TaF5 binary system

The phase equilibria in the K2TaF7–TaF5 binary system were determined up to x TaF5 = 0.5 by means of differential scanning calorimetry. XRD diffraction analysis of solidified mixtures was performed. Besides the K2TaF7 and KTaF6 phases, the presence of a third phase was observed, as well. It was suggested that the last phase melts incongruently.
Blanka Kubikova, Miroslav Boca, Marcelle Gaune-Escard, Monatshefte für Chemie, June 2008, Volume 139, Issue 6, pp 587-590

B2843 – Phase Diagram and Thermodynamic and Transport Properties of the DyBr3-LiBr Binary System

The phase diagram of the DyBr3-LiBr binary system was derived from DSC measurements. It exhibits two eutectics and has two stoichiometric compounds. The first compound, Li3DyBr6, melts congruently at 803 K. The second one, Li6DyBr9 decomposes in the solid state at 656 K. The composition of the two eutectic mixtures, x(DyBr3) = 0.156 and 0.321, respectively, was determined by the Tamman method. The respective eutectic temperatures are 787 and 791 K. The electrical conductivity of Li3DyBr6 compound was measured in the liquid and solid phase. It was found to be a solid electrolyte with a high electrical conductivity at around room temperature. Some additional electrical conductivity measurements performed on solid samples confirmed the existence of Li6DyBr9.
B. Kubikova, L. Rycerz, I. Chojnacka, Marcelle Gaune-Escard, Journal of Phase Equilibria and Diffusion Vol. 30 No. 5 2009

B2829 – Co3O4–Co2ZnO4 spinels: The case for a solid solution

In prior first-principles theoretical work we predicted a complete solid solution in the Co3O4–Co2ZnO4 system, with a negligibly small mixing enthalpy. In this work we tested this prediction on bulk, large-grained specimens across the Co3O4–Co2ZnO4 join, combining oxide melt solution calorimetry, differential scanning calorimetry, precise lattice parameter measurements, anomalous X-ray and neutron diffraction, and in situ electrical measurements. The calorimetric results confirm the presence of a solid solution at high temperatures, but with a large enthalpy of mixing that exceeds the predicted value. Because Co3O4 and Co2ZnO4 have essentially identical lattice parameters, this energetic destabilization must arise from factors other than the strain energy resulting from size mismatch. Changes in Co3þ spin states vs. temperature and zinc content are proposed to account for the positive excess enthalpy, and may also provide additional entropy to stabilize the solid solution at high temperature.
Nicola H. Perry, Thomas O. Mason, Chengcheng Ma, Alexandra Navrotsky, Yezhou Shi, Joanna S. Bettinger, Michael F. Toney, Tula R. Paudel, Stephan Lany, Alex Zunger, Journal of Solid State Chemistry 190 (2012) 143–149

B2817 – Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides

Heat capacity and enthalpy increments of ternary bismuth tantalumoxides Bi4Ta2O11, Bi7Ta3O18 and Bi3TaO7 were measured by the relaxation time method (2–280 K), DSC (265–353 K) and drop calorimetry (622–1322 K).
J. Leitner, V. Jakes, Z. Sofer, D. Sedmidubsky, K. Ruzicka, P. Svoboda, Journal of Solid State Chemistry 184 (2011) 241–245

B2752 – Calorimetric Studies of Natural Talc: Enthalpy of Dehydroxylation

The standard dehydroxylation enthalpy of natural talc Mg3[Si4O10](OH)2 (87.8 ± 9.0 kJ/mol at 298.15 K) and the enthalpy of formation of dehydrated talc from the elements (?f H (298.15 K) = –5527.0 ± 9.0 kJ/mol) were determined for the first time using Hess’s law, based on the total values of the enthalpy increments in heating a sample from room temperature to 973 K and the enthalpies of dissolution at 973 K for dehydrated talc measured in this work and those previously determined for talc and corresponding oxides.
L. P. Ogorodova, I. A. Kiseleva, Russian Journal of Physical Chemistry A, 2011, Vol. 85, No. 10, pp. 1857–1859

B2707 – The detection of carbonate in the martian soil at the Phoenix Landing site: A laboratory investigation and comparison with the Thermal and Evolved Gas Analyzer (TEGA) data

Data collected by Phoenix Lander’s Thermal and Evolved Gas Analyzer (Phoenix-TEGA) indicate carbonate thermal decomposition at both low and high temperatures. The high-temperature thermal decomposition is consistent with calcite, dolomite, or ankerite, (3–6 wt.%) or any combination of these phase or, presumably, solid solutions of these phases having intermediate composition. The low-temperature thermal decomposition is consistent with the presence of magnesite or siderite, their solid solutions, or any combination of magnesite and siderite, and possibly other carbon-bearing phases (e.g., organics). The carbonate concentration for the low temperature release, assuming magnesite–siderite, is 1.0 wt.%. This revised interpretation of the Phoenix-TEGA data resulted from new laboratory measurements of carbonate decomposition at a Phoenix-like 12 mbar atmospheric pressure. Phoenix carbonate was inherited in ejecta from the Vastitas Borealis and Scandia regions, inherited from material deposited by aeolian processes, and/or formed in situ at the Phoenix Landing site (pedogenesis). Inherited carbonate implies multiple formation pathways may be represented by carbonates at the Phoenix Landing site. Soil carbonates and associated moderate alkalinity indicate that the soil pH is favorable for microbial activity at the Phoenix Landing site and presumably throughout the martian northern plains
B. Sutter, W.V. Boynton, D.W. Ming, P.B. Niles, R.V. Morris, D.C. Golden, H.V. Lauer, C. Fellows, D.K. Hamara, S.A. Mertzman, Icarus 218 (2012) 290–296

B2706 – Perchlorate induced low temperature carbonate decomposition in the Mars Phoenix Thermal and Evolved Gas Analyzer (TEGA)

Simulated Thermal Evolved Gas Analyzer (TEGA) analyses have shown that a CO2 release detected between 400 C and 680 C by the Phoenix Lander’s TEGA instrument may have been caused by a reaction between calcium carbonate and hydrated magnesium perchlorate. In our experiments a CO2 release beginning at 385 12 C was attributed to calcite reacting with water vapor and HCl gas from the dehydration and thermal decomposition of Mgperchlorate. The release of CO2 is consistent with the TEGA detection of CO2 released between 400 and 680 C, with the amount of CO2 increasing linearly with added perchlorate. X-ray diffraction (XRD) experiments confirmed CaCl2 formation from the reaction between calcite and HCl. These results have important implications for the Mars Science Laboratory (MSL) Curiosity rover. Heating soils may cause inorganic release of CO2; therefore, detection of organic fragments, not CO2 alone, should be used as definitive evidence for organics in Martian soils.
K.M. Cannon, B. Sutter, D. W. Ming, W. V. Boynton, R. Quinn, Geophysical Research Letters, Vol. 39, L13203, 2012

B2696 – Thermochemistry of iron manganese oxide spinels

Oxide melt solution calorimetry has been performed on iron manganese oxide spinels prepared at high temperature. The enthalpy of formation of (MnxFe1-x)3O4 at 298K from the oxides, tetragonal Mn3O4 (hausmannite) and cubic Fe3O4 (magnetite), is negative from x = 0 to x = 0.67 and becomes slightly positive for 0.670.6) spinels of intermediate compositions. The enthalpies of formation are discussed in terms of three factors: oxidation–reduction relative to the end-members, cation distribution, and tetragonality. A combination of measured enthalpies and Gibbs free energies of formation in the literature provides entropies of mixing. DSmix; consistent with a cation distribution in which all trivalent manganese is octahedral and all other ions are randomly distributed for x>0.5; but the entropy of mixing appears to be smaller than these predicted values for x<0.4
Sophie Guillemet-Fritsch, Alexandra Navrotsky, Philippe Tailhades, Hervé Coradina, Miaojun Wang, Journal of Solid State Chemistry 178 (2005) 106–113

B2685 – Review of the thermodynamic and transport properties of EuBr2–RbBr binary system

Differential Scanning Calorimetry was used to study phase equilibrium in EuBr2–RbBr binary system. It was established that this system includes two eutectics and three stoichiometric compounds. First of them, Rb2EuBr4, decomposes peritectically at 778 K. Second one, RbEuBr3, undergoes the solid–solid phase transition at 732 K and melts incongruently at 852 K. Third compound, RbEu2Br5, melts congruently at 888 K. The composition and temperature values of eutectics were determined as x(EuBr2) = 0.316; Teut = 776 K and x(EuBr2) = 0.797; Teut = 859 K. Mixing enthalpy was measured by direct calorimetry on the whole composition range. The minimum of the mixing enthalpy occurs around the composition x(EuBr2) & 0.4. The electrical conductivity of liquid mixtures was also investigated over the whole composition range and measured down to temperatures below solidification. The specific conductance (liquid phase) plotted against the mole fraction of EuBr2 shows a broad minimum at x(EuBr2) * 0.6. The activation energy for conductivity changes with temperature. Results obtained are discussed in terms of possible complex formation.
Leszek Rycerz, Ewa Ingier-Stocka, Slobodan Gadzuric, Marcelle Gaune-Escard, J Therm Anal Calorim (2010) 101,455–461

B2676 – Thermodynamics of natural tourmalines—Dravite and schorl

The experimental data on the heat capacities and enthalpies of formation from the elements of two natural tourmalines: dravite (Na0.53Ca0.31K0.03)(Mg2.72Al6.22Li0.02Ti0.08Fe0.12 2+)Si5.92B2.92 (OH)2.85F0.27O27.59 and schorl (Na0.82Ca0.13K0.03)(Fe2.232+Fe0.223+Al5.90Mg0.28Mn0.09Li0.02Ti0.11)Si6.04B3.11(OH)3.00F0.02O27.80 have been obtained. The heat capacities were measured by DSC method from T = 270 K to 700 K. High temperature enthalpy increments were determined on the Tian–Calvet microcalorimeter at interval of 712–973 K using the “drop” method. The standard molar enthalpies of formation from the elements were determined by high-temperature solution calorimetry in molten lead borate at T = 973 K on the Tian–Calvet microcalorimeter.
L.P. Ogorodova, L.V. Melchakova, I.A. Kiseleva, I.S. Peretyazhko, Thermochimica Acta 539 (2012) 1– 6

B2654 – Thermodynamic properties of pentalead tris(vanadate) chloride

In the present work the temperature dependences of pentalead tris(vanadate) chloride heat capacity have been measured for the first time in the range from 7 to 350 K. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity Cp ° (T), enthalpy H°(T) ? H°(0), entropy S°(T) ? S°(0) and Gibbs function G°(T) ? H°(0), for the range from T ? 0 to 350 K. The differential scanning calorimetry in temperature interval 298–1473 K was applied to measure temperatures of phase transition and melting of compound under study. The high-temperature X-ray diffraction in range 298–1073 K was used for the determining thermal expansion coefficients.
A.V. Knyazev, E.N. Bulanov, N.N. Smirnova, N.Yu. Kuznetsova, I.A. Letyanina, E.D. Pryamova, Thermochimica Acta 515 (2011) 79–83

B2651 – Crystal structure and thermodynamic properties of potassium antimony tungsten oxide

In the present work potassium antimony tungsten oxide with pyrochlore structure is refined by the Rietveld method (space group Fd3m, Z = 8). The temperature dependences of heat capacity have been measured for the first time in the range from 7 to 370 K for this compound. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity , enthalpy H°(T) ? H°(0), entropy S°(T) ? S°(0) and Gibbs function G°(T) ? H°(0), for the range from T ? 0 to 370 K. The differential scanning calorimetry was applied to measure the incongruent melting temperature of compound under study. The high-temperature X-ray diffraction was used for the determining thermal expansion coefficients.
Aleksandr V. Knyazev, Ivan G. Tananaev, Nataliya Yu. Kuznetsova, Nataliya N. Smirnova, Irene A. Letyanina, Igor V. Ladenkov, Thermochimica Acta 499 (2010) 155–159

B2633 – Shape-dependent surface energetics of nanocrystalline TiO2

We report the direct determination of surface enthalpies for nanophase TiO2 anatase with different morphologies derived from drop solution calorimetry in a molten sodium molybdate (3Na2O?4MoO3) solvent at 702 °C. The energetics of surface hydration has been measured using a Calvet microcalorimeter coupled with a gas dosing system. The surface enthalpies of hydrated surfaces for anatase TiO2 nanoparticles, nanowires and sea-urchin-like assemblies are 0.51 ± 0.05, 1.07 ± 0.28, and 1.29 ± 0.16 J m?2, respectively, whereas those of anhydrous surfaces are 0.74 ± 0.04, 1.24 ± 0.28, and 1.41 ± 0.16 J m?2, respectively. The trend in TiO2, which shows higher surface enthalpies for more complex nanostructures, is consistent with that reported in ZnO. The shape-dependent surface enthalpy at the nanoscale level is discussed in terms of exposed surface structures. The enthalpies of hydration appear to be similar for all morphologies
Tae-Jin Park , Andrey A. Levchenko , Hongjun Zhou , Stanislaus S. Wong, Alexandra Navrotsky, J. Mater. Chem., 2010, 20, 8639-8645

B2631 – Refined heat capacity of LaPO4 in the temperature range 0–1600 K

The critical analysis of literature heat capacity data in the temperature range 0–1600 K was carried out. It was shown that joining of Cp(T) curves obtained by the different methods was performed improperly. Experimental heat capacity of LaPO4 was measured in the region 16–324 K by the adiabatic calorimetry. The obtained data allows to consist the results of different works and to fit the lanthanum orthophosphate heat capacity in the wide temperature range. Standard thermodynamic properties were calculated on the basis of the refined heat capacity data: = 102.5 ± 0.2 J K?1 mol?1, S0(298.15 K) = 108.7 ± 0.2 J K?1 mol?1, H0(298.15 K) ? H0(0 K) = 17.44 ± 0.03 kJ mol?1, ?0(298.15 K) = 50.21 ± 0.20 J K?1 mol?1.
K.S. Gavrichev, M.A. Ryumin, A.V. Tyurin, V.M. Gurevich, L.N. Komissarova, Thermochimica Acta, 474 (2008) 47–51

B2621 – Calorimetric Investigation of PrBr3-MBr Liquid Mixtures (M = Na, K, Rb, Cs)

The molar enthalpies of mixing (?mixHm) in liquid alkali bromide-praseodymium(III) bromide mixtures have been measured with a Calvet-type high temperature microcalorimeter over the entire composition range at 1070 K. All of the melts are characterized by negative enthalpies of mixing with a minimum value shifted toward the alkali bromide-rich compositions that are located in the vicinity of x(PrBr3)?0.4. The magnitude of the mixing enthalpy depends on the ionic radius of the alkali metal, radius of the common halide ion, and the ionic radius of the lanthanide(III) cation.
Leszek Rycerz, Marcelle Gaune-Escard, J. Chem. Eng. Data, 2011, 56, 3273–3276

B2620 – Calorimetric Investigation of the CeBr3-MBr Liquid Mixtures (M = Na, K, Rb, Cs)

The molar enthalpies of mixing (?mixHm) in the liquid cerium(III)?alkali metal bromide mixtures were measured with a Calvet- type high temperature microcalorimeter over the entire composition range at 1073 K. Mixing the two liquid components was achieved by using the “break-off ampule technique”. All the melts are characterized by negative enthalpies of mixing with a minimum value of approximately ?5.3 kJ·mol?1, ?12.7 kJ·mol?1, ?16.1 kJ·mol?1, and ?18.4 kJ·mol?1, for M = Na, K, Rb, and Cs, respectively. For all the systems, the minimum of the enthalpy of mixing is shifted toward the alkali bromide-rich compositions and located in the vicinity of x(CeBr3) 0.4. The composition dependence of the interaction parameter ?, with a broad minimum at x(CeBr3) 0.2 for the systems with KBr, RbBr, and CsBr is indicative of LnBr63? complexes formation in the melts.
Leszek Rycerz, Marcelle Gaune-Escard, J. Chem. Eng. Data, 2009, 54, 2622–2625

B2607 – Heat capacity, enthalpy and entropy of strontium niobate Sr2Nb2O7 and calcium niobate Ca2Nb2O7

The heat capacity and the enthalpy increments of strontium niobate Sr2Nb2O7 and calcium niobate Ca2Nb2O7 were measured by the relaxation time method (2–300 K), DSC (260–360 K) and drop calorimetry (720–1370 K). Temperature dependencies of the molar heat capacity in the form Cpm = 248.0 + 0.04350T ? 3.948 × 106/T2 J K?1 mol?1 for Sr2Nb2O7 and Cpm = 257.2 + 0.03621T ? 4.434 × 106/T2 J K?1 mol?1 for Ca2Nb2O7 were derived by the least-square method from the experimental data. The molar entropies at 298.15 K, Sm°(298.15 K) = 238.5 ± 1.3 J K?1 mol?1 for Sr2Nb2O7 and Sm°(298.15 K) = 212.4 ± 1.2 J K?1 mol?1 for Ca2Nb2O7, were evaluated from the low-temperature heat capacity measurements.
J. Leitner, M. Hampl, K. R?ži?ka, M. Straka, D. Sedmidubský, P. Svoboda, Thermochimica Acta, 475 (2008) 33–38

B2606 – Calorimetric investigation of the La2Zr2O7, Nd2Zr2O7, Sm2Zr2O7 and LaYO3 compounds and CALPHAD assessment of the La2O3–Y2O3 system

Temperature dependence of heat capacity of the La2Zr2O7, Nd2Zr2O7, Sm2Zr2O7 and LaYO3 is measured in the temperature range of 298.15–1373 K by differential scanning calorimetry (DSC). The enthalpy of formation from oxides for LaYO3 was measured by high-temperature lead borate solution calorimetry using transposed temperature drop method. Transformations in the LaYO3 were experimentally studied using differential thermal analysis (DTA) up to 2173 K. The obtained results for heat capacity and enthalpy of formation of the LaYO3 and temperatures of transformations were used to re-optimize thermodynamic parameters of the La2O3–Y2O3 system.
O. Fabrichnaya, M.J. Kriegel, J. Seidel, G. Savinykh, L.P. Ogorodova, I.A. Kiseleva, H.J. Seifert, Thermochimica Acta 526 (2011) 50–57

B2592 – Thermochemistry and kinetics of silica dissolution in NaOH aqueous solution

Dissolution of increasing amounts of silica (?-cristobalite) in the same volume of a 4% weight of sodium hydroxide solution was followed by microcalorimetry in a closed cell at temperature up to 130 °C. The process led to the formation of a dissolved entity whose formula depends on the Na2O/SiO2 ratio. At the beginning dissolution gave [3Na2O, 4SiO2] entity and when increasing dissolved silica amounts, the latter transforms into [Na2O, 2SiO2]. Kinetic study showed that dissolution starts by a very rapid step with about 10% of the whole heat energy released and continued with a very slow process. Kinetic analysis showed that the latter agrees with two successive silica first-order reactions scheme. The resulting activation energy values are of the same magnitude order of that deduced from the isoconversional model.
Meriem Fertani-Gmati, Mohamed Jemal, Thermochimica Acta 513 (2011) 43-48

B2591 – Kinetics and thermodynamics of the attack of a phosphate ore by acid solutions at different temperatures

A calorimetric study of the kinetics and thermodynamics of the attack of a phosphate ore from Gafsa region (Tunisia) by phosphoric acid and by a mixture of phosphoric acid and sulfuric acids is undertaken at different temperatures. Two samples of the same ore having different grain size have been used. At 25 °C, the dissolution enthalpy in phosphoric acid solution equals ?233.6 ± 2.2 J/g for both of the samples. Attack by the mixture of acids is strongly dependent on the solid granulometry. Interpretation of the calorimetric results by Avrami model shows the existence of three domains attributed to phosphate ore dissolution/H2PO4? neutralisation, hemihydrate (HH) precipitation and hemihydrate/dihydrate (DH) transformation. The attack by the acid mixture was performed at higher temperatures and showed in addition the transitional formation of the anhydrous sulfate (AH) at T ? 55 °C, which transforms into dihydrate after the HH/DH transformation.
K. Antar, M. Jemal, Thermochimica Acta 474 (2008) 32-35

B2568 – Nanoceria Energetics of Surfaces, Interfaces and Water adsorption

The surface and interface enthalpies of CeO2 were studied by high temperature oxide melt solution calorimetry combined with water adsorption calorimetry.
Shmuel Hayun, Tatiana Y. Shvarevaa, Alexandra Navrotsky, J.Am. Ceram. Soc. 94 (2011) 3992-3999

B2564 – Thermophysical properties measurement by drop calorimetry and flash method

The methods for precise determination of thermophysical properties are investigated aiming the determination of thermal conductivity through the equation: l = a.Cp.r (thermal diffusivity, heat capacity and density, respectively). The method for heat capacity determination is based on drop calorimetry (Setaram MHTC 1500oC) where a quasi-Calvet type sensor surrounds a crucible and measures the heat flow due to sample drop from ambient up to the cell temperature. Sapphire references were dropped alternatively allowing the determination of the calorimetric constant required for sample drops calculation. The measured enthalpies were fitted as a function of temperature while its derivative gives the Cp = f(T) curve. The flash method for thermal diffusivity determination has been developed by the author*, who has built a diffusivimeter prototype. One special software was written including the transient heat transfer thermal quadrupole theory besides traditional methods, like Parker and temporal moments. The thermal quadrupole is an hybrid analyticalnumerical method where the heat equation is solved in Laplace domain, undergoing later a numerical inversion to real space. The practical result is seen on precision of diffusivity determination, typically into the 1-3% range. The results obtained by drop and flash methods were used to calculate the sample thermal conductivity as a function of temperature.
Thomaz Augusto Guisard Restivo, Bernard Legendre, Thermochimica Acta

B2562 – A DSC study of the NaNO3–KNO3 system using an innovative encapsulation technique

An innovative encapsulation technique designed for the DSC high temperature measurements of the volatile samples is presented in this study. Stainless steel crucibles with a screwed bolt were developed for this purpose. The technique was demonstrated on the phase diagram measurement of the NaNO3–KNO3 system and the obtained results are presented in this study. Up to date two thermodynamic assessments of the NaNO3–KNO3 phase diagram have been made, one characterized by a single eutectic point with limited solubilities in the solid state in both NaNO3 and KNO3 rich corners, whereas the other version prefers a continuous solid solubility with minimum on the liquidus line. Based on our results we confirm limited solubilities in the solid state.
O. Beneš, R.J.M. Konings, S. Wurzer, M. Sierig, A. Dockendorf, Thermochimica Acta, 509 (2010) 62–66

B2546 – Phase diagram and electrical conductivity of the CeBr3–CsBr binary system

Phase equilibrium in the CeBr3–CsBr binary system was established from differential scanning calorimetry (DSC). This system includes three compounds, namely Cs3CeBr6, Cs2CeBr5 and CsCe2Br7; and three eutectics located at CeBr3 molar fraction x = 0.125; 0.459 and 0.700, respectively. Cs3CeBr6 undergoes a solid–solid phase transition at 712 K and melts congruently at 1034 K. Cs2CeBr5 decomposes in the solid state into Cs3CeBr6 and CsCe2Br7 at 685 K. The third compound, CsCe2Br7, melts congruently at 877 K. The electrical conductivity of CeBr3–CsBr liquid mixtures was measured down to temperatures below solidification over the whole composition range. Results obtained are discussed in term of possible complex formation.
Leszek Rycerz, Ewa Ingier-Stocka, Marcelle Gaune-Escard, J Therm Anal Calorim (2009) 97,1015–1021

B2536 – Heat capacity, enthalpy and entropy of calcium niobates

Heat capacity and enthalpy increments of calcium niobates CaNb2O6 and Ca2Nb2O7 were measured by the relaxation time method (2–300 K), DSC (260–360 K) and drop calorimetry (669–1421 K). Temperature dependencies of the molar heat capacity in the form Cpm=200.4+0.03432T–3.450·106/T 2 J K–1 mol–1 for CaNb2O6 and Cpm=257.2+0.03621T–4.435·106/T 2 J K–1 mol–1 for Ca2Nb2O7 were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, Sm0(CaNb2O6, 298.15 K)=167.3±0.9 J K–1 mol–1 and Sm0 (Ca2Nb2O7, 298.15 K)=212.4±1.2 J K–1 mol–1, were evaluated from the low temperature heat capacity measurements. Standard enthalpies of formation at 298.15 K were derived using published values of Gibbs energy of formation and presented heat capacity and entropy data: ?fH0(CaNb2O6, 298.15 K)= –2664.52 kJ mol–1 and ?fH0(Ca2Nb2O7, 298.15 K)= –3346.91 kJ mol–1.
J. Leitner, K. Ruzicka, D. Sedmidubskú, P. Svoboda, Journal of Thermal Analysis and Calorimetry, Vol. 95 (2009) 2, 397–402

B2499 – Calorimetric study of dissolution kinetics of phosphorite in diluted acetic acid

In this report, we present a thermodynamic and kinetic study of the selective dissolution of calcite from low-grade phosphate ores (Epirus area, Greece) by dilute acetic acid at isothermal conditions. A twin calorimeter with two identical membrane vessels, for the acid dissolution process, and for the reference was used. The curves of rate vs. time of the phosphorite dissolution for various temperatures show that the maximum ( & qmax) was increased, whereas the time (tpeak) to achieve the corresponding & qmax values was decreased, as the experimental temperature was increased. The dissolution enthalpy was increased from 13.1 to 16.7 kJ mol–1, as the experimental temperature was increased from 10.0 to 28.0°C. The chemical analysis of the supernatant solutions shows that the main process was the calcite dissolution. The reaction model with general form, ln(1/(1–X))=ktm, was found to fitted the experimental data regardless of the experimental temperature. These results were assigned in the presence of two different kinds of particles in the phosphorite. The activation energy of the dissolution process was found 69.7 kJ mol–1. The SEM micrographs of acid dissolution samples showed two different textures after acid dissolution.
T. C. Vaimakis, E. D. Economou, C. C. Trapalis, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 3, 783–789

B2498 – Standard enthalpy of formation of disodium hydrogen phosphate hexahydrate and sodium diphosphate

Commercial disodium hydrogen phosphate dodecahydrate (Na2HPO4 12H2O) was used as a precursor for synthesizing disodium hydrogen phosphate hexahydrate (Na2HPO4 6H2O) and sodium diphosphate (Na4P2O7). The purity of the synthesized products was checked up by IR spectroscopy and X-ray diffraction. The heat of dissolution of these compounds, in acid solutions of several concentrations (w/w) of H3PO4 was measured in a C-80 SETARAM calorimeter. Many dilution and mixing processes were also realized in the calorimeter in order to get the standard enthalpy of formation of these products. The values obtained for the enthalpies of formation are: ( 3210.5) and ( 3516.5) kJ mol 1 for sodium diphosphate (Na4P2O7) and disodium hydrogen phosphate hexahydrate (Na2HPO4 6H2O), respectively.
H. Gmati-Ben Khaled, I. Khattech, M. Jemal, J. Chem. Thermodynamics 43 (2011) 521–526

B2496 – Measurement of reaction enthalpy during pressure oxidatiuon of sulphide minerals

A calorimetric method for determining the enthalpy of the aqueous oxidation of sulfide minerals at high temperatures and oxygen pressures has been developed and evaluated under conditions relevant to industrial pressure oxidation operations. This information is important for heat balance calculation and optimization of the pressure reactor design. Experiments were carried out on a differential scanning calorimeter (DSC) with a commercial mixing cell. Enthalpy measured during oxidative dissolution of pyrite (Valdenegrillos, Spain), pentlandite with pyrrhotite (Sudbury, Ontario, Canada) and impure chalcopyrite (Victoria, Australia) minerals at 150°C and partial oxygen pressures of 3.4 and 5.5 MPa have been performed and found to be consistent with theoretical estimations.
I. Bylina, L. Trevani, S. C. Mojumdar, P. Tremaine, V. G. Papangelakis

B2495 – Microcalorimetric investigation of water vapor adsorption on silica gel

Water vapor adsorption on silica gel was investigated using Tian–Calvet-type microcalorimetry. Differential heat of adsorption data was obtained. The setup of microcalorimetry was used volumetric system to determine adsorption isotherms of water vapor–silica gel. The Langmuir model was used in the interpretation of the adsorption data. The Clausius–Clapeyron diagram was also given. Effective mass diffusivity of water vapor in the silica gel particle as a function of temperature was also determined. The silica gel, which was degassed under vacuum at 10-7 mbar and 120 C for 18 h, was found to adsorb 0.6, 0.98, 1.1, 1.4, 2, 3.5, 11, 13, and 14 wt% water vapor at 120, 110, 100, 90, 75, 60, 40, 35, and 30 C, respectively. The diffusivities of water vapor inside the silica gel for short- and long-range periods were described using kinetics data as a function of temperature in the Arrhenius form.
Hasan Demir, Moghtada Mobedi, Semra Ülku, J Therm Anal Calorim (2011) 105, 375–382

B2465 – Spectroscopic and thermal studies of bentonites from Ünye, Turkey

Three bentonites from Turkey were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), differential thermal analysis (DTA), thermogravimetric analysis (TG), Fourier transform infrared (FT-IR), magic angle spinning nuclear magnetic resonance (MAS NMR) and surface area measurement techniques. The XRD patterns showed that all three bentonite samples (B1, B2 and B3) were mainly composed of montmorillonite accompanied by cristobalite. In addition, albite appears in B3 sample studied. The heats of immersion of the bentonite samples (B1, B2 and B3) measured with a Calvet calorimeter at 30 C in water were determined as 75.70, 54.69 and 68.22 J/g, respectively.
Meryem Sakizci, Burcu Erdogan Alver, Özgür Alver, Ertugrul Yörükogullari, Journal of Molecular Structure 969 (2010) 187–191

B2463 – Shape-dependent surface energetics of nanocrystalline TiO2

We report the direct determination of surface enthalpies for nanophase TiO2 anatase with different morphologies derived from drop solution calorimetry in a molten sodium molybdate (3Na2O.4MoO3) solvent at 702°C. The energetics of surface hydration has been measured using a Calvet microcalorimeter coupled with a gas dosing system. The surface enthalpies of hydrated surfaces for anatase TiO2 nanoparticles, nanowires and sea-urchin-like assemblies are 0.51 ± 0.05, 1.07 ± 0.28, and 1.29 ± 0.16 J m 2, respectively, whereas those of anhydrous surfaces are 0.74 ± 0.04, 1.24 ± 0.28, and 1.41 ± 0.16 J m 2, respectively. The trend in TiO2, which shows higher surface enthalpies for more complex nanostructures, is consistent with that reported in ZnO. The shape-dependent surface enthalpy at the nanoscale level is discussed in terms of exposed surface structures. The enthalpies of hydration appear to be similar for all morphologies.
Tae-Jin Park, Andrey A. Levchenko, Hongjun Zhou, Stanislaus S. Wongb, Alexandra Navrotsky, J. Mater. Chem., 2010, 20, 8639–8645

B2460 – Thermodynamic characteristics of phase conversion of structural isomers for volatile complex of ruthenium (III) trifluoroacetylacetonate

The comprehensive analysis of volatile b-diketonate compound—ruthenium(III) trifruoroacetylacetonate (Ru(tfac)3)—was carried out. By means of flow method in quasi-equilibrium conditions and static method the temperature dependencies of saturated vapor pressure have been measured over solid and liquid cis- and transmodifications of Ru(tfac)3 and isomer mixture. The thermodynamic characteristics of sublimation, evaporation, melting, and phase conversion have been calculated for structural isomers. Also by differential-scanning calorimetry the temperature meanings and the thermodynamic characteristics of melting have been determined for individual isomers of Ru(tfac)3 and their mixtures. By XRD the structures for cis- and trans-modifications have been determined. Both structures consist of neutral molecules arranged in pseudo layers.
S. V. Sysoev, T. N. Cheremisina, L. N. Zelenina, S. V. Tkachev, K. V. Zherikova, N. B. Morozova, N. V. Kuratieva, J Therm Anal Calorim (2010) 101:41–44

B2459 – Calorimetric search for the discontinuity in Fe0.96S–Ni0.96S solid solutions

Heat capacity of unstable quenched solid solutions (Fe1–xNix)0.96S was measured by DSC (enthalpy method and scanning heating). According to optic microscopy and X-ray powder diffraction, the samples are homogeneous phase of NiAs type with unit cell parameters changing regularly with composition. Heat capacity changes with composition irregularly due to the difference in magnetic properties of the end members: Cp/1.96R=4.1 for Fe-rich samples and 3.3 for Ni-rich ones. There is no exact limit between two types of magnetic ordering. Instead, samples with intermediate composition (0.7
V. A. Drebushchak, E. F. Sinyakova, Journal of Thermal Analysis and Calorimetry, Vol. 89 (2007) 1, 303–307

B2458 – Changes in the heat capacity of Al2O3–Cr2O3 solid solutions near the point of antiferromagnetic phase transition in Cr2O3

Al2O3–Cr2O3 solid solutions with 0, 4, 7, 10 and 20 mol% of corundum were synthesized using a high-pressure/high-temperature apparatus and characterized by X-ray powder diffraction. Calorimetric measurements were carried out using DSC-111 (Setaram). Heat capacity was measured by the enthalpy method in a temperature range of 260–340 K, near magnetic phase transition in pure Cr2O3 (305 K). Magnetic contribution into the heat capacity was derived and found to change irregularly with the composition. Heat capacity of solid solutions remains constant in a relatively wide range of composition, while the Cp values of the end members differ significantly. This phenomenon is very important for the modeling of the thermodynamic functions of intermediate solid solutions.
V. A. Drebushchak, A. I. Turkin, Journal of Thermal Analysis and Calorimetry, Vol. 90 (2007) 3, 795–799

B2457 – Fluorophenyl derivatives of elements II–VI groups. Phase transitions thermodynamics and growing films by CVD

The enthalpies and temperatures of melting of RSi(CH3)3, R4Si, R3P, R3As, R3Sb, R3Bi, R2Te and R2Hg (R=C6F5) were obtained by scanning calorimetry measurements. The pressure of the saturated and unsaturated vapors of RSi(CH3)3, R2Si(CH3)2, R4Si, R3Ga, R3P, R3As, R3Sb, R3Bi, R2Te and R2Hg has been measured by the static method with a membrane-gauge manometer. It was established that all investigated substances proceeded to vapor as monomers. Equations approximating the dependences of saturated vapor pressures on temperature and the enthalpies and entropies of vaporization were obtained. Grafite films with silicon intercalated up to 25 at.% were grown by CVD using R4Si as a precursor. These films showed semiconductor properties in the temperature interval 80–300 K.
L. N. Zelenina, T. P. Chusova, Yu. G. Stenin, V. V. Bakovets, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 3, 723–727

B2453 – Molar heat capacity and thermodynamic properties of crystalline Ho(Asp)Cl2,6H2O

The molar heat capacity, Cp,m, of a complex of holmium chloride coordinated with L-aspartic acid, Ho(Asp)Cl2·6H2O, was measured from 80 to 397 K with an automated adiabatic calorimeter. The thermodynamic functions HT–H298.15 and ST–S298.15 were derived from 80 to 395 K with temperature interval of 5 K. The thermal stability of the complex was investigated by differential scanning calorimeter (DSC) and thermogravimetric (TG) technique, and the mechanism of thermal decomposing of the complex was determined based on the structure and the thermal analysis experiment.
B. P. Liu, X. C. Lv, Z. C. Tan, Z. H. Zhang, Q. Shi, L. N. Yang, J. Xing, L. X. Sun, T. Zhang, Journal of Thermal Analysis and Calorimetry, Vol. 89 (2007) 1, 283–287

B2451 – Low-temperature heat capacity and thermodynamic properties of crystalline lead formate

As one 3-D coordination polymer, lead formate was synthesized; calorimetric study and thermal analysis for this compound were performed. The low-temperature heat capacity of lead formate was measured by a precise automated adiabatic calorimeter over the temperature range from 80 to 380 K. No thermal anomaly or phase transition was observed in this temperature range. A four-step sequential thermal decomposition mechanism for the lead formate was found through the DSC and TG-DTG techniques at the temperature range from 500 to 635 K.
J. Zhang, Y. Y. Liu, Z. H. Zhang, X. C. Lv, L. X. Sun, F. Xu, Z. C. Tan, T. Zhang, Y. Sawada, Journal of Thermal Analysis and Calorimetry, Vol. 89 (2007) 2, 643–647

B2431 – Thermodynamic properties of strontium metaniobate SrNb2O6

The heat capacity and the enthalpy increments of strontium metaniobate SrNb2O6 were measured by the relaxation method (2–276 K), micro DSC calorimetry (260–320 K) and drop calorimetry (723–1472 K). Temperature dependence of the molar heat capacity in the form Cpm=(200.47±5.51)+(0.02937±0.0760)T–(3.4728±0.3115)×106/T 2 J K–1 mol–1 (298–1500 K) was derived by the least-squares method from the experimental data. Furthermore, the standard molar entropy at 298.15 K Sm 0 (298.15 K)=173.88±0.39 J K–1 mol–1 was evaluated from the low temperature heat capacity measurements. The standard enthalpy of formation ?fH0 (298.15 K)= –2826.78 kJ mol–1 was derived from total energies obtained by full potential
J. Leitner, M. Hampl, K. Ruzicka, M. Straka, D. Sedmidubskú, P. Svoboda, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 3, 985–990

B2368 – Humidity controlled calorimetric investigation of the hydration of MgSO4 hydrates

The isothermal heat of hydration of MgSO4 hydrates was studied by humidity controlled calorimetry. Two hydrates, starkeyite (MgSO4·4H2O) and a mixture of MgSO4 hydrates with summary 1.3 mol H2O were investigated. The solid–gas reactions were initiated at 30°C and 85% relative humidity. The heat of hydration was determined in a circulation cell in the calorimeter C80 (Setaram). The crystal phases formed after the hydration process were analyzed by thermogravimetry (TG) and X-ray powder diffraction (XRD). Starkeyite reacted with the water vapour to the thermodynamic stable epsomite and the MgSO4 hydrate mixture with 1.3 mol water to hexahydrite. The hydration heats of starkeyite and themixture were determined to be –169±3 and –257±5 kJmol–1, respectively.
K. Posern, Ch. Kaps, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 3, 905–909

B2365 – Measurement of Contact Angles for Fumed Silica Nanospheres Using Enthalpy of Immersion Data

The hydrophobicity of fine particles is important for their behavior at interfaces, for example, in stabilizing emulsions. In this study, contact angles were evaluated for silanized fumed silica nanospheres with mean primary diameter of about 12 nm, using heat flow microcalorimetry. Three systems were investigated: water–air–nanospheres, toluene–air–nanospheres, and toluene– water–nanospheres. For the water–air–nanospheres system, npropanol at various concentrations in water was used to aid in dispersing the nanospheres, and the enthalpy of immersion between water, air, and nanospheres was obtained by extraploting to zero n-propanol concentration. Measurements of enthalpy of immersion for toluene–air–nanospheres system were straightforward, as all the nanospheres samples were dispersible in toluene. The enthalpy of immersion for toluene–water–nanospheres system was calculated from the data for the aforementioned first and the second systems. For water–air–nanosphere systems, contact angles were in the range of 14 to 118±, corresponding to enthalpy of immersion from¡0.0905 to 0.0041 J/m2. For the case of toluene–air–nanospheres systems, the contact angles varied from 72 to 94± with corresponding enthalpy of immersion from ¡0.0295 to ¡0.0189 J/m2. For toluene–water–nanospheres systems, however, contact angles were in the range of 0 to 96±, corresponding to enthalpy of immersion from ¡0.0717 to ¡0.0175 J/m2.
Nianxi Yan, Yadollah Maham, Jacob H. Masliyah, Murray R. Gray, Alan E. Mather, Journal of Colloid and Interface Science 228, 1–6 (2000)

B2311 – Heat capacity of indium nitride

The heat capacity of the solid indium nitride was measured, using the Calvet TG-DSC 111 differential scanning microcalorimeter (Setaram, France), in the temperature between (314–978 K). The temperature dependence of the heat capacity can be presented in the following form: Cp=41.400+0.499 10–3T–135502T–2–26169900 T–3.
Iwona Zieborak-Tomaszkiewicz, R. Wierzewski and P. Gierycz, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 2, 649–653

B2301 – Etude cinétique et thermodynamique de la dissolution de la fluorapatite dans l’acide phosphorique

A modification on the reversal cells of a C-80 SETARAM calorimeter allows a Joule effect in the reaction cells to determine a transfer function in experimental conditions close to those of dissolution of a solid in a liquid. The calorimeter was then used to determine in isothermal conditions both thermodynamic and kinetic parameters associated with dissolution of synthetic fluorapatite in phosphoric acid solutions. Due to the rapidity of reaction, the heat flow recordings were deconvoluted and the resulting curves were analyzed iteratively to obtain the rates of digestion and the enthalpy of dissolution at 298K of fluorapatite in phosphoric acid solution containing 10, 18 or 30 wt% P2O5. The results agree with a two-step dissolution mechanism. The first step is the dissolution of the solid in phosphoric acid, and the second is the formation of the complex Ca(H2PO4)+.
K. Brahim, I. Khattech, J.P. Dubès, M. Jemal, Thermochimica Acta 436 (2005) 43–50

B2298 – Thermal analysis and calorimetry methods

Thermal analysis is a group of techniques which study the changes in the properties of a sample occurring while the sample is subjected to a controlled temperature programme. Calorimetric methods measure heat changes which occur during a process. Important changes on a molecular level occur to a material as it is heated, and their study may enable the analyst to draw valuable conclusions about the sample, its previous history, preparation, chemical nature and the likely behaviour during its proposed use. The temperature at which a particular event takes place, or the temperature range over which a reaction happens, is often characteristic of the nature and history of a sample [1]. Calorimetry encompasses a very large variety of techniques, including titration, flow, reaction, or sorption calorimetry
Simona Bennici and Aline Auroux, Metal oxides catalysis, Vol.1, Wiley 2009

B2293 – Phase transitions of K2TaF7 within 680 – 800oC

Three thermal effects on heating/cooling of K2TaF7 in the temperature interval of 680 – 800oC were investigated by the DSC method. The values determined for the enthalpy change of the individual processes are: ?transIHm(K2TaF7; 703oC) = 1.7(2) kJ mol–1, ?transIHm(K2TaF7; 746oC) = 19(1) kJ mol–1 and ?transIIIHm(K2TaF7; 771oC) = 13(1) kJ mol–1. The first thermal effect was attributed to a solid-solid phase transition; the second to the incongruent melting of K2TaF7 and the third to mixing of two liquids. These findings are supported by in situ neutron powder diffraction experiments performed in the temperature interval of 654 – 794oC.
Ladislav Kosa, Iveta Macková, Ivo Proks, Ondrej Pritula, ?ubomír Smr?ok Central European Journal of Chemistry proof version Miroslav Bo?a, Håkan Rundl?f

B2292 – Calorimetric studies of the enthalpies of formation of Al3Ni2, AlNi and AlNi3

Two calorimetric methods: solution and direct reaction techniques were used for determination of the enthalpies of formation of two advanced aluminides: AlNi and AlNi3 as the main candidates for the high-temperature application. The same comparison was made for Al3Ni2 due to the similarity of the structure with AlNi. The special construction of solution calorimetry enables to determine the high temperature dependence of the enthalpies of formation of these intermetallic phases and to compare them with existing literature information and with theoretical calculations. Temperature dependence of the enthalpies of formation may explain the differences between experimental results and ab initio calculations at 0 K and may be attributed to the different reference state of the compound and its components. Differences between the numerical values of enthalpies of formation of these intermetallic phases are discussed in terms of structural similarities and combined with literature data of excess Gibbs energies to calculate excess entropies responsible for high temperature stability. This article reviews the progress made on calorimetric studies used for determination of the formation enthalpies of AlNi, AlNi3 and Al3Ni2 and compares them with first principle calculations as the source for verification of phase equilibria of Al-Ni system and phase diagram calculations from theoretical estimates.
K. Rzyman, Z. Moser, Progress in Materials Science 49 (2004) 581-606

B2291 – Heat perception measurements of the different parts found in a car passenger compartment

This work describes an instrument able to reproduce the human thermal rendering of interior parts in cars. Synthetic materials are used to replace the human skin. The design starts with a thermal sizing of different layers of these materials to reproduce the behaviour of a real finger. The construction of the device is based on latex deposit process able to ensure an accurate thickness and provide a good mechanical resistance. Measurements have been carried out on different kinds of materials used in automotive industry. Good correlations have been found between these experimental results and a sensory human evaluation. Thermal sensory perceptions related to the sense of touch can now be measured using a physical instrument. This work has been protected by a patent in order to permit an industrial development.
A. Sarda, R. Deterre, C. Vergneault, Measurement 35 (2004) 65-75

B2290 – Optical properties of CeBO3 and CeB3O6 compounds: first-principles calculations and experimental results

The cerium borates o-CeBO3, m-CeBO3 and CeB3O6 have been shown to be isostructural to their lanthanum derivatives. From diffuse reflectance, electron energy loss spectroscopy (EELS) and band structure calculations, it has been evidenced that a Ce3+ 4f-5d transition is responsible for weak absorption peaks around 3.5 eV while the O2p-Ce5d charge transfer gives rise to a strong absorption around 7 eV. Starting from self-consistent full potential LAPW calculations, the dielectric tensors of the three compounds were computed and compared to experimental data. It results in a satisfactory fit between the observed and the calculated extinction coefficient k and the index of refraction n.
F. Goubin, Y. Montardi, P. Deniard, X. Rocquefelte, R. Brec, and S. Jobic, Journal of Solid State Chemistry 177 (2004) 89-100

B2282 – Thermodynamic evaluation and modeling of the Fe-Co-O system

A complete critical evaluation and thermodynamic modeling of the phase diagrams and thermodynamic properties of oxide phases in the Fe-Co-O system is presented. Optimized equations for the thermodynamic properties of oxide phases are obtained which reproduce all available thermodynamic and phase equilibrium data within experimental error limits from 25°C to above the liquidus temperatures at all compositions and oxygen partial pressures from metal saturation to 100 bar. The optimized thermodynamic properties and phase diagrams are believed to be the best estimates presently available. The database of the model parameters can be used along with software for Gibbs energy minimization in order to calculate any type of phase diagram section. New experimental results are reported for the equilibrium compositions of spinel and cobaltowustite (CW) at 1200°C in air.
I-H. Jung, S.A. Decterov, A.D. Pelton, H-M. Kim, Y-B. Kang, Acta Materialia 52 (2004) 507-519

B2278 – Ferroelectric phase transition in the whitlockite-type Ca9Fe(PO4)7; crystal structure of the paraelectric phase at 923 K

A newly discovered phase transition in Ca9Fe(PO4)7 is studied by high-temperature X-ray powder diffraction (XRD) and electron diffraction (ED), high-resolution electron microscopy, second-harmonic generation (SHG), differential scanning calorimetry, dielectric and electrical conductivity measurements. The phase transition temperature, Tc, is 890 ± 10 K. Dielectric measurements reveal the ferroelectric nature of the phase transition. A spontaneous polarization of about 2-3 µC cm-2 is estimated from SHG. The phase transition from a polar ferroelectric form beta (space group R3c), to a centrosymmetric paraelectric form beta' (space group R3c), is reversible and of first order. The evolution of the crystal structure and lattice parameters is studied by high-temperature XRD and ED. The structural parameters of beta'-Ca9Fe(PO4)7 are refined by the Rietveld method from XRD data at 923 K in the space group R3c (Z = 6) with lattice parameters a = 10.3878(2) Å and c = 37.8387(4) Å (Rwp = 1.48% and RI = 2.16%). Both beta- and beta'-Ca9Fe(PO4)7 are related to the whitlockite-type structure. The beta --> beta' phase transition in Ca9Fe(PO4)7 is accompanied by a disordering of the Ca2+ ions at the Ca3 sites and orientational disordering of the P1O4 tetrahedra.
B.I. Lazoryak, V.A. Morozov, A.A. Belik, S.Yu. Stefanovich, V.V. Grebenev, I.A. Leonidov, E.B. Mitberge, S.A. Davydov, O.I. Lebedev, G. Van Tendeloo, Solid State Sciences 6 (2004) 185-195

B2273 – The structural role of Ti in aluminosilicate liquids in the glass transition range: Insights from heat capacity and shear viscosity measurements

The shear viscosities and 1 bar heat capacities of glasses and melts along the 67mol% silica isopleth in the system SiO2-Al2O3-Na2O-TiO2 have been determined in the temperature ranges 780-1140 K and 305-1090 K respectively. Anomalous behaviour of both these properties is observed for compositions rich in TiO2 and/or Al2O3, an observation attributed to liquid-liquid phase separation followed by anatase crystallization. For samples which do not show anomalous behaviour, it is found that the partial molar heat capacity of the TiO2 component previously determined in Al-free compositions reproduces our heat capacities to within 1.3%. Viscosity data show that addition of TiO2 tends to increase viscosity and melt fragility at constant temperature. Furthermore, heat capacity and viscosity data may be combined within the framework of the Adam-Gibbs theory to extract values of the configurational entropy of the liquids and qualitative estimates of the variation of the average energy barrier to viscous flow. Configurational entropy at 900K is inferred to decrease upon addition of TiO2, in contrast to previous results from Al-free systems. The compositional limit separating normal from anomalous behaviour, as well as the data for homogenous melts have been used to constrain the structural role of Ti in these samples. Our data are consistent with a majority of Ti in five-fold coordination associated with a titanyl bond, in agreement with previous spectroscopic studies. Furthermore, we find no evidence for a Ti-Al interaction in our samples, and we are led to the conclusion that Al and Ti are incompletely mixed, a hypothesis consistent with the observed reduction of configurational entropy upon addition of TiO2, suggesting an important role of medium range order in controlling the variations in thermodynamic properties.
M. Roskosz, M.J. Toplis and P. Richet, Geochimica et Cosmochimica Acta 68 (2004) 591-606

B2235 – High tilted antiferroelectric liquid crystalline materials

Phase transitions, smectic layer structure, helical pitch and electrooptical properties of recently prepared high tilted antiferroelectric compounds are characterized. The compounds enable to prepare broad temperature range (-20 to 100°C) orthoconic antiferroelectric mixtures, having 45° tilt independent of temperature in broad temperature range, and exhibiting excellent contrast and grey level scale.
R. Dabrowski, J. Gasowska, J. Oton, W. Piecek, J. Przedmojski, M. Tykarska, Displays 25 (2004) 9-19

B2222 – Ultra-fast isothermal calorimetry using thin film sensors

Anewapplication of an ultra-fast thin film calorimeter is described.Acommercially available sensor, thermal conductivity gauge TCG-3880 (Xensor Integrations, NL) was utilized as a measuring cell for isothermal calorimetric measurements. The sensor consists of a thin membrane (500 nm) with a semi conducting heater and a semi conducting thermopile, which are produced using integrated-circuit (IC) technology. To allow fast scanning sample size should be small too. Samples with masses of about 100 ng were measured. Different modes of operation were realized: (i) temperature scans over hundreds of Kelvin with rates up to 10,000 K/s; (ii) isothermal heat flow measurements with a time resolution of a few milliseconds; (iii) ac-mode for heat capacity measurements in the frequency range from 1 to 140 Hz at scanning or isothermally. In contrary to classical ac calorimeters beside heat capacity enthalpy changes can be monitored simultaneous. All these modes can be combined to realize experimental conditions needed to follow isothermal processes in time. As an example, we present isothermal crystallization experiments for fast crystallizing polymers. Heat flow as well as heat capacity was measured after quenching the sample from above the melting temperature to the crystallization temperature. Crystallization kinetics for polycaprolactone (PCL) and polyethylene (PE) are presented in a wide temperature range.We were able to followisothermal crystallization of PCL in the whole temperature range between melting and glass transition.
S. Adamovsky, C. Schick, Thermochimica Acta 415 (2004) 1-7

B2221 – TOF-SIMS study of pyridine intercalated nanorods of bismuth molybdate

Intercalation of pyridine resulted into nanorods of bismuth molybdates, which were characterized by TEM, IR, solid-state NMR, and XRD. However, the ambiguity of the nature of intercalated pyridine, which was expected to be as pyridine, pyridinium ion or pyridine bonded to bismuth molybdate has been resolved using TOF-SIMS. Static and temperature dependent TOF-SIMS supported the nature of intercalated pyridine species as pyridinium ion.
A.V. Ghule, C-Y. Chen, F-D. Mei, Y-C. Ling, Applied Surface Science 231-232 (2004) 840-844

B2202 – DSC studies on reactions of the elements with sulfur

The sulfidation reaction of the elements in sealed silica tubes methods has been studied by differential scanning calorimetry (DSC) with a heating rate of 10°C min-1 at temperatures between 25 and 800°C. The reaction pathways were investigated by thermoanalytical and X-ray methods. The elements tested were as follows: Ag, Al, B, Bi, Cd, Co, Cr, Cu, Fe, Ga, Ge, Hf, In, Mg, Mn, Mo, Nb, Ni, P, Pb, Pt, Si, Sn, Ta, Ti, V, W, Zn and Zr. The sulfidation temperature of the elements has been determined from DSC data.
H. Wada, K. Takada, T. Sasaki, Solid State Ionics 172 (2004) 421-424

B2172 – (CuBr)2P8Se3: preparation, structural, and vibrational spectroscopic characterization of an adduct of P8Se3 cages to Cu2Br2 rhombs

Orange-red (CuBr)2P8Se3 was obtained from stoichiometric amounts of CuBr, P and Se by melting and subsequent annealing at 380°C for 1 month. The crystal structure was determined from single crystal X-ray data. (CuBr)2P8Se3 crystallizes in the orthorhombic system, space group Pbcm (No. 57), with a = 8.761(1) Å; b = 11.957(1) Å; c = 13.858(1) Å; V = 1451.8(3) Å3; and Z = 4. This compound consists of neutral P8Se3 cage molecules attached to Cu2Br2 rhombs. Vibrational spectroscopic data are reported for (CuBr)2P8Se3 and for the homologous (CuI)2P8Se3. The wavenumbers of the Cu-Br and Cu-I vibrational modes show an excellent correlation with the corresponding Cu-X bond lengths.
S. Nilges, T. Nilges, H. Haeuseler, A. Pfitzner, Journal of Molecular Structure 706 (2004) 89-94

B2165 – Structural, vibrational and dielectric properties of the new mixed solution K0.84(NH4)1.16SO4.Te(OH)6

Synthesis, crystal structure, DSC characterization, dielectric and Raman measurements are given for a new mixed solution K0.84(NH4)1.16- SO4.Te(OH)6 (KNST). X-ray studies showed that the title compound crystallizes in the monoclinic system (P 21/c) with the following parameters: a = 14.929(5) Å, b = 6.558(1) Å, c = 11.325(1) Å, beta = 120.17(2)° and Z = 4. The structure can be regarded as being built of isolated TeO6 octahedra, SO4 tetrahedra and K+/NH+4 cations. The main feature of this structure is the coexistence of two types of hydrogen bonds O-H...O and N-H...O ensuring the cohesion of the crystal. Crystals of K0.84(NH4)1.16SO4.Te(OH)6 undergo two endothermic peaks at 425 and 480 K and a shoulder at 470 K. These transitions detected by DSC and analyzed by dielectric measurements using the impedance and modulus spectroscopy techniques. Raman scattering measurements on K0.84(NH4)1.16SO4.Te(OH)6 material taken between 300 and 620 K are reported in this paper. The spectra indicate clearly two phase transitions.
L. Ktari, M. Dammak, A. Hadrich, A. Cousson, M. Nierlich, F. Romain, T. Mhiri, Solid State Sciences 6 (2004) 1393-1401

B2156 – Search for new materials in sputtered V(1-x)C(x) films

In this work, the vanadium-carbon system has been explored in a wide range of atomic carbon content x (0.01
A. Aouni, P. Weisbecker, Tran Huu Loi, E. Bauer-Grosse, Thin Solid Films 469-470 (2004) 315-321

B2134 – High-temperature calorimetry of (La(1-x)Lnx)PO4 solid solutions

The enthalpy increment of the monazite-type solid solutions of LaPO4 with NdPO4, EuPO4 and GdPO4 has been measured by drop calorimetry at T = 1000 K. The results show deviations (excess enthalpy) from ideal behaviour that have been interpreted in terms of lattice strains resulting from the ion size effects of substitution of La3+ by Ln3+. For (La0.5Gd)0.5PO4 also the temperature dependence has been determined for T = (515 to 1565) K, indicating that the excess enthalpy decreases with increasing temperature.
K. Popa, R.J.M. Konings, T. Geisler, J. Chem. Thermodynamics 39 (2007) 236-239

B2133 – The heat capacity of BaUO4

The heat capacity of barium uranate BaUO4 has been measured in the temperature range (1.9 to 1570) K in order to resolve the discrepancy between two existing low-temperature calorimetric studies on this compound. Our results are in good agreement with one of the two earlier studies, and the impact of this finding is discussed.
K. Popa, E. Colineau, F. Wastin, R.J.M. Konings, J. Chem. Thermodynamics 39 (2007) 104-107

B2126 – Heat capacity and heat content of BiNb5O15

The heat capacity and the heat content of bismuth niobate BiNb5O14 were measured by the relaxation time method, DSC and drop method, respectively. The temperature dependence of heat capacity in the form Cpm=455.84 + 0.06016T - 7.7342 10^6/T 2 (J K-1 mol-1) was derived by the least squares method from the experimental data. Furthermore, the standard molar entropy at 298.15 K Sm=397.17 J K-1 mol-1 was derived from the low temperature heat capacity measurement.
M. Hampl, J. Leitner, K. Ruzicka, M. Straka and P. Svoboda, Journal of Thermal Analysis and Calorimetry 87 (2007) 553-557

B2125 – Heat capacity and heat content of BiNb5O14

The heat capacity and the heat content of bismuth niobate BiNb5O14 were measured by the relaxation time method, DSC and drop method, respectively. The temperature dependence of heat capacity in the form Cpm=455.84 + 0.06016T - 7.7342 10^6/T 2 (J K-1 mol-1) was derived by the least squares method from the experimental data. Furthermore, the standard molar entropy at 298.15 K Sm=397.17 J K-1 mol-1 was derived from the low temperature heat capacity measurement.
M. Hampl, J. Leitner, K. Ruzicka, M. Straka and P. Svoboda, Journal of Thermal Analysis and Calorimetry 87 (2007) 553-556

B2107 – Synthesis and characterization of a new (2-NH2-6-CH3C5H4N)H2XO4 (X = P, As)

Crystals of 2-amino-6-methylpyridinium dihydrogenmonophosphate (denoted as 2A6MPP) and 2-amino-6-methylpyridinium dihydrogenmonoarsenate (denoted as 2A6MPAs), have been prepared and grown at room temperature. They crystallize with triclinic unit cells and are isotopic. The following unit cell parameters were found, (2-NH2-6-CH3C5H4N)H2PO4: a = 7.5165(6), b = 8.2640(5), c = 8.5674(7) Å , alpha = 64.845(5), beta = 80.156(3), gamma = 85.783(5), Z = 2, V = 474.61(6) Å3; (2-NH2-6- CH3C5H4N)H2AsO4: a = 7.6011(4), b = 8.4261(6), c = 8.7074(6) Å , alpha = 64.228(3), beta = 81.047(4), gamma = 85.972(4), Z = 2, V = 496.09(6) Å3. The common space group is P¯1. We have determined the structure of the phosphate. It exhibits infinite (H2PO4)n n chains. The organic groups (2-NH2-6-CH3C5H4N)+ are anchored between adjacent polyanions through multiple hydrogen bonds. The thermal property of the compound was investigated as well as was the IR property supported by group theoretical analyses.
A. Chtioui, A. Jouini, Materials Research Bulletin 41 (2006) 569-575

B2105 – Growth and characterization of nonlinear optical crystal BaCaBO3F

Colorless and transparent BaCaBO3F single crystals were grown by employing the Kyropoulos method. A well-developed morphology of BaCaBO3F crystals is observed, but it differs depending on the growth direction. Differential scanning calorimetry analysis showed that BaCaBO3F crystal melts congruently at 1083.4°C. The optical transmission spectrum of the BaCaBO3F crystal was measured at room temperature, and it was found to be transparent in the 220-2500nm wavelength range.
G. Zhang , H. Liu, X. Wang, F. Fan, P. Fu, Journal of Crystal Growth 289 (2006) 188-191

B2095 – Effect of temperature on hydration kinetics and polymerization of tricalcium silicate in stirred suspensions of CaO-saturated solutions

Tricalcium silicate was hydrated at 274, 278, 283, 298, and 313 K in stirred suspensions of saturated CaO solutions under a nitrogen-gas atmosphere until the end of deceleratory period. The suspension conductivities and energy flows were measured continuously. The individual reaction rates for tricalcium silicate dissolution, calcium silicate hydrate precipitation, and calcium hydroxide precipitation were calculated from these measurements. The results suggest that the proportion of tricalcium silicate dissolved was determined by the rate of tricalcium silicate dissolution and the time to very rapid calcium hydroxide precipitation. The time to very rapid calcium hydroxide precipitation was more sensitive to changes in temperature than was the rate of tricalcium silicate dissolution, so that the proportion of tricalcium silicate hydration dissolved by the deceleratory period increased with decreasing temperature. The average chain length of the calcium silicate hydrate ascertained by magic-angle spinning nuclear magnetic resonance spectroscopy increased with increasing temperature.
S.A. Grant, G.E. Boitnott, C.J. Korhonen, R.S. Sletten, Cement and Concrete Research 36 (2006) 671-677

B2093 – Enthalpy increments of Ba2Te3O8(s) and Ba3Te2O9(s) compounds

The enthalpy increments of the compounds Ba2Te3O8(s) and Ba3Te2O9(s) were measured in the temperature range 298-965 K, using a high temperature Calvet calorimeter. The values were least square fitted in the following temperature dependent polynomial equations: ?HT 298.15K (J/mol)Ba2Te3O8(s) = -77, 233 + 234.87 T + 0.08108 T2 (298.15-862.8K), ?HT 298.15K (J/mol)Ba2Te3O8(s) = 21, 533 - 209.39 T + 0.46007 T2 (862.8-965 K), ?HT 298.15K (J/mol)Ba3Te2O9(s) = -116, 177 + 338.96 T + 0.00741 T2 + (4, 310, 572)/T. The temperature differentials of the above equations gave the heat capacity equations for the respective compounds, which were compared with Neumann-Kopp's estimated heat capacities. As heat capacity of TeO3 was not available in literature, it was estimated from that of TeO2. Using the Gibbs energy of formation data of Ba3Te2O9(s), reported in literature, ?fH° 298.15K, and S° 298.15K of the compound were calculated as -2258 kJ/mol and 822 J/(mol K), respectively.
R. Agarwal, Z. Singh, Journal of Alloys and Compounds 414 (2006) 230-234

B2059 – Preparation and properties of sodium iron orthooxomolybdates, NaxFey(MoO4)z

Five different crystalline phases are established in the quaternary system Na-Fe-Mo-O with isolated MoO4 tetrahedra: NaFe(MoO4)2, Na3Fe2(MoO4)3, alpha- and beta-NaFe2(MoO4)3 and NaFe4(MoO4)5. The optimized conditions for sample preparation are described together with structural analyses by X-ray and neutron powder diffraction. The observed crystal structures are compared with known structure types. The hightemperature behaviour, thermal expansion, decomposition or congruent melting, is reported together with some preliminary characterisation of oxygen release as requested for catalytic activity in partial oxidation of hydrocarbons. Magnetic properties and antiferromagnetic ordering have been studied by magnetisation measurements and neutron diffraction.
H. Ehrenberg, E. Muessig, K.G. Bramnik, P. Kampe, T. Hansen, Solid State Sciences 8 (2006) 813-820

B2047 – High-temperature heat capacity of zirconolite (CaZrTi2O7)

Enthalpy increment measurements in the range of (520 to 1570) K were carried out utilizing drop calorimetry on zirconolite (CaZrTi2O7). The high-temperature dependence of the heat capacity of zirconolite has been determined from the simultaneous analysis of our enthalpy increment measurements and published low-temperature heat capacity data.
P. Pöml, T. Geisler, R.J.M. Konings, J. Chem. Thermodynamics 38 (2006) 1013-1016

B2046 – Isobaric specific heat capacity of water and aqueous cesium chloride solutions for temperatures between 298 K and 370 K at p = 0.1 Mpa

There has been some controversy regarding the uncertainty of measurements of thermal properties using differential scanning calorimeters, namely heat capacity of liquids. A differential scanning calorimeter calibrated in enthalpy and temperature was used to measure the isobaric specific heat capacity of water and aqueous solutions of cesium chloride, in the temperature range 298 K to 370 K, for molalities up 3.2 mol.kg-1, at p = 0.1 MPa, with an estimated uncertainty (ISO definition) better than 1.1%, at a 95% confidence level. The measurements are completely traceable to SI units of energy and temperature. The results obtained were correlated as a function of temperature and molality and compared with other authors, obtained by different methods and permit to conclude that a DSC calibrated by Joule effect is capable of very accurate measurements of the isobaric heat capacity of liquids, traceable to SI units of measurement.
M.J.V. Lourenço, F.J.V. Santos, M.L.V. Ramires, C.A. Nieto de Castro, J. Chem. Thermodynamics 38 (2006) 970-974

B2043 – Phase diagram and thermodynamics of the La2O3-Ga2O3 system revisited

Previous thermodynamic description of the La2O3-Ga2O3 system has been updated based on new experimental data on the liquidus and the enthalpies of formation of LaGaO3 and La4Ga2O9 measured by high-temperature oxide melt drop solution calorimetry as well as calculated from first-principles. The existing contradictions were successfully resolved. Both the phase diagram and thermodynamic data were reproduced with high accuracy by thermodynamic calculations using the CALPHAD method.
M. Zinkevich, S. Geupel, F. Aldinger, A. Durygin, S.K. Saxena, Mei Yang, Zi-Kui Liu, Journal of Physics and Chemistry of Solids 67 (2006) 1901-1907

B2039 – Crystal structure and physicochemical properties of a new organic condensed phosphate (C7H10NO)3P3O9.4H2O

Chemical preparation, X-ray characterization, IR spectroscopy and thermal analysis of a new cyclotriphosphate: (C7H10NO)3- P3O9.4H2O abbreviated as OACTP, are reported. This mixed organo-mineral compound crystallizes in the monoclinic system with P21/n space group, the unit cell dimensions are: a = 6.605(3) Å , b = 26.166(3) Å , c = 18.671(8) Å , beta = 91.95(3)°, Z = 4 and V = 3255(2) Å3. The structure was solved using a direct method and refined to a reliability R-factor of 0.043 using 3931 independent reflections (I > 2?I). Atomic arrangement exhibits infinite (P3O9 2H2O)n 3n- chains connected by organic cations. The thermal behavior and the IR spectroscopic studies of this new compound are discussed.
L. Guelmami, T. Guerfel, A. Jouini, Materials Research Bulletin 42 (2007) 446-455

B2029 – Heat capacities of some ternary oxides in the system Ba-Fe-O using differential scanning calorimetry

Ternary oxides such as BaFe12O19(s), BaFe2O4(s), Ba2Fe2O5(s), Ba3Fe2O6(s) and Ba5Fe2O8(s) of Ba-Fe-O system were synthesized by solidstate reaction route taking stoichiometric proportions of preheated BaCO3(s) and Fe2O3(s) powders of high purities. The standard molar heat capacities of these ternary oxides were determined using differential scanning calorimetry from 310 to 850 K. A heat capacity anomaly was observed for BaFe12O19(s), a member of magnetoplumbite group and largely used as hard ceramic magnet exhibited a heat capacity anomaly at 725K in differential scanning calorimetric result. This anomaly is due to the magnetic order-disorder transition from ferrimagnetic state to paramagnetic state of the compound and the transition temperature has been termed as Curie temperature (TC). Thermodynamic functions such as ?fHm° (298.15 K), Sm° (298.15 K), Sm° (T ), Cp,m°(T ), Hm° (T ), {Hm° (T ) - Hm° (298.15 K)}, Gm°(T ), fef (free energy function), ?fHm°(T ) and ?fGm°(T ) for these ternary oxides were also calculated from 298 to 1000K using the second law analysis.
S.K. Rakshit, S.C. Parida, Smruti Dash, Ziley Singh, B.K. Sen, V. Venugopal, Journal of Alloys and Compounds 438 (2007) 279-284

B2014 – Synthesis, structure and thermal behaviour of a barium-glutarate framework

A hybrid framework material has been synthesized via a gel diffusive technique. Its X-ray single crystal structure has been determined at 120 K, in the tetragonal space group P4 2/mbc. The ligand is partially deprotonated giving interesting supramolecular bonding formed by hydrogenoglutarate anion, which can act as a building synthon. The layer-type polymeric structure is built up from isolated polyhedra linked via conventional carboxylate bridges and forming inorganic layers in the plane (001). Along [001], layers consisting of the methylene spacers of the ligands, complete the three-dimensional framework. The thermal analysis performed by TGA and DSC in air and under N2, respectively, revealed the high stability of the non-templated framework (up to 210°C) and showed several phase transitions and one solid-state reaction detected by an exothermic peak at 500°C.
K. Aliouane, A. Djeghri, A. Guehria-Laidoudi, S. Dahaoui, C. Lecomte, Journal of Molecular Structure 832 (2007) 150-155

B2002 – Three-dimensional ionic frameworks built up from La (III) and Ce (III) succinates

Two three-dimensional ionic open-framework rare-earth succinates have been synthesized. The lanthanum-based compound, 1, was obtained by the silica gel technique and the cerium-based compound, 2, via grown phase under reflux. These two coordination polymers are isostructural. Their layer-type structure is built up from infinite chains of one-edge-sharing polyhedra, discrete chloride ions and lattice water molecules. Strong hydrogen bonds cross link the two-dimensional substructure into a three-dimensional open-framework exhibiting wide channels parallel to [1 0 0] direction. The tetratopic succinate ligand, involved in a syn-anti bridging-chelating mode, links the metal atoms through µ2-oxo bridges. The thermal analysis confirms the high stability of the materials, probably due to the infinite metal-oxygen-metal arrays.
N. Rahahlia, B. Benmerad, A. Guehria-Laïdoudi, S. Dahaoui, C. Lecomte, Journal of Molecular Structure 833 (2007) 42-48

B1983 – The heat capacity of NdPO4

The heat capacity of neodymium orthophosphate has been measured in the temperature range (0.6 to 1570) K. From the results the excess (electronic) heat capacity has been derived by subtracting the lattice heat capacity derived from the heat capacity of the isostructural LaPO4 and GdPO4, reported earlier. The calculated excess heat capacity thus obtained is in reasonable agreement with that calculated from the crystal field energies.
K. Popa, F. Jutier, F. Wastin, R.J.M. Konings, J. Chem. Thermodynamics 38 (2006) 1306-1311

B1947 – Energetics of charge order transition in Bi(1-x)SrxMnO3

The transition from the high-temperature pseudocubic form of the perovskite manganites Bi(1-x)SrxMnO3, x = 0.3; 0.5; 0.8, to their orthorhombically distorted charge-ordered state is examined. As the experimental probe the measuring of the heat capacity by heat flux DSC incremental method above 300K and by relaxation method below 300K is used. While a broad symmetrical transition spanning the temperature interval ?T~500K with a maximum at the apparent TCO~500K is observed for x = 0.5, the other two compositions reveal typical lambda-shaped peaks often considered as typical for the second order transitions. The total entropy release on heating is interpreted in terms of a simultaneous change of charge, orbital and spin degree of freedom.
D. Sedmidubsky, A. Strejc, O. Benes, K. Ruzicka, J. Hejtmanek, P. Javorsky, M. Nevriva, C. Martin, Journal of Solid State Chemistry 179 (2006) 3798-3804

B1946 – Synthesis and crystal structure of metal-organic frameworks [Ln2(pydc-3,5)3(H2O)9]n3nH2O (LnDSm, Eu, Gd, Dy; pydc-3,5Dpyridine-3,5-dicarboxylate) along with the photoluminescent property of its europium one

Rare-earth metal-organic frameworks, [Ln2(pydc)3(H2O)9]n3nH2O (LnDSm, Eu, Gd, Dy; pydcDpyridine-3,5-dicarboxylate), were synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The solid-state photoluminescence measurements exhibited red light-emitting characteristic of europium (III) coordination polymer. The title compounds consist of onedimensional dual chains, in which each metal atom is nine-coordinated with oxygen atoms.
Q. Shi, S. Zhang, Q. Wang, H. Ma, G. Yang, W-H Sun, Journal of Molecular Structure 837 (2007) 185-189

B1924 – Crystal structure, phase transition and thermal behaviour of dabcodiium hexaaquacopper(II) bis(sulfate), (C6H14N2)[Cu(H2O)6](SO4)2

A new organically templated metal sulfate has been synthesized and characterized. At room temperature, dabcodiium hexaaquacopper( II) bis(sulfate), (C6H14N2)[Cu(H2O)6](SO4)2 crystallizes in the monoclinic symmetry (space group P21/n) with the following unit cell parameters: a = 6.9533(2), b = 12.5568(2), c = 9.9434(2) Å ; b = 90.526(1) and Z = 2. Its crystal structure is built from isolated [Cu(H2O)6]2+, (SO4)2- and disordered (C6H14N2)2+ ions linked together by a hydrogen-bonding network. The title compound undergoes a reversible phase transition of the first-order type at 265.7/281.8 K on heating-cooling runs. Below the phase transition temperature, the structure is fully ordered.
H. Naïli, W. Rekik, T. Bataille, T. Mhiri, Polyhedron 25 (2006) 3543-3554

B1908 – Heat capacity, enthalpy and entropy of bismuth niobate and bismuth tantalate

The heat capacity and the heat content of bismuth niobate BiNbO4 and bismuth tantalate BiTaO4 were measured by the relaxation method and Calvet-type heat flux calorimetry. The temperature dependencies of the heat capacities in the form Cpm = 128.628+0.03340 T -1991055/T2+136273131/T3 (JK-1 mol-1) and 133.594+0.02539 T - 2734386/T2+235597393/T3 (JK-1 mol-1) were derived for BiNbO4 and BiTaO4, respectively, by the least-squares method from the experimental data. Furthermore, the standard molar entropies at 298.15K Sm(BiNbO4) = 147.86 JK-1 mol-1 and Sm(BiTaO4) = 149.11 JK-1 mol-1 were assessed from the low temperature heat capacity measurements. To complete a set of thermodynamic data of these mixed oxides an attempt was made to estimate the values of the heat of formation from the constituent binary oxides.
M. Hampl, A. Strejc, D. Sedmidubsky, K. Ruzicka, J. Hejtmanek, J. Leitner, Journal of Solid State Chemistry 179 (2006) 77-80

B1902 – Neutron structural and vibrational studies of dipotassium selenate tellurate

At room temperature the potassium selenate tellurate K2SeO4.Te(OH)6 (KSeTe) was prepared from water solution of H6TeO6 and K2SeO4. Its structure has been determined from single crystal using neutron diffraction data. KSeTe is monoclinic with C2/c space group. The unit cell parameters are: a = 11.572(9) Å, b = 6.437(7) Å, c = 13.938(1) Å, beta = 106.07(7)°, V = 997.7(1) Å3 and Z = 4. The main feature of this structure is the presence of two different and independent anions (TeO6 6- and SeO4 2-) in the same unit cell. The structure is built by layers of TeO6 octahedra altering with planes of SeO4 tetrahedra linked by a network of hydrogen bonds performed by protons belonging to the OH hydroxide groups. DSC measurements indicate that the crystals of K2SeO4.Te(OH)6 undergo three endothermal peaks at 433, 480 and 495 K. Raman scattering measurements on KSeTe material taken between 300 and 620K are reported in this paper. The spectra indicate clearly these phase transitions.
M. Dammak, T. Mhiri, A. Cousson, Journal of Alloys and Compounds 407 (2006) 176-181

B1895 – Water and magmas: Thermal effects of exsolution

The temperature changes caused by water exsolution from magma have been determined through calorimetric measurements performed on phonolitic and albitic compositions. The enthalpies of mixing of water with these melts have been derived from HF solution calorimetry, made at 323 K on glass samples containing up to 5 wt.% water, together with heat capacity data for the same series of samples. Mixing between aluminosilicate melts and water appears nearly ideal at magmatic temperatures, with small enthalpies of mixing that are negative for both melts at low pressures but can become positive for albite at high pressure. Regardless of the endothermic or exothermic nature of the process, water exsolution is associated with negligible temperature changes of only a few degrees even when 5 wt.% H2O is degassed. However, thermal effects might be greater for more depolymerized melts such as basalts and related compositions.
P. Richet, G. Hovis, A. Whittington, Earth and Planetary Science Letters 241 (2006) 972-977

B1884 – Heat capacity, enthalpy and entropy of Li2CO3 at 303.15-563.15K

Measurements of the heat capacity of lithium carbonate were carried out with a heat conduction calorimeter in the temperature range of 303.15-563.15K at atmospheric pressure. The temperature dependence of the heat capacity is Cp (J mol-1 K-1) = 92.80 + 0.09T - 1.91 x 10^6.T -2. The thermodynamic functions with reference temperature 298.15 K, calculated in the same temperature range are: HT - H298 (kJ mol-1) = -48.92 + 0.14T + 6.68 x 10^5.T -2, ST - S298 (J mol-1 K-1) = -53.73 + 0.24T - 1.55 x 10^6.T -2.
L. Kourkova, G. Sadovska, Thermochimica Acta 452 (2007) 80-81

B1883 – Kinetics and thermodynamics of the attack of fluorapatite by a mixture of sulfuric and phosphoric acids at 55°C

A calorimetric study of kinetics and thermodynamics of the attack of a synthetic fluorapatite by a mixture of sulfuric and phosphoric acids is undertaken at 55°C. The global enthalpy of the attack equals -409.3 kJ/mol. The recorded thermograms show two peaks leading to calcium sulfate hemihydrate and dihydrate, respectively. The deconvoluted curves were analysed iteratively. A kinetic mechanism based on simultaneous reactions has been proposed for the first peak and confirmed thermochemically by comparing the enthalpies deduced from iteration and that determined from experimental and calculated routes. The second peak of the thermogram was attributed to transformation of calcium sulfate hemihydrate into gypsum according to a dissolution/precipitation scheme. These phenomena are of order one and two, respectively.
K. Antar, M. Jemal, Thermochimica Acta 452 (2007) 71-75

B1874 – Thermodynamic and spectroscopic studies on the phase transition of BaHf(PO4)2

We have studied the thermal properties of BaHf(PO4)2 during the heating from the room temperature up to 1600K by thermal analysis and drop calorimetry and up to 835K by Raman spectroscopy. A phase transition appears at about 791K during heating and at 744K during cooling. For the high-temperature polymorph we determined the crystal class and the most likely space groups based on Raman spectroscopic data. The enthalpy of the transition was derived from the high-temperature heat capacity measurements.
K. Popa, R.J.M. Konings, O. Benes, T. Geisler, A.F. Popa, Thermochimica Acta 451 (2006) 1-4

B1873 – Matériaux de référence pour les techniques d’analyse thermique et de calorimétrie et méthodes de mesure calorimétriques

L'article fait le point sur la disponibilité et les travaux qui sont menés dans le domaine des matériaux de référence pour les techniques de calorimétrie et d'analyse thermique. Les méthodes de mesure calorimétriques sont largement répandues dans les laboratoires d'analyse physico-chimique et permettent en particulier de caractériser le comportement thermique des matériaux,de déterminer les paramètres thermodynamiques comme les températures et les chaleurs latentes de changement d'état (fusion,cristallisation,sublimation,évaporation,..), les enthalpies de réaction, la capacité calorifique,.. Comme tout appareil de mesure,un analyseur thermique ou un calorimètre doit être étalonné en température et en énergie avec l'aide de matériaux de référence. Alors que les principaux fournisseurs dans le domaine sont historiquement le NBSaméricain (aujourd'hui le NIST) et la société anglaise LGC,aujourd'hui l'élaboration et la certification de matériaux de référence pour les méthodes d'analyse thermique et de calorimétrie connaissent un vifregain d'intérêt. Le PTB allemand a introduit récemment sur le marché différents matériaux de référence,et un projet de développement est en cours au Japon. C'est dans ce contexte que le BNM a commandé une étude destinée à faire le point sur besoins en matériaux de référence dans le domaine calorimétrique et à entreprendre des expérimentations préliminaires qui ont été réalisées dans le laboratoire du Professeur Bernard Legendre à l'Université de Paris-Sud, en relation avec Jean-Rémy Filtzet Bruno Hay (BNM-LNE).
P. Le Parlouër, B. Legendre, Revue Française de Métrologie n°1, Volume 2005-1

B1861 – Crystal structure (at T = 163 K) and phase transitions of NH4HgI3.H2O

NH4HgI3.H2O crystallizes in the monoclinic system, space group Cc (No. 9), with: a= 10.9865(11) Å; b= 9.7683(10) Å; c= 8.6759(9) Å; beta = 90.395(8)°; V = 931.07(16)Å3 and Z = 4 (T = 163 K). Refinement of single crystal X-ray data lead to R(F) = 0.0271. The structure consists of tetrahedra [HgI4] linked by common corners to infinite chains, running parallel to [0 0 1]. The ammonium groups and water molecules are located between the chains ensuring the stability of the structure by hydrogen bonding contacts: N-H. . . I, O-H. . . I and N-H. . . O. Differential scanning calorimetry reveals three anomalies at 219, 345 and 375 K. The peak at 219 K, according to the single crystal X-ray diffraction, was attributed to an orientational disorder of ammonium groups. IR-spectroscopy shows that the NH4HgI3.H2O compound loses crystallization water gradually in the temperature range (350-540 K).
M. Loukil, A. Kabadou, I. Svoboda, A. Ben Salah, H. Fuess, Journal of Alloys and Compounds 386 (2005) 107-114

B1852 – Thermodynamic properties of undoped and Fe-doped LiMn2O4 at high temperature

Thermodynamic properties of undoped and Fe-doped LiMn2O4 were studied at temperatures from room temperature to 1473 K and in oxygen partial pressures from 50 to 105 Pa by XRD, TG-DTA and drop calorimetric methods. For undoped LiMn2O4, three phase transitions (T1, T2, T3) in TG-DTA measurement were observed in various oxygen partial pressures, though in O2 any anomaly was not observed at T3. For doped LiMn2KxFexO4, the starting temperature of weight-loss of oxygen at T1 decreased with increasing doped content for xO0.1. Phase transition temperature at T2 decreased with increasing doped content, but any anomaly in TG-DTA curve was not observed at T3 for all Fe-doped LiMn2O4. Chemical potential diagram in the Li-Mn-O system was established on the basis of TG-DTA and high-temperature XRD results. The enthalpies of the disproponation reaction (DHZ547G70 JgK1 at xZ0 and DHZ573G120 JgK1 at xZ0.3) for LiMn2KxFexO4 at T2 calculated from chemical potential diagram were in good agreement with the values (DHZ534G25 JgK1 at xZ0 and DHZ537G26 JgK1 at xZ0.3) obtained from high-temperature drop calorimeter within the experimental error, respectively.
T. Tsuji, H. Umakoshi, Y. Yamamura, Journal of Physics and Chemistry of Solids 66 (2005) 283-287

B1844 – Growth of piezoelectric single crystals by the flux method

Transparent single crystals of the piezoelectric materials alpha-GaPO4 have been grown by the spontaneous nucleation method from Li2Mo3O10 flux. The solubility of alpha-GaPO4 in Li2Mo3O10 flux has been determined between 650 and 950°C. Lattice parameters of crystals have been measured by X-ray diffraction. Result of infrared spectroscopy indicates the possibility of growing alpha-GaPO4 crystal without hydroxyl groups by the flux method.
M. Beaurain, P. Armand, P. Papet, Journal of Crystal Growth 275 (2005) e279-e282

B1842 – Thermochemical studies on SrFe12O19(s)

The citrate-nitrate gel combustion route was used to prepare SrFe12O19(s) powder sample and the compound was characterized by X-ray diffraction analysis. A solid-state electrochemical cell of the type: (-)Pt, O2(g)/ {CaO(s) + CaF2(s)}//CaF2(s)//{SrFe12O19(s) + SrF2(s) + Fe2O3(s)}/O2(g), Pt(+) was used for the measurement of emf as a function of temperature from 984 to 1151 K. The standard molar Gibbs energy of formation of SrFe12O19(s) was calculated as a function of temperature from the emf data and is given by: DfG m(SrFe12O19, , s, T)/kJ mol-1 (± 1.3) = 5453.5 + 1.5267 (T/K). Standard molar heat capacity of SrFe12O19(s) was determined in two different temperature ranges 130-325 K and 310-820 K using a heat flux type differential scanning calorimeter (DSC). A heat capacity anomaly was observed at 732 K, which has been attributed to the magnetic order-disorder transition from ferrimagnetic state to paramagnetic state. The standard molar enthalpy of formation, DfH m (298.15 K) and the standard molar entropy, S m(298.15 K) of SrFe12O19(s) were calculated by second law method and the values are 5545.2 kJ mol-1 and 633.1 J K-1 mol-1, respectively.
S.K. Rakshit, S.C. Parida, S. Dash, Z. Singh, R. Prasad, V. Venugopal, Materials Research Bulletin 40 (2005) 323-332

B1806 – Standard enthalpy of formation of lanthanum oxybritholites

Lanthanum-bearing silicate-oxyapatites or britholites, Ca10-xLax(PO4)6-x(SiO4)xO with 1
K. Ardhaoui, J. Rogez, A. Ben Chérifa, M. Jemal and P. Satre, Journal of Thermal Analysis and Calorimetry 86 (2006) 553-559

B1805 – Thermodynamic studies of (R)-binol-menthyl dicarbonates

The (R)-BINOL-menthyl dicarbonates, one of the most important compounds in catalytic asymmetric synthesis, was synthesized by a convenient method. The molar heat capacities Cp,m of the compound were measured over the temperature range from 80 to 378 K with a small sample automated adiabatic calorimeter. Thermodynamic functions [HT-H298.15] and [ST-S298.15] were derived in the above temperature range with a temperature interval of 5 K. The thermal stability of the substance was investigated by differential scanning calorimeter (DSC) and a thermogravimetric (TG) technique.
X.-C. Lv, Z.-C. Tan, Z.-A. Li, Y.-S. Li, J. Xing, Q. Shi and L.-X. Sun, Journal of Thermal Analysis and Calorimetry 86 (2006) 541-546

B1804 – Thermodynamic study of a series lithium beta-diketonates

Thermal behaviour of a series of lithium beta-diketonates: Li(dpm) (dpm=dipivaloylmethanate (2,2,6,6-tetramethylheptane-3,5- dionate)), Li(pta) (pta=pivaloyltrifluoracetonate (2,2-dimethyl-6,6,6-trifluoro-3,5-hexanedionate)), Li(tfa) (tfa=trifluoracetylacetonate (1,1,1-trifluoro-2,4-pentandionate)), Li(hfa) (hfa=hexafluoracetylacetonate (1,1,1,5,5,5-hexafluoro-2,4-pentandionate)) has been investigated. Gas phase composition of these complexes has been established. Temperature dependences of vapor pressure of lithium compounds were obtained by static and dynamic methods, and thermodynamic parameters were calculated. Dependence of compound volatility on ligand structure is shown. For Li(dpm) detailed investigation has been done by differential scanning calorimetry (DSC).
E.S. Filatov, S.V. Sysoev, L.N. Zelenina, T.P. Chusova, V.A. Logvinenko, P.P. Semyannikov and I.K. Igumenov, Journal of Thermal Analysis and Calorimetry 86 (2006) 537-539

B1802 – Etude cinétique et thermodynamique de l’attaque d’une fluorapatite par des mélanges d’acides sulfurique et phosphorique à 25°C

L'étude thermodynamique et cinétique de l'attaque d'une fluorapatite synthétique par des mélanges d'acides sulfurique et phosphorique a été réalisée à 25°C par calorimétrie. La valeur de l'enthalpie globale de cette attaque est égale à -407.0 kJ/mol. L'interprétation des résultats calorimétriques par le modèle d'Avrami a permis de mettre en évidence l'existence de 2 étapes dont la première est la dissolution du solide, et la seconde, la précipitation du gypse. Le traitement par itération des courbes déconvoluées a permis de déduire les paramètres cinétiques et l'enthalpie de précipitation. Cette dernière ne s'écarte que de 2.3% de celle déterminée expérimentalement. L'ordre par rapport aux ions calcium et aux ions sulfate est trouvé égal à 2 et 0.5 respectivement.
K. Antar, K. Brahim, M. Jemal, Thermochimica Acta 449 (2006) 35-41

B1801 – Enthalpy of mixing in 0.8[xB2O3-(1-x)SiO2]-0.2K2O melts at 973K

0.8[xB2O3-(1-x)SiO2]-0.2K2O (with 0
A.P. Ahoussou, J. Rogez, A. Kone, Thermochimica Acta 447 (2006) 109-111

B1789 – Di-ureasil ormolytes doped with Mg2+ ions. Part 1: Morphological, thermal and electrochemical properties

Poly(oxyethylene) (POE)/siloxane-based materials incorporating magnesium triflate (Mg(CF3SO3)2) were synthesized by the sol-gel process. The host Class II hybrid matrix (di-ureasil) employed is composed of a siliceous framework to which short POE chains are covalently bonded through urea linkages. Ormolytes with salt composition n (molar ratio of oxyethylene moieties per Mg2+ ion) ranging from V to 1 were investigated. The nanohybrid with n =20, which is thermally stable up to 360°C, exhibits the highest conductivity (e.g., approximately 4.0 10 6 and 6.7 10 5 S cm 1 at 35 and 104°C, respectively). The redox stability domain of this material spans from 3.0 to +2.0 V vs. Mg/Mg2+.
S.C. Nunes, V. de Zea Bermudez, M.M. Silva, S. Barros, M.J. Smith, E. Morales, L.D. Carlos, J. Rocha, Solid State Ionics 176 (2005) 1591 - 1599

B1787 – Structural and conductivity study of a newprotonic conductor Cs0.86(NH4)1.14SO4 Te(OH)6

The crystal structure of Cs0.86(NH4)1.14SO4 Te(OH)6 is determined by X-ray diffraction analysis. The space group is P21=c with a = 13,681(3) Å, b = 6,608(1) Å, c = 11,362(2) Å, beta = 106,65(3)° and Z = 4 at 293 K. The structure is refined to R = 2,9%. The distribution of atoms can be described as isolated TeO6 octahedra and SO4 tetrahedra. The Cs+ and NH4 + cations, occupying the same positions, are located between these polyhedra. The main feature of this structure is the coexistence of two types of anions in the same crystal related by network hydrogen bonds. The mixed solid solution cesium ammonium sulphate tellurate exhibits two phase transitions at 470 and 500 K. These transitions, detected by differential scanning calorimetric, are analyzed by dielectric measurements using the impedance and modulus spectroscopy techniques.
M. Dammak, L. Ktari, A. Cousson, T. Mhiri, Journal of Solid State Chemistry 178 (2005) 2109-2116

B1786 – Synthesis and thermochemical study of ligand substitution reactions of aminobis(phosphines), Ph2P(R)NPPh2, with [Me2Pt(COD)]

The reactions of aminobis(phosphines), Ph2PN(R)PPh2 (R = H, Me, Et, nPr, nBu, Ph), with Me2Pt(COD) led to the formation of four-membered metallacycles in good yield. The enthalpies of the ligand substitution reactions are measured by the anaerobic solution calorimetry in THF at 30°C.
M.S. Balakrishna, S. Priya, W. Sommer, S.P. Nolan, Inorganica Chimica Acta 358 (2005) 2817-2820

B1771 – Phase diagram and electrical conductivity of EuBr2-LiBr binary system

The phase diagram of the EuBr2-LiBr binary system was established from DSC investigations. It includes the LiEu2Br5 compound which melts incongruently at 781K and a eutectic at molar fraction of EuBr2, x = 0.319, melting at 723 K. The electrical conductivity of EuBr2-LiBr liquid mixtures was measured over the whole composition range as a function of temperature.
S. Gadzuric, E. Ingier-Stocka, L. Rycerz, M. Gaune-Escard, Journal of Alloys and Compounds 397 (2005) 63-67

B1753 – Phase diagram and electrical conductivity of the EuBr2-NaBr binary system

DSC was used to study phase equilibrium in the EuBr2-NaBr system. It represents a typical example of simple eutectic system with the eutectic composition, x(EuBr2) = 0.546, and eutectic temperature 762 K. The electrical conductivity of EuBr2-NaBr liquid mixtures was measured down to temperatures of solidification. Reflectance spectra of the pure components and their solid mixtures (after homogenisation in the liquid state) with different composition were recorded in order to confirm the reliability of the constructed phase diagram.
E. Ingier-Stocka, S. Gadzuric, L. Rycerz, M. Cieslak-Golonka, M. Gaune-Escard, Journal of Nuclear Materials 344 (2005) 120-123

B1752 – Thermodynamic and structural properties of high temperature solid and liquid EuBr2

Heat capacity of solid and liquid EuBr2 was measured by differential scanning calorimetry in the temperature range 300-1100 K. The temperature and enthalpy of fusion were also determined experimentally. By combination of these results with the literature data on the entropy at 298.15 K, S0m(EuBr2; s; 298.15 K), and the standard molar enthalpy of formation, DformH0m(EuBr2; s; 298.15 K), the thermodynamic functions of europium dibromide were calculated up to T = 1300 K. Preliminary structural investigations were conducted both by reflectometry and Raman spectroscopy.
L. Rycerz a, S. Gadzuric b,d, E. Ingier-Stocka a, R.W. Berg c,M. Gaune-Escard, Journal of Nuclear Materials 344 (2005) 115-119

B1739 – Lithium ion conductive oxysulfide, Li3PO4-Li3PS4

"Ionic conductivity of Li3PS4 was enhanced by the two ways: quenching method and addition of Li3PO4. The quenching method froze its high-temperature phase partially down to room temperature and increased its ionic conductivity by three times. Addition of Li3PO4 resulted in the formation of a new metastable phase, the composition of which was considered to be around 0.25Li3PO4-0.75Li3PS4. Its conductivity at room temperature was 7.3 10 5 S cm 1, which was about 100 times higher than that of Li3PS4."
K. Takada, M. Osada, N. Ohta, T. Inada, A. Kajiyama, H. Sasaki, S. Kondo, M. Watanabe, T. Sasaki, Solid State Ionics 176 (2005) 2355 - 2359

B1737 – Thermodynamical control of the grain size of LiCoPO4 powders

The control of the grain size distribution of the LiCoPO4 compound was achieved by a thermodynamically monitored heating regime of the used ceramic route. For this purpose, on the basis of calorimetric (DSC-TG) measurements collected in non-isothermal and isothermal regime and then related to the grain size of the final product via equations, the irreversibility degree of the heating regime was determined. Grain size of the final product was revealed by scanning electron microscopy (SEM), while the purity of the final product was discussed from thermodynamic calculations (DSC and TG) and confirmed by X-ray diffraction analysis (XRD). The purity and the grain size of the product was tested a priori, using a series of heating regimes and then the accuracy of the established model was checked.
V. Grigorova, D. Roussev, P. Deniard, S. Jobic, Journal of Physics and Chemistry of Solids 66 (2005) 1598-1608

B1717 – Alizarin crystals: An extreme case of solvent induced morphology change

The organic compound alizarin (1,2-dihydroxy-9,10-anthraquinone) normally crystallizes as very long needles. However, if alcohol is used as solvent, a completely different, triangular shape is obtained. Due to disorder and twinning of the crystals single crystal X-ray diffraction could not be used to establish a possible difference in crystal structure. Differential scanning calorimetry, IR and Raman spectroscopy and powder X-ray diffraction show that the two forms of alizarin are isostructural. From this it follows that solvent influence rather than polymorphism causes the difference in crystal habit. Surface examination, using optical, scanning electron and atomic force microscopy provides information on the mechanism of habit change, which is introduced by the blocking of growth of specific crystal faces in the alcohol solutions.
R.E. Algra, W.S. Graswinckel, W.J.P.van Enckevort , E. Vlieg, Journal of Crystal Growth 285 (2005) 168-177

B1687 – Determination of the enthalpy of fusion of K3TaF8 and K3TaOF6

The areas of the fusion and crystallization peaks of K3TaF8 and K3TaOF6 have been measured using the DSC mode of the high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities and the temperature dependence of the used calorimetric method sensitivity, the values of the enthalpy of fusion of K3TaF8 at temperature of fusion 1039 K: ?fusHm(K3TaF8; 1039 K) = (52 ± 2) kJ mol-1 and of K3TaOF6 at temperature of fusion 1055 K: ?fusHm(K3TaOF6; 1055 K) = (62 ± 3) kJ mol-1 have been determined.
L. Kosa and I. Mackova, Thermochimica Acta 447 (2006) 209-211

B1677 – Heat capacities and thermodynamic functions of the tellurates(IV) of zinc and cadmium

The temperature dependencies of the molar heat capacities of ZnTeO3, Zn2Te3O8, CdTeO3 and CdTe2O5 are determined. The experimental data are statistically processed using the least squares method to determine the parameters in the equations for the corresponding compounds: Cp,m=a+b(T/K)-c(T/K)-2. These equations and the standard molar entropies are used to determine ?T0S0m, ?TTH0m and (?0m+?T,0H0m/T) for T'=298.15 K.
G. Gospodinov and L. Atanasova, Journal of Thermal Analysis and Calorimetry 82 (2005) 439-442

B1676 – Calorimetric study of cesium hexafluoroarsenate CsAsF6 at elevated temperatures

The heat capacity of cesium hexafluoroarsenate, CsAsF6, was measured from 300 to 850 K by differential scanning calorimetry. The results indicate that the structural transformation from the rhombohedral to cubic phase, occurring in the range 235-360 K, relates to gradual transition completed isothermally. The enthalpy of the transition is 6.015±0.186 kJ mol-1, and its entropy is 17.21±0.58 J K-1 mol-1?Rln8, which suggests that this structural transition belongs to the order-disorder type. The thermodynamic properties of CsAsF6 were evaluated in the range 10-760 K.
G. A. Sharpataya, K. S. Gavrichev, A. V. Khoroshilov, V. N. Plakhotnik and V. M. Gurevich, Journal of Thermal Analysis and Calorimetry 82 (2005) 339-346

B1668 – Molar heat capacities of the tellurites CoTeO3, MnTeO3 and MnTe6O13 in medium temperature range

The temperature dependence of the molar heat capacities of the tellurites CoTeO3, MnTeO3 and MnTe6O13 are determined. By statistical manipulation of the values obtained, the parameters in the equations for the corresponding compounds showing this dependence are determined using the least-squares method. These equations and the standard molar entropies are used to determine the thermodynamic functions for T'=298.15 K.
G. Gospodinov and L. Atanasova, Journal of Thermal Analysis and Calorimetry 83 (2006) 273-276

B1650 – Thermodynamics of BaNd2Fe2O7(s) and BaNdFeO4(s) in the system BaNdFeO

Two compounds, BaNd2Fe2O7(s) and BaNdFeO4(s) in the quaternary system BaNdFeO were prepared by citrate-nitrate gel combustion route and characterized by X-ray diffraction analysis. Heat capacities of these two oxides were measured in two different temperature ranges: (i) 130-325 K and (ii) 310-845 K, using a heat flux type differential scanning calorimeter. Two different types of solid-state electrochemical cells with CaF2(s) as the solid electrolyte were employed to measure the e.m.f. as a function of temperature. The standard molar Gibbs energies of formation of these quaternary oxides were calculated as a function of temperature from the e.m.f. data. The standard molar enthalpies of formation from elements at 298.15 K, ?fHm° (298.15 K) and the standard entropies, Sm° (298.15 K) of these oxides were calculated by the second law method. The values of ?fHm° (298.15 K) and Sm° (298.15 K) obtained for BaNd2Fe2O7(s) are: -2756.9 kJ mol-1 and 234.0 J K-1 mol-1 whereas those for BaNdFeO4(s) are: -2061.5 kJ mol-1 and 91.6 J K-1 mol-1, respectively.
S.K. Rakshit, S.C. Parida, S. Dash, Z. Singh and V. Venugopal, Thermochimica Acta 443 (2006) 98-104

B1647 – Enthalpy of mixing in 0.8[xB2O3-(1 – x)P2O5]-0.2Na2O glasses at 298 K

0.8[xB2O3-(1 - x)P2O5]-0.2Na2O (with 0 < x < 1) glasses have been characterized by solution calorimetry at 298 K in acid solvent. The experimental data showed a strong negative departure of the enthalpy of mixing from the ideality described by the equation (in kJ/mol): ?H = x(1 - x)(-660.2 + 570x). The results were interpreted on the basis of the structural data. Enthalpies of mixing were consistent with sub-regular solution behaviour.
A.P. Ahoussou, J. Rogez and A. Kone, Thermochimica Acta 441 (2006) 96-100

B1638 – Détermination des capacités thermiques en fonction de la température par calorimétrie de chute

Le LNE dispose d'une installation de mesure de capacité thermique massique basée sur le principe de la calorimétrie de chute. Cet équipement est destiné à l'étalonnage en enthalpie et en capacité thermique de matériaux de référence. De nombreuses précautions doivent être prises afin de réaliser ce type de mesure avec une faible incertitude. Le laboratoire LCPMB de Châtenay-Malabry présente dans ce document les procédures et conditions expérimentales qu'il applique dans le cadre de ces travaux de recherches pour une détermination précise des fonctions enthalpie et capacité thermique. The LNE has developed a bench for specific heat measurement based on the principle of the drop calorimetry. This set-up is intended for the calibration of reference materials for enthalpy and specific heat measurement. Many cautions must be taken in order to carry out this kind of measurement with a small uncertainty. The LCPMB Laboratory of Châtenay-Malabry presents in this document the procedures and experimental conditions which it applies within the framework of these research tasks for an accurate determination of the enthalpy and specific heat functions.
B. Legendre, D. de Girolamo, P. Le Parlouër et B. Hay, Revue Française de Métrologie n° 5, Volume 2006-1

B1601 – Calorimetric investigation on mechanically activated storage energy mechanism of sphalerite and pyrite

The structural changes of mechanically activated sphalerite and pyrite under different grinding conditions were determined by X-ray powder diffraction (XRD), laser particle size analyzer and elemental analysis. The storage energy of mechanically activated sphalerite and pyrite was measured by a calorimetric method. A thermochemical cycle was designed so that mechanically activated and non-activated minerals reached the same final state when dissolved in the same oxidizing solvent. The results show that the storage energy of mechanically activated sphalerite and pyrite rises with increased in grinding time, and reaches a maximum after a certain grinding period. The storage energy of mechanically activated pyrite decreases when heated under inert atmosphere. The storage energy of mechanically activated sphalerite and pyrite remains constant when treated below 573 K under inert atmosphere. The percentage of the storage energy caused by surface area increase during mechanical activation decreases with increasing grinding time. These results support our opinion that the mechanically activated storage energy of sphalerite is closely related to lattice distortions, and the mechanically activated storage energy of pyrite is mainly caused by the formation of reactive sites on the surface.
Z. Xiao, Q. Chen, Z. Yin, H. Hu, D. Wu, Thermochimica Acta 436 (2005) 10-14

B1588 – The high-temperature heat capacity of LnPO4 (Ln=La, Ce, Gd) by drop calorimetry

The high-temperature heat capacity of three lanthanide orthophosphates of monazite structure have been measured in the temperature range (450 to 1570) K. The data have been analysed in terms of a lattice term, represented by the 4f0 and 4f7 compounds LaPO4 and GdPO4, and an electronic term for CePO4. The calculated excess heat capacity thus obtained is in reasonable agreement with that calculated from the crystal field energies.
K. Popa, D. Sedmidubsky, O. Benes, C. Thiriet, R.J.M. Konings, J. Chem. Thermodynamics 38 (2006) 825-829

B1587 – High temperature heat capacity of Nd2Zr2O7 and La2Zr2O7 pyrochlores

The enthalpy increment measurements were performed using drop calorimetry on two lanthanide zirconates Ln2Zr2O7, Ln = La, Nd, with pyrochlore structure. The temperature dependence of heat capacity in the range (298 to 1550) K was derived by simultaneous linear regression of the measured enthalpies combined with the heat capacity data around ambient temperature. The obtained heat capacity Cp(T ) is compared to the limit of constant volume lattice Cv calculated from the analysis of low temperature specific heat data using a combined Debye-Einstein harmonic approximation model.
D. Sedmidubsky, O. Benes, R.J.M. Konings, J. Chem. Thermodynamics 37 (2005) 1098-1103

B1585 – Heat capacity, enthalpy and entropy of bismuth niobate and bismuth tantalate

The heat capacity and the heat content of bismuth niobate BiNbO4 and bismuth tantalate BiTaO4 were measured by the relaxation method and Calvet-type heat flux calorimetry. The temperature dependencies of the heat capacities in the form Cpm = 128.628 + 0.03340 T - 1991055/T2+136273131/T3 (J K-1 mol-1) and 133.594+0.02539 T - 2734386/T2+235597393/T3 (JK-1 mol-1) were derived for BiNbO4 and BiTaO4, respectively, by the least-squares method from the experimental data. Furthermore, the standard molar entropies at 298.15K Sm(BiNbO4) = 147.86 JK-1 mol-1 and Sm(BiTaO4) = 149.11 JK-1 mol-1 were assessed from the low temperature heat capacity measurements. To complete a set of thermodynamic data of these mixed oxides an attempt was made to estimate the values of the heat of formation from the constituent binary oxides.
M. Hampl, A. Strejc, D. Sedmidubsky, K. Ruzicka, J. Hejtmanek, J. Leitner, Journal of Solid State Chemistry 179 (2006) 77-80

B1580 – The high temperature behavior of barium zirconium diorthophosphate

Barium zirconium diorthophosphate BaZr(PO4)2 was synthesised and its high temperature behavior was studied. At room temperature the compound was found to have a monoclinic structure, in agreement with earlier literature reports. A monoclinic-to-hexagonal phase transition at about 733 K was found by differential thermal analysis; this transition was confirmed by X-ray diffraction and drop calorimetry.
K. Kopa, R.J.M. Konings, P. Boulet, D. Bouëxière, A.F. Popa, Thermochimica Acta 436 (2005) 51-55

B1576 – Thermal characteristics of solid-solid phase transitions in long-chain dialkyl ammonium salts

A series of symmetrical dialkyl ammonium salts, DCnX, has been prepared and characterized with respect to temperature and enthalpy of solid-solid phase transitions, temperature of melting, thermal stability as well as the reversibility of the phase transitions. The number of carbon atoms, Cn, was varied between 8 and 18 and as anions X halides, nitrate, chlorate, perchlorate and hydrogen sulphate had been chosen. In dependence on chain length and anion type transition temperatures from 20 to 100°Cwere observed. Mass specific solid-solid transition enthalpies reach values of 185 J g-1, which makes this class of substances attractive for heat storage applications. The influence of anion type on the transition enthalpies is explained in terms of packing requirements, hydrogen bond network formation and contributions from hindered anion rotation.
S. Steinert, W. Voigt, R. Glausch, M. Neuschutz, Thermochimica Acta 435 (2005) 28-33

B1574 – Etude cinétique et thermodynamique de la dissolution de la fluorapatite dans l’acide phosphorique

A modification on the reversal cells of a C-80 SETARAM calorimeter allows a Joule effect in the reaction cells to determine a transfer function in experimental conditions close to those of dissolution of a solid in a liquid. The calorimeter was then used to determine in isothermal conditions both thermodynamic and kinetic parameters associated with dissolution of synthetic fluorapatite in phosphoric acid solutions. Due to the rapidity of reaction, the heat flow recordings were deconvoluted and the resulting curves were analyzed iteratively to obtain the rates of digestion and the enthalpy of dissolution at 298 K of fluorapatite in phosphoric acid solution containing 10, 18 or 30 wt% P2O5. The results agree with a two-step dissolution mechanism. The first step is the dissolution of the solid in phosphoric acid, and the second is the formation of the complex Ca(H2PO4)+.
K. Brahim, I. Khattech, J.P. Dubes, M. Jemal, Thermochimica Acta 436 (2005) 43-50

B1545 – Calcium hydroxyapatite solubilisation in the hydrochloric and perchloric acids

Enthalpy of solution of calcium hydroxyapatite Ca10(PO4)6(OH)2 (CaHap) in hydrochloric and perchloric acid solutions is measured by an isoperibol calorimeter and a C80 microcalorimeter. The former device is adapted to reactions occurring in concentrated acid solutions, whereas the microcalorimeter is suitable for slow processes happening in diluted acid solutions. Some solution mechanisms are suggested for different pH ranges. They are confirmed by complementary solution in the same solvent of the entities produced by the reaction between CaHap and the acid. These entities are CaCl2; Ca(ClO4)2.nH2O; Ca(H2PO4)2 and H3PO4. Extrapolation of solution enthalpies to pH=7 leads to the solution enthalpy of (CaHap) in pure water, which is -406.2 kJ mol-1 from HCl and -437.3 kJ mol-1 from HClO4.
K. Ardhaoui, A. Ben Cherifa, M. Jemal, Journal of Thermal Analysis and Calorimetry 81 (2005) 251-254

B1524 – Calorimetric study on two biphenyl liquid crystals

The molar heat capacities of the two biphenyl liquid crystals, 3BmFF and 3BmFFXF3, with a purity of 99.7 mol% have been precisely measured by a fully automated precision adiabatic calorimeter in the temperature range between T = 80 and 350 K. Nematic phase-liquid phase transitions were found between T = 297 K and 300 K with a peak temperature of Tpeak = (298.071±0.089) K for 3BmFF, and between T = 316 and 319 K with a peak temperature of Tpeak = (315.543±0.043) K for 3BmFFXF3. The molar enthalpy (?trsHm) and entropy (?trsSm) corresponding to these phase transitions have been determined by means of the analysis of the heat capacity curves, which are (15.261 ± 0.023) kJ mol-1 and (51.202 ± 0.076) J K-1 mol-1 for 3BmFF, (31.624 ± 0.066) kJ mol-1 and (100.249 ± 0.212) J K-1 mol-1 for 3BmFFXF3, respectively. The real melting points (T1) and the ideal melting points (T0) with no impurities of the two compounds have been obtained from the fractional melting method to be (298.056 ± 0.018) K and (298.165 ± 0.038) K for 3BmFF, (315.585 ± 0.043) K and (315.661 ± 0.044) K for 3BmFFXF3, respectively. In addition, the transitions of these two biphenyl liquid crystals from nematic phase to liquid phase have further been investigated by differential scanning calorimeter (DSC) technique; the repeatability and reliability for these phase transitions were verified.
G-L. Zhou, Z-C. Tan, Y-Y. Di, X-Z. Lan, L-X. Sun, T. Zhang, Thermochimica Acta 423 (2004) 83-88

B1518 – Study on synthesis of TPA-Silicalite-1 from initially clear solution of various base concentrations by in situ calorimetry, potentiometry, and SAXS

The synthesis process of TPA-silicalite-1 from a series of initially clear solutions (with a general formula based on mole ratios of the components x:25:480:100 TPAOH:SiO2:H2O:C2H5OH, where TPA = tetrapropylammonium, x = 3-13) was investigated using small-angle X-ray scattering (SAXS), in situ calorimetry, and in situ pH measurement. The size of the nanoparticles detected in the initially clear solutions decreases from 8.5 to 2.5 nm as x increases from 3 to 13. Crystal growth from these solutions at 95°C is first exothermic and then endothermic. The exo-endo thermal switch coincides with a jump in the solution alkalinity. With increasing x the integral heat of exothermic crystal growth decreases monotonically from -0.61 kJ/mol (per mole of Si in the mixture) at x = 4 and approaches zero at x = 12. The integral heat of endothermic crystal growth increases to approach a plateau (0.26 kJ/mol of Si) at x = 7. Crystal growth is fastest at x = 6-7 and relatively slower at x either higher than 7 or lower than 6. At x = 6-11 the zeolite particles assume similar spherical shape and size, about 100 nm in diameter. Outside this range (x < 6 or x > 11), particle size increases significantly. The percentage yield of the zeolite product (on silica basis) can be linearly correlated to x (yield % = 119.7 - 6.34x) from x = 5 to x = 11.5. Outside this linear zone the yield is below this trend at both lower and higher x. The thermodynamic and kinetic aspects of the synthesis process are analyzed and discussed in terms of total surface area reduction of silicate species during crystal growth, effect of surface charge density on kinetics and mechanism of crystal growth, relationship between thermal switch and solution pH jump, and the change in enthalpy and entropy of the synthesis system.
S. Yang, A. Navrotsky, D. Wesolowski, J. Pople, Chem. Mater. 16 (2004) 210-219

B1509 – A comparison between melting-solidification and capillary condensation hysteresis in mesoporous materials: application to the interpretation of thermoporometry data

A methodology based on thermoporometry is proposed to evidence the hysteresis phenomenon observed between melting and solidification of a confined fluid. This method allows plotting hysteresis loops comparable to those observed for gas adsorption-desorption. It is applied to solids with various pore structure, size or connectivity. The hysteresis loops obtained have common features with those observed for capillary condensation suggesting the same type of classification. These are interpreted by similarities between the microscopic mechanisms of displacement of a phase by another in pore systems.
I. Beurroies, R. Denoyel, P. Llewellyn, J. Rouquerol, Thermochimica Acta 421 (2004) 11-18

B1490 – Thermodynamics of natural tourmaline-elbaite

The first experimental data on the heat capacities, enthalpies of formation from the oxides and elements of a natural elbaite: (Na0.48Ca0.44K0.02)(Li1.45Mn0.05Fe0.033+Mg0.09)Al7.01Si6.00B3.05(OH)2.57F0.44O27.18 (Malkhan pegmatite field, east Siberia, Russia) have been obtained. The heat capacities of elbaite were measured by DSC method from T=270 to 540 K. High-temperature enthalpy increments were determined on the Tian-Calvet microcalorimeter at interval of 569-1023 K using the drop method. A value of C°p,m(298.15 K)=757.3 J K-1 mol-1was obtained and the resultant C°p,m(T) equation in the interval T=298.15-1023 K was calculated: C°p,m=919.7+366.2x10^(-3) T -241.4x10^5 T^(-2) ( K-1 mol-1) (±1.4%). The standard molar enthalpy of formation from the elements was determined by high-temperature solution calorimetry in molten lead borate at T=973 K on the Tian-Calvet microcalorimeter. The value of ?fH°m (298.15 K) of elbaite was found to be -15129±19 kJ mol-1. The value of ?fG°m (298.15 K) was calculated as -14 213 kJ mol-1.
L. P. Ogorodova, L. V. melchakova, I. A. Kiseleva, I. S. Peretyazhko, Thermochimica Acta 419 (2004) 211-214

B1488 – Heat capacities of aqueous electrolyte solutions of tetrapentylammonium bromide at temperatures between 20°C and 80°C

K. Nasirzadeh, J. Kröner, W. Kunz, Proceedings ICTAC, Chia Laguna (2004)

B1467 – Low-temperature heat capacity and thermodynamic properties of crystalline carboxin (C12H13NO2S)

Carboxin was synthesized and its heat capacities were measured with an automated adiabatic calorimeter over the temperature range from 79 to 380 K. The melting point, molar enthalpy (?fusHm) and entropy (?fusSm) of fusion of this compound were determined to be 365.29±0.06 K, 28.193±0.09 kJ mol-1 and 77.180±0.02 J mol-1 K-1, respectively. The purity of the compound was determined to be 99.55 mol% by using the fractional melting technique. The thermodynamic functions relative to the reference temperature (298.15 K) were calculated based on the heat capacity measurements in the temperature range between 80 and 360 K. The thermal stability of the compound was further investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The DSC curve indicates that the sample starts to decompose at ca. 290°C with the peak temperature at 292.7°C. The TG-DTG results demonstrate the maximum mass loss rate occurs at 293°C corresponding to the maximum decomposition rate.
M-H. Wang, Z-C. Tan, X-H. Sun, F. Xu, L-G. Kong, L-X. Sun, T. Zhang, Thermochimica Acta 411 (2004) 203-209

B1457 – Preparation, crystal structure, thermal decomposition mechanism and thermodynamic properties of [Co(H2O)6](NTO)2.2H2O

The single crystal of cobalt compound of 3-nitro-1,2,4-triazol-5-one (NTO) ([Co(H2O)6](NTO)2.2H2O) was prepared and the crystal structure has been determined by a four-circle X-ray diffractometer. The compound is monoclinic with space group Cc and unit cell parameters of a=2.3163 (2) nm, b=0.6451 (1) nm, c=1.4123 (1) nm, beta=123.96 (1)°, V=1.7504 (3) nm3 and Z=4. Based on the thermal analysis, the thermal decomposition mechanism of [Co(H2O)6](NTO)2.2H2O has been derived. From measurements of the enthalpy of solution in water at 298.15 K, the standard enthalpy of formation, lattice enthalpy and lattice energy have been determined as -(2594.7±4.5), -2753.19, and -2718.19 kJ mol-1, respectively.
J. Song, J. Huang, H. Ma, R. Hu, Thermochimica Acta 416 (2004) 43-46

B1456 – Thermal decomposition mechanism and thermodynamic properties of [Ni(H2O)6](NTO)2.2H2O

The single crystal of nickel complex of 3-nitro-1,2,4-triazol-5-one (NTO), [Ni(H2O)6](NTO)2.2H2O was prepared and the crystal structure was determined by a four-circle X-ray diffractometer. Based on the results of thermal analysis, the thermal decomposition mechanism of [Ni(H2O)6](NTO)2.2H2O was derived. From measurements of the enthalpy of solution in water of [Ni(H2O)6](NTO)2.2H2O at 298.15 K, the standard enthalpy of formation, lattice enthalpy and lattice energy have been determined as -(2585.6±4.5), -2832.59, and -2797.58 kJ mol-1, respectively.
J. Song, J. Huang, H. Ma, R. Hu, Thermochimica Acta 416 (2004) 39-42

B1455 – Calorimetric studies on leaching of mechanically activated sphalerite in FeCl3 solution

The thermal behaviors of the leaching of mechanically activated sphalerite were investigated for the first time by calorimetry. The specific granulometric surface area and the structural disorder sphalerite were also analyzed by X-ray diffraction laser particle size analyzer and X-ray powder diffraction (XRD) analysis, respectively. A new method to measure the mechanically activated storage energy of minerals was proposed by designing a thermochemical cycle that made mechanically activated and non-activated mineral reaching the same final state while leaching in FeCl3 solution. The results indicate that the mechanically activated storage energy of sphalerite rises with the increased grinding time and is closely related to the lattice distortions and crystallite sizes. The calorimetric results of the products from sieved in water or ethanol medium and the products from 2 h treatment of mechanically activated sphalerite under pure argon (99.99 vol.%) at different temperatures indicate that the mechanically activated storage energy of sphalerite is caused mainly by changes of the crystal structure, and the reactivity of mechanically activated sphalerite is difficult to lose.
Z. Xiao, Q. Chen, Z. Yin, H. Hu, P. Zhang, Thermochimica Acta 416 (2004) 5-9

B1451 – Thermal effects of solvation processes on alkali metal alcoxide formation and stability

The formation of alkali metal alcoxides by an alcohol reacting on the elemental metal itself cannot be completed under stoichiometric conditions. As a consequence of solvation, the chemical activity of the reacting alcohol is drastically reduced. Thus, the reaction cannot undergo completion without a large excess of alcohol with respect to the alkali metal. Moreover, solvation processes can drop the reaction kinetics down to nearly zero. When an excess of alkali metal is reacted with alcohol, the heat accumulated by solvation can be suddenly released by an addition of pure alcohol. Extremely dangerous thermal runaways can be started this way.
A. Hadj Mebarek, C. Cogneville, S. Helle, S. Walter, Journal of Thermal Analysis and Calorimetry 74 (2003) 293-307

B1450 – Thermodynamique des mélanges binaires LiPO3-Pb(PO3)2. Diagramme de phases et étude thermodynamique du liquide

Study of solid-liquid phase diagram of LiPO3-Pb(PO3)2 binary system, in certain calcination conditions, shows the existence of several metastable phasis. When heated at a temperature of 723 K the binary mixtures lead uncompletely to a defined compound Pb2Li(PO3). On heating these ternary solid mixtures, three eutectic reactions have been observed: (1) LiPO3+Pb(PO3)2Liquid at a temperature of 793 K (2) LiPO3+Pb2Li(PO3)5Liquid at a temperature of 843 K (3) Pb2Li(PO3)5+Pb(PO3)2Liquid at a temperature of 891 K The metastable liquid phase appears in the system at temperature of 793 K. DTA experiments performed on the binary LiPO3-Pb(PO3)2 mixtures, show a superposition of two diagrams. The first one is metastable and the second represents the stable equilibrium phase diagram. Measurements of liquid enthalpy of binary LiPO3-Pb(PO3)2 system at temperature of 979.65 K were reported. The corresponding values were very small and so the binary system can be considered as athermal. Assuming an ideal behaviour, the liquidus curves in the metastable diagram were calculated and the eutectic reaction (LiPO3-Pb(PO3)2Liquid) was confirmed at 793 K.
C. Marhag, H. Said, P. Satre, C. Favotto, J. Rogez, Journal of Thermal Analysis and Calorimetry 74 (2003) 275-285

B1444 – Calorimetric study of thermal decomposition of lithium hexafluorophosphate

Enthalpy of formation of lithium hexafluorophosphate was calculated based on the differential scanning calorimetry study of heat capacity and thermal decomposition. It was found that thermal decomposition of LiPF6 proceeds at normal pressure in the temperature range 450-550 K. Enthalpy of LiPF6 decomposition is d H(LiPF6, c, 298.15 K)=84.27±1.34 kJ mole-1. Enthalpy of formation of lithium hexafluorophosphate from elements in standard state is f H 0(LiPF6,c, 298.15 K) = -2296±3 kJ mol-1.
K.S. Gavrichev, G.A. Sharpataya, A.A. Smagin, E.N. Malyi, V.A. Matyukha, Journal of Thermal Analysis and Calorimetry 73 (2003) 71-83

B1434 – Thermal and conductometric studies of NdBr3-LiBr binary system

The heat capacity of solid NdBr3 was measured by Differential Scanning Calorimetry in the temperature range from 300 K up to the melting temperature. The heat capacity of liquid NdBr3 was also determined. These results were least-squares fitted to a temperature polynome. The melting enthalpy of NdBr3 was measured separately. DSC was used also to study phase equilibrium in the NdBr3-LiBr system. The results obtained provided a basis for constructing the phase diagram of the system under investigation. It represents a typical example of simple eutectic system. The eutectic composition, x(NdBr3)=0.278, was obtained from the Tamman construction. This eutectic mixture melts at 678 K. The electrical conductivity of NdBr3-LiBr liquid mixtures and of pure components was measured down to temperatures below solidification. Reflectance spectra of the pure components and their solid mixtures (after homogenisation in the liquid state) with different composition were recorded in order to confirm the reliability of the constructed phase diagram.
L. Rycerz, E. Ingier-Stocka, M. Cieslak-Golonka, M. Gaune-Escard, Journal of Thermal Analysis and Calorimetry 72 (2003) 241-251

B1433 – Phase diagram and electrical conductivity of TbBr3-NaBr binary system

Several experimental techniques were used to characterise the physicochemical properties of the TbBr3-NaBr system. The phase diagram determined by DSC, exhibits an eutectic and a Na3TbBr6 stoichiometric compound that decomposes peritectically (759 K) shortly after a solid-solid phase transition (745 K). The eutectic composition, x(TbBr3)=39.5 mol%, was obtained from the Tamman method. This mixture melts at 699 K. With the corresponding enthalpy of about 16.1 kJ mol-1. Diffuse reflectance spectra of the pure components and their solid mixtures (after homogenisation in the liquid state) confirmed the existence of new phase exhibiting its own spectral characteristics, which may be possibly related to the formation of Na3TbBr6 in this system. Additionally, the electrical conductivity of TbBr3-NaBr liquid mixtures was measured down to temperatures below solidification over the whole composition range.
L. Rycerz, M. Cieslak-Golonka, E. Ingier-Stocka, M. Gaune-Escard, Journal of Thermal Analysis and Calorimetry 72 (2003) 231-239

B1425 – Thermochemical properties of Bi2CuO4

The heat capacity and the heat content of Bi2CuO4 were measured by Calvet calorimetry (300-570 K) and by drop calorimetry (670-970 K), respectively. The temperature dependence of the heat capacity in the form Cpm=185.249+1.453x10^(-3) T - 4.730x10^6) T^(-2) +4.620x10^8 T^(-3) was derived by the least square method. The enthalpy of solution of Bi2CuO4 as well as the stoichiometric mixture of Bi2O3 and CuO in the lead borate melt were measured at 970 K. The heat of formation of Bi2CuO4 from the constituent binary oxides and elements at 298.15 K are -14.63±1.47 and -740.12 kJ mol-1, respectively.
A. Strejc, D. Sedmidubsky, K. Ruzicka, J. Leitner, Thermochimica Acta 402 (2003) 69-74

B1415 – Oxide melt solution calorimetry of rare earth oxides : techniques, problems, cross-checks, successes

Key to the evaluation of the long-term durability and reactivity of REE-materials is the accurate determination of their thermodynamic properties. High-temperature oxide melt solution calorimetry offers an effective methodology for the determination of enthalpies of formation for REE-materials. Calorimetric techniques and crosschecks are summarized that demonstrate that consistent and correct thermodynamic data can be generated using lead borate and sodium molybdate solvents. A summary of recent calorimetric studies of REE-orthophosphates and REE-oxyapatites illustrates the successful application of our techniques in quantifying formation enthalpies and elucidating energetic trends.
K.B. Helean and A. Navrotsky, Journal of Thermal Analysis and Calorimetry 69 (2002) 751-771

B1413 – Enthalpies of phase transitions and heat capacity of TbCl3 and compounds formed in TbCl3-MCl systems (M=K, Rb, Cs)

The molar enthalpies of the solid-solid and solid-liquid phase transitions were determined by differential scanning calorimetry for pure TbCl3 and KTb2Cl7, RbTb2Cl7, CsTb2Cl7, K3TbCl6, Rb3TbCl6 and Cs3TbCl6 compounds. Both types of compounds, i.e. M3TbCl6 and MTb2Cl7 (M=K, Rb, Cs) melt congruently and show additionally a solid-solid phase transition with a corresponding enthalpy trs H 0 of 6.1, 7.6 and 7.0 kJ mol-1 for potassium, rubidium and caesium M3TbCl6 compounds and trs H 0 of 17.1 (rubidium) and of 12.1 and 10.9 kJ mol-1 (caesium) for MTb2Cl7 compounds, respectively. The enthalpies of fusion were measured for all the above compounds with the exception of Rb3TbCl6 and Cs3TbCl6. The heat capacities of the solid and liquid compounds have been determined by differential scanning calorimetry (DSC) in the temperature range 300-1100 K. The experimental heat capacity strongly increases in the vicinity of a phase transition, but varies smoothly in the temperature ranges excluding these transformations. Cp data were fitted by an equation, which provided a satisfactory representation up to the temperatures of C p discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained agreed satisfactorily with these experimental data
L. Rycerz, M. Gaune-Escard, Journal of Thermal Analysis and Calorimetry 68 (2002) 973-981

B1358 – Diagrammes de phases de l’équilibre liquide-solide détermination expérimentale et prédiction

B. Belhachemi, 28ème JEEP (2002) 169-174

B1355 – Thermal decomposition of B-N-H compounds investigated by using combined thermoanalytical methods

The thermal decomposition of borazane BH3NH3 in the temperature range up to 500 K has been studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) combined with the FTIR spectroscopic and mass spectrometric analysis of the gas phase. Above 340 K borazane is decomposed in stages as the temperature is increased. The exothermic decomposition is accompanied by the release of approximately 2.2 mol H2/mol BH3NH3. This corresponds to a remarkable hydrogen storage density of 14.3 mass% related to the mass of borazane. In the gas phase above the solid decomposition residue monomeric aminoborane (BH2NH2), borazine (BHNH)3, which is the boron-nitrogen analog of benzene, and traces of diborane B2H6 were found beside hydrogen. The release of significant quantities of borazine was observed only at temperatures above 400 K.
F. Baitalow, J. Baumann, G. Wolf, K. Jaenicke-Robler, G. Leitner, Thermochimica Acta 391 (2002) 159-168

B1354 – Determination of standard enthalpies of formation of the tellurites of the rares earths Y, La, Ce and Pr by DSC method

The standard enthalpies of tellurites of Y, La, Ce and Pr were determined by differential scanning calorimetric (DSC) method. The completeness of the chemical reactions between the metal oxides and tellurous oxide were checked by DSC and X-ray powder diffraction methods. The calculated standard enthalpies are presented.
G.G. Gospodinov, G. Baikusheva-Dimitrova, Journal of Thermal Analysis and Calorimetry 68 (2002) 103-107

B1353 – Thermodynamic study of the molten salt binary system KHSO4-NaHSO4

The partial molar enthalpies of mixing of NaHSO4 and KHSO4 have been measured at 528 K by dropping samples of pure compounds into molten mixtures of NaHSO4 and KHSO4 in Calvet calorimeter. From these values the molar enthalpy of mixing has been deduced. The same method has been used for the determination of the heat capacity of the two pure compounds in the solid and liquid states. The phase diagram of this system has been confirmed by conductometric and thermal analysis methods. By an optimization method the excess entropy of the liquid mixtures was also calculated.
G. Hatem, K.M. Eriksen, R. Fehrmann, Journal of Thermal Analysis and Calorimetry 68 (2002) 25-30

B1346 – High-temperature heat capacity and thermodynamic functions of zinc telluride

High-temperature heat capacities were measured using the Setaram DSC 111 in the temperature range 290-925 K. Experimental data were smoothed jointly with earlier determined low-temperature heat capacities to calculate thermodynamic properties in temperature range 15-925 K. Extrapolation of heat capacity curve to 1500 K allows to calculate Gibbs free energy at high temperatures.
K.S. Gavrichev, G.A. Sharpataya, V.N. Guskov, J.H. Greenberg, T. Feltgen, M. Fiederle, K.W. Benz, Thermochimica Acta 381 (2002) 133-138

B1345 – Heat capacity of mixed oxides in the Bi2O3-CaO system

The low-temperature heat capacities of mixed oxides in the Bi-Ca-O system have been determined by the relaxation method at temperatures from 15 to about 225 K. The high-temperature heat capacities have been measured from 340 to about 1030 K using differential scanning calorimetry (DSC) in a stepwise mode. From the results, standard molar entropies and molar heat capacities at 298.15 K as well as their temperature dependencies were evaluated.
P. Abrman, D. Sedmidubsky, A. Strejc, P. Vonka, J. Leitner, Thermochimica Acta 381 (2002) 1-7

B1335 – High temperature calorimetric studies of silicate melts

Silicate melts are complex inorganic molten salts harboring a variety of temperature dependent speciation and structural changes. Their thermodynamic properties pose difficult experimental challenges. Direct measurement of enthalpies of fusion, enthalpies of dissolution of crystalline oxides into the melt, and enthalpies of mixing in the molten state requires specialized calorimeters, sample containment, and experimental procedures. The Thermochemistry Facility at the University of California at Davis is well equipped to handle these problems. Using a variety of calorimetric and ancillary equipment (see Table 1), we can design experiments in the range 200 - 1773 K (Navrotsky, 1997).
A. Navrotsky, Setaram news n°6 (2001)

B1320 – The measurement of hydration heats for magnesium chloride with low water by means of DSC

The heats of hydrationreactions for MgCl24H2O and MgCl22H2O include two parts, reaction enthalpy and adsorption heat of aqueous vapor on the surfaces of magnesium chloride hydrates. The hydration heat for the reactions MgCl24H2O+2H2OMgCl26H2O and MgCl22H2O+2H2OMgCl24H2O, measured by DSC-111, is -30.36 and -133.94 kJ mol-1,respectively. The adsorption heat of these hydration processes, measured by head-on chromatography method, is -13.06 and -16.11 kJ mol-1, respectively. Themolar enthalpy change for the above two reactions is -16.64 and -118.09 kJ mol-1, respectively. The comparison between the experimental data and the theoretical values for these hydration processes indicates that the results obtained in this study are quite reliable.
J. Chen, P. Ma, G. Chen, F. Chen, Journal of Thermal Analysis and Calorimetry 65 (2001) 777-786

B1319 – Thermophysical investigations of the polymorphous phases of calcium carbonate

1. Results of thermodynamic and kinetic investigations for the different crystalline calcium carbonate phases and their phase transition data are reported and summarized (vaterite: V; aragonite: A; calcite: C). AC: T tr=455±10°C, tr H=403±8 J mol-1 at T tr, VC: T tr=320-460°C, depending on the way of preparation,tr H=-3.2±0.1 kJ mol-1 at T tr,tr H=-3.4±0.9 kJ mol-1 at 40°C, S V = 93.6±0.5 J (K mol)-1, AC: E A=370±10 kJ mol-1; XRD only, VC: E A=250±10 kJmol-1; thermally activated, iso- and non-isothermal, XRD 2. Preliminary results on the preparation and investigation of inhibitor-free non-crystalline calcium carbonate (NCC) are presented. NCCC: T tr=276±10°C,tr H=-15.0±3 kJ mol-1 at T tr, T tr - transition temperature, tr H - transition enthalpy, S - standard entropy, E A - activation energy. 3. Biologically formed internal shell of Sepia officinalis seems to be composed of ca 96% aragonite and 4% non-crystalline calcium carbonate.
G. Wolf, C. Günther, Journal of Thermal Analysis and Calorimetry 65 (2001) 687-698

B1313 – Enthalpy increments of SrRuO3(s)

A. Banerjee, R. Prasad, V. Venugopal, Thermans (2002) 285-286

B1308 – Enthalpies of formation of YGa2 and LaGa2 by solution calorimetry

R. Babu, B. Prabhakara Reddy, K. Nagarajan, PR Vasudeva Rao, V. Venugopal, Thermans (2000) 56-58

B1295 – Low temperature behaviour of refined products from DSC measurements and their thermodynamical modelling

The low temperature behaviour of five distillation cuts (230-375°C) from crude oil from different sources (North Sea, Africa and Middle East) provided by the Portuguese refinery Petrogal, was studied. Precipitation curves for these cuts, showing the evolution of the fraction of solid n-alkanes with temperature, were measured by DSC and the compositions of the cuts were analysed by gas chromatography (GC). The measured precipitation curves have been compared with the predictions from a thermodynamical model using the compositional analysis. The model results agree well with the experimental data indicating that the model used can be an adequate tool to predict the low temperature behaviour of refined oil products.
A.J.N. Queimada, C. Dauphin, I.M. Marrucho, J.A.P. Coutinho, Thermochimica Acta 372 (2001) 93-101

B1277 – The dissolution of silica and alumina in silicate melts : in situ high temperature calorimetric studies

High temperature calorimetry using molten silicate solvents has been used to evaluate, in situ, the mixing properties of two network-forming oxides Al2O3 and SiO2 in several silicate melts at 1760 K. In K2O - SiO2 solvents, the partial molar enthalpy of mixing of super cooled liquid SiO2 ranges from -11.4 to +4.6 kJ/mol as SiO2 concentration is increased from 66 to 75 mole %. For mixed cation solvents (0.2CaO, 0.8K2O)-SiO2, the partial molar enthalpy of mixing ranges from -10.6 to - 3.6 kJ/mol for the same composition range. The energetics reflect the depolymerization of the silicate melt framework and the formation of melt species with Si-O-Mn+ bonds. Decreased field strength of the network modifying cation, Mn+, favors Si-O-Mn+ formation. However, as predicted by Le Chatelier's Principle, since Si-O-Mn+ formation is exothermic, this species becomes less dominant as temperature is increased. This temperature-dependence of the depolymerizing reactions, which define silicate melt structure, may relate to the configurational changes of alkali silicate melts which result in non-Arrhenian structural relaxation. The enthalpy of solution of Al2O3 depends on the composition of the silicate solvent and the concentration of Al2O3. The enthalpy of solution ranges from 33.3 to 151.7 kJ/mol for the concentration range 0 to 10 mole % Al2O3 in potassium silicate solvents. In mixed cation solvents, the enthalpy of solution ranges from 33.6 to 64.4 kJ/mol in the concentration range O to 10 mole % Al2O3. The dissolution of Al2O3 in these silicate solvents reflects the interaction between supercool ed Al2O3 liquid and the existing melt species and is also influenced by the identity of the charge-balancing cation. In potassium end-member melts, the low degree of interaction between K+ and the polymerized framework means that Al3+ cation repulsions dominate the melt energetics and results in an ordered melt with predominance of K-O-Al species and a strong concentration dependence of the enthalpy of solution. In mixed cation melts the ability of Ca2+ to perturb the melt network results in a melt that has a variety of structural environments for AlO4 tetrahedra. Accordingly the concentration dependence of the heat of solution is less pronounced.
M.C. Wilding, A. Navrotsky, N. Jb. Miner. Abh. 172 (1998) 177-201

B1276 – High temperature calorimetric studies of the heat of solution of La2O3 in silicate liquids

High temperature calorimetry at 1760 K has been used to measure the heat of solution of La2O3 in a series of simple alkali and alkaline earth silicate liquids. The heat of solution in these solvents is strongly exothermic and varies as a function of liquid composition. However, the variation of the heat of solution does not follow simple trends related to cation size or charge and varies little with La2O3 concentration. The variation of heat of solution with composition of the liquid reflects the ability of La(III) to perturb the transient silicate framework and compete with other cations for oxygen. This complex pattern of melt energetics is consistent with recent spectroscopic measurements which suggest extreme perturbation of the silicate framework by La(III), sufficient to isolate oxygen from silicon. This interpretation suggests the presence of phase-ordered regions rich in La(III) consistent with incipient liquid-liquid immiscibility suggested by previous calorimetric studies. Within error the heat capacity of La-bearing silicate liquids is the same over the super-cooled liquid range as in the stable liquid, with no evidence for the large heat capacities associated with melt restructuring. Thus the energetics of the liquid are dominated by the exothermic reactions which form La-clusters and these phase-ordered regions do not dissociate as temperature increases up to 1760 K.
M.C. Wilding, A. Navrotsky, Journal of Non-Crystalline Solids 265 (2000) 238-251

B1274 – Cooling rates of hyaloclastites : applications of relaxation geospeedometry to undersea volcanic deposits

Glass fragments from three different hyaloclastites have been used to evaluate the range of cooling rates experienced by undersea volcanic deposits. We found that the glass fragments retain structures with a range of apparent quench rates from 25 to 0.15 K min-1. The most rapid cooling rates are interpreted to be those resulting from cooling of the lava near the water interface. Simple conductive cooling models produce a range of quench rates comparable to those of the more rapidly cooled samples. The very slow apparent quench rates are unlikely to result from simple linear cooling through the glass transition, because of the onset of crystallization; instead, they are indicators of a more complex thermal history that involves the annealing of glasses at temperatures within the glass transition interval for a dwell time sufficient to allow the relaxation of the glass to lower temperature structures. The thermal history recorded in these samples illustrates the complexity of eruptive processes and demonstrates that quench rates for natural glasses retain information relevant to more complex cooling models.
M. Wilding, D. Dingwell, R. Batiza, L. Wilson, Bull. Volcanol. 61 (2000) 527-536

B1226 – Heat capacity of CuO in the temperature range of 298.15-1300 K.

The isobaric heat capacity of CuO was measured in the temperature range of 350-1130 K by DSC. The temperature dependence of the heat capacity exhibits rather unusual course which can be explained by significant magnetic contribution extending up to 900 K. The derived heat capacity polynomial equation fits the published experimental heat content data up to 1300 K with sufficient accuracy.
J. Leitner, D. Sedmidubsky, B. Dousova, A. Strejc, M. Nevriva, Thermochimica Acta 348 (2000) 49-51

B1225 – Heat transfer modeling of a DSC plate transducer.

A model is presented which describes the heat transfer between the subsystems of a DSC plate transducer. For the modeling, the DSC plate transducer is divided into seven subsystems with locally uniform temperature. The simulation program for the solution of the model equations is based on the Runge-Kutta-Fehlberg method. Appropriate planning of the experiments can be derived as a result. Thus, the expense of the preliminary experiments can be reduced. In addition, the model allows the measured results to be interpreted more easily.
A. Lindemann, J.Schmidt, Thermochimica Acta 337 (1999) 219-226

B1219 – Calibration of the SETARAM High-Temperature Calorimeter for determination of heat capacity of phases in the Sr-Cu-O system.

A high-temperature Setaram calorimeter was calibrated to measure the heat capacities of Sr-Cu-O phases. The indicated temperature was calibrated through the solidification points of pure metals (ITS-90). Powdered CuO having similar emissivity and heat conductivity to the measured materials was used as a standard for caloric calibration. Two different methods of measurement were examined. Working in continuous scanning mode, the 'classical' three-step method of heat flow rate calibration was used, while for the discontinuous method the respective peak areas were calibrated. The sensitivity calibration curve for the discontinuous method was evaluated from two successive runs carried out on the reference material. The calibrated calorimeter was used for determination of temperature dependences (473-1133 K) of heat capacity of the SrCuO2, Sr2CuO3 and Sr14Cu24O41 phases. Obtained Cp,m0 data measured by the step-by-step procedure were evaluated by two different methods. In the first method, the mean value of Cp,m0 was obtained by dividing the enthalpy change attributed to a given change of temperature by a corresponding ?T. The second method consisted of summing the individual enthalpy contributions and subsequent differentiation of the resulting temperature dependence of enthalpy. Both these approaches yielded comparable results with relative standard deviations of 2-3% from the standard polynomial fit Cp,m0 = a + bT + cT-2. The temperature dependences of heat capacity of measured phases were compared with the low-temperature data taken from the literature as well as with the estimated curves. Our results exhibit a systematic shift to lower Cp,m0 values.
M. Nevriva, D. Sedmidubsky, J. Leitner, Thermochimica Acta 347 (2000) 123-128

B1218 – Calibration of a DSC : its importance for the traceability and uncertainty of thermal measurements.

A differential scanning calorimeter was calibrated by Joule effect and by easuring the temperature of fusion of several pure (99.999%) metals. Repeatability and reproducibility tests were performed to access the accuracy of the instrument, the stability of the calibration constant and the correction to the temperatures of fusion was obtained experimentally. The results demonstrate that this calorimeter is capable of producing data of enthalpies of fusion with an uncertainty of 1.5%, temperatures of fusion between 0.1 and 0.2 K, and heat capacities with an uncertainty of 1.5%, all at a 95% confidence level. In order to calculate the uncertainty of the measurements performed, a discussion about the traceability in thermal measurements and its key elements (relation to 'stated references', unbroken chain of comparisons and stated uncertainties of those references) is done. A possible structure of the traceability chain in DSC and DTA measurements is presented.
C.A. Nieto de Castro, M.J.V. Lourenço, M.O. Sampaio, Thermochimica Acta 347 (2000) 85-91

B1206 – Enthalpy of phase transitions and heat capacity of stoichiometric compounds in LaBr3-MBr systems (M=K,Rb,Cs)

Molar enthalpies of solid-solid and solid-liquid phase transitions of the LaBr3, K2LaBr5, Rb2LaBr5, Rb3LaBr6 and Cs3LaBr6 compounds were determined by differential scanning calorimetry. K2LaBr5 and Rb2LaBr5 exist at ambient temperature and melt congruently at 875 and 864 K, respectively, with corresponding enthalpies of 81.5 and 77.2 kJ mol-1. Rb3LaBr6 and Cs3LaBr6 are the only 3:1 compounds existing in the investigated systems. The first one forms from RbBr and Rb2LaBr5 at 700 K with an enthalpy of 44.0 kJ mol-1 and melts congruently at 940 K with an enthalpy of 46.7 kJ mol-1. The second one exists at room temperature, undergoes a solid-solid phase transition at 725 K with an enthalpy of 9.0 kJ mol-1 and melts congruently at 1013 K with an enthalpy of 57.6 kJ mol-1. Two other compounds existing in the CsBr-based systems (Cs2LaBr5 and CsLa2Br7) decompose peritectically at 765 and 828 K, respectively. The heat capacities of the above compounds in the solid as well as in the liquid phase were determined by differential scanning calorimetry. A special method - step method developed by SETARAM was applied in these measurements. The heat capacity experimental data were fitted by a polynomial temperature dependence.
L. Rycerz and M. Gaune-Escard, Journal of Thermal Analysis and Calorimetry 56 (1999) 355-363

B1196 – Thermochemistry of the decomposition of some cobalt compounds.

Differential scanning calorimetry (DSC) was used to determine the molar enthalpies of dehydration and decomposition of CoC2O4.2H2O, Co(HCOO)2.2H2O and [Co(NH3)6]2(C2O4)3.4H2O. The first stage of dissociation of each compound is a single-step dehydration both in air and argon atmospheres. The next stages are decomposition processes influenced by experimental parameters. The enthalpies of dehydration and decomposition vary from compound to compound in each atmosphere. The obtained data have been related to the macromechanisms proposed for the thermal decomposition and the parallel-consecutive decomposition-oxidation processes.
E. Ingier-Stocka, L. Rycerz, Journal of Thermal Analysis and Calorimetry 56 (1999) 547-552

B1169 – Conductrometric, density and thermal measurements of the M2S2O7 (M = Na, K, Rb, Cs) salts.

Physico-chemical properties, such as densities, conductivities, enthalpies of phase transitions and melting points, have been measured and summarised for the alkali pyrosulphates Na2S2O7, K2S2O7, Rb2S2O7, Cs2S2O7. The densities of the molten pyrosulphates could be expressed by the linear expression ?=A+B(T-Tm) where Tm is the middle temperature of the temperature range measured, i.e. from the melting point and up to 550°C at the maximum. The specific conductivities of the molten pyrosulphates have been expressed by the equation ?=A+B(T-Tm)+C(T-Tm)2+D(T-Tm)3 in the temperature range from the melting point and up to 500°C at the maximum. From these measurements also the activation energy for the equivalent conductivity of the alkali cations in the melts could be calculated and compared to the analogous alkalisulphates. By calorimetric investigations of the alkali pyrosulphates the temperatures of fusion, the enthalpies and entropies of fusion and possible solid-solid transitions together with the molar heat capacities of the solid and liquid pyrosulphates at 300-800 K, have been obtained and discussed in relation to the conductrometric measurements and the few related previous investigations.
G. Hatem, F. Abdoun, M. Gaune-Escard, K.M. Eriksen, R. Fehrmann, Thermochimica Acta 319 (1998) 33-42

B1155 – Thermochemical investigations of calcium carbonate phase transitions. I. Thermal activated vaterite-calcite transition

The vaterite-calcite transition above 630 K has been studied by isothermal and non-isothermal differential scanning calorimetry. Vaterite samples prepared under different conditions were investigated. The transition temperature is strongly dependent on the sample preparation. The observed transition enthalpy Htr is nearly equal for different samples and experimental conditions. From 28 measurements a value of Htr-(3.12±0.11) kJ mol-1 was obtained. The activation energy for the polymorphic transition was calculated from the Arrhenius plot and by use of isoconversional methods, as a function of the degree of conversion. The influence of the kinetic model distortion and experimental uncertainties on the obtained data was discussed. The actual value of the activation energy was assessed at Ea=(250±10) kJ mol-1 for nearly all examined samples. Functions, corresponded to the model mechanism of nuclei formation and growth, provide the unambiguous consideration of the transition kinetic for the investigated vaterite samples. Differences in the dynamic behaviour of several samples at the transition are established.
F. Baitalow, G. Wolf, H-G. Schmidt, Journal of Thermal Analysis and Calorimetry 52 (1998) 5-16

B1143 – Etude du comportement thermique et de la chaleur spécifique du tétrahydrurobéryllate de dilithium Li2BeH4.

The thermal behavior of dilithium-tetrahydridoberyllate Li2BeH4 has been studied up to 825 K by simultaneous DSC-TGA measurements. A solid-solid transition between the hexagonal phenakite form (Be2SiO4) previously described and a possible high-temperature cubic form (Li2SO4-HT) occurs at 536±2 K. In addition the thermal decomposition has been characterized by measuring the mass of gas released during heating up to 1075 K. Two distinct steps in the temperature ranges 545-575 K and 905-935 K indicate a total loss of two moles of hydrogen per mole of hydride. The variation of specific heat against temperature has been measured in the 180-420 K range by differential microcalorimetry. A weak but reproducible and reversible anomaly can be detected in the 320-350 K range. This anomaly is marked by a change in the slope of the Cp vs. T curve. The change in the slope clearly corresponds to a maximum in the vicinity of 340 K on the Cp/T vs T representation. This thermodynamic behavior could be interpreted as a superconductivity criterion when correlated with magnetic irreversibilities previously observed for the same compound. Thus, LiBe2H4 could appear like a type-II superconductor with a critical temperature Tc=(340±10) K. However this remarkable potential property requires resistivity measurements to be definitely established.
S. Contreras, R. Lucas, J.M. Létoffé, J.P. Bastide, A. Bouamrane, M. Diot, P. Claudy, Thermochimica Acta 313 (1998) 75-81

B1137 – Enthalpy of dilution in aqueous systems of single solutes ammonia, sodium sulfate and ammonium sulfate: Experimental results and modeling

The enthalpy of dilution in the sodium sulfate-water, ammonium sulfate-water and ammonia-water systems was measured at temperatures from 313 to 373 K with a Calvet-type batch calorimeter using specially designed mixing cells. The mixing cells allow to pressurize the solutions. The formation of a gas phase during the experiments is thus avoided. Experimental results for the enthalpy of dilution are reported and compared to literature data and correlations.
B. Rumpf, F. Weyrich, G. Maurer, Thermochimica Acta 303 (1997) 77-91

B1132 – Temperature calibration of temperature-modulated differential scanning calorimeters.

Calibration of differential scanning calorimeters (DSC) is essential because it is not possible to calculate heat-flow rate and sample temperature directly from the quantities measured. The question arises whether the calibration used in the conventional DSC mode is also valid for temperature-modulated DSC (TMDSC). To prove this, a well-defined transition is needed which does not disturb the temperature profile within the sample during the modulation, the response of the whole system (calorimeter, sample, transition) must be linear. Some low-energy liquid-crystal transitions behave in this way under certain conditions and can be used for temperature calibration in TMDSC. The procedure is demonstrated for a smectic-A-nematic transition in a cyanobiphenyl liquid crystal (SOCB). Limitations of the method are discussed - in particular, rate effects. The TMDSC measurements also give some information about the order of phase transitions (80CB: SN - second-order; NI - firstorder).
A. Hensel, C. Schick, Thermochimica Acta 304/305 (1997) 229-237

B1128 – Enthalpy increments of strontium and barium zirconates.

Enthalpy measurements on SrZrO3(s) and BaZrO3(s ) were carried out using a Calvet micro-calorimeter. The increase in enthalpies with temperature were analyzed by least squares with the constraint that H°(T) - H ° (298.15 K) at 298.15 equals zero and Cp° (298.15 K) equals the literature value. The dependence of enthalpy on temperature was: H°(T) - H°(298.15 K)(J/mol) = 126.62T(K) + 5.478 x 10^(-3) T^2(K) + 23.553 x 10^5/T(K) - 46138 (SrZrO3 (s)) H°(T) - H°(298.15 K)(J/mol) = 128.53T(K) + 2.571 x 10^(-3) T^2(K) + 25.204 x 10^5/T(K) - 47003 (BazrO3(s)) The first differential of the above equations with respect to temperature gave Cp°(T). Gibbs free energy functions were evaluated using S°(298.15) values from the literature.
A. Banerjee, S. Dash, R. Prasad, V. Venugopal, Thermochimica Acta 298 (1997) 59-64

B1100 – Thermobarometric study of KNO3 phase transitions

In this work, a thermobarometric study of bulk KNO3 submitted to pressure less than 150 MPa has been performed by means of the Metabolemeter system. The effect of pressure on the transitions between the different phases I, II and III have been analysed. Endothermic transformation from II to I takes place through phase III. On cooling from phase I, a coexistence between the phases II and III, metastable at room temperature, is always obtained.
J. Font, J. Muntasell, Thermochimica Acta 293 (1997) 167-170

B1098 – Dissolution enthalpy of NaCl in water at 25°C, 45°C, 60°C. Determination of the Pitzer’s parameters of the (H2O-NaCl) system and the molar dissolution enthalpy at infinite dilution of NaCl in water between 25°C and 100°C

The dissolution enthalpy of sodium chloride in water was measured until saturation at 24.4°C, 44.3°C and 59.2°C using a C80D differential calorimeter (SETARAM). The experimental data were fitted using Pitzer's ion interaction model and the value of the dissolution enthalpy per mole of salt at infinite dilution was found at each temperature by treating as adjustable parameter. Using these calorimetric measurements, the analytical expression of the variation of Pitzer's parameters were established with respect to temperature. The validation of this expression is made by the measurement of vapour equilibrium of binary solution {H2O---NaCl} closed to saturation. Excellent agreement between experimental and calculated values of water activity has been found using our Pitzer's model parameters.
N. Hubert, R. solimando, A. Pere, L. Schuffenecker, Thermochimica Acta 294 (1997) 157-163

B1091 – Déshydratation de l’alun d’ammonium. 2. Interprétation des résultats expérimentaux.

The formation of the two kinds of partially dehydrated amorphous alum can be explained by the water vapour gradient which appears within the sample during dehydration and by existence of a critical water pressureP c at the reaction interface. The mechanisms of dehydration at low and high pressure are described.
F. Mauss, M. Murat, J.M. Missiaen, B. Guilhot, Journal of Thermal Analysis 47 (1996) 1663-1677

B1090 – Déshydratation de l’alun d’ammonium. 1. Résultats expérimentaux.

Dehydration of hydrated ammonium alum is a function of physical gaseous pressure. During dehydration, two kinds of partially dehydrated amorphous alum appears. These solids differ in texture and residual water composition.
F. Mauss, M. Murat, J.M. Missiaen, B. Guilhot, Journal of Thermal Analysis 47 (1996) 799-813

B1080 – Energetics of formation of KF-GdF3 binary-intermediate compounds.

Enthalpies of formation were measured for KGdF4, K2GdF5 and KGd2F7 using the transposed temperature drop calorimetry method. These compounds were synthesized by conventional solid state reaction methods using mixtures of KF and GdF3. The measured enthalpies of formation from fluorides for KGdF4, K2GdF5 and KGd2F7 were - 22.3, - 16.1 and - 18.3 kJ mol-1, respectively. From these measurements, enthalpies of formation from the elements were computed to be - 2290.0, - 2852.4 and - 3985.2 kJ mol-1 for the respective compounds. These enthalpies were compared with estimated values calculated by two methods previously reported to be effective for multicomponent oxides. Estimated values compare favorably with measured data, with deviations ranging from 0.5 to 2.9%. The errors of 0.5-2.9% correspond to a 16-85 kJ mol-1 uncertainty range for ?fH0 of ternary fluorides from binary fluorides. One of these methods, based on the summation of ?fH0 values for the constituent binary fluorides, is recommended for the K---Gd---F compounds.
J.O. Eckert, I-C. Lin, M.M. Lencka, P.M. Bridenbaugh, A. Navrotsky, R.A. Laudise, R.E. Riman, Thermochimica Acta 286 (1996) 233-243

B1079 – Accuracy and precision of heat capacity measurements using a heat flux differential scanning calorimeter.

The accuracy and precision of a Setaram DSC 121 for the measurement of heat capacities of solids in the continuous mode was tested using sapphire and benzoic acid. The influence of the heating rate, mass of sample, and position of the crucible in the measuring tube on the obtained results is discussed. In the temperature range studied (320-440 K for sapphire and 320-370 K for benzoic acid) the accuracy and precision of the determination, based on the average results of three independent experiments, are better than 1% provided that adequate experimental conditions (large sample masses and low heating rates) and data handling procedures are used.
T.M.V.R. de Barros, R.C. Santos, A.C. Fernandes, M.E. Minas da Piedade, Thermochimica Acta 269/270 (1995) 51-60

B1078 – Solid state reactions of chromium(III)-substituted heteropoly tungstates with chromium(III) ammine cations.

The reaction of chromium ammine complexes with chromium-substituted Keggin anions in aqueous solution forms insoluble salts which were then heated to temperatures of 240 and 350°C. The thermal behaviour of the ammine complexes is dominated by a strong exothermic reaction which is interpreted as a linking reaction (condensation) between chromium from the complex ammine cation and the heteropolyanion. Thermal treatment of the title compounds yields products that are soluble in water and could be crystallized as potassium salts in several cases. A chromium-caped Keggin anion is the proposed structure.
M. Feist, K. Wassermann, H-J. Lunk, Thermochimica Acta 269/270 (1995) 465-473

B1077 – Enthalpy, heat capacity, second-order transitions and enthalpy of fusion of Li4SiO4 by high-temperature calorimetry

The enthalpy of Li4SiO4 was obtained between 363 and 1300 K using isothermal drop calorimetry. Anisothermal calorimetry was used for the identification of two second-order transitions and the measurement of the enthalpy of fusion. The smoothed enthalpy between 298 and 1300 K results in H°(T) - H°(298) - 17156 + 73.694 T + 0.103210 T2 - 4163115 T-1 J mol-1. The heat capacity was derived by differentiation. The value extrapolated to 298 K is Cp,298 = 182.1 J K-1 mol-1. The critical temperatures of the second-order transitions are Tc1 = 938 K and Tc2 = 996 K. The enthalpy of fusion is ?fusH = 53 kJ mol-1 at the melting temperature Tm = 1531 K. An isotope effect of the 6Li enrichment on the melting temperature and enthalpy of fusion could not be discerned.
H. Kleykamp, Thermochimica Acta 287 (1996) 191-201

B1072 – Calorimetric study of alkali metal tetrafluoroborates.

Temperatures and enthalpies of phase transitions at temperature above ambient were determined for potassium tetrafluoroborate, lithium tetrafluoroborate, and lithium tetrafluoroborate mono- and trihydrate. It was demonstrated that lithium tetrafluoroborate has only one phase transition in the solid at 300 K.
K. Gavrichev, G.A. Sharpataya, V.E. Gorbunov, Thermochimica Acta 282/283 (1996) 225-238

B1069 – Thermoanalytical and X-ray study of some alkylammonium tetrachlorozincates.

DSC and X-ray studies on mono-, di-, tri- and tetraalkylammonium tetrachlorozincates (alkyl is ethyl, propyl, n-butyl or sec-butyl) were performed in the range 173-500 K. Transition temperatures, enthalpies, entropies, and also lattice parameters of the compounds are given.
R. Blachnik, C. Siethoff, Thermochimica Acta 278 (1996) 39-47

B1067 – Reversible folding in sepiolite : study by thermal and textural analysis.

The structural changes of sepiolite under thermal treatment, and their reversibility, have been examined by thermogravimetry. These changes have been related to the textural changes, determined by N2 adsorption under similar conditions. The folding of this material starts at 390°C, from this temperature the microporosity of the material disappears. This folding is reversible, becoming permanent at 570°C. From 390 to 570°C the surface area remains stable, corresponding to the external surface area of the mineral.
R. Ruiz, J.C. del Moral, C. Pesquera, I. Benito, F. Gonzalez, Thermochimica Acta 279 (1996) 103-110

B1066 – Formation enthalpies of MBr-NdBr3 liquid mixtures (M = Li, Na, K, Rb, Cs).

Molar enthalpies of mixing ?mixHm0, of the LiBr-NdBr3, NaBr-NdBr3, KBr-NdBr3, RbBr-NdBr3, and CsBr-;NdBr3 liquid binary systems have been measured with a Calvet-type high-temperature microcalorimeter under argon at 1063 K over the whole composition range. Mixing of the two liquid components was carried out using a break-off ampoule technique. For all the systems, the enthalpies of mixing were negative and their minima (at ?NdBr3 ? 0.4) were -0.7, -5.4, -12.4, -17.8 and -20.1 kJ mol-1, respectively. The results have been compared with data previously published for MCl-NdCl3 systems and discussed in terms of possible complex formation.
M. Gaune-Escard, A. Bogacz, L. Rycerz, W. Szczepaniak, Thermochimica Acta 279 (1996) 11-25

B1065 – Formation enthalpies of the MBr-LaBr3 liquid mixtures (M = Li, Na, K, Rb, Cs)

Molar enthalpies of mixing of the LiBr-LaBr3, NaBr-LaBr3, KBr-LaBr3, RbBr-LaBr3 and CsBr-LaBr3 systems have been measured with a Calvet-type high-temperature micro-calorimeter. The enthalpies decrease gradually from -0.67 kJ mol-1 for the lithium system through -4.32, -10.73 and -14.97 kJ mol-1 for the sodium, potassium, and rubidium systems to -16.81 kJ mol-1 for that of cesium at the composition of the 3 MBr.LaBr3 compound. The results have been discussed in terms of the conformal solution theory of Davis as well as in terms of relative ionic potentials.
M. Gaune-Escard, A. Bogacz, L. Rycerz, W. Szczepaniak, Thermochimica Acta 279 (1996) 1-10

B1064 – Thermodynamics of CaCO3 phase transitions.

Thermodynamic quantities of the aragonite ---> calcite transition, were evaluated using results of calorimetric investigations. (1) Dissolution enthalpies of the CaCO3 polymorphs aragonite and calcite measured near room temperature with different calorimeter, (2) the enthalpy of the spontaneous phase transformation obtained by differential scanning calorimetry, (3) heat capacities and heat capacity differences determined with a heat flux calorimeter as well as previously determined, (4) e.m.f data on Gibbs-energies of the phase transition were processed simultaneously with an optimization routine developed recently. The optimized data set (25°C) given below corresponds reasonably with CODATA recommendations, however, the precision has markedly improved. ?G* / J mol-1 = -840 ± 20 ?H* / J mol-1 = 440 ± 50 ?S* / J mol-1 K-1 = 4.3 ± 0.2 ?Cp* / J mol-1 K-1 = 0.0 ± 0.2
G. Wolf, J. Lerchner, H. Schmidt, H. Gamsjäger, E. Königsberger, P. Schmidt, Journal of Thermal Analysis 46 (1996) 353-359

B1044 – Le système (PbO + SiO2).

M. Mathon, J.P. Bros, M. Gaune-Escard, JEEP (1996) 116-119

B1042 – Phase diagram of the K2S2O7-KHSO4 system.

K.M. Eriksen, R. Fehrmann, G. Hatem, M. Gaune-Esacrd, O.B. Lapina, V.M. Mastikhin, JEEP (1996) 13-16

B1025 – Standard enthalpy of formation of metal (K, Ba, Li, Ca, Gd, Pb, Cu and Zn) salts of NTO.

From measurements of the enthalpy of solution of metal salts of 3-nitro-l,2,4-triazol-5-one (NTO) in water, the standard enthalpies of formation of KNTO-H20, Ba(NTO)2-3H20, LiNTO-2H20, Ca(NTO)2.4H20 and Gd(NTO)3.7H20 were determined as -(676.9 ± 2.6), -(1627.0 ± 2.5), -(966.6.3 ± 2.2), -(1905.5 ± 4.4) and -(3020.1± 6.4) kJ.mol -I, respectively. From measurements of the enthalpy of precipitation of KNTO.H20 crystal with Pb(NOa)2(aq), CuSO4(aq) and Zn(NO3)2(aq), the standard enthalpies of formation of Pb(NTO)2.H20, Cu(NTO)2.2H20 and Zn(NTO)2.H2O were determined as -(247.4 ± 5.9), -(712.1 ± 5.4) and -(628.8 ± 5.7) kJ.mol-1, respectively.
Z. Meng, R. Hu, Journal of Thermal Analysis 45 (1995) 79-86

B1023 – Determination of the enthalpy of fusion of K3TiF7

The enthalpy of fusion of K3TiF7 at the melting temperature (1048 K) has been determined by treatment of the values measured using a high-temperature calorimeter in the DSC mode with a scanning rate of 1 K min-1. The value obtained was ?fusHm(K3TiF7) = 57 ± 2 kJ mol-1.
K. Adamkovicova, L. Kosa, I. Nerad, I. Proks, J. Strecko, Thermochimica Acta 262 (1995) 83-86

B1020 – Aqueous solution of sodium sulfate. Determination of the dissolution enthalpy at 25, 27.5 and 45°C

The dissolution enthalpy of sodium sulfate in water was measured until saturation at 24.4, 27.5 and 44.3°C using a C80D differential calorimeter (Setaram). The experimental data were fitted using Pitzer's ion interaction model and the value of the dissolution enthalpy per mole of salt at infinite dilution was found at each temperature, by treating (?dissH)8 as an adjustable parameter.
N. Hubert, M. Bouroukba, L. Schuffenecker, Thermochimica Acta 259 (1995) 41-48

B1019 – The heat capacities of yttrium silicates between 773 and 1673 K

U. Kolitsch, H.J. Seifert, H-L. Lukas, F. Aldinger, Conference of SFMC, DMG and OMG Strasbourg (1995)

B1017 – Etude des propriétés physico-chimiques du cyclotriphosphate decahydrate de manganese Mn3(P3O9)2.10H2O

K. Sbai, K. Brouzi, 26th Vacuum technique 225-232

B1016 – Thermal properties of TiO2-RuO2 solid solution

T. Mitsuhahsi, A. Watanabe, JSCTA (1995) 200-201

B1013 – Determination of the enthalpy of fusion of K2TiF6

The enthalpy of fusion of K2TiF6 at the melting temperature (1172 K) was measured by a high-temperature calorimeter in the DSC mode with a scanning rate of 1 K min-1. The measured value was ?fusHm(K2TiF6) = (21 ± 1)kJ mol-1.
K. Adamkovicova, L. Kosa, I. Nerad, I. Proks and J. Strecko, Thermochimica Acta 258 (1995) 15-18

B0947 – Determination of the enthalpy of fusion of NaMgF3 and KMgF3

The enthalpy of melting of NaMgF3 and KMgF3 at the dystectic temperature of fusion of these compounds was determined using a high-temperature calorimeter, the Setaram HTC 1800 K. It was found that ?fusHm(NaMgF3; 1303 K) = (66 ± 4) kJ mol-1 and ?fusHm(KMgF3; 1343 K) = (96 ± 5) kJ mol-1. The given error is calculated at the level of reliability (1 - a) = 0.95.
K. Adamkovicova, P. Fellner, L. Kosa, I. Nerad, I. Proks, J. Strecko, Thermochimica Acta 242 (1994) 23-26

B0946 – Calorimetric and conductometric investigations of the systems K2S2O7-V2O5 and K2S2O7-K2SO4-V2O5 in the range 390-500°C

The systems K2S2O7---V2O5 and K2S2O7---K2SO4---V2O5 are important for the catalytic oxidation of SO2 to SO3. The enthalpies of mixing of solid V2O5 and liquid K2S2O7 have been measured in the whole liquidus range, i.e. up to a mole fraction of around XV2O5 = 0.5, at 400 and 450°C. The enthalpy of liquid-liquid mixing could then be calculated and ?Hmix was found to be strongly exothermic, the partial enthalpy at infinite dilution in K2S2O7, ?HV2O5, being -85.0 kJ mol-1 at 450°C. The local minimum for ?Hmix found at XV2O5 = 0.33 indicates the formation of a dimeric complex (VO2)2(SO4)2S2O4-7 (or possibly formulated as (VO)2O(SO4)4-4) over the whole temperature range 400-450°C. However, lowering the temperature in this range apparently increases the formation of polymeric complexes such as (VO2SO4)n-n. The enthalpy of liquid-liquid mixing at 400 and 450°C has also been obtained for K2SO4 as well as for the three cross-sections K2S2O7.V2O5, 2K2S2O7.V2O5 and 3K2S2O7.V2O5 of the binary system. In these pseudo-binary systems dimeric and polymeric complexes such as (VO2)2(SO4)4-3 and (VO2(SO4)2)3n-n are also probably formed in which polymerization seems to increase at lower temperatures. With increased addition of K2SO4, a compound, probably K3VO2(SO4)2, precipitates. Finally, the conductivities of the same three pseudo-binary cross-sections have been measured in the temperature range 390-500°C and at 20 totally different compositions in the range XK2SO4 = 0-0.55. For each composition and temperature T in the measured range, the conductivity can be expressed by an equation of the form k = A(X) + B(X)(T - 450) + C(X)(T - 450)2 + D(X)(T - 450)3. The calculated molar conductivities exhibit a large deviation from ideality, supporting the concept of strong interaction between the components of the melts.
G. Hatem, R. Fehrmann, M. Gaune-Escard, Thermochimica Acta 243 (1994) 63-77

B0945 – Heat capacity measurement of some oxides with tunnel structure by thermophile type DSC

T. Mitsuhashi, Y. Michiue, Y. Fujiki

B0944 – Non ideality of Mg2SiO4 – Fe2SiO4 olivine solid solutions based on solution calorimetry

M. Akaogi

B0939 – Thermal behaviour of graphite intercalation compounds with oxide of difluoride of phosphoryl

We present in this paper the thermal analysis (calorimetry, TG and DSC) of the first stage P2O3F4 graphite intercalate compound in atmospheric pressure and high pressure. By heating we obtain always exfoliation phenomenon. The heating of exfoliated graphite shows an important oxidation resistance in comparison with another exfoliated graphite. This oxidation resistance has been studied also by thermal analysis like TG, in oxygen atmosphere. Carbon foil rebuilding from exfolied graphite keeps these interesting antioxidation properties.
P. Vast, Journal of Thermal Analysis 41 (1994) 1433-1439

B0937 – Assessment of the surface tension of various divided solids

We have attempted to calculate the surface tension of some solids using immersion calorimetry measurements along with the interfacial model of van Oss [1, 2, 3, 4].
T. Zoungrana, J.M. Douillard, S. Partyka, Journal of Thermal Analysis 41 (1994) 1287-1293

B0928 – Comportement thermique du difluorodioxophosphate ferreux

Difluorodioxophosphates may be used as ceramic phosphate precursor, and their thermal behaviours are very important. In this paper we study by TG and DTA the thermal stability for iron(II) salt. In argon atmosphere, we obtain in a first time the melting of salt at 240°C then the classical breaking up into solid orthophosphate and POF3 exhaust. If the sample of iron(II) difluorodioxophosphate is heating in air, we do not obtain the melting phenomena, but at the same temperature an exothermic phenomenon that conducts to the formation of iron(III). We observe a mass increase. By IR analysis, we can show that this oxidation is obtained without change of difluorodioxophosphate structure
P. Vast, A. Semmoud, Journal of Thermal Analysis 41 (1994) 1489-1493

B0926 – Surface tension of talc and talc-chlorite mixtures

It is possible to estimate surface tension of high-energy solids combining the immersion microcalorimetry thermodynamics and Van Oss' model. In this study we have applied this method on talc and talc-chlorite samples in order to obtain thermodynamic values which permit to understand surface properties useful in the industrial applications of these solids. Some talcite samples are preferentially used in specific industrial applications because they are less hydrophobic or more lamellar. This method seems to be reliable to classify the solids and predict some properties.
J.M. Douillard, H. Malandrini, T. Zoungrana, F. Clauss, S. Partyka, Journal of Thermal Analysis 41 (1994) 1205-1210

B0925 – Quartz-coesite-stishovite transitions : thermodynamic properties and high-pressure phase equilibria

M. Akaogi, H. Yusa, K. Shiraishi, T. Suzuki, JSCTA (1994) 98-99

B0924 – Tetragonal-Monoclinic phase transition enthalpy and temperature of ZrO2-CeO2 solid solutions

DSC (differential scanning calorimeter) measurements were performed to investigate the tetragonal-monoclinic (t-m) transition enthalpy of the compositionally homogeneous ZrO2-X mol% CeO2 solid solution of X = 0, 4, 8, and 12. The transition enthalpy decreases linearly with an increase of CeO2 content. The m => t transition enthalpy on heating agreed well with the inverse t => m one obtained during cooling. With increasing X, the DSC peak broadens and the transition temperature distribution of each sample increases, while the thermal hysteresis is almost independent of X.
M. Yashima, T. Mitsuhashi, H. Takashina, M. Kakihana, T. Ikegami, M. Yoshimura, J. Am. Ceram. Soc. 78 (1995) 2225-2228

B0920 – Calorimetric investigation of PrCl3-NaCl and PrCl3-KCl liquid mixtures

The present work is part of the thermodynamic research performed on the LnCl3---MCl systems (where Ln is lanthanide and M is alkali metal). The molar enthalpies of mixing ?mixHm in the NaCl---PrCl3 and KCl---PrCl3 liquid binary systems were measured at 1122 K over the whole composition range under argon at atmospheric pressure, with an accuracy of about 6%. The apparatus used was a Calvet-type high-temperature microcalorimeter and mixing of the two liquid components was obtained by the break-off ampoule technique. In the systems, the enthalpies of mixing values are negative, with a minimum value of about -7 and -16 kJ mol-1 for NaCl---PrCl3 and KCl---PrCl3, respectively, at xPrCl3 ? 0.4. These values are very similar to those relative to the systems MCl---LnCl3 previously investigated. The molar enthalpies of formation ?fHm(K3PrCl6, 1, 1122 K)/kJ mol-1, ?fHm(Rb3PrCl6, 1, 1122 K)/kJ mol-1 and ?fHm(Cs3PrCl6, 1, 1122 K)/kJ mol-1, according to the reaction 3MCl(1) + PrCl3(1) = M3PrCl6(1), are equal to -55.9, -66.4, and -80.4 kJ mol-1 respectively, and are almost identical (in the limits of experimental uncertainty) to those of the compounds M3LnCl6 (where M is K, Rb, Cs, and Ln is La, Ce, Nd) previously investigated. The least-squares coefficients A, B, C, D and E of the equation for the interaction parameter x = A + Bx + Cx^2+ Dx^3+ Ex^4 (in kJ mol-1) are presented.
M. Gaune-Escard, L. Rycerz, W. Szczepaniak, A. Bogacz, Thermochimica Acta 236 (1994) 59-66

B0916 – Mixing properties in the continuous solid solution of the system KNO3-NaNO3

A previous reinvestigation of the binary phase diagram KNO3---NaNO3 has confirmed the existence of a continuous subsolidus solid solution. The mixing enthalpy in this solid phase, determined by solution calorimetry at 474 K, is presented. A positive and asymmetric deviation from ideality is observed. The results are well fitted by the Van Laar model.
H. Zamali, T. Jriri, J. Rogez, M. Jemal, J.C. Mathieu, Thermochimica Acta 233 (1994) 1-11

B0913 – Melting of Tutton’s salts studied by DSC

The melting behaviour of 27 Tutton's salts [MI2MII(SO4)2 . 6H2O] has been investigated by DSC. The melting point TF and the enthalpy of fusion ?FH of these double salts were determined by the same method. The Tutton's salt with the cations MI= NH4 and MII = Zn offers a remarkably high value of ?FH (285 J/g). From the DSC curves, conclusions have been drawn concerning the mechanism of fusion. The investigated Tutton's salts melt more or less incongruently. The melting process occurs in either one or two steps. In a two-stage melting mechanism the salt first melts with settling of a lower double salt hydrate. The second step seems to be the melting or dissolution of this lower double salt hydrate.
W. Voigt, S. Göring, Thermochimica Acta 237 (1994) 13-26

B0912 – Enthalpies and heat capacities of Li2SiO3 and Li2ZrO3 between 298 and 1400 K by drop calorimetry

The enthalpies of Li2SiO3 and Li2ZrO3 were measured between 368 and 1414 K by an isoperibol Setaram HTC 1800 drop calorimeter. The calibration procedure is described. The smoothed enthalpies between 298 and 1400 K are: H°T - H°298 = - 51157 + 125.860T + 0.01713T2 + 3614467T-1 J/mol H°T - H°298 = -46453 + 134.857T + 0.00740T2 + 1671251T-1 J/mol The standard deviation is ? 3%. The heat capacities were derived by differentiation. The values extrapolated to 298 K are: Cp,298 = (95.4 ± 3.1)J/K mol Cp,298 = (120.4 ± 3.0)J/K mol
H. Kleykamp, Thermochimica Acta 237 (1994) 1-12

B0911 – Etude expérimentale et modélisation des équilibres solide-liquide des binaires eau-nitrate d’yttrium, de baryum, de cuivre. Partie 1. Les systèmes binaires H2O-Ba(NO3)2 et H2O-Y(NO3)3

An experimental study of solid-liquid equilibria of H2O---Ba(NO3)2 and H2O---Y(NO3)3 systems has been conducted using conductimetry and controlled thermal flux analysis. The solid phases were studied using X-ray diffraction, thermogravimetry and chemical analysis such as calcination and DCP.Calorimetric analysis using DSC on the water-barium nitrate eutectic has given the transformation enthalpy (303 J g-1) and the specific heat capacities of the solid and the liquid mix between -20 and + 15°C.The invariant transformation temperatures of the H2O---Y(NO3)3 system have been determined or qualified and the measured metastable melting point of the tetra-, penta- and hexahydrate are respectively 120.4, 77.8 and 51.8°C.A thermodynamic study of the phase equilibria of the two systems has been achieved taking into account ionic dissociation and solvation phenomena. It shows that the barium nitrate in aqueous solution behaves as a binary electrolytic compound, that the yttrium nitrate in aqueous solution is dissociated and that the yttrium ion tends to solvate itself mainly into tetra-, octa- and dodecahydrate.The model used provides an excellent representation of the equilibrium curves. The metastable fusion enthalpies of the various hydrates have been computed and the validity check of these values has been successfully conducted on yttrium nitrate pentahydrate.
R. Bouchet, R. Tenu, J.J. Counioux, Thermochimica Acta 241 (1994) 229-246

B0908 – Calorimetric investigation of NdCl3-MCl liquid mixtures (where M is Na, K, Rb, Cs)

The molar enthalpies of mixing ?mixHm in the liquid NaCl---NdCl3, KCl---NdCl3, RbCl---NdCl3 and CsCl---NdCl3 binary systems have been measured over the whole composition range at 1124, 1065, 1122 and 1122 K, respectively, with an accuracy of about 6%. The apparatus used was a Calvet-type high-temperature microcalorimeter and mixing of the two liquid components was obtained by the break-off ampoule technique. In the investigated systems, the enthalpies of mixing are negative with minimum values at about -5.7, -16.6, -20.2 and -23.4 kJ mol-1, respectively, at ?NdCl3 = 0.4. These values are almost identical, within the experimental accuracy, to those in other previously investigated MCl---LnCl3 mixtures. The molar enthalpies of formation ?fHm(K3NdCl6, 1, 1065)/kJ mol-1, ?fHm(Rb3NdCl6, 1, 1122)/kJ mol-1 and ?fHm(Cs3NdCl6, 1, 1122)/kJ mol-1, according to the reaction 3 MCI(1) + LnCl3(1)= M3LnCl6(1), are equal to -55.2, -68.8 and -80.8 kJ mol-1, respectively. The least-squares coefficients A, B, C, D, E of the equation for the interaction parameter ?= A + B? + C?2 + D?3 + E?4?4 (in kJ mol-1) are presented.
M. Gaune-Escard, A. Bogacz, L. Rycerz, W. Szczepaniak, Thermochimica Acta 236 (1994) 67-80

B0900 – Les systèmes ternaires fondus BaF2-MF-ZrF4. Détermination calorimétrique de l’enthalpie d’excès – Partie 2. M est Li, K

Nous présentons dans ce travail nos résultats relatifs à la mesure par calorimétríe haute-température des enthalpies de formation des deux systèmes ternaires BaF2-KF-ZrF4 et BaF2-LiF-ZrF4. La température expérimentale est voisine de 1173 K pour chaque sec
G. Hatem, K. Mahmoud and M. Gaune-Escard, Thermochimica Acta 230 (1993) 15-28

B0889 – Enthalpies of non-isothermal phase transitions in binary systems

Two kinds of non-isothermal phase transitions in binary systems are considered: transformation of one phase into another and transition from two phases to one phase following an isothermal three-phase reaction (eutectic, peritectic or incongruent melting)
G.G. Chernik, Thermochimica Acta 220 (1993) 37-54

B0888 – Mixing properties in the continuous solid solution of the system AgNO3-NaNO3

The binary phase diagram for AgNO3-NaNO3 has been previously reinvestigated and shows, in particular, a continuous subsolidus solid solution. The mixing enthalpies in this solid phase determined by solution calorimetry at 474 K are presented here. The res
H. Zamalia, J. Rogez, M. Jemal and J.C. Mathieu, Thermochimica Acta 220 (1993) 27-35

B0879 – Thermochemistry and structure of the liquid Na2O-GeO2 system

The integral molar enthalpy of mixing of the liquid mixture Na2O-GeO2 was measured in the composition range from 15 to 100 mol. % GeO2 at 1400 K by the drop-mixing method using a differential high-temperature integrated heat-flux calorimeter. The partial
M. Fan, F. Müller and W. Wilsmann, Thermochimica Acta 224 (1993) 19-32

B0875 – A study by thermal analysis of the reversible folding in palygorskite under vacuum thermal treatment

The structural changes of a Spanish palygorskite, and their reversibility, have been examined by thermal analysis under vacuum. These changes have been related to the textural values obtained under similar conditions by N, adsorption-desorption. The folding of this material under vacuum starts at 125°C, where its microporosity disappears. This folding is reversible up to 300°C. From 125°C the specific surface area remains stable, corresponding to the external surface of the mineral. Thermal treatment above 300°C generates irreversible folding in the structure.
F. Gonzalez, C. Pesquera and I. Benito, Thermochimica Acta 223 (1993) 83-91

B0857 – Thermodynamic data for some complex oxides used in electrolamp production

G.G. Gospodinov and V.M. Marchev, Thermochimica Acta 222 (1993) 143-147

B0856 – The temperature relations of the thermodynamic quantities of Ca, Sr, Ba and Pb zirconates

G.G. Gospodinov and V.M. Marchev, Thermochimica Acta 222 (1993) 137-141

B0846 – Enthalpie de formation des mélanges liquides NaF-NdF3 et diagramme d’équilibre des phases

M. Berkani, G. Hatem, M. Gaune-Escard, JEEP (1993) 131-137

B0845 – Etude du système binaire Na3AIF6-Ba3Al2F12

P. Peretz, G. Hatem, M. Gaune-Escard, JEEP (1993) 125-130

B0842 – Thermostatisierter Probeneinwurf an einem Einwurfkalorimeter – höhere Meßgenauigkeit bei kürzerer Meßzeit –

W. Notter, E. Hahne, ULM (1993)

B0840 – Kalibrierung des HTC 1800-Einwurfkalorimeters und Messung der Enthalpie von Li2SiO3 und Li2ZrO3 zwischen 298 und 1400K

H. Kleykamp, ULM (1993)

B0831 – Détermination de l’enthalpie standard de formation de l’hydrurofluorure de potassium magnesium KMgH2F

L'enthalpie standard de formation de l'hydrurofluorure KMgH2F a été déterminée à partir de la mesure dans un microcalorimètre de type Calvet de l'enthalpie de la réaction KF+Mg+H2=>KMgH2F. La valeur trouvée (-806 ±4kJ mol-1) corrige celle obtenue par une approche différente au cours d'un travail antérieur (-762.6 ± 10 kJ mol-1).
J. Carré, A. Bouamrane, J. P. Bastide, J.M. Létoffé and P. Claudy, Thermochimica Acta 210 (1992) 307-309

B0825 – Thermal analysis in the synthesis and crystal formation of oxides

Vapour phase treatment at elevated temperatures with an activating agent is an effective method of synthesis and purposeful modification of amorphous and fine-grained crystalline substances. In the systems amorphous silica-quartz and amorphous AI(OH)3 -crystalline -Al2O3 different forms of bound water are of prime importance. DTA, TG, DSC, NMR H, 29Si, 27A1, IR spectroscopy, electron- and optical microscopy methods have been used. The interaction of water molecules with the base skeleton and with hydroxide groups on the surface and in the bulk of the silica is of primary significance for modification of the silica structure. The proportion of different forms of the bound water determines the integral evaporation enthalpy of water. Various properties of silica are determined by weak bound water in the surface layer of the material. In the sequence AI(OH)3 - alpha-Al2O3 the structure transformation is observed according to the following scheme: y-AI(OH)3- y-AIOOH- alpha- Al2O3, which takes place during the vapour phase treatment with activator.
V.B. Lazarev, G.P. Panasjuk and A.G. Panasjuk, Journal of Thermal Analysis 38 (1992) 141-152

B0813 – Analysis of Mg2Si04 and CaMgSi2O6

M. Akahogi, JTAS (1992) 236-237

B0805 – Enthalpies of the hydrolysis reaction of Al3+ ion between 25 and 150°C

The heat produced when NaOH is added to Al3+ (m0Al 0.03 mol kg-1) in water has been measured in the range 25-150°C. These calorimetric data are consistent with the chemical model proposed by Mesmer and Baes which considers two polynuclear and one polymeric hydrolytic species of aluminium ion. Other models which consider, in addition, the presence of mononuclear species might be valid as well, while models involving these latter species alone should be ruled out, at least in the experimental conditions adopted in this work. A simple equation is proposed for calculating the enthalpy of formation of hydrolytic species of aluminium from the measured value of the average enthalpy for addition to aqueous Al3+ of one mole of hydroxy groups.
G. Conti, P. Gianni, S. Giannarelli and E. Matteoli, Thermochimica Acta 209 (1992) p 81-101

B0804 – Determination of enthalpy of fusion of K3FSO4

The enthalpy of melting of K3FSO4 at 1148 K has been determined using a hightemperature calorimeter, the Setaram HTC 1800 K. ?fusHm(K3FSO4 is found to equal 86 ± 3 kJ mol-1. The given error is calculated at the level of reliability (1 - alpha) = 0.95.
K. Adamkovicova, L. Kosa, I. Nerad, I. Proks, P. Fellner, Thermochimica Acta 209 (1992) 77-79

B0803 – High temperature phase transitions in rare-earth element niobates R3NbO7

Refractory compounds based on oxides of rare-earth metals (REMs) and niobium are promising materials for use in different areas of modern engineering. However, the body of published data on complex physicochemical studies of the aforementioned phases is extremely restricted, especially for the high temperature range. The purpose of the present study was to probe the thermophysical properties of R3NbO7 (R = Y, La-Lu) at T 298 K and to identify the phase transitions that occur.
A.N. Klimenko, Yu.S. Kozlov, V.S. Sergeev and E.A. Pastukhov, Thermochimica Acta 209 (1992) 331-338

B0790 – Enthalpies of formation for Group IV selenides (GeSe2, GeSe2(am), SnSe, SnSe2, PbSe) by direct-combination drop calorimetry

We have determined the enthalpies of formation for GeSe2(cr), SnSe2(cr), SnSe(cr), and PbSe(cr) and for amorphous GeSe2 using direct-combination drop calorimetry. Our results are as follows: ?fHom(GeSe2, cr, 298 K) = - 84.4 ± 1.8 kJ mol-1, ?fHom(GeSe2, am, 298 K) = - 76.5 ± 1.0 kJ mol-1, ?fHom(SnSe2, cr, 298 K) = - 126.9 ± 1.6 kJ mol-1, ?Hom(SnSe, cr, 298 K) = - 93.8 ± 3.3 kJ mol-1, and ?fHom(PbSe, cr, 298 K) = - 96.3 ± 1.1 kJ mol-1. From our results for ?fHom(GeSe2, cr, 298 K) and ?fHom(GeSe2, am, 298 K), we have calculated the enthalpy of the process GeSe2(am)=>GeSe2(cr) to be (-7.9±2.1) kJ mol-1.
S. Boone and O.J. Kleppa, Thermochimica Acta 197 (1992) 109-121

B0789 – Identification d’un nouvel hydrate de l’acide nitrique pouvant contribuer à la destruction de l’ozone stratosphérique

K. Ji, J.C. Petit, JEEP (1992)

B0772 – Microcalorimetric characterization of coal surface properties during its preparation

P.F. Rossi, G. Oliveri, A. Vettor, JCAT (1992) 313-320

B0768 – Etude par microcalorimétrie des réactions de synthèse et décomposition de l’hexaammoniacate de chlorure de nickel

V. Goetz, A. Marty, JCAT (1992) 431-438

B0763 – Dynamic measurements by heat flux calorimetry

A simple procedure for the deconvolution of signals from a heat flux calorimeter has been tested using the hydrolysis of tert-butyl chloride as a test reaction. Satisfactory results have been obtained even when the half-life of the reaction was as short as about twice the response time of the calorimeter. The results provide some guidance in the selection of correction parameters for various experimental configurations.
T. Boddington, H.A. Chia, P. Halford-Maw, Feng Hongtu and P. G. Laye, Thermochimica Acta 195 (1992) 365-372

B0762 – Thermodynamics of copper binding with some polycarboxylic acids derived from natural amino acids

Copper(II) binding data for four polycarboxylic acids in 0.1 M NaClO4 at 25°C obtained by calorimetric measurements are reported. The polymers studied were poly(N-methacryloyl--alanine), poly(N-methacryloyl--aspartic acid), poly(N-methacryloyl--glutamic acid) and poly(N-methacryloyl--asparagine) obtained from the corresponding natural amino acids. Two different pH domains were studied to account for the formation of different kinds of complexes. In the low pH range where only (RCOO)2Cu complexes are formed for the four polymers, the enthalpy of copper binding is positive, rather low and nearly the same for all the polymers. At higher pH, in the domain where the polymer side chain undergoes deprotonation of the amide group induced by copper, the metal binding is an even more endothermic process. Thus, the binding of copper to these polymers is entirely entropy-driven. In fact, the entropy change, obtained from combination of calorimetric data and potentiometric data, is largely positive in every case and indicates an extensive desolvation of copper ion and carboxylate groups during the binding process.
M. Morcellet, Thermochimica Acta 195 (1992) 335-341

B0761 – Thermodynamics of the copper complexation of a polyelectrolyte derived from lysine

Calorimetric measurements have been made at 25°C in 0.1 M NaClO4 in order to determine the heats of dissociation and the copper coordination of a polyampholyte derived from -lysine, a natural aminoacid. Combining these values with data from potentiometric titrations, the enthalpy of formation of each of the two ligand-metal complexes formed in this system could be determined. These values were compared with those of the model small molecule in order to account for the polyelectrolyte effect.
M. Morcellet, Thermochimica Acta 195 (1992) 277-286

B0756 – Thermal studies on A2U4O12 and A2U4O13 (A =Cs/Rb) by high temperature calorimeter

S. Jayanthi, V.S. Iyer, V. Venugopal, D.D Sood, ITAS (1991) 223-226

B0754 – Thermal investigation of acid-activated attapulgites: influence of isomorphic substitution in the octahedral sheet

Two samples of Spanish attapulgite with different degrees of isomorphic substitution in the octahedral sheet were studied. Both the aluminium-rich and magnesium-rich samples were activated with hydrochloric acid of various concentrations. TG and DSC curves of activated as well as natural attapulgite were obtained. From the analysis of these curves, the influence of the degree of isomorphic replacement of Mg2+ by Al3+ on the results of the acid activation was deduced.
F. Gonzalez, C. Pesquera and I. Benito, Thermochimica Acta 194 (1992) 239-246

B0753 – Determination of the enthalpy of fusion of Na3FSO4

The enthalpy of melting of Na3FSO4 at a temperature of 1060 K was measured by a high-temperature calorimeter, the SETARAM HTC 1800 K. It was found that ?Hfus(Na3FSO4) = 69 kJ mol-1±4 kJ mol-1. The given error is calculated at the level of confidence (1 - alpha) = 0.95.
K. Adamkovicova, P. Fellner, L. Kosa, P. Lazor, I. Nerad and I. Proks, Thermochimica Acta 191 (1991) 57-61

B0740 – Le polymorphisme du sulfate de sodium anhydre et les phases intermédiaires, glasérite et aphtitalite, dans le binaire Na2SO4-K2SO4

Au cours d'études devant conduire à une valorisation de co-produits, les équilibres entre phases condensées du binaire Na2SO4-K2SO4 ont été repris. Si le dimorphisme du sel de potassium est bien établi, le polymorphisme du sulfate de sodium fait l'objet de controverses. Les phases intermédiaires: glasérite (NaK3(SO4)2) admise comme réalisant une solution solide étendue et, aphtitalite (NaKSO4) absente des équilibres hétérogénes, apparaissent dans ce travail avec des compositions stoechiométriques. La première est l'objet d'un invariant péritectoïde à 444°C, la seconde conduit à une transformation congruente vers 470°C. Aux températures plus élevées, l'arrangement hexagonal commun aux deux sulfates est observé.
N. Mofaddel, R. Bouaziz and M. Mayer, Thermochimica Acta 185 (1991) 141-153

B0735 – Physico-chemical transformations under pressure of coacervates and gels of polyphosphates

The physico-chemical transformations of gels and coacervates of polyphosphates (x MO - y P205 - z CaO - n H20, where M = Na or Mg) were investigated under pressure by thermobarometrie analysis. In every ease, the thermobarograms had the same general shape; the transformations were identified by using the infrared spectra of the products obtained at various stages of the analysis and the thermograms obtained by differential scanning calorimetry. The most important result was that the free water release can be detected via a considerable and progressive decrease in pressure resulting from a strong volume decrease. At higher temperature, the hydrolysis of the systems leads to pressure increases.
A. Squalli, G. Palavit, L. Montagne, P. Vast and J.M. Buisine, Journal of Thermal Analysis 37 (1991) 1043-1051

B0733 – Thermodynamic properties of strontium and barium feldspars

Thermodynamic data on Sr and Ba feldspars, SrAl2Si2O8 and BaAl2Si2O8 (celsian), are necessary to calculate the thermodynamics of solid solutions in natural feldspars and to understand the geochemical behaviour of these two elements. Previously the enthalpy of formation of Sr feldspar and celsian had been determined by high temperature solution calorimetry in a lead borate melt. The molar heat capacities of two synthetic Sr and Ba compounds were measured by differential scanning calorimetry between 312 and 712 K. In addition, heat capacities were calculated from a model of the vibrational spectra using optical frequencies measured by IR spectroscopy. The measured and calculated heat capacity values were used to calculate the standard entropies: S298.15(SrAl2Si2O8) = 218.5±4.0 J K-1 mol-1 and S298.15(BaAl2Si2O8) = 231.5±4.0 J K-1 mol-1, and also to propose the recommended equations and for 250
I. V. Chernyshova, Y.V. Semenov, V.M. Agoshov, M. Gambino, P. Gaune and J.P. Bros, Thermochimica Acta 175 (1991) 119-127

B0728 – Suivi d’un procédé de phosphatation par calorimétrie.

T. Joly, P. Vast, G. Palavit, JCAT (1991) 193-199

B0724 – Les systèmes ternaires fondus ZrF4-BaF2-MF: détermination calorimétrique de l’enthalpie d’excès. Partie I. M=Na

Nous présentons dans ce travail nos résultats relatifs à la détermination par calorimétrie haute-température des enthalpies de formation de mélanges liquides du système ternaire BaF2 -NaF-ZrF4 et des mélanges binaires limitrophes BaF2-NaF et BaF2-ZrF4. Les méthodes de mélanges utilisées, "chutes directes" ou "chutes indirectes", ont été sélectionnées en fonction des propriétés physico-chimiques des systèmes. Les températures d'étude sont voisines de 1250 K pour les différentes sections du système ternaire, 1307 K. pour BaF2-NaF, et 1023 K pour BaF2-ZrF4. Les domaines de composition sont le plus large possible mais tels que les pertes par vaporisation n'excèdent pas 10%. Les résultats obtenus sont interprétés en terme de formation d'espèces ioniques complexes dans les mélanges contenant du fluorure de zirconium.
G. Hatem, K. Mahmoud and M. Gaune-Escard, Thermochimica Acta 182 (1991) 91-106

B0722 – Differential scanning calorimetry studies on aged iron(III)-chromium(III)-hydroxide coprecipitates

DSC measurements in air from 20 to 800° are reported on aged iron(III)-chromium(III) copreeipitated hydroxides (with Fe3+:Cr 3+ wt % ratios of 9:1, 7:3, 1:1, 3:7 and 1:9). A comparison of the DSC profiles of aged coprecipitates with the thermal behaviour of freshly precipitated and well characterized samples provided information on the modification occurring in the structure and reactivity of the coprecipitates on prolonged aging.
X. Devaux, A.C. Vajpei, A. Rousset, A. Rocher, M. Brieu, Uma, Kailash Chandra and I.P. Saraswat, Journal of Thermal Analysis 36 (1990) 529-543

B0721 – Calorimetry of phase transition and melting in silicates

High temperature reaction calorimetry is used to study phase transitions and melting reactions in silicates. Two types of calorimeters are used in our laboratory: a custom built Calvet-type twin microcalorimeter for solution, drop-solution, and transposed-temperature-drop calorimetry near 700°C and a commercial Setaram HT-1500 calorimeter for transposed-temperature-drop and step-scan measurements at 600-1500°C. The two types of calorimeters are complementary in their capabilities and together can be used to tailor a calorimetric experiment to the exact conditions needed for a specific reaction. Metastable phases quenched from ultra-high pressure or prepared as glasses, thin films, or gels present special challenges in determining their energetics. A new differential drop-solution calorimetric method has been developed. A sample contained in a capsule made of the lead borate glass used as calorimetric solvent is dropped into one side of a twin microcalorimeter at the same time as an empty capsule is dropped on the other side. The increased sensitivity and accuracy of this method has allowed the determination of the enthalpy of formation of the high pressure perovskite polymorph of MgSiO3 using a single 5 mg sample. The enthalpy of the reaction MgSiO3 (orthopyroxene) = MgSiO3 (perovskite) is 110 ± 5 kJ/mol; that of the ilmenite-perovskite transition is 59 ± 8 kJ/mol. These values support phase equilibrium studies which indicate that reactions forming MgSiO3-rich perovskite at the 670 km discontinuity in the earth's mantle generally have negative P-T slopes. The energy systematics of pyroxene, garnet, ilmenite, and perovskite structures in silicates and germanates have been determined. The step-scan and transposed-temperature-drop methods also are giving new information on nonquenchable phase transitions, including those involving rapid order-disorder reactions, at 600-1500°C. The spinels MgAl2O4 and NiAl2O4, and the pseudobrookite MgTi2O5 each show complex cation positional order-disorder. The orientation transition in CaCO3 (calcite) near 987°C has been characterized by in situ calorimetry, analyzed in terms of Landau-type order parameters, and applied to understanding apparent curvature in measured calcite-aragonite phase equilibria. Melting and crystallization reactions in silicates at 1100-1500°C have been measured directly by using the Setaram HT-1500 calorimeter in step scanning mode. The heat capacities of silicate liquids have also been measured. Results for CaMgSi2O6 (diopside) agree well with previous thermochemical data. Crystallization runs provide kinetic as well as thermodynamic information. The ternary system CaMgSi2O6-NaAlSi3O8-CaAl2Si2O8 (diopside-albite-anorthite), as a model for igneous rocks, is being studied in detail by this method.
A. Navrotsky, Thermochimica Acta 163 (1990) 13-24

B0716 – Thermal and thermodynamic properties of the selenites of the elements from group IV in the periodic table

The conditions necessary for the formation of basic lead selenites which result from the thermal dissociation of PbSeO3 were investigated, as well as their thermodynamic properties.
G.G. Gospodinov and B.G. Bogdanov, Thermochimica Acta 146 (1989) 15-19

B0710 – Einfluß von Ti02 auf die Oberflächenkristallisation von Glas mit der stöchiometrischen Zusammensetzung des Cordierits (2MgO.2Al2O3.5SiO2)

T. Hübert, R. Müller, M. Kirsch, Silikattechnik 40 (1989) 205-208

B0706 – Design and characteristics of a differential calorimeter for high-temperature measurements.

A high-temperature differential calorimeter developed from the Setaram "HT 1500 Calorimeter" has been built for isothermal measurements in inorganic systems at temperatures between 600 and 1750 K. Details of the mechanical design, the auxiliary equipment and the performance (mode of operation) of the calorimeter are given. Enthalpie effects ranging from about 5 to 200 J have been measured with a reproducibility and accuracy of approximately ± 2,5%. During calorimetric measurements conducted over a period of several months at high temperatures, the new differential calorimeter proved reliable and safe to operate.
W. Wilsmann and F. Müller, Thermochimica Acta 151 (1989) 309-318

B0682 – Enthalpies of solution of RbCI in water at 298.15 K and low molalities

The enthalpies of solution of RbCl in water have been measured at 298.15 K in the molality range 0.003-0.095 mol kg-1. The molality range was extended to lower concentrations with respect to previous works in the literature to obtain a better extrapolation to infinite dilution. After treating all the data, a new value for the enthalpy of solution at infinite dilution, ?solH?m has been obtained.
A. Sanahuja and J.L. Gomez-Estévez, Thermochimica Acta 156 (1989) 85-89

B0680 – Kinetic parameters of thermal decomposition of anisaldehyde-girard T complexes of cobalt and copper bromides from TG and DSC data

The kinetic parameters relating to the thermal decompositions of the Co(II) and Cu(II) hydrazone complexes of general formula [ML2Br2]C12, where L = anisaldehyde-Girard T cation: CH3OC6H4CH = N-NHCOCH 2 =/~(CH 3 )3, and M = Co(lI) or Cu(II), were evaluated from TG and DSC data. The thermal stabilities of the cobalt and copper complexes are discussed.
M.E.M. Emam, Journal of ThermaI Analysis 34 (1988) 1241-1246

B0678 – Calcium chloride hexahydrate-ammonium chloride binary solutions : a DSC study

Experimental results of DSC analyses of binary mixtures of calcium chloride hexahydrate and ammonium chloride are presented and analysed. Evidence for the formation of a mixed compound CaCl2 . 2NH4Cl . 2H2O is given.
J. Guion, M. Laugt and M. Teisseire, Thermochimica Acta 138 (1989) 39-45

B0675 – Thermodynamics of the protonation of some polyelectrolytes

Calorimetric measurements have been made at 25°C in water to determine the heats of dilution and dissociation of some polyelectrolytes derived from natural amino acids. Similar measurements were made with their model small molecules to account for the polyelectrolyte effect. Potentiometric titrations were also carried out to determine the free enthalpy of dissociation of the polyelectrolytes as a function of the degree of dissociation. Both sets of data were used to calculate the variation of the entropy of dissociation. The experimental results are discussed in terms of the structure of the polymers and the arrangement of water around the charged groups.
M. Morcellet, Thermochimica Acta 142 (1989) 165-173

B0674 – Thermal decomposition of tertiary-butylperoxybenzoate by heat flux calorimetry

The use of a heat flux calorimeter for thermal hazard evaluation has been investigated using tertiary-butylperoxybenzoate as a 'model' substance. The results indicate a complex decomposition mechanism where the kinetic parameters depend on the temperature and extent of reaction. The results offer confirmation of the experimental and analytical procedures.
P.G. Laye and D.C. Nelson, Thermochimica Acta 153 (1989) 221-229

B0673 – Enthalpies de formation des mélanges liquides ZrF4-MF (M=Li, Na, K, Rb)

Par calorimétrie haute température nous avons mesuré les enthalpies de formation des mélanges de sels fondus suivants: LiF+ZrF4 à T = 1150 K avec 0 < xZrF4 < 0,809 NaF+ZrF4 à T = 1282 K avec 0 < xZrF4 < 0,504 KF+ZrF4 à T = 1160 K avec 0 < xZrF4 < 0,652 RbF+ZrF4 à T = 1090 K avec 0 < xZrF4 < 0,701 Toutes les précautions expérimentales ont été prises pour limiter les pertes de ZrF4 par évaporation. L'incertitude sur les enthalpies de mélange peut varier de 12% (LiF+ZrF4) à 3% (RbF + ZrF4). Les enthalpies de formation de ces mélanges liquides ont été calculées en prenant comme valeur de l'enthalpie de fusion de ZrF4 celle proposée par McDonald et al. (J. Chem. Eng. Data, 7 (1962) 83) et en supposant qu'elle ne varie pas avec la température. Pour tous ces systèmes les enthalpies de mélange sont fortement exothermiques et les minima sont déplacés vers les régions riches en fluorure alcalin. De plus ces mêmes mesures nous ont permis de contrôler quelques points des diagrammes d'équilibre des phases et d'évaluer les enthalpies de formation et de fusion des composés 3KF,ZrF4 et 3RbF,ZrF4.
G. Hatem, F. Tabaries and M. Gaune-Escard, Thermochimica Acta 149 (1989) 15-26

B0664 – Etude thermodynamique du système fondu KF-NdF3.

T. Jriri, M. Gaune-Escard, G. Hatem, AFCAT (1990) 361-370

B0662 – Calorimètre isotherme à balayage linéaire de la pression étalonnage et comparaison : technique piezothermique

S.L. Randzio, J-P.E. Grolier, J.R. Quint, AFCAT (1990), 315-323

B0659 – Energie de formation de coacervats de polyphosphates en fonction de leur formulation.

L. Montagne, G. Palavit, P. Vast, M. Morcellet, AFCAT (1990) 235-241

B0651 – Thermal properties of Na2MoO4(s) and Na2Mo2O7(s) by high-temperature Calvet calorimetry in the temperature range 335 K to 760 K

Enthalpy increment ?298.15 KTHmo measurements were made on Na2MoO4(s) and Na2Mo2O7(s) in the temperature range 335 K to 760 K by the drop method using a high-temperature Calvet calorimeter. The calorimeter was calibrated using an electrical method and synthetic sapphire SRM-720 (Al2O3). An on-line computer was used for acquiring and processing results from the calorimeter. The enthalpy increments for Na2MoO4(s) and Na2Mo2O7(s) were least-squares fitted to a polynomial with temperature and are given by: Na2MoO4(s): ?T298.15 KH/(J.mol-1)±109=-38795+113.7(T/K)+0.0546(T/K)2, (335 to 520 K) ?T298.15 KH/(J.mol-1)±111=-38598+142.8(T/K)+0.00458(T/K)2, (520 to 720 K) ?T298.15 KH/(J.mol-1)±538=-105740+270.7(T/K) (720 to 760K) Na2Mo2O7(S): ?T298.15 KH/(J.mol-1)±318=-62413105740+190.6(T/K)+0.0589(T/K)2, (335 to 760 K) The thermal properties of Na2MoO4 and Na2Mo2O7 were obtained using the above experimental values. These are the first experimental results on the thermal properties of these compounds.
V.S. Iyer, Renu Agarwal, K.N. Roy, S. Venkateswaran, V. Venugopal and D.D. Sood, J. Chem. Thermodynamics 22 (1990) 439-448

B0647 – Standard enthalpy of formation of the monoclinic form of Cs2CdI4

J.P. Auffredic and V. Touchard, Thermochimica Acta 162 (1990) 463-464

B0646 – Standard enthalpy of formation of Cd3(OH)5NO3

J-P. Auffredic, Thermochimica Acta 162 (1990) 461-462

B0645 – Enthalpie standard de formation d’échantillons zéolithiques de type MFI. Stabilisation de cette structure par les cations tetra-, tri- et dipropylammonium

Calorimetric measurements have been carried out on specimens of high silica and silica-alumina MPI-type zeolites (MFI and (Si,Al)MFI) and their propylammonium precursors, denoted R-MFI and TPA-(Si,Al)MFI respectively, where R represents tetrapropylammonium (TPA), tripropylammonium (TRIPA) and dipropylammonium (DIPA). Standard enthalpies of formation at 298.2 K for these materials were determined by solution calorimetry in 25% HF. The following values per unit cell content were obtained The resulting standard enthalpies of formation for the precursors of the reactants are: These values expressing the contribution of the various organic species to the lattice stabilization show that, as expected, the energy gain is significant for TPA only
J. Patarin, M. Soulard, H. Kessler, J. L. Guth, M. Diot, Thermochimica Acta 146 (1989) 21-38

B0636 – Some aspects of the thermal behaviour of In2Se3.

On the basis of measurements of the specific heat capacity from 7 to 525 K and of DTA investigations from 300 K up to the melting point, it was possible to clarify the problem of the occurrence of the two room-temperature modifications of In2Se 3.
U-C. Boehnke, G. Kühn, G.A. Berezovskii and T. Spassov, Journal of Thermal Analysis 32 (1987) 115-120

B0629 – Temperature dependence of the heat capacity of water in small pores

The temperature dependence of the heat capacity of vicinal water has been measured in 242-A silica pores. The data are discussed in light of measurements of other physical properties of vicinal (interfacial) water. Notable heat capacity "spikes" were observed at temperatures which may be related to the previously discussed structural transitions in vicinal water. Physiological anomalies have been observed by various authors at these same temperatures. This work will be discussed in light of a statistical thermodynamic model for vicinal water proposed by Etzler (ref 31).
F.M. Etzler and J.J. Conners, Langmuir 6 (1990) 1250-1253

B0627 – Thermochemical study of the liquid systems BaO-B2O3 and CaO-B2O3

Mesure par calorimétrie des enthalpies de mélange pour des compositions de 30 à 100% en B[2]O[3] et pour des températures de 1551 à 1725 K
F. Müller, S. Demirok, Glastechnische Berichte 62 (1989) 142-149

B0625 – Thermodynamic functions of alkaline earth monouranates from calorimetric measurements

High temperature differential calorimetry was used to determine the enthalpy increments of BaUO4, alpha-SrUO4 and CaUO4 relative to room temperature. The measurements covered the temperature range 1000-1735 K. From these enthalpy values other thermodynamic functions, such as CXXXpT, SXXXT and -(GXXXT - HXXX298)T, were deduced using CXXXp298 and SXXX298 from the literature. The high temperature CXXXpT values for the monouranates obtained in this study are discussed in relation to the low temperature data available in the literature.
R. Saha, R. Babu, K. Nagarajan and C.K. Mathews, Thermochimica Acta 131 (1988) 183-189

B0601 – Solid-state e.m.f and calorimetric measurements on Cs2Cr2O7 (l)

?fGmo(Cs2O7 l, T) has been determined in the temperature range 797 to 874 K using a solid-oxide-electrolyte galvanic cell of the type: Pt|Cs2Cr2O7(l)+Cs2CrO4(s)+Cr2O3(s)|0.85ZrO2+0.15CaO|air|Pt where p(O2) in air is taken to be 21.21 kPa. The measured e.m.f.s could be represented by: (E/mV) ± 0.5 = 160.0 - 0.08104(T/K). Using the above equation and the reported values of ?fGmo(Cs2CrO4, s) and ?fGmo(Cs2Cr2O3, s), ?fGmo(Cs2Cr2O7, l) calculated in the temperature range 797 to 874 K, is given by ?fGmo(Cs2Cr2O7, l, T)/kJ.mol-1) ± 10 = -2023 + 0.5262 (T/K). The melting and transition temperatures, molar enthalpies of fusion and of transition, and (?298.15KTHmo(Cs2Cr2O7, l) in the temperature range 662 to 826 K were determined using a high-temperature Calvet microcalorimeter. These results were used to evaluate ?fGmo(Cs2Cr2O7, 298.15 K) and the value of -(2100 ± 10) kJ.mol-1 compares well with the values reported in the literature.
V. Venugopal, V.S. Iyer, Renu Agarwal, K.N. Roy, R. Prasad and D.D. Sood, J. Chem. Thermodynamics 19 (1987) 1047-1051

B0600 – Enthalpy-increment measurements for Csl(s) and Cs2CrO4(s) by high-temperature Calvet calorimetry

Molar thermodynamic properties of CsI(s) and Cs2CrO4(s) have been evaluated by measuring ?298.15 KTHmo using a Calvet high-temperature calorimeter by a drop technique. The enthalpy increments were treated by least-squares analyses using the constraints that ?298.15 KTHmo at 298.15 K and Cp,m(298.15 K) are equal to the reported literature values. Enthalpy increments for CsI(s) and Cs2CrO4(s) are represented for CsI(s) by ?298.15KTHmo/(J.mol-1) = 43.53(T/K)+0.01178(T/K)2-187100(K/T)-13398, (314 to 822 K) and for Cs2CrO4(s) by ?298.15KTHmo/(J.mol-1) = 114.32(T/K)+0.05789(T/K)2+247810(K/T)-40063, (333 to 822 K) The agreement between the interpolated and the input values is within ±0.25 per cent for CsI(s) and ±0.21 per cent for Cs2CrO4(s). Using the values of ?298.15 KTHmo, Cp, m(298.15 K), and ?0TSmo(298.15 K), Cp, m(s, T) and ?0TSmo have been evaluated.
V. Venugopal, Renu Agarwal, K.N. Roy, R. Prasad and D.D. Sood, J. Chem. Thermodynamics 19 (1987) 1105-1110

B0599 – Determination of thermal properties of Cs2Cr2O7 (s,l) by high temperature calvet calorimetry

Enthalpy increments have been determined for caesium dichromate in the temperature range 335 to 826 K using a high temperature Calvet micro calorimeter. A solid-solid transition has been observed at (620.5 ± 1.5 K) and the melting temperature was found to be (657.0 ±1.0) K. The corresponding enthalpy values are (15.6 ± 0.2) kJ/mol and (17.0 ± 0.22) kJ/mol. The results thus obtained are utilised for the evaluation of molar heat capacities, standard entropies and free energy functions for Cs2Cr2O7(s, l). The enthalpy increment values were fitted to a polynomial and can be represented by eqs. (1) to (3), respectively: (HT° - H°298.15)(Cs2Cr2O7, s) (J/mol) = -6.410 x 10^4 + 1.939 x 10^2 T(K) + 7.441 x 10^(-2) T(K)^2 (335 to 620.5 K), (1) (HT° - H°298.15)(Cs2Cr2O7, s) (J/mol) = 1.313 x 10^6 - 4.137 x 10^3 T(K) + 3.517 T(K)^2 (620.5 to 656 K), (2) (HT° - H°298.15)(Cs2Cr2O7, l) (J/mol) = - 1.218 x 10^5 +3.890 x 10^2 T(K) (657 to 826 K). (3)
R. Prasad, Renu Agarwal, K.N. Roy, V.S. Iyer, V. Venugopal and D.D. Sood, Journal of Nuclear Materials 167 (1989) 261-264

B0596 – Optimisation des fonctions d’excès et calcul du diagramme d’équilibre des phases de mélanges binaires de carbonates alcalins

C. Pelce, M. Gaune-Escard, G. Hatem, 16èmes JEEP (1990) 29-34

B0591 – DSC studies on the kinetics of decomposition of manganese dioxide

The kinetics of the thermal decomposition of manganese dioxide are studied with the DSC method. A non-isothermal reaction model consisting of two stages linked by the basic equation of interface reaction control is derived and the model agrees very well with the course of this decomposition reaction almost over the full range of reaction. Kinetic parameters for this reaction are calculated using this model and the methods of Kissinger, Duswalt and Ozawa.
C. Qiyuan and C. Xinmin, Thermochimica Acta 123 (1988) 61-71

B0586 – Thermodynamic study of the solid-liquid equilibria in the MPO3-LaP3O9 systems (M = Li, Na, K, Rb, Cs, Ag, Tl)

The enthalpies of fusion of the MPO3 (M = Li, Na, K, Rb, Cs, Ag, Tl) polyphosphates were determined by calorimetry. The MPO3-LaP3O9 binary systems were investigated for the first time by DTA. The study shows in all cases the existence of one or both of the two intermediate compounds: MLa(PO3)4 and M2La(PO3)5. The solid-liquid equilibria of the MPO3-LaP3O9 systems were submitted to a thermodynamic exploitation. With the exception of lithium, silver and thallium polyphosphates, whose crystallization fields are very limited, the liquidus curves of the other polyphosphates were put in equation. The melting point of LaP3O9, which undergoes a chemical decomposition before melting, was calculated and the obtained value was in agreement with the results of the thermogravimetric analysis. Starting with simplified hypotheses, the liquidus curves were recalculated and the thermodynamic functions characterizing the stable or metastable melting of the corresponding solid phases were obtained. Comparison of the measured and calculated values of the melting enthalpy of MPO3 polyphosphates shows, for the concentrations rich in alkali polyphosphates, the existence of associations in the liquid state.
D. Ben Hassen, N. Kbir-Ariguib, M. Trabelsi, R. Tenu and J-J. Counioux, Thermochimica Acta 116 (1987) 85-100

B0577 – Etude de la capacité calorifique molaire du titanate de plomb de différente stoechiométrie

Détermination par calorimétrie différentielle programmée. Enthalpie de la transition ferro-paraélectrique
P. Knauth, G. Schwitzgebel, Ann. Chim. Fr. 11 (1986) 537-542

B0552 – A study of thermal behaviour of sodium and zinc diphosphates

Phase transitions in Na4P2O7, Zn2P2O7 and Na2ZnP2O7 in the temperature range 20-800°C have been studied by X-ray diffraction, high-temperature microscopy, electrical conductivity, differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Na4P2O7 has five reversible polymorphic transformations at 402.7, 512.0, 518.3, 542.7 and 554.4°C, respectively. Zn2P2O7 undergoes one reversible polymorphic transformation at 128.2°C. In the studied temperature range Na2ZnP2O7 does not exhibit polymorphism and melts congruently at 779.0°C. The enthalpies of phase transitions have been determined by DSC method.
V.B. Lazarev, I.D. Sokolova, G.A. Sharpataya, I.S. Shaplygin and I.B. Markina, Thermochimica Acta 86 (1985) 243-249

B0546 – Experimental study on baseline drifts of a Tian-Calvet type calorimeter

The stability of a Tian-Calvet type calorimeter used in enthalpy of solution determinations has been analysed. The mechanical action necessary for starting the solution process causes a permanent drift on the baseline. The influence on the total energy involved in a solution process has been quantitatively determined by a series of blank experiments (without real solution process). As a result of this experimental study a baseline correction method is proposed.
A. Sanahuja, Thermochimica Acta 90 (1985) 9-14

B0545 – Enthalpy of solution of aqueous sodium chloride at 303.15, 308.15, and 313.15 K

The enthalpies of solution of NaCl in water at 303.15, 308.15, and 313.15 K have been measured as a function of molality in a heat-flux calorimeter. The covered range is 0.005 to 0.12 mol.kg-1. Values for the apparent relative molar enthalpies have been used to analyse the experimental results. The enthalpies of solution at infinite dilution at 303.15, 308.15, and 313.15 K obtained are 3.32, 2.78, and 2.25 kJ.mol-1, respectively
A. Sanahuja and E. Cesari, J. Chem Thermodynamics 17 (1985) 823-827

B0539 – Phasenumwandlungen bei ABC2-Halbleitern vom chalcopyrit-typ

The entropy change of the phase transition from the chalcopyrite to the sphalerite structure of compounds AIBIIIc vl and AIIBIVc V was determined with a Setaram Microthermatanalyzer and a DSC 111 heat flow calorimeter. From these results one can not generally decide the order of the phenomenon, but the discussion gives hints as to a firstorder transition. On the basis of a simple correlation between the ratio of the lattice constants extrapolated up to the melting temperature and the reduced temperature of the phase transition, it is possible to oredict the order disorder behaviour.
W. Möller, G. Kühn and W. Engel, Journal of Thermal Analysis 30 (1985) 383-389

B0530 – Combination of DSC 111 and thermobalance : new Setaram simultaneous TG-DSC 111

The new SETARAM simultaneous TG-DSC 111 combining the well known capacities of the DSC 111 with the qualities of a symmetrical balance of very high precision is presented. The new instrument is especially designed for all investigations relative to interactions between gases and solid or liquid samples and to materials stability.
P. Le Parlouër, Thermochimica Acta 92 (1985) 371-374

B0529 – DSC study of polymorphism of Na4P2O7

The DSC data on the heat capacity and the entropies of sodium diphosphate transformations have shown that the transition of Na4P2O7 from low-temperature to high-temperature modification proceeds continuously through intermediate states following the order-disorder mechanism.
V.B. Lazarev, I.D. Sokolova and G.A. Sharpataya, Thermochimica Acta 92 (1985) 301-304

B0526 – DSC study of the thermodynamics and the kinetics of structural transformations of silica in a water vapour atmosphere

The enthalpies of dehydration and crystallization of amorphous silica with the formation of quartz have been determined by the differential scanning calorimetry method in a water vapour atmosphere. It has been,found that the dehydration enthalpy value depends on the character of the preliminary treatment of silica. The effective activation energy of the growth of quartz nuclei has been estimated based on the Kolmogorov-Kazeev equation for the silica crystallization kinetics.
G.A. Sharpataya, G.P. Panasyuk, G.P. Budova, Z.P. Ozerova, I.L. Voroshilov and V.B. Lazarev, Thermochimica Acta 93 (1985) 271-274

B0523 – Intérêt de l’analyse thermique dans l’étude des milieux bidimensionnels : Application à quelques composés d’intercalation du graphite

P. Vast, G. Palavit, AICAT, Ferrara, (1986) 146-149

B0521 – Etude thermodynamique des systèmes MCl-BiCl3 (M=Li, Na, K, Rb) : II. Température, enthalpie de fusion et capacité calorifique des composés définis.

Z. Benkhaldoun, M. Gambino, G. Hatem, J.P. Bros, M. Gaune-Escard, AICAT, Ferrara, (1986) 284-295

B0513 – New possibilies of Calvet’s calorimetry : Combination of DSC and TG

A DSC-111 calorimeter and an MTB-10-8 differential microbalance are used to build a new instrument that combines the characteristics of both devices.The kinetics of two simultaneous reactions can be studied on the new instrument if only one or both reactions involve a change in weight. FFT method was employed in order to obtain true DSC curves.
G.K. Demensky, L.A. Petrov, Y.V. Tarasenko, O.A. Teplov and A.A. Baikov, Thermochimica Acta 92 (1985) 265-268

B0508 – Calorimetric study of high pressure polymorphs of Li2WO4 and Li2MoO4

Heats of transition among the Li2WO4 polymorphs, Li2WO4I (phenacite-type structure), Li2WO4II, Li2 WO4III, and Li2WO4IV, and that between Li2MoO4 (phenacite) and Li2MoO4(spinel) were measured by transposed temperature drop calorimetry. The heats of fusion of Li2WO4I and Li2MoO4(ph) were also obtained. Using these data, the phase boundaries among the polymorphs of Li2WO4 and of Li2MoO4 were calculated. The calculated phase diagrams were compared with those reported previously. They agree well for Li2WO4 but show significant discrepancies, perhaps related to problems in attaining equilibrium at lower temperature, for Li2MoO4.
E. Takayama-Muromachi, A. Navrotsky and S. Yamaoka, Journal of Solid State Chemistry 65 (1986) 241-250

B0502 – Etude thermodynamique des systèmes MCl-BiCl3 (M=Li,Na,K,Rb)

Z. Benkhaldoun, G. Hatem, M. Gaune-Escard, AICAT, Ferrara, (1986) 134-145

B0498 – Thionyl and sulfuryl chloride evaluation for high-rate applications

V. Danel, J.P. Descroix, G. Sarre, 32nd Int Power Sources Symposium (1986)

B0491 – Calorimétrie à conduction et thermogénèse. Déconvolution des signaux II. Filtrages numérique et électronique inverses. Asservissements.

J. Navarro, V. Torra, E. Cesari, J.L. Macqueron, R. Prost, J.P. Dubes, H. Tachoire, Bulletin de la Société Chimique de France n°1-2 (1982) 54-64

B0490 – Calorimétrie à conduction et thermogénèse. Déconvolution des signaux I. Introduction. Méthodes numériques utilisant la totalité de la fonction de transfert instrumentale.

J. Navarro, V. Torra, E. Cesari, J.L. Macqueron, R. Prost, J.P. Dubes, H. Tachoire, Bulletin de la Société Chimique de France n°1-2 (1982) 49-53

B0474 – Thermodynamic treatment and calorimetric study of H+/Li+ ion exchange on alpha-titanium phosphate

The thermodynamics of H+/Li+ ion exchange on alpha-Ti(HPO4)2.H2O have been studied, and titration curves and exchange isotherms have been obtained at 298.15, 313.15, and 328.15(±0.1) K. The exchanger hydrolysis and the corrected isotherms have been calculated. The equilibrium constants, the standard molar Gibbs free energies, enthalpies, and entropies of the reactions have been all determined. The molar enthalpies of the exchange reaction have been measured calorimetrically. The thermodynamic and calorimetric results are compared.
C.G. Guarido, M. Suarez, J.R. Garcia, R. Llavona and J. Rodriguez, J. Chem Thermodynamics 17 (1985) 63-68

B0471 – Calorimetric determination of H+/Na+ ion exchange on alpha-titanium phosphate

Ion exchange in the system H+/Na+ on alpha-titanium phosphate (a-TP) at 25 "C when the process is carried out under static conditions was studied. Titration and hydrolysis curves were obtained and the exchange isotherm was determined. The substitution was followed by X-ray diffraction. Direct calorimetric measurements were performed at different extents of the exchange and the enthalpy variations for the system were obtained. The results of this study are compared to those of a similar one carried out by classic thermodynamic methods.
M. Suarez, J.R. Garcia, J. Rodriguez, The Journal of Physical Chemistry 88 (1984) 157-159

B0467 – A new method for the simultaneous determination of the size and the shape of pores : the thermoporometry

A thermodynamic study of the liquid-solid phase transformations in porous materials provides the relationships between the size of the pores in which solidification takes place and the temperature of the triple point of the divided liquid, on the one hand, and between this temperature and the apparent solidification energy on the other hand. The experimental study of the phase transformations, carried out by means of a microcalorimeter, gives the values of the parameters necessary to calculate the free SOLID = liquid interphase extension energy yls at different temperatures. A formula yls = f(T) is given for water and benzene. Once this factor is known, it is possible to study the numerical relationship between pore-radius and freezing energy at the equilibrium temperature. By using these relations together with the solidification thermogram (the recording of the power evolved by the solidification of a capillary condensate during a linear decrease of temperature) the authors have been able to determine pore distribution curves. An emphasis is put on the comparison between this method, thermoporometry, and the B.J.H. method. Last of all the comparison of the experimental data for solidification and melting provide information concerning pore shape by means of the evaluation of a thermodynamic shape factor or by a method of simulation of porous material.
M. Brun, A. Lallemand, J-F. Quinson and C. Eyraud, Thermochimica Acta 21 (1977) 59-88

B0461 – Adsorption of hydrogen on zinc oxide

B. Fubini, E. Giamello, G. Della Gatta, G. Venturello, Journal of the Chemical Society. Faraday Transactions 78 (1982) 153-164

B0443 – Etude par potentiométrie et par calorimétrie des équilibres de substitution par les ions bromures des atomes de chlore des complexes de l’or trivalent en milieux aqueux à 25°C

En milieux aqueux, les ions bromures réagissent sur les ions tétrachloro-aurates(III) selon des réactions de substitution successives (j) AuCl5-jBr-j-1 + Br- = AuCl4-jBr-j + Cl- où j = 1-4. Nous avons déterminé les constantes apparentes des équilibres successifs par potentiométrie à 25°C dans des milieux aqueux de force ionique comprise entre 0.1 M et 0.15 M. Nous avons obtenu les valeurs suivantes: K1 = 378,5±5, K2 = 118,9±3, K3 = 54,5±1, K4 = 35,2±1. Nous avons également mesuré par microcalorimétrie les variations d'enthalpie au cours des réactions dans les mêmes conditions expérimentales. Ces mesures nous ont permis de déterminer les enthalpies molaires des réactions de substitution successives, rapportées à 1 kg de solvant. Nous avons obtenu les valeurs suivantes (en J mole-1): ?H1 = -15940±50, ?H2 = -15940±50, ?H3 = -13660±50, ?H4 = -13660±50.
G. Cudey, L. Schuffenecker, J.B. Bourdet and J. Lozar, Thermochimica Acta 67 (1983) 1-15

B0442 – Developments in immersion calorimetry: design and testing of an improved seal-breaking technique

A new design of cell for the use in immersion calorimetry using the Calvet calorimeter (Setaram MS70) is described and tested. Corrections for the energies of bulb breaking and evaporation of liquid can be made to about ± 1 mJ. The measured corrections are in generally good agreement with those calculated, although some minor discrepancies seem to be related to the design of the calorimeter which under certain circumstances fails to detect the whole of the heat flux.
D.H. Everett, A.G. Langdon and P. Maher, J. Chem. Thermodynamics 16 (1984) 981-992

B0429 – The enthalpy of dilution of aqueous sodium chloride to 673 K using a new heat-flow and liquid-flow microcalorimeter. Excess thermodynamic properties and their pressure coefficients

A new heat-flow and liquid-flow calorimeter utilizing a Calvet microcalorimeter is described; it can be used to measure excess enthalpies of liquids at temperatures and pressures up to 700 K and 50 MPa. The sensitivity of the calorimetric apparatus permits observations to be made on sufficiently dilute solutions to allow good extrapolations to infinite dilution required for derivation of excess thermodynamic properties as well as standard-state quantities. The enthalpies of dilution of aqueous solutions of NaCl from 0.1 to 5 mol.kg-1 at temperatures from 323 to 673 K have been measured. Isobaric observations were made at two different pressures at each experimental temperature which permitted derivation of pressure coefficients for the first time. The following excess thermodynamic properties have been calculated from the results from 0.1 to 5 mol.kg-1 at the saturation vapor pressure of water and from 373 K to the temperature indicated: apparent relative molar enthalpy L?(623 K), activity coefficient ?(623 K), osmotic coefficient ?(623 K), relative partial molar enthalpy L2(623 K), and excess molar heat capacity Cp, mE(523 K). Pressure coefficients of these excess properties have been calculated from the results. No values of the excess thermodynamic properties for any electrolyte have been previously available above 573 K. In addition, all these excess properties except Cp, mE have been calculated to the supercritical temperature 673 K and 41.5 MPa. Comparisons with values in the literature demonstrate that the calorimeter is capable of precise enthalpy measurements which lead to accurate thermodynamic properties and their pressure coefficients at high temperatures and pressures.
R.H. Busey, H.F. Holmes and R.E. Mesmer, J. Chem. Thermodynamics 16 (1984) 343-372

B0420 – Calorimetric determination of surface areas: Possibilities of a modified Harkins and Jura procedure

The immersion calorimetric method of Harkins and Jura for determining specific surface areas of powders was reexamined in the light of results obtained with 11 powders of different chemical nature and having specific surface areas ranging from 0.6 to 129 m2 g-1. Microcalorimetric determinations were performed, using water (and, to a smaller extent, butanol, pentanol, and n-decane) as the adsorbate and as the immersion liquid. Less than two water layers appears to be enough to "screen" completely the solid surface. This leads to a modified procedure which avoids the previous shortcomings arising from interparticulate condensation and also from the thickness of the preadsorbed layer. The experimental reproducibility is of ±0.1 m2 g-1 ± 1% (of the measured value).
S. Partyka, F. Rouquerol and J. Rouquerol, Journal of Colloid and Interface Science 68 (1979) 21-31

B0397 – Entropies de changement d’état du sulfate de lithium

G. Hatem et al., AFCAT, La Gaillarde (1983) 96

B0373 – Differential calorimetric study of the polymer Al13O4(OH)28(H2O)3+8 and an amorphous aluminium trihydroxide gel in aqueous solution

The enthalpy of formation at 298.15 K of the polymer Al13O4(OH)28(H2O)3+8 and an amorphous aluminium trihydroxide gel was studied using an original differential calorimetric method, already developed for adsorption experiments, and aluminium-27 NMR spectroscopy data. ?Hf "Al13" (298.15 K) = - 602 ± 60.2 kJ mole-1 and ?Hf Al(OH)3 (298.15 K) = - 51 ± 5 kJ mole-1. Using theoretical values of ?GR "Al13" and ?GR Al(OH)3, we calculated ?Gf "Al13" (298.15 K) = - 13282 kJ mole-1; ?Sf "Al13" (298.15 K) = + 42.2 kJ mole-1; ?Gf Al(OH)3 (298.15 K) = - 782.5 kJ mole-1; and ?Sf Al(OH)3 (298.15 K) = + 2.4 kJ mole-1.
J. Y. Bottero, S. Partyka, F. Fiessinger, Thermochimica Acta 59 (1982) 221-229

B0371 – Method zur Bestimmung von Standardbildungsenthalpien thermi. instabiler Verbindungen durch Eiwurfkalorimetrie

D. Petzold et al.

B0368 – Temperatures and enthalpies of melting of alkali-metal perrhenates

Melting temperatures and enthalpies of melting were determined for alkali-metal perrhenates by differential enthalpic analysis using a high-temperature Calvet microcalorimeter. The following values were obtained: for LiReO4: 692 K and 24.9 KJ . mol-1; for NaReO4: 693 K and 33 kJ . mol-1; for KReO4: 828 K and 36 kJ.mol-1; for RbReO4: 878 K and 34 kJ.mol-1; for CsReO4: 893 K and 34 kJ . mol-1
W. Lukas and M. Gaune-Escard, J. Chem. Thermodynamics 14 (1982) 593-597

B0367 – Excess enthalpies of the charge-asymmetric reciprocal molten salt mixtures: {LiF + K2SO4} and {KF + Li2SO4}

The aim of the present work was the experimental determination by high-temperature calorimetry of the excess enthalpies of the two molten-salt mixtures: {xLiF + (1 - x)K2SO4} and {xLi2SO4 + (1 -x)KF} which are the diagonals of the {Li+ + K+ + F- + SO42-} asymmetrical ternary reciprocal system. From the results it was possible to evaluate the enthalpy difference ?Ho associated with the exchange reaction characterizing this reciprocal mixture: 0.5Li2SO4(1)+KF(1)=0.5K2SO4(1)+LiF(1) . This value was found in good agreement with that calculated from standard thermodynamic quantities for the four pure salts. An estimation procedure enabled us to calculate the ternary excess enthalpies for the two diagonals, which we then compared with those obtained experimentally.
G. Hatem and M. Gaune-Escard, J. Chem. Thermodynamics 14 (1982) 893-899

B0339 – Die bestimmung der bildungsenthalpien von in thermischen zersetzungsreaktionen auftretenden verbindungen durch einwurfkalorimetrie – Bildungsenthalpie AlCl3.6 H2O, amorph-Al2O3, y-Al2O3, Al2O3.2 H2O.2 HCl

The heats of formation of stable compounds produced during thermal decomposition reactions were determined by measurements of enthalpies of reactions. The investigations were performed by using a heat-flow dropping calorimeter. The validity of the method was confirmed by measurement of the heat of formation of calcium carbonate. All calorimetric results had an accuracy of ± 2%. The heats of formation under standard conditions, ?BH°298 kJ mol-1, for AICI3.6H2O, amorphous AI2O3, gamma-Al2O3 and AI2O3. 2H2O. 2HCl are -2667 ± 8, -1625 ± 39, -1654 ± 39, and -2626 ± 4, respectively.
R. Naumann und D. Petzold, Journal of Thermal Analysis 20 (1981) 319-330

B0335 – Heat capacity and thermodynamic properties of ramsdellite, Li2Ti3O7, and spinel, Li4/3Ti5/3O4

The heat capacity and heat content Li4/3Ti5/3O4 and Li2Ti3O7 have been measured in the temperature range 198-960 K. The lattice and dilation contributions to the heat capacity have been estimated. The standard thermodynamic functions and the high temperature enthalpy and entropy have been derived. The lattice heat capacity of Li4/3Ti5/3O4 spinel appears to be consistent with the phonon model put forward by Grimes.
V.I. Kolotyrkin, J.A. Kessler, V.A. Shchelkotunov, I.V. Gordeyev, Yu.G. Metlin and Yu.D. Tretyakov, Thermochimica Acta 43 (1981) 27-33

B0333 – Partial molar excess enthalpies of molten (cadmium chloride +potassium chloride)

The partial molar excess enthalpies of the two components have been measured by drop calorimetry for {(1 - x)CdCl2 + xKCl}(l) over its entire composition range at 857 K and for x = 0.5 at 717 K. Consistency was tested using the Gibbs-Duhem relation. The excess heat capacity of the melt was also measured at x = 0.5 and was found to be very near zero. The two partial molar excess enthalpies, independent of temperature, are plotted against x so that anomalous behaviour near x = 0.5 can be seen. Tables of partial molar excess enthalpies are given.
B. Cristol, J. Houriez and D. Balesdent, J. Chem. Thermodynamics 13 (1982) 937-945

A2379 – Preparation of novel organovermiculites with antibacterial activity using chlorhexidine diacetate

The novel antibacterial organovermiculites with different mass ratios of chlorhexidine diacetate (CA) were successfully prepared by ion exchange reactions. The resultant organovermiculites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal properties of prepared organovermiculites were investigated by simultaneous thermogravimetry (TG) and differential thermal analysis (DTA). The antibacterial activity of prepared organovermiculites against Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding minimum inhibitory concentration (MIC). Antibacterial studies showed that the organovermiculites strongly inhibited the growth of variety of microorganisms.
Sylva Holešová, Marta Valášková, Eva Plevová, Erich Pazdziora, Katerina Matejová, Journal of Colloid and Interface Science 342 (2010) 593–597

A2378 – The potential use of Tithonian–Barremian detrital deposits from central Tunisia as raw materials for ceramic tiles and pigments

The aim of this study is to evaluate Tunisian Tithonian–Barremian deposits for the manufacture of ceramic tiles and pigments. Three major geological domains were sampled: the North–South axis, Central Atlas and Southern Atlas. The Tithonian clay sediments (Sidi Khalif Formation) and Barremian sands (Sidi Aich Formation) outcrop exclusively in central Tunisia. X-ray diffraction revealed a predominance of illite and kaolinite and variable amounts of quartz, dolomite and feldspars in the Tithonian clays. Their technological properties were assessed in pressed ceramic tiles after firing at different temperatures. Lab-scale tests involved determinations of porosity, bending strength and linear shrinkage, and results were compared with those of commercial tiles from Tunisia and Italy. The main constituents of the Barremian sands are quartz and K-feldspars. Lab-scale tests were carried out to produce blue Co-olivine and Co-willemite pigments. Formulations showed stability and high crystallinity after calcination at 1300 °C. CIELab measurements confirmed the development of interesting blue coloration by the pigments when applied in transparent and opaque glazes. Their coloring performance was similar to that of the commercial equivalents tested.
W. Hajjaji, B. Moussi, M. Hachani, M. Medhioub, A. Lopez-Galindo, F. Rocha, J.A. Labrincha, F. Jamoussi, Applied Clay Science 48 (2010) 552–560

A2372 – Specific signatures of ?-alumina powders prepared by calcination of boehmite or gibbsite

The specific signatures of ?-Al2O3 powders by a combination of X-ray diffraction (Rietveld analysis), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thermal analysis (TG–DTA) and cathodoluminescence (CL) were investigated. Thus, ?-alumina was prepared by calcination of boehmite or gibbsite at 1573 K for 24 h. The size of ?-alumina crystallites obtained using boehmite precursor was smaller than that obtained using gibbsite precursor. The difference in oxygen vacancies (F+-centers) amount between ?-Al2O3 powder obtained by calcination of gibbsite and boehmite was confirmed by CL spectra. Furthermore, the Ti3+ emission at 1.71 eV is absent in ?-Al2O3 powder obtained by calcination of gibbsite. CL has been demonstrated as a possible method for differentiation between the various ?-alumina powders.
A. Boumaza, A. Djelloul, F. Guerrab, Powder Technology 201 (2010) 177–180

A2353 – NH4-smectite: Characterization, hydration properties and hydro mechanical behaviour

Leachates in waste landfills are characterized by the presence of ammonium ions in large excess. These ammonium ions can be exchanged with the interlayer cations in clay and modify the physical and chemical properties of clay geochemical barriers in waste landfills and drive to environmental problems. The purpose of this study was to understand the hydro-physical changes of a smectite in the presence of ammonium ions. An ammonium smectite was prepared by cation exchange from a natural montmorillonite (Wyoming). The samples were characterized and their properties were compared by the use of a set of complementary techniques (X-ray diffraction, infrared spectroscopy, N2 adsorption–desorption BET technique, thermal analysis, and percolation experiments). The main effect was a modification of the porosity and its network, and reduced crystalline swelling. These effects changed the hydraulic conductivity and macroscopic swelling of the clay. The oedometer experiments, which allow simulating the pressure on small amounts of samples, proved the strong increase of the permeability of NH4-smectite. This last point is of great importance in an environment point of view and raises questions on the impermeability behaviour on the long term of the clay geochemical barriers with the presence of ammonium ions in waste landfills.
M. Gautier, F. Muller, L. Le Forestier, J.-M. Beny, R. Guegan, Applied Clay Science 49 (2010) 247–254

A2343 – Mixed-metal carbonates as precursors for the synthesis of nanocrystalline Mn–Zn ferrites

A mixed Mn–Zn–Fe carbonate was prepared by precipitation of metal ions with ammonium carbonate and control of pH=7. Nanocrystalline Mn–Zn ferrite powders were synthesized by thermal decomposition of the carbonate precursor at 500 °C in air. The mean crystallite size of the ferrite particles is 14 nm with a specific surface of 74 m2/g. The magnetization at 5 K of the Mn–Zn ferrite powders (66 emu/g) is smaller than the saturation magnetization of the bulk material. Hysteresis loop measurements indicate ferrimagnetic behavior at 5 and 298 K with a small coercivity at room temperature.
A. Angermann, E.Hartmann, J.Töpfer, Journal of Magnetism and Magnetic Materials 322 (2010) 3455–3459

A2339 – Characterization and AC conductivity of polyaniline–montmorillonite nanocomposites synthesized by mechanical/chemical reaction

Polyaniline–clay nanocomposites were prepared by solid state polymerization of aniline chloride in the interlayer of montmorillonite through the use of persulfate of ammonium as oxidant. The proportion of aniline to clay and the molar ratio of oxidant to aniline are being varied. The analyse of UV visible and FTIR spectroscopy demonstrated that aniline has been polymerized to polyaniline (PANI) in its conducting emeraldine form. The conformation adopted by PANI chains in the clay interlayer depended on the molar ratio of aniline to montmorillonite. Thermogravimetric analysis of the nanocomposites suggested that polyaniline chains are more thermally stable than those of free polyaniline prepared by solid–solid reaction. The AC conductivity data of different synthesized nanocomposites were analyzed as a function of frequency. Low frequency conductivities of polyaniline/montmorillonite nanocomposites materials ranges from 0.18 to 5.6 × 10?3 S/cm. All characterization data were compared to those of free polyaniline that was synthesized using a solid–solid reaction.
Imene Bekri-Abbes, Ezzeddine Srasra, Reactive & Functional Polymers 70 (2010) 11–18

A2302 – Influence of divalent metal on the decomposition products of hydrotalcite-like ternary systems MII–Al–Cr (MII = Zn, Cd)

Layered double hydroxides (LDHs) containing MII, AlIII, and CrIII in the brucite-like layers (M = Cd, Zn) with different starting Al/Cr molar ratios and nitrate/carbonate as the interlayer anion have been prepared following the coprecipitation method at a constant pH: ZnII–AlIII–CrIII–CO32? at pH = 10, and CdII–AlIII–CrIII–NO3? at pH = 8. Two additional MII,AlIII–LDH samples (M = Cd, Zn) with chromate ions (CrO42?) in the interlayer have been prepared by ionic exchange at pH = 9 and 8, respectively, starting from MII–AlIII–NO3?. The samples have been characterised by absorption atomic spectrometry, powder X-ray diffraction (PXRD), FT-IR spectroscopy and transmission electron microscopy (TEM). Their thermal stability has been assessed by DTA-TG and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 °C show diffraction lines corresponding to ZnO and ZnAl2?xCrxO4 for the Zn-containing samples, and diffraction lines attributed to CdO and CdCr2O4 and (Al,Cr)2O3 for the Cd-containing ones. Additionally a minority oxide, Cd2CrO5, is observed to CdII–AlIII–LDH samples with chromate ions in the interlayer.
M.R. Pérez, I. Crespo, M.A. Ulibarri, C. Barriga, V. Rives, J.M. Fernández, Materials Chemistry and Physics 132 (2012) 375– 386

A2300 – Crystallographic and structural transformations of sedimentary chalcedony in flint upon heat treatment

The early occurrence of intentional heat treatment of silica rocks has recently become a key element in the discussion about the cultural modernity of prehistoric populations. Lithic vestiges are the only sources that remain of this process and the understanding of the material’s properties and transformations are essential for reconstructing the conditions and parameters applied during heat treatment. Several models of the structural transformations upon heating have been proposed in the current literature. These models are often contradictory and do not account for the most recent structural and mineralogical data on chalcedony. In order to propose a new model, we elaborated an experimental procedure and applied different techniques involving infrared spectroscopy, solid state NMR, X-ray diffraction and electron microscopy. The results show that the major transformation to happen is the loss of silanole (SiOH) and the creation of new Si–O–Si bonds according to the reaction: Si?OH HO–Si ? Si–O–Si + H2O. This reaction starts between 200 °C and 300 °C and causes an increase in the hardness of the rocks. The maximal annealing temperature and the ramp rate are the functions of the ability of the structure to evacuate newly created H2O and depend on the size of the specimen and the volume of its porosity. These results also show that the annealing duration at maximum temperature can be relatively short (<50 min) for a sufficiently large amount of transformation to be accomplished.
Patrick Schmidt, Sylvie Masse, Guillaume Laurent, Aneta Slodczyk, Eric Le Bourhis, Christian Perrenoud, Jacques Livage, François Fröhlich, Journal of Archaeological Science 39 (2012) 135-144

A2291 – Slow diuron release formulations based on clay–phosphatidylcholine complexes

Slow release formulations of the herbicide diuron were designed to reduce the risk of water pollution resulting from conventional formulations. The new formulations were based on herbicide incorporation in phosphatidylcholine (PC) vesicles that were sorbed on the clay mineral montmorillonite. The active ingredient contents of the formulations reached up to 28% w:w. Thermal analysis revealed that the closely packed arrangement of PC on the clay enhanced diuron sorption by disrupting the interactions among PC molecules. Adsorption experiments using diuron were performed in soils with different physico-chemical properties to evaluate the relationship between the sorption and the mobility of the herbicide. In soil column experiments with sandy soil, the herbicide in PC–clay-based formulations mainly accumulated in the top soil, and there was a one-third reduction in leaching compared to the commercial formulation. The differences in leaching (compared to the commercial formulation) were lower when using loam soil due to its higher sorption of the herbicide and hysteresis effects. In the sandy soil, bioassay experiments showed a higher herbicidal activity in the top-soil layer for the PC–clay formulations than for the commercial formulation. Therefore, PC–clay formulations of this herbicide can be used at lower doses than recommended, thereby reducing the environmental risks associated with the application of diuron formulations.
Tomás Undabeytia, Esther Recio, Celia Maqueda, Trinidad Sánchez-Verdejo, Vladimir Balek, Applied Clay Science 55 (2012) 53–61

A2287 – Luminescence emission of natural NaCl

The luminescence properties of synthetic alkali halides in general and different doped synthetic sodium chloride (NaCl) in particular have been widely studied. However, the spectral emission of natural NaCl has been scarcely reported. Accordingly, this work reports on the thermoluminescence (TL), infrared stimulated luminescence (IRSL) and radioluminescence (RL) response of the well-characterized natural NaCl (by means of X-ray fluorescence and differential thermal and thermogravimetric techniques) in the range of 200–800 nm. As observed in the 3D-TL plots, the main emission of the irradiated samples appears in the UV-blue region and can be deconvoluted into four groups of components (at 70, 180, 220 and 315 °C) assuming first order kinetics. The non-irradiated samples exhibited a negligible luminescence signal. The RL response reveals the appearance of five bands peaked at 290, 370, 430, 500 and 620 nm. The IRSL spectral emission shows a low intensity broad band with non-well defined peaks.
Y. Rodriguez-Lazcano, V.Correcher, J.Garcia-Guinea, Radiation PhysicsandChemistry81(2012)126–130

A2272 – Crystal structure, thermal analysis and magnetic properties of the bis (2-amino-5-ammoniopyridinium) hexachloridomanganate(II)

Single crystals of the novel Bis(2-amino-5-ammoniopyridinium) hexachloridomanganate(II), (C5H9N3)2MnCl6, 1, were grown by slow evaporation solution technique at room temperature. The compound was characterised by IR, differential thermal analysis (TG-DTA), single crystal X-ray diffraction and temperature dependent magnetic susceptibility. The structure consists of isolated [MnCl6]2? octahedral anions and 2-Amino-5-ammoniopyridinium [C5H9N3]+ cations, 2-A-apy, which are connected together via C/N–H?Cl hydrogen bonds. Cation…cation, offset-face-to-face interactions (?–? stacking) between identical antiparallel 2-A-apy cations and cation…anion, C/N–H?Cl hydrogen bonding cause to the formation of a three-dimensional supramolecular architecture, in which they may be effective in the stabilization of the crystal structure. The magnetic data show that this material display weak antiferromagnetic coupling on cooling, without any transition observed above 1.8 K. Antiferromagnetic properties might be attributed to exchange coupling mediated by the semi-coordinate Mn?Cl bonds.
Sondra Walha, Houcine Naili, Samia Yahyaoui, Basem Fares Ali, Mark M. Turnbull, Tahar Mhiri, Thierry Bataille, Solid State Sciences 13 (2011) 204-208

A2268 – Extraction of beryllium from Indian beryl by ammonium hydrofluoride

A new technique of decomposing beryl ore at low temperature with ammonium hydrofluoride (NH4HF2) is proposed. Removing the fluorides of silicon and aluminium from the reaction product as volatile and insoluble compounds, respectively, have been investigated experimentally and the feasibility of the process has been established to extract beryllium fluoride (BeF2) as a soluble compound. The sequence of reaction of beryl ore with the strong fluorinating agent NH4HF2 has been studied by TG/DSC, intermediates and final products were identified by XRD. The product yield was found to be up to 93%. A process flow sheet to produce beryllia (BeO) and BeF2 for subsequent magnesiothermic reduction to produce beryllium metal is proposed based on the experiments conducted at bench scale. Methods of recycling NH4HF2 have been suggested, thereby making the proposed route superior to the conventional methods in terms of recovery, low temperature of operation, fluoride recycling, and significant reduction in effluent as well as improved safety in handling of beryllium.
D.D. Thorat, B.M. Tripathi, D. Sathiyamoorthy, Hydrometallurgy 109 (2011) 18–22

A2250 – The use of dolomite as foaming agent and its effect on the microstructure of aluminium metal foams—Comparison to titanium hydride

In this paper dolomite MgCa(CO3)2 a naturally occurring mineral was demonstrated to be an effective foaming and stabilizing agent for aluminium with several notable advantages relative to the currently used titanium hydride foaming agent. Characteristic cell structures and microstructural features of foams produced with a dolomite foaming agent are examined and the properties of dolomite based foams produced in a one step process are compared with those produced using titanium hydride based process. The most notable structural feature of dolomite based foams is a smaller cell size and thinner cell faces. Foaming with MgCa(CO3)2 also gives rise to a marked increase in the stability of molten foams with a large range of foaming temperatures possible, and an almost complete absence of melt drainage even with extended foaming times. Many of these properties are attributed to the cell surfaces being covered by a thin oxide film formed during the foaming process.
D.P. Papadopoulos, H. Omar, F. Stergioudi, S.A. Tsipas, N. Michailidis, Colloids and Surfaces A: Physicochem. Eng. Aspects 382 (2011) 118–123

A2249 – Structural, thermal and dielectric studies on the novel solution grown (4-dimethylaminopyridinium) chloroantimonate(III) and chlorobismuthate(III) crystals

The single crystals of the following 4-dimethylaminopyridinium chloroantimonates(III) and chlorobismuthates(III) have been grown by the solvent evaporation method: (C7H11N2)SbCl4, (C7H11N2)BiCl4 and (C7H11N2)4Bi2Cl10. The one-dimensional (1D) structures for (C7H11N2)SbCl4 or (C7H11N2)BiCl4 and the zero-dimensional (0D) one for (C7H11N2)4Bi2Cl10 have been solved by the single-crystal X-ray diffraction method. (C7H11N2)SbCl4 and (C7H11N2)BiCl4 appeared to be isomorphous and crystallize in the monoclinic space group, C2/c, whereas (C7H11N2)4Bi2Cl10 in the orthorhombic one, Imma. The molecular arrangements in the subsequent crystal lattices have been studied. For all three compounds by using the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) no structural phase transition has been detected in temperature region between 100 and 400 K. Nevertheless, the dielectric relaxation processes in temperature region 100–450 K and frequency range between 100 Hz and 2 MHz have been found in all crystals studied. The experimental results of the real and imaginary parts of the dielectric permittivity allow us to estimate the parameters of the relaxation processes, i.e. macroscopic relaxation times, ?, and activation energies, EA. The dynamics of the dipolar organic cations is expected to contribute to the relaxations process in the crystals under investigation.
I. P?owas, P. Szklarz, R. Jakubas, G. Bator, Materials Research Bulletin 46 (2011) 1177–1185

A2215 – Structural and spectroscopic studies of neodymium complexes with S(+)-mandelic acid

The crystal structure of tetraaquahexakis-S(+)-mandelatodineodymium trishydrate was determined by the X-ray diffraction method. The compound crystallizes in the monoclinic space group P21 with the following unit cell parameters: a = 10.536(2), b = 16.089(3), c = 15.316(3) Å, ? = 97.96(2)°. The structure consists of polymeric [Nd2(Man)6(H2O)4·3H2O]? chains (where ManH = S(+)-2-hydroxy-2-phenylacetic acid or S(+)-mandelic acid), with two symmetry independent Nd+3 ions. Both neodymium ions are nine-coordinate but differ in their environments. Nd(1) is surrounded by two water molecules, five carboxylate and two hydroxyl oxygen atoms, Nd(2) is coordinated by two water molecules, four carboxylate and three hydroxyl oxygen atoms. Crystals of neodymium mandelate complex were characterized by thermal analysis as well as by IR and UV–vis–NIR absorption spectroscopy
Micha? Babij, Przemys?aw Starynowicz, Anna Mondry, Journal of Molecular Structure 1006 (2011) 672–677

A2199 – The energetics of nanophase calcite

Calcium carbonate (CaCO3) is an important component of the near-surface environment. Understanding the nature of its precipitation is important for a variety of environmental processes, as well as for the geologic sequestration of anthropogenic carbon dioxide. Calcite is the most thermodynamically stable bulk polymorph, but energy crossovers may exist that could favor the precipitation of vaterite or aragonite with decreasing particle size. The purpose of this study is to determine the surface energy of calcite, which is the first step towards understanding the effect of particle size on thermodynamic stability in the calcium carbonate system. The enthalpies of five well-characterized calcite samples (four nanophase and one bulk) were measured by acid solution isothermal and water adsorption calorimetric techniques. From the calorimetric data, the surface energies of calcite were determined to be 1.48 ± 0.21 and 1.87 ± 0.16 J/m2 for hydrous and anhydrous surfaces. These values are similar to those measured for many oxides but larger than predicted from computational models for idealized calcite surfaces. The surfaces of synthetic CaCO3 particles contain a range of planes and defect structures, which may give rise to the difference between the experimental and modeled values.
Tori Z. Forbes, A.V. Radha, Alexandra Navrotsky, Geochimica et Cosmochimica Acta 75 (2011) 7893–7905

A2194 – Specific surface area of clay minerals: Comparison between atomic force microscopy measurements and bulk-gas (N2) and -liquid (EGME) adsorption methods

The specific surface area of natural particles is an important parameter to quantify processes such as mineral dissolution and sorptive interactions in soils and sediments. In this study, the external specific surface area (SSA), specific edge surface area (ESA) and specific basal surface area (BSA) of an illite (Inter-ILI) and a montmorillonite (Ceratosil) were determined by atomic force microscopy (AFM) and compared with the SSA obtained by N2 gas adsorption (BET) and by liquid adsorption using ethylene glycol monomethyl ether (EGME). For the illite we found an SSA of 41 ± 3 m2 g? 1 by BET and of 83 ± 5 m2 g? 1 by analysing 54 particles by AFM. For the montmorillonite BET we estimated a SSA of 61 ± 2 m2 g? 1, whereas the analysis of 62 particles by AFM images gave a much larger mean SSA of 346 ± 37 m2 g? 1. We assume that the sample treatment prior to AFM imaging (involving dispersion by NaOH in a dilute dispersion and sonication for 2 min) resulted in delamination of the clay mineral particles. The ESA was 5.6 ± 0.4 m2 g? 1 for the illite, and 15 ± 2 m2 g? 1 for the montmorillonite. This leads to an ESA/BSA ratio of 0.07 for the illite and 0.05 for the montmorillonite for the delaminated particles. For the untreated, non-delaminated particles we calculated an ESA/BSA ratio of 0.16 for the illite and of 0.27 for the montmorillonite. The specific surface area as estimated by EGME was 112 m2 g? 1 for the illite and 475 m2 g? 1 for the montmorillonite, i.e. about 30–40% larger than the respective AFM values. However, this difference in specific surface area was not in agreement with the expected interlayer surface area of both minerals.
Felix Macht, Karin Eusterhues, Geertje Johanna Pronk, Kai Uwe Totsche, Applied Clay Science 53 (2011) 20–26

A2187 – Composite membranes based on Nafion® and plasma treated clay charges: Elaboration and water sorption investigations

Composite polymer membranes were prepared by incorporation of modified layered inorganic clay (Laponite) into Nafion® membranes. The modification of Laponite particles was performed by the plasma activation process and the chemical grafting of sulfonic groups as well as by the direct plasma sulfonation. The modified Laponite particles incorporated into a polymer film contribute to an increase of the proton conductivity of composite membranes at high temperatures (85 °C). For the first time the water vapor sorption properties of the modified clay and the composite membranes were investigated varying water activity conditions (from 0.1 to 0.95) by means of microgravimetry. The BET adsorption model as well as models of Park and Feng were applied to the experimental data. The parameter values (concentration of the adsorbed water, specific capacity and different aggregation constants) were found to agree well with the measured ones.
Kateryna Fatyeyeva,?, Corinne Chappey, Fabienne Poncin-Epaillard, Dominique Langevin, Jean-Marc Valleton, Stephane Marais, Journal of Membrane Science 369 (2011) 155–166

A2152 – Hydrometallurgical processing of nontronite type lateritic nickel ores by MHP process

The research work presented in this paper determined the optimum conditions at which nickel and cobalt could be obtained at maximum efficiency from the column leach liquor of the lateritic nickel ore existing in Gördes region of Manisa in Turkey by performing effective hydrometallurgical methods. This column leach solution was initially neutralized and purified from its basic impurities by a two-stage iron removal process, nickel and cobalt were precipitated in the form of mixed hydroxide precipitate from the purified leach solution by a two-stage precipitation method called “MHP” and a manganese removal process was performed at the optimum conditions determined experimentally. By decreasing manganese concentration with this process to an acceptable level yielding at most 10% Mn in hydroxide precipitate, it was possible to produce a qualified MHP product suitable to the current marketing and standard conditions. The experiments conducted showed that by maintaining recycle leaching with sulfuric acid at which 95% of Ni–Co could be recovered from the precipitates, about 81% of Ni and 63% of Co in the lateritic nickel ore (9.72 kg Ni/ton of ore and 0.28 kg Co/ton of ore) could be extracted as mixed hydroxide precipitate by MHP process.
C.H. Köse, Y.A. Topkaya, Minerals Engineering 24 (2011) 396–415

A2151 – High pressure acid leaching of a refractory lateritic nickel ore

This paper describes the experimental findings of the extraction of nickel and cobalt by high pressure acid leaching (HPAL) of a refractory limonitic nickel laterite ore from the Gördes region of Manisa in Turkey. By optimizing the basic HPAL process parameters: leaching at 255 °C with 0.30 sulfuric acid to ore weight ratio with a particle size of 100% ?850? for 1 h of leaching, it was found that 87.3% of nickel and 88.8% of cobalt present in the ore could be extracted into the pregnant leach solution (PLS). However, these extraction results were found to be relatively low compared with other similar studies. In order to understand the possible reasons for this relatively lower extraction, further investigations have shown that together with a problem related to the kinetics of the dissolution reactions, a persistent acid resistant refractory mineral present in this sample also limited the leaching process. Attempts were made with different additives to solve this problem. The effects of chemical additives such as HCl, Na2SO4, FeSO4, Cu+ and sulfur were tested and the effect of each addition on the degree of extraction of nickel and cobalt was determined.
S. Kaya, Y.A. Topkaya, Minerals Engineering 24 (2011) 1188–1197

A2130 – The study of aluminum loss and consequent phase transformation in heat-treated acid-leached kaolin

This study investigates the effect of Al leaching during Fe removal from kaolin to mullite. Heat-treated kaolin was obtained by heating natural kaolin at 400, 500, 600, 700, 800 and 900 °C. The heat-treated kaolin was then leached at 100 °C with 4 M, 3 M, 2 M, 1 M, 0.2 M solution of H2SO4 and 0.2 M solution of oxalic acid. The dried samples were sintered to 1300 °C for 4 h at a heating rate of 10 °C min?1. X-ray diffractometry and differential thermal analysis were used to study the phase transformation of kaolin to mullite. It was found that 700 °C is the optimum preheat-treatment temperature to leach out Fe and also Al for both types of the acids used. The majority of the 4 M sulfuric acid-treated kaolins formed the cristobalite phase when sintered. On the other hand, 1 M, 0.2 M sulfuric acid and 0.2 M oxalic acid leached heat-treated kaolin formed mullite and quartz phase after sintering.
Choo Thye Foo, Che Seman Mahmood, Mohamad Amran Mohd Salleh, Materials Characterization, 62 (2011) 373-377

A2128 – Detection of evolved oxygen from the Rocknest eolian bedform material at Mars (SAM) instrument at the Mars Curiosity landing

The Sample Analysis at Mars (SAM) instrument onboard the Curiosity rover detect-ed an O2 gas release from the Rocknest eolain bedform (Fig. 1). The detection of perchlorate (ClO4-) by the Mars Phoenix Lander’s Wet Chemisty Laboratory (WCL) [1] suggests that perchlorate is a possible can-didate for evolved O2 release detected by SAM. The perchlorate would also serve as a source of chlorine in the chlorinated hydrocarbons detected by the SAM quadrupole mass spectrometer (QMS) and gas chroma-tography/mass spectrometer (GCMS) [2,3]. Chlorates (ClO3-) [4,5] and/or superoxides [6] may also be sources of evolved O2 from the Rocknest materials. The work objectives are to 1) evaluate the O2 release temperatures from Rocknest materials, 2) compare these O2 release temperatures with a series of perchlo-rates and chlorates, and 3) evaluate superoxide O2- sources and possible perchlorate interactions with oth-er Rocknest phases during QMS analysis.
B. Sutter1, D. Archer, D. Ming, J. L. Eigenbrode, H. Franz, D. P. Glavin, A. McAdam, P. Mahaffy, J. Stern, R. Navarro-Gonzalez, C. McKay

A2127 – Detection of evolved carbon dioxide in the Rocknest eolian bedform by the Sample Analysis at Mars (SAM) instrument at the Mars Curiosity landing site

The Sample Analysis at Mars (SAM) instrument detected four releases of carbon dioxide (CO2) that ranged from 100 to 700?C from the Rocknest eolian bedform material (Fig. 1). Candidate sources of CO2 include adsorbed CO2, carbonate(s), combusted organics that are either derived from terres-trial contamination and/or of martain origin, occluded or trapped CO2, and other sources that have yet to be determined. The Phoenix Lander’s Thermal Evolved Gas Analyzer (TEGA) detected two CO2 releases (400-600, 700-840?C) [1,2]. The low temperature release was attributed to Fe- and/or Mg carbonates [1,2], per-chlorate interactions with carbonates [3], nanophase carbonates [4] and/or combusted organics [1]. The high temperature CO2 release was attributed to a calci-um bearing carbonate [1,2]. No evidence of a high temperature CO2 release similar to the Phoenix materi-al was detected in the Rocknest materials by SAM. The objectives of this work are to evaulte the tempera-ture and total contribution of each Rocknest CO2 re-lease and their possible sources.
B. Sutter, D. Archer, A. McAdam, H. Franz, D.W. Ming, J. L. Eigenbrode, D. P. Glavin, P. Mahaffy, J. Stern, R. Navarro-Gonzalez, C. McKay,

A2113 – Polynuclear complexes constructed by lanthanides and pyridine-3,5-dicarboxylate ligand: Structures, thermal and luminescent properties

Sodium salt of pyridine-3,5-dicarboxylic acid (H2pdc) reacts with the chloride (or nitrate) salt of lanthanides(III) (from La to Lu, except Pm) under hydrothermal conditions to form different kinds of coordination frameworks. The compounds of the general formula Ln2pdc3·nH2O (pdc2? = C5H3N(COO)22?, n = 2.64–14) are characterized in the solid state by elemental analysis, IR spectroscopy, TG-DSC and TG-FTIR analyses, single-crystal X-ray diffraction, and X-ray powder diffraction (XRPD) techniques as well as fluorescent spectroscopy. The crystalline compounds form isostructural groups: Sm-Gd, Tb-Er and Tm-Lu. The crystal structures of [Ho2pdc3(H2O)2]·0.64H2O (1), [Er2pdc3(H2O)2]·0.68H2O (2) and [Yb4pdc6(H2O)18]·10H2O (3) compounds are reported. The compounds 1 and 2 are built up from metallic centrosymmetric dimers connected by pdc2? ligands into the 3D frameworks. There are observed 1D channels occupied by water molecules. In compound 3, the four Yb(III) centers are bridged through pdc2? ligands into the cyclic tetranuclear structure. These molecules are further assembled into a 3D supramolecular framework. This appears to be a rare example of cyclic polynuclear compounds generated by lanthanide(III) ions and polycarboxylate ligands. The luminescent properties of the complexes in visible and infrared regions upon UV excitation are discussed.
Renata ?yszczek, Liliana Mazur, Polyhedron 41 (2012) 7–19

A2111 – Structural characterization of dodecyltrimethylammonium (DTMA) bromide modified sepiolite and its adsorption isotherm studies

In this study, dodecyltrimethylammonium (DTMA) bromide was used to modify natural sepiolite via an ion exchange reaction to form DTMA-sepiolite. Sepiolite and DTMA-sepiolite were then characterized by using Brunauer–Emmett–Teller (BET), elemental analysis, XRD, FT-IR, thermogravimetric (TG) and zeta potential analysis techniques. The BET surface area of sepiolite significantly decreased from 152.14 m2 g–1 to 88.63 m2 g–1, after the modification, due to the coverage of the pores of sepiolite. DTMA was located onto sepiolite according to the differential thermogravimetric (dTG) peaks of DTMA-sepiolite. XRD results confirmed the interaction between DTMA+ cations and sepiolite. FT-IR spectra indicated the existence of DTMA functional groups on sepiolite surface. After the characterization was accomplished, adsorption isotherm studies of naphthalene, which is the first member of the polycyclic aromatic hydrocarbons (PAHs), were carried out. The maximum adsorption capacity of DTMA-sepiolite for naphthalene was determined from Langmuir isotherm equation at pH 6 and 20 °C as 1.88 × 10–4 mol g?1 or 24.09 mg g?1.
A. Safa Özcan, Özer Gök, Journal of Molecular Structure 1007 (2012) 36–44

A2089 – Crystal structure,spectroscopic,magnetic and electronic structure studies of a novel Cu(II) amino acid complex [Cu(L-arg)2(H2O)]2(P4O12) 8H2O

Single crystals of a novel copper (II) complex with the amino acid l-arginine (l-arg) and cyclotetraphosphate, [Cu(l-arg)2(H2O)]2(P4O12)·8H2O, were prepared in aqueous solution and were characterized by X-ray diffraction, spectroscopy (diffuse reflectance, UV–vis and IR) and thermal analysis. Magnetic measurements and electronic structure calculations were also performed. Crystal structure determination reveals that this compound has a nonsymmetrical atomic arrangement, containing mainly a binuclear [Cu(l-arg)2(H2O)]24+ cation and an uncoordinated cyclotetraphosphate counter-anion (P4O124?). The tetravalent cation contains two independent Cu(II) ions in two different chemical environments. This compound exhibits an antiferromagnetic (AFM) to paramagnetic (PM) phase transition at a temperature (TN) lower than 2 K. The values of paramagnetic Curie–Weiss temperature (?cw) and the exchange parameter (J/KB) emphasize the existence of an antiferromagnetic interaction between the neighboring copper ions.
H. Hemissi, M.Nasri, S.Abid, S.S.Al-Deyab, E.Dhahri, E.K.Hlil, M.Rzaigui, Journal of Solid State Chemistry 196 (2012) 489–497

A2076 – Effect of iron phase on the strengthening of lateritic-based “geomimetic” materials

The present work aims to investigate the action of associated iron species contained in lateritic clays in the strengthening process of “geomimetic” materials (compressive strength of 12 MPa). The starting products are a lateritic clay from Cameroon, fulvic acid and lime. The synthesis involves acidic and alkaline reactions followed by a curing period of 18 days at 60 °C under water-saturated atmosphere. Since goethite (?-FeOOH), hematite (?-Fe2O3) and ferrihydrite (5Fe2O3·9H2O) are the main iron compounds in the raw clay, investigations have been carried out to identify to which extend each of these phases participates in the consolidation process. It appears that hematite and ferrihydrite may contribute to the consolidating mechanism since the as obtained “geomimetic” products exhibit characteristic compressive strength of 8.3 and 4.5 MPa respectively. Besides, the use of goethite leads to consolidated products with characteristic compressive strength of 6.5 MPa. The strengthening is effective when the synthesis of iron species is performed separately (no direct precipitation onto kaolin particles). Moreover, among the various model samples tested, only those elaborated with goethite were resistant towards water seeping and wearing. Hence, goethite is considered as the major active phase in the dissolution precipitation reaction which leads to bridging ferric gels.
Gisèle Lecomte-Nana, Hervé Goure-Doubi, Agnès Smith, Alain Wattiaux, Gilles Lecomte, Applied Clay Science 70 (2012) 14–21

A2062 – Effect of surface resistance on cyclohexane uptake curves in Silicalite-1 crystals

Adsorption kinetics of cyclohexane in a variety of Silicalite-1 samples were measured by gravimetric uptake experiments. The kinetic appears as dependent upon the history of the crystals. Samples stored for several months before calcination (with their micropores full of template) exhibit a kinetic drop by almost an order of magnitude. Surprisingly, physico-chemicals analysis do not show any differences between these samples (no modification of their crystallinity or morphology, and no residual carbon is detected in the pore network). The kinetic drop is therefore attributed to a modification of the crystals surface, induced by a long-time contact with the template or cyclohexane molecules. Aged and as-synthesized (non-calcined) samples were etched by an HF solution, so as to “purify” the surface of the crystals. After a few minutes of treatment, the aged samples recover their initial adsorption kinetic, confirming that the kinetic drop is induced by the partial blocking of the entrance of the pores. Moreover, some of the as-synthesized crystals also show a rise of their adsorption kinetic, showing that surface resistance can be present ab initio, depending on the synthesis conditions. In an attempt to produce an accelerated aging effect, hydrothermal treatments were performed on non-calcined crystals. However, the treatments conditions are too severe, and induce variations in the crystal structure.
Laurent Gueudré, Nicolas Bats, Elsa Jolimaître, Microporous and Mesoporous Materials 147 (2012) 310–317

A2057 – Surface modifications of illite in concentrated lime solutions investigated by pyridine adsorption

The surface properties and functionality of an illite-containing clay mineral in alkaline solutions containing increasing quantities of calcium hydroxide were investigated using FTIR monitored pyridine adsorption at various temperatures. Results showed that the binding behavior of electron donor pyridine molecules to illite platelets is mostly governed by electron acceptor sites located at the edges of the clay particles. The binding of bulky hydrated calcium ions at the surface of the illite platelets decreases the surface area of illite. Moderate thermal treatments up to 450 °C do not affect the structure of the clay mineral but strongly decrease the number of Lewis and Brönsted sites available at the edges of the clay platelets.
K.L. Konan, C. Peyratout, A. Smith, J.-P. Bonnet, P. Magnoux, P. Ayrault, Journal of Colloid and Interface Science 382 (2012) 17–21

A2045 – Synthesis and structural transformations of the ‘‘glaserite’’ type zirconosilicate Na3 xH1+xZrSi2O8 yH2O

A hydrous sodium zirconosilicate material with “glaserite” type structure and generalized formula Na3?xH1+xZrSi2O8·yH2O, 0 < x < 3, 0 < y < 1 is synthesized in the system Na2O:ZrO2:SiO2:H2O at 200 °C. Its crystal structure is composed of zirconium and silicon polyhedra connected to build layers additionally stacked to form 3D zipper-like network. Within the network there are cavities interconnected to channels with irregular shapes where the sodium atoms and water molecules reside. It is found that with synthesis duration the crystal structure gradually transforms from higher symmetrical into triclinic one. The structure of the triclinic form – Na3HZrSi2O8·0.4H2O was refined from powder diffraction data. It crystallizes in the space group P-1 with lattice parameters a = 9.05234, b = 5.56121, c = 6.96219 Å, ? = 92.178, ? = 90.839, ? = 90.288°. To the best of our knowledge the studied compound is the only water-containing material with “glaserite” type structure.
Vladislav V. Kostov-Kytin, Rosica P. Nikolova, Diana D. Nihtianova, Materials Research Bulletin 47 (2012) 2324–2331

A2042 – Bi[NC5H3(CO2)2](OH2)xF (x=1 and 2):New one-dimensional Bi-coordination materials—Reversible hydration and topotactic decomposition to ?-Bi2O3

Two one-dimensional bismuth-coordination materials, Bi[NC5H3(CO2)2](OH2)xF (x=1 and 2), have been synthesized by hydrothermal reactions using Bi2O3, 2,6-NC5H3(CO2H)2, HF, and water at 180 °C. Structures of the two materials were determined by single-crystal X-ray diffraction. Although they have different crystal structures, both Bi-organic materials shared a common structural motif, a one-dimensional chain structure consisting of Bi3+ cations and pyridine dicarboxylate linkers. Detailed structural analyses include infrared spectroscopy, thermogravimetric analysis, and reversible hydration reactions for the coordinated water molecules were reported. Also, thermal decomposition of the rod-shaped Bi[NC5H3(CO2)2](OH2)F single crystals at 800 °C led to ?-Bi2O3 that maintained the same morphology of the original crystals
Hye Rim Jeon, Dong Woo Lee, Kang Min Ok, Journal of Solid State Chemistry 187 (2012) 83–88

A2028 – The role of microstrain on the thermostructural behaviour of industrial kaolin deformed by ball milling at low mechanical load

The high-temperature structural behaviour of kaolin deformed by compaction and shear in a ball mill was investigated by extending the temperature range to 1500 °C. The deformation was induced for the first time with steps of low mechanical load through a specifically built planetary ball milling working in a controlled thermodynamic environment (25 °C and at a vacuum of 0.13 Pa). The investigated kaolin was made of about 65% of a well-ordered kaolinite, 10% of dickite and 25% of quartz. The mechanical energy transfer to the material was measured via the microstrain < ?2>1/2 because we wanted to investigate the details of the evolution of the kaolin modification as a function of the microstrain. At the very early stage of milling (up to 1 h), no strain was accumulated in the kaolinite structure which, however, presented lamination, layer flattening and texturing. Further milling induced a progressive reduction of the stacking layer coherence and an increase of the microstrain, in both cases as a non linear function of the deformation time. The thermo-structural behaviour of kaolin was investigated by TG-DTA in a helium atmosphere at 10 °C/min of heating rate. In the medium temperature range (400–1000 °C), the mechanical milling affected the dehydroxylation reaction of kaolinite by a significant anticipation of about 300 °C of the temperature range, which usually occurs between 400 and 800 °C. Other reactions related to the formation of a Si-spinel and other intermediate phases were observed. The mechanical deformation severely influenced of the high-temperature reactions related to mullite and cristobalite formation. All thermal reactions linearly correlate to the microstrain < ?2>1/2 accumulated in the kaolinite structure. The reported data are of particular usefulness in industrial applications involving grinding or milling of kaolin.
Francesco Dellisanti, Giovanni Valdrè, International Journal of Mineral Processing 102–103 (2012) 69–77

A2016 – Surface properties evolution of attapulgite by IGC analysis as a function of thermal treatment

At low temperatures, thermal treatment of attapulgite clay causes a loss of mass due to the elimination of linked, zeolitic and crystallized water molecules. At high temperatures, there is a junction of particles until total melting of the attapulgite fibers. This transformation reduces significantly the volume of the porous network resulting in the drop in the value of specific surface area and causing important changes in the textural, structural and surface properties of the raw attapulgite. The inverse gas chromatography shows sensitivity of the attapulgite sample to the effect of temperature through the decrease of the dispersive component of the surface energy ?sd. The evolution of the nanomorphological index, a measurement of the surface nanorugosity, follows the appearance of surface roughness on carbonates with the increase of the temperature. The surface heterogeneity, determined by calculating the distribution functions of adsorption energies also underlines the morphology changes and the formation of new phases under the effect of temperature.
Lilya Boudriche, Rachel Calvet, Boualem Hamdi, Henri Balard, Colloids and Surfaces A: Physicochem. Eng. Aspects 399 (2012) 1– 10

A2014 – An efficient route to aqueous phase synthesis of nanocrystalline c-Al2O3 with high porosity: From stable boehmite colloids to large pore mesoporous alumina

In this paper we emphasise the important role of Pluronic F127 on the porosity of mesoporous alumina prepared from boehmite colloids. By focusing on the F127/boehmite interactions we show how the concepts of interface science may help to predict and improve the textural characteristics of mesoporous alumina. By varying the synthetic parameters, in particular the copolymer content, we show that the porosity of ?-Al2O3 can be enhanced by 400% and the average pore diameter can be expanded from 5 to 14 nm. These results are discussed in terms of interactions between the Pluronic F127 and boehmite colloids, and are correlated to the critical micelle concentration (CMC) of the copolymer. The textural characteristics of the mesoporous alumina can be further improved either by introducing hydrocarbons in the preformed boehmite/copolymer sols or by concentrating the sols. In comparison with as-synthesised alumina, those prepared with F127 showed improved thermal stability. Furthermore, boehmite/copolymer sols were stable for all surfactant concentrations investigated and can give high quality coatings suitable for catalytic applications.
Rudina Bleta, Pierre Alphonse, Lisa Pin, Marie Gressier, Marie-Joëlle Menu, Journal of Colloid and Interface Science 367 (2012) 120–128

A2010 – Physicochemical, crystalline and morphological characteristics of bricks used for ground waters purification in Bangui region (Central African Republic)

The development and improvement of natural water and wastewater purification technologies utilizing low-cost raw materials like bricks are necessary to make possible easy application in poor countries. The present work concerns the detailed studies on a soil which is commonly used to make bricks by craftsmen in Bangui region (Central African Republic). The chemical and mineralogical composition of this soil before and after thermal transformation, and its crystalline, morphological and surface properties were determined by combining several techniques: X-ray Diffraction (XRD), ThermoGravimetric Analyses (TGA), Differential Thermal (DTA) Analyses, TGA/Mass Spectrometry (MS), 27Al and 29Si NMR spectroscopy, and Environmental Scanning Electron Microscopy (ESEM; an apparatus equipped with an Energy Dispersive X-ray Spectrometer, EDS). The basic brick making led to an interesting mesoporous material that was found to be a good adsorbent for Fe(II) removal from contaminated natural waters. Column experiments further revealed significant improvement of the sorption capacity of this brick when its surface was coated with iron oxy-hydroxide. ESEM/EDS micro-analyses revealed that FeOOH was preferentially deposited onto brick clays (mainly disordered metakaolinite), thus showing the key role played by these minerals in the study water treatment when compared to the sorption performances obtained with raw sand and FeOOH-coated sand.
S.C. Dehou, M. Wartel, P. Recourt, B. Revel, J. Mabingui, A. Montiel, A. Boughriet, Applied Clay Science 59–60 (2012) 69–75

A1983 – Rehydration of dehydrated CaFe-L(ayered)D(ouble)H(ydroxide) followed by thermogravimetry, X-ray diffractometry and dielectric relaxation spectroscopy

In this contribution the rehydration process of a dehydrated CaFe-LDH is described with the combination of thermogravimetric (TG), X-ray diffraction (XRD) and dielectric relaxation spectroscopic (DRS) measurements. Dehydration was followed by TG and the major steps were identified. For studying the rehydration procedure the dehydrated samples were treated in the 6–97% relative humidity range at several preset vapour contents at 298 K. For equilibration 72 h were allowed. Then, the XRD diffractograms and the DRS spectra were registered and the thermal behaviour of the partially rehydrated samples was also studied. From these measurements the various forms of water molecules interacting with the LDH were deduced and their relaxation behaviour in the rehydration procedure is described.
V. Bugris, H. Haspel, Á. Kukovecz, Z. Kónya, M. Sipiczki, P. Sipos, I. Pálinkó, Journal of Molecular Structure (2012)

A1908 – Thermoanalytical, magnetic and structural study of Co(II) complexes with substituted salicylaldehydes and neocuproine

In this study, simultaneous TG/DTG-DTA technique was used for two cobalt(II) complexes with neocuproine(neoc) and the anion of a substituted salicylaldehyde ligand (X-salo) (X = 3-OCH3, or 5-CH3) with the general formula [Co(X-salo)2(neoc)], to determine their thermal degradation in inert atmosphere, which was found to be a multi-step decomposition related to the release of the ligand molecules. The solid material at 1300 °C (verified with PXRD) was a mixture of carbonaceous metal cobalt. Evolved gas analysis by coupled TG-MS verified the elimination of a formaldehyde molecule in the first decomposition stage, initially proposed by the percentage mass loss data. By single-crystal X-ray diffraction analysis an octahedral geometry of the complex [Co(3-OCH3-salo)2(neoc)] was found. The variable temperature magnetic susceptibility measurements showed a paramagnetic nature of the complexes, in accordance with their molecular structure. Finally, for the determination of the activation energy (E) two different methods (the isoconversional methods of Ozawa, Flynn and Wall (OFW) and Friedman) were used comparatively
Maria Lalia-Kantouri, Maria Gdaniec, Agnieszka Czapik, Konstantinos Chrissafis, Wieslawa Ferenc, Jan Sarzynski, Christos D. Papadopoulos, J Therm Anal Calorim (2012) 109, 131–139

A1904 – Synthesis, thermal analysis, and spectroscopic and structural characterizations of zinc(II) complexes with salicylaldehydes

In this study, three new zinc(II) complexes with 5-substituted salicylaldehyde ligands (X-saloH) (X = 5-chloro, 5-nitro and 5-methyl) with the general formula [Zn(X-salo)2(CH3OH)n], (n = 0 or 2) were synthesized. An octahedral geometry was found for both the complexes [Zn(5-NO2-salo)2(CH3OH)2] and [Zn(5-Cl-salo)2(CH3OH)2] by single-crystal X-ray diffraction analysis. These complexes were characterized also by spectroscopy (IR and 1H-NMR). Simultaneous TG/DTG–DTA techniques were used to analyze their thermal behavior under inert atmosphere, with particular attention to determine their thermal degradation pathways, which was found to be a multi-step decomposition accompanied by the release of the ligand molecules. Finally, the kinetic analysis of the decomposition processes was performed by applying both the isoconversional Ozawa–Flynn–Wall (OFW) and the Kissinger–Akahira–Sunose (KAS) methods.
Ariadni Zianna, Stefano Vecchio, Maria Gdaniec, Agnieszka Czapik, Antonis Hatzidimitriou, Maria Lalia-Kantouri, J Therm Anal Calorim, 2012

A1903 – Synthesis of bismuth mixed oxide by thermal decomposition of a coprecipitate precursor

Bismuth mixed oxide powders were prepared by oxalate coprecipitation process. The thermal decomposition behaviour of the coprecipitate precursors has been followed by thermal analysis (TG-DTA) and FTIR spectroscopy. During the decomposition of the precursor, several intermediates species were detected and a mechanism of formation of mixed oxide by this method is proposed. After the thermal treatment, the precursor obtained of suggested formula Ca3[Bi6O6(C2O4)4(OH)3NO3]0.5H2O, has led to the formation of CaBi2O4 at shorter reaction time than the traditional ceramic method. In order to consolidate the results, the coprecipitation in absence of oxalic precipitant under the same conditions was examined. XRD and scanning electron spectroscopy were used to study particles sizes and morphology
Abdellah Bahmani, Mayouf Sellami, Noureddine Bettahar, J Therm Anal Calorim (2012) 107, 955–962

A1901 – Phase equilibria in the YPO4–Rb3PO4 system

The phase equilibria occurring in the YPO4–Rb3PO4 system were investigated by thermoanalytical methods, X-ray powder diffraction, and ICP-OES. On the basis of the obtained results, its phase diagram is proposed. It was found that the system includes two intermediate compounds Rb3Y(PO4)2 and Rb3Y2(PO4)3. The Rb3Y(PO4)2 compound melts congruently at 1300 °C. The Rb3Y2(PO4)3 orthophosphate was previously unknown. This intermediate compound is high-temperature unstable and decomposes within the temperature range 1300–1330 °C to YPO4 and Rb3Y(PO4)2. The decomposition process is irreversible. It was found that the Rb3Y2(PO4)3 orthophosphate is isostructural with Rb3Yb2(PO4)3 and crystallizes in the cubic system (a = 1.70226 nm).
W. Szuszkiewicz, E. Radominska, T. Znamierowska, P. Wilk, J Therm Anal Calorim, 2012

A1900 – Magnesium sulphate complexes with hexamethylenetetramine and 1,10-phenanthroline. Thermal, structural and spectroscopic properties

The magnesium sulphate complex compounds of general formulae [Mg(H2O)6]2+·2(C6H12N4)·SO4 2?·5(H2O) (1) and Mg(C12H8N2)(H2O)3SO4 (2) have been synthesized, characterised by elemental and thermal analysis, IR, UV–VIS and fluorescence spectroscopy, and X-ray crystallography. The obtained compounds are air stable at room temperature and well soluble in water. In the structures of the investigated complex compounds the O–H?O, O–H?N, and C–H?O hydrogen bonds exist, and they create N2C 2 2 (8), R 2 2 (8) (compound 1) and N1C 1 1 (6), N1R 2 2 (12) (compound 2) patterns. Their thermal decomposition processes in the investigated atmospheres (air and helium) are different. After the slightly similar dehydratation, the observed transitions and the obtained final products are different (in helium atmosphere the sulphate ion of studied compounds undergoes decomposing what does not take place in air atmosphere). The UV–VIS spectrum of 2 shows maxima that are typical for ? ? ?* and n ? ?* transitions, and fluorescence spectrum of the same compound displays its great fluoresce properties. The 1 does not exhibit absorption in the investigated region of electromagnetic spectrum due to the absence of respect chromophore groups. The IR spectrum of 2 shows typical vibrations for chelating amine molecule. An interesting fact is that in 1 the SO stretching vibrations (existing at 1119 and 1182 cm?1) are doubled in comparison to the magnesium sulphate whilst in 2 these vibrations are absent.
Tomasz Sieranski, Rafal Kruszynski, J Therm Anal Calorim (2012) 109, 141–152

A1894 – Thermal decomposition of sodium propoxides. Kinetic studies using model-free method under isothermal and non-isothermal conditions

Sodium alkoxides, namely, sodium n-propoxide and sodium iso-propoxide were synthesized and characterized by various analytical techniques. Thermal decomposition of these compounds was studied under isothermal and non-isothermal conditions using a thermogravimetric analyzer coupled with mass spectrometer. The onset temperatures of decomposition of sodium n-propoxide and sodium iso-propoxide were found to be 590 and 545 K, respectively. These sodium alkoxides form gaseous products of saturated and unsaturated hydrocarbons and leave sodium carbonate, sodium hydroxide, and free carbon as the decomposition residue. Activation energy, Ea, and pre-exponential factor, A, for the decomposition reactions were deduced from the TG data by model-free (isoconversion) method. The Ea for the decomposition of sodium n-propoxide and sodium iso-propoxide, derived from isothermal experiments are 162.2 ± 3.1 and 141.7 ± 5.3 kJ mol-1, respectively. The values obtained from the non-isothermal experiments are 147.7 ± 6.8 and 133.6 ± 4.1 kJ mol-1, respectively, for the decomposition of sodium n-propoxide and sodium iso-propoxide.
K. Chandran, M. Kamruddin, P. Muralidaran, V. Ganesan, J Therm Anal Calorim, 2012

A1890 – Kinetics of the thermal dehydration of potassium titanium oxalate, K2TiO(C2O4)2 2H2O

The thermal dehydration reaction of potassium titanium oxalate, K2TiO(C2O4)2 2H2O, has been studied by means of thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC) in nitrogen atmosphere at different heating rates. K2TiO(C2O4)2 2H2O dehydrates in a single step through a practically irreversible process. The activation energy involved and its dependence on the conversion degree were estimated by evaluating the thermogravimetric data according to model-free methods, and values of activation energy were determined for the dehydration reaction. Activation energy values were also evaluated from DSC data using isoconversional methods. The complexity of the dehydration of K2TiO(C2O4)2 2H2O is illustrated by the dependence of E on the extent of conversion, a (0.05
K. Muraleedharan, P. Labeeb, J Therm Anal Calorim (2012) 109:89–96

A1867 – Study of the fluorite–pyrochlore–fluorite phase transitions in Ln2Ti2O7 (Ln=Lu, Yb, Tm)

The ordering processes in Ln2Ti2O7 (Ln=Lu, Yb, Tm) are studied by X-ray diffraction, thermal analysis, infrared absorption (IR) spectroscopy, and electrical conductivity measurements. The coprecipitation method followed by freeze-drying was used for Ln2Ti2O7 synthesis. The region of low-temperature fluorite phase existence is 600 °C1,600 °C. The conductivity values are 5.10-3 S/cm for Tm2Ti2O7, 6.10-3 S/cm for Yb2Ti2O7, and 10-2 S/cm for Lu2Ti2O7 at 740 °C. This order–disorder transition leads to a 2 orders of magnitude conductivity growth and a 10–30 times permittivity increase in Ln2Ti2O7 samples obtained at 1,700 °C.
A. V. Shlyakhtina, L. G. Shcherbakova, A. V. Knotko, A. V. Steblevskii, J Solid State Electrochem (2004) 8, 661–667

A1815 – Thermal behaviour of magnesium-containing fluorapatite

Pure fluorapatite (Fap) and magnesium-substituted fluorapatite with various Mg contents were synthesised by precipitation reactions. Scanning electron microscopy micrographs showed that the use of Mg led to a change of the grain morphology. Chemical analysis and X-ray diffraction (XRD) indicated that Mg introduced in the solutions was incorporated into fluorapatite. However, samples heated at different temperatures showed that some Mg amount was adsorbed to the surface of the particles in an amorphous state, which crystallised inMg2F(PO4) at 650 ?C. This phase was detected up to a temperature of 1120 ?C. Above this value, it disappeared following its dissolution in the liquid phase formed from a eutectic between fluorapatite and fluorine. The specific surface area (SSA) decreased strongly with increasing temperature. At low temperatures, the surface reduction was due to the agglomeration of the grains. With the improvement of the crystallisation, when the temperature increased, surface diffusion took place. At higher temperatures, before the densification occurred, surface diffusion was in competition with gaseous diffusion which became dominant
M. Hidouri, K. Bouzouita, F. Kooli, I. Khattech, Materials Chemistry and Physics 80 (2003) 496–505

A1806 – Phase equilibria in the YPO4–Rb3PO4 system

The phase equilibria occurring in the YPO4–Rb3PO4 system were investigated by thermoanalytical methods, X-ray powder diffraction, and ICP-OES. On the basis of the obtained results, its phase diagram is proposed. It was found that the system includes two intermediate compounds Rb3Y(PO4)2 and Rb3Y2(PO4)3. The Rb3Y(PO4)2 compound melts congruently at 1300 °C. The Rb3Y2(PO4)3 orthophosphate was previously unknown. This intermediate compound is high-temperature unstable and decomposes within the temperature range 1300–1330 °C to YPO4 and Rb3Y(PO4)2. The decomposition process is irreversible. It was found that the Rb3Y2(PO4)3 orthophosphate is isostructural with Rb3Yb2(PO4)3 and crystallizes in the cubic system (a = 1.70226 nm).
W. Szuszkiewicz, E. Radominska, T. Znamierowska, P. Wilk, J Therm Anal Calorim (2013) 111, 63–69

A1770 – Thermochemical studies on RE2O2CO3 (REZGd, Nd) decomposition

Thermochemistry in the decomposition of gadolinium di-oxycarbonate, Gd2O2CO3(s) and neodymium di-oxycarbonate, Nd2O2CO3(s) was studied over the temperature region of 774–952 K and 775–1105 K, respectively. The equilibrium properties of the decomposition reactions were obtained by tensimetric measurement of the CO2(g) pressure over the biphasic mixture of RE2O2CO3(s) and RE2O3(s) at different temperatures (REZGd, Nd) and also by thermogravimetric analysis of the decomposition temperature at different CO2 pressures. The temperature dependence of the equilibrium pressure of CO2 thus measured could be given by: ln pCO2/Pa (± 0.13) = -22599.1/T + 35.21 (774
A.N. Shirsat, K.N.G. Kaimal, S.R. Bharadwaj, D. Das, Journal of Physics and Chemistry of Solids 66 (2005) 1122–1127

A1758 – Luminescence properties of a new green emitting Eu2+-doped barium chlorosilicate phosphor

A new intense green light-emitting phosphor, the Eu2+-doped (BaO–BaCl2–SiO2) phosphor system, was synthesized at 800°C by the conventional high-temperature solid-state reaction. Its structure and luminescence properties were investigated by using thermogravimetrydifferential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), diffuse reflection spectra, photoluminescence (PL) and photoluminescence excitation (PLE) spectra. The photoluminescence spectrum reveals that this phosphor can be efficiently excited by near-ultraviolet (UV) light and blue light in the wavelength region covering 280 and 480 nm, which perfectly matches the emission wavelength of near-UV light-emitting diodes (LEDs). It emits an intense green light peaking at 502 nm, which is promising to develop possible applications for white LEDs.
H. Du, J. Sun, Z. Xia, J. Sun, Appl Phys B (2009) 96, 459–463

A1707 – Thermal and spectroscopic properties of light lanthanides (III) and sodium complexes of 2,5-pyridinedicarboxylic acid

Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln2L3 nH2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na2L H2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas Na2L H2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of mCOOH vibrations at 1736 and 1728 cm-1 disappear on complex spectra and mas and ms of COO- groups appear thus indicating that complexation process took place.
Zofia Rzaczynska, Anna Danczowska-Burdon, Justyna Sienkiewicz-Gromiuk, J Therm Anal Calorim (2010) 101, 671–677

A1706 – Synthesis, spectroscopic and thermal studies of 2,3-naphthalenedicarboxylates of rare earth elements

The complexes of rare earth elements with 2,3-naphthalenedicarboxylic acid of the formula: Ln2(C12H6O4)3 nH2O, where Ln = La(III)-Lu(III) and Y(III); n = 3 for La(III), Ce(III); n = 6 for Pr(III)-Yb(III) and Y(III) and n = 5 for Lu(III) have been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis (TG, DTG, DTA and TG-FTIR) and X-ray analysis. They are sparingly soluble in water and stable at room temperature. During heating in air atmosphere, they lose all water molecules in several steps, generally in two or three steps, except for the La(III) and Ce(III) complexes which lose all water molecules in one step. The anhydrous compounds are stable up to about 773 K and then decompose to corresponding oxides. The thermal decomposition is connected with the release of water molecules (443 K), carbon dioxide (713 K) and hydrocarbons.
Z. Rzaczynska, A. Kula, J. Sienkiewicz-Gromiuk, A. Szybiak, J Therm Anal Calorim (2011) 103, 275–281

A1705 – Phase equilibria in the system Rb3PO4–Ba3(PO4)2

The system Rb3PO4–Ba3(PO4)2 was investigated by thermoanalytical methods, X-ray powder diffraction, ICP, and FT-IR. On the basis of the obtained results its phase diagram was proposed. For this system with one intermediate compound, BaRbPO4, we found that this compound melts congruently at 1700 C, exhibits a polymorphic transition at 1195 C and is high-temperature unstable. Also, the intermediate compound was subject to gradual decomposes to Ba3(PO4)2 (the solid phase) and vaporization (with conversion of phosphorus and rubidium oxides into vapor phase). We also found that Rb3PO4 melts congruently at 1450 C and shows a polymorphic transition at 1040 C. Regarding Ba3(PO4)2, we have confirmed that it melts congruently at 1605 C and exhibits a polymorphic transition at 1360 C.
E. Radominska, T. Znamierowska, W. Szuszkiewicz, J Therm Anal Calorim (2011) 103, 761–766

A1704 – Modified Pechini synthesis of La, Ce, and Pr orthophosphates and characterization of obtained powders

In this study, lanthanum, cerium, and praseodymium orthophosphates were synthesized by the modified Pechini method. The compounds were analyzed using XRD, TG/DSC, FTIR methods, and the isothermal nitrogen adsorption technique. The results showed that mesoporous and nanocrystalline powders can be synthesized by this method. Moreover, due to the limited formation of lanthanide polyphosphates on the surface of the powders the modified Pechini method allows better control of the compound stoichiometry in comparison with the commonly used method of phosphates precipitation from solutions rich in H3PO4.
Aleksandra Matraszek, Ewa Radominska, Irena Szczygiel, J Therm Anal Calorim (2011) 103, 813–819

A1669 – Hydrogen Reduction of Oxidized Nickel Concentrates

Thermal gravimetric analysis was used to investigate the weight change of Ni/Cu/Co calcines upon heating in an inert as well as hydrogen atmosphere. The two calcines investigated contained approximately 50 wt pct combined of hematite and magnetite in addition to sulfides of Ni, Cu, Co, and Fe. Mass spectrometry was used to analyze the gas species evolved during heating and reduction. The calcine samples are 100 pct less than 100 ?m with hematite/magnetite rims around a central sulfide core. When heating the calcines at 10 °C/min in hydrogen, reduction starts at around 400 °C and is nearly complete at about 700 °C with all the reducible oxygen removed. Isothermal reduction tests show that at temperatures from 650 °C to 800 °C, half the oxygen is removed in less than 4 min. The TGA results combined with microscopic analysis show that the reduction followed a uniform internal reduction model. The reduced calcines will quickly get re-oxidized if they are allowed to contact air while they remain hot.
C.J.B. Crowe, T.A. Utigard, Metallurgical and Materials Transactions A, Volume 34B, Decembre 2003—805

A1654 – A hitherto unrecognised band in the Raman spectra of silica rocks: influence of hydroxylated Si–O bonds (silanole) on the Raman moganite band in chalcedony and flint (SiO2)

Chalcedony is a spatial arrangement of hydroxylated nanometre-sized a-quartz (SiO2) crystallites that are often found in association with the silica mineral moganite (SiO2). A supplementary Raman band at 501 cm-1 in the chalcedony spectrum, attributed to moganite, has been used for the evaluation of the quartz/moganite ratio in silica rocks. Its frequency lies at 503 cm-1 in sedimentary chalcedony, representing a 2 cm-1 difference with its position in pure moganite. We present a study of the 503 cm-1 band’s behaviour upon heat treatment, showing its gradual disappearance upon heating to temperatures above 300 °C. Infrared spectroscopic measurements of the silanole (SiOH) content in the samples as a function of annealing temperature show a good correlation between the disappearance of the 503 cm-1 Raman band and the decrease of structural hydroxyl. Thermogravimetric analyses reveal a significant weight loss that can be correlated with the decreasing of this Raman band. X-ray powder diffraction data suggest the moganite content in the samples to remain stable.
Patrick Schmidt, Ludovic Bellot-Gurlet, Aneta Slodczyk, François Fröhlich, Phys Chem Minerals (2012) 39, 455–464

A1644 – Structural transformations of Muscovite at high temperature by X-ray and neutron diffraction

Structural transformations of Muscovite at temperature up to 1095 °C were determined using powder X-ray and neutron diffraction. Data were collected at room temperature from preliminary heated and quenched samples at 650 °C, 980 °C and 1095 °C. X-ray data were interpreted by either Rietveld method and neutron data, which complete the structural information by a better assignation of oxygen positions. With neutron data atom position was refined by fitting Pair Distribution Functions. It was found to be a progressive but continuous microstructural change, with the formation of an increasingly disorganized structure, but the layered organization of muscovite is maintained up to 1095 °C. Rietveld refinements from X-ray confirm the 6 to 5 coordination of Al atoms above 650 °C. It induces some structural changes as the orientation and mutual position of tetrahedrons in silicate layers. Pair Distribution Function refinements show the weakening of the long range structural organization, above 5 Å. At lower distance, a local order is maintained and the preferential alignments of both alumina unit pairs and silica tetrahedron were observed. This residual structural order of high-temperature muscovite is favorable to the achievement of textured ceramics.
F. Gridi-Bennadji, B. Beneu, J.P. Laval, P. Blanchart, Applied Clay Science 38 (2008) 259–267

A1632 – Aqueous Syntheses of Forsterite (Mg2SiO4) and Enstatite (MgSiO3)

Forsterite MgSiO4 and enstatite MgSiO3 were synthesized by two different aqueous processes. TEOS was directly hydrolyzed in aqueous solutions ofmagnesiumnitrate, giving solutions ofmagnesiumnitrate and silicic acid. For the first process these solutions were spray-dried and the powders heat treated to decompose the nitrate; and for the second one they were precipitated in a solution of ethylenediamine as a base, the resulting precipitate was filtered, washed and dried. Spray-dried or precipitated, no specific thermal event was detected by thermal analysis for the crystallization of forsterite (500–1000?C) while a strong and sharp exothermic peak traduced the crystallization of enstatite at 800?C. Very minor secondary phases could be detected by X-ray diffraction up to 1200?C for the spray-dried powders, while the precipitated powders presented a higher chemical homogeneity, but much care had to be taken for a quantitative precipitation. As some minor secondary phases like SiO2 or some polymorphs of MgSiO3 could be not detected by XRD up to 1300?C, higher thermal treatments were necessary to control the purity or the desired phase.
André Douy, Journal of Sol-Gel Science and Technology 24, 221–228, 2002

A1602 – Synthesis and thermal decomposition of [Bi6O6(OH)2](NH2C6H4SO3)4

An investigation of the interaction of Bi(III) with an aqueous solution of sulfanilic acid at a higher temperature is performed. As a result, a new composition [Bi6O6(OH)2](NH2C6H4SO3)4 is precipitated. This Bi(III) complex is characterized by various methods: elemental analysis, DTA, TG–MS, DSC, FTIR, and powder X-ray diffraction. Based on the experimental results, X-ray diffraction indexation as well as thermal decomposition products of the compound are suggested.
Alexander Zahariev, Nikolay Kaloyanov, Christian Girginov, Veneta Parvanova, Thermochimica Acta 528 (2012) 85– 89

A1585 – Thermal decomposition kinetics of potassium iodate

The thermal decomposition of potassium iodate (KIO3) has been studied by both non-isothermal and isothermal thermogravimetry (TG). The non-isothermal simultaneous TG–differential thermal analysis (DTA) of the thermal decomposition of KIO3 was carried out in nitrogen atmosphere at different heating rates. The isothermal decomposition of KIO3 was studied using TG at different temperatures in the range 790–805 K in nitrogen atmosphere. The theoretical and experimental mass loss data are in good agreement for the thermal decomposition of KIO3. The non-isothermal decomposition of KIO3 was subjected to kinetic analyses by model-free approach, which is based on the isoconversional principle. The isothermal decomposition of KIO3 was subjected to both conventional (model fitting) and model-free (isoconversional) methods. It has been observed that the activation energy values obtained from all these methods agree well. Isothermal model fitting analysis shows that the thermal decomposition kinetics of KIO3 can be best described by the contracting cube equation.
K. Muraleedharan, M. P. Kannan, T. Ganga Devi, J Therm Anal Calorim (2011) 103, 943–955

A1578 – Comparison of Different Synthesis Methods to Produce Lithium Triborate and Their Effects on Its Thermoluminescent Property

Lithium triborate (LiB3O5) was produced by different synthesis methods, which included high-temperature solid-state reaction, microwave-assisted high-temperature solid-state reaction, and precipitation-assisted high-temperature solid-state reaction. After the synthesis, metal oxides (CuO and Al2O3) were doped into LiB3O5 to enhance its thermoluminescent (TL) properties, and the TL intensities were compared with each other. The identification and characteristics of undoped and doped LiB3O5 were determined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) analyses, differential thermal analyses (DTA), scanning electron microscopy (SEM), and particle size analyzer. The glow curves were obtained by using a TL reader. The results showed that synthesis routes affected the physical and structural properties of lithium triborate, which have an important effect on its TL intensity.
Tolga Depci, Gulhan Ozbayoglu, Aysen Yilmaz, Metallurgical and Materials Transactions A, Volume 41A, October 2010—2585

A1553 – Chemostratigraphy of Lago Albano sediments (Central Italy): geochemical evidence of palaeoenvironmental changes in late Quaternary

The results of the geochemical investigation on bulk sediment from three cores collected in Albano crater lake (Central Italy) are reported, and the main markers of the palaeoenvironmental changes in the last 26 ka are discussed. The sediment of Lago Albano consists of grey silt and mud, and is made of volcanogenic, calcareous, siliceous and organic material. Some tephra layers provide a chronological framework for the sequence. The chemical features of the sediments are strongly impacted by the Alban Hills volcanism (Roman volcanic area), but there are also strong changes of organic / inorganic matter ratios, owing to variations in biological productivity and terrigeous supply from the catchment. Six chemostratigraphic zones record the main steps of the transition from the cold and dry climate of Glacial Maximum to the warmer and more humid Holocene climate. The most useful geochemical indices are: biogenic silica, CO2 , Br and organic content (OM) for biological productivity; Al,Y, CIA (Chemical Index of Alteration), Al/Rb, Ti/Zr and Y/Al ratios for terrigenous clastic material; OM/Al ratio for organic / terrigenous ratio; S/Fe and Mo/Fe ratios and Authigenic U for redox diagenetic conditions of the lake sediment. The geochemical records agree rather well with those of the lithological and paleomagnetic studies, and despite the information obtained are less detailed than those acquired by the study of biological remains, the palaeoenvironmental significance inferred is consistent. A comparison of the chemostratigraphic results of Lago Albano with those obtained on coeval sediments from Central and Southern Italy lakes supports the role of the geochemical investigation as important complement to more sophisticated techniques in the palaeoenvironmental reconstructions.
Federico Lucchini, E. Dinelli, N. Calanchi, Journal of Paleolimnology 29, 109–122, 2003

A1552 – Phase Transformation of Calcium Phosphates by Electrodeposition and Heat Treatment

The effect of heat treatment on the calcium phosphate deposited on Ti-6Al-4V substrate using an electrolytic process is investigated. The calcium phosphate was deposited in a 0.04 M Ca(H2PO4)2ÆH2O (MCPM) solution on a Ti-6Al-4V substrate at 333 K (60 °C), 10 V, and 80 Torr for 1 hour, and calcined at various temperatures for 4 hours. The X-ray diffraction (XRD) results demonstrate that the phases are dicalcium phosphate (CaHPO4, DCPD) and hydroxyapatile [Ca(PO4)6 (OH)2, HAP] for the as-deposited samples. When the deposited sample was calcined at 873 K (600 °C) for 4 hours, the XRD results show that the transformation of DCPD to HAP occurs. Moreover, HAP converts to b-TCP, CPP, and CaO. For the sample calcined at 1073 K (800 °C) for 4 hours, the scanning electron microscopy (SEM) micrograph reveals that the crack of the calcined sample propagates with a width of about 3 lm. This result is due to HAP becoming decomposed and converting to b-TCP, CPP, CaO, and H2O. The vaporization of H2O within the calcined sample promotes the crack propagation and growth.
Wei-Jen Shih, Moo-Chin Wang, Kuo-Ming Chang, Cheng-Li Wang, Szu-Hao Wang, Wang-Long Li, Hong-Hsin Huang, Metallurgical and Materials Transactions B, Volume 41A, December 2010—3509

A1551 – Thermal Analysis of Lithium Peroxide Prepared by Various Methods

Behavior of lithium peroxide samples at heating in air was studied by the methods of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). In the temperature range from 32 to 82º" all the studied samples we found to react with water vapor forming lithium peroxide monohydrate as confirmed by the methods of chemical analysis and of qualitative X-ray phase analysis. It was found experimentally that in the temperature range from 340 to 348º" lithium peroxide began to decompose into lithium oxide and oxygen, the starting temperature depended on the method of preparation of lithium peroxide. For all the studied samples polymorphism in the temperature range from 25 to 340º" was not detected
Yu. A. Ferapontov, N. V. Kokoreva, N. P. Kozlova, and M. A. Ul’yanova, Russian Journal of General Chemistry, 2009, Vol. 79, No. 5, pp. 891–894

A1534 – Du choix du précurseur pour la synthèse de poudres d’oxydes La1–xSrxMnO3

Different precursor powders (carbonates, oxalates, citrates) of strontium-doped lanthanum manganites have been prepared by soft-chemistry methods. After calcination, these precursors lead to mixed oxides with the perovskite-like structure LaxSr1–xMnO3. The size, the morphology, and the non-stoichiometry coefficient of the oxide powders depend on those of precursor as well as on the thermal treatment conditions. Thermal analysis studies of the precursors’ thermolysis show that only the citrates are really ‘mixed’. Thus the perovskite phase is obtained from 600 °C instead of 850 °C using oxalate or 900 °C using carbonate precursors. Moreover, only the citrate method allows us to vary the morphology, the specific surface area, and the non-stoichiometry of the oxide powder in a wide range
Sophie Guillemet-Fritsch, Pierre Alphonse, Christophe Calmet, Hervé Coradin, Philippe Tailhades, Abel Rousset, C. R. Chimie 8 (2005) 219–227

A1514 – Influence of water vapor pressure on the induction period during Li2SO4·H2O single crystals dehydration

The dehydration of Li2SO4·H2O single crystals at 80 °C has been studied by means of both isothermal thermogravimetry at 2.6, 3.6 and 4.6 hPa of water vapor and environmental scanning electron microscope. Thermogravimetric experiments allowed the determination of induction periods. Distributions of these isoconversion induction periods for a large number of single crystals showed that increasing the water vapor pressure produced a longer induction period. Moreover, the shape of the distributions of the induction periods over a large number of single crystals changed from one mode at 2.6 hPa to two modes at 3.6 and 4.6 hPa. Using an environmental scanning electron microscope, this result could be attributed to differences in nucleation rates at edges and faces of the single crystals.
Loïc Favergeon, Michèle Pijolat, Thermochimica Acta 521 (2011) 155-160

A1506 – Thermal stability investigation of organo-acid-activated clays by TG-MS and in situ XRD techniques

Organo-acid-activated clays were prepared with different surfactant contents by reaction of hexadecyltrimethylammonium hydroxide solution and acid-activated clays. The intercalated cations adopted different orientation in the interlayer spacing of the acid-activated clays and their thermal stability depended on the up taken amounts, acidity of the clay sheets and on the heating temperatures. The thermal stability of these materials was investigated using TG-MS, and followed by the in situ X-ray diffraction in nitrogen atmosphere. The clay sheets affected the decomposition of the surfactants, and as per consequence the thermal stability of the surfactants. TG-MS revealed that different types of water molecules were detected during the heating process with additional CO2, alkanes and alkenes species at temperatures above 200 °C. The interlayer spacing collapsed after completed degradation of the intercalated surfactants.
Fethi Kooli, Thermochimica Acta 486 (2009) 71-76

A1505 – A study on isothermal kinetics of thermal decomposition of cobalt oxalate to cobalt

Thermal decomposition of cobalt oxalate (CoC2O4·2H2O) was studied using TG, DTA and XRD techniques. Non-isothermal studies revealed that the decomposition occurred in two main stages: removal of water and next decomposition of CoC2O4 to Co. Isothermal kinetic studies were conducted for the second stage of decomposition at six different temperatures between 295 and 370 °C in reducing (He + 15 vol% H2) atmosphere. Kinetic equation was found to obey g(?) = [?ln(1 ? ?)]1/n = kt relationship with varying values of n between 2 and 4. The variation of activation energy between 73.23 and 119 kJ mol?1 from the lowest to the highest temperature of decomposition indicated the multi-step nature of the process. SEM analysis revealed the formation of nano-size powder in this temperature range. Thermal decomposition at 550 °C for 30 min was found to be optimum condition producing fine size, non-pyrophoric and spherical powder in larger scale of production. Both hcp and fcc phases were present in the cobalt powder at room temperature.
S. Majumdar, I.G. Sharma, A.C. Bidaye, A.K. Suri, Thermochimica Acta 473 (2008) 45-49

A1502 – Chemical preparation and thermal behavior of neodymium cyclotriphosphate pentahydrate NdP3O9·5H2O: A study by Controlled Rate Thermal Analysis (CRTA)

A new neodymium cyclotriphosphate pentahydrate powder, NdP3O9·5H2O, has been prepared using a classical chemistry method and characterized by X-ray diffraction and infrared spectroscopy techniques. The IR spectrum shows the characteristic bands of cyclotriphosphates as the triplet in the range 1055–1007–917 cm?1.The thermal behavior of the titled compound was also carried out using conventional thermal analysis techniques (TG and DSC) under air atmosphere and Controlled transformation Rate Thermal Analysis (CRTA) technique under constant water vapour pressure of 5 hPa. It was shown that thermal treatment in air, with linear heating rate of 10 K min?1, favourites the structure breakdown as soon as the release of water molecules starts. In this case an amorphous compound is obtained, which then crystallizes at 1073 K and gives the polyphosphate Nd(PO3)3. However, by CRTA technique at PH2O=5?hPa, the water molecules are eliminated with a lower rate which permits to save the initial structure up to an advanced dehydration step. The breakdown of the initial structure is immediately followed by the crystallization of the anhydrous polyphosphate Nd(PO3)3 phase in the temperature range 455 K < T < 793 K.
Kais Nahdi, Mokhtar Férid, Malika Trabelsi Ayadi, Thermochimica Acta 487 (2009) 54-59

A1495 – Investigation of Fe-based oxyhydroxy-fluoride with hollandite-type structure

Well crystallized Fe-based oxyhydroxy-fluoride with the FeO(OH0.2F0.8)·0.2H2O chemical composition has been prepared from hydrolysis of Fe trifluoride under supercritical CO2 conditions. Investigation by Mössbauer spectroscopy and neutron diffraction show that this compound crystallize in the monoclinic symmetry (SG: I2/m, a = 10.447(7) Å, b = 3.028(2) Å, c = 10.445(4) Å, ? = 90.00(3)°). Taking into account the Fe–O(F) bond distances, F? anions are mainly located on the common vertices of Fe octahedra whereas OH? groups occupy mainly the shared edges of the Fe octahedra. Two various highly distorted octahedral sites have been identified with Fe–O/F bond distances varying from 1.90 Å to 2.31 Å. One Fe site is more distorted than in FeO0.8OH1.2·0.2Cl akaganeite because of the random distribution of F?/OH?/O2? in the vicinity of this Fe cation.
Alain Demourgues, Alain Wattiaux, Journal of Fluorine Chemistry, 132 (2011) 690–697

A1490 – Determination of standard enthalpy of vaporization and thermal decomposition reactions from derivative thermogravimetric (DTG) curves

The paper proposes the use of the derivative thermogravimetric (DTG) curve for the acquisition of equilibrium vapor pressure and dissociation pressure for the materials and derivation of their standard enthalpy of formation from single DTG curve recorded under optimum experimental conditions, such as heating rate and the sweep rate of the carrier gas passed over the sample. The vapor pressure and the standard enthalpy of sublimation (?subH ° 298.15) of CdI2 and the dissociation pressure and the standard enthalpy of formation of CaCO3 derived from their DTG curves are found to be in good agreement with the best assessed values reported in the literature.
S. Kolay, R. Mishra, D. Das, S.R. Dharwadkar, Thermochimica Acta, 512 (2011) 110–117

A1483 – Dehydroxylation kinetic and exfoliation of large muscovite flakes

The thermal transformations of muscovite flakes are a key point in many applications because besides dehydroxylation a significant exfoliation process occurs. Dehydroxylation kinetic is experimented by isothermal TG analyses in the 700–850°C temperature range and described with the Avrami theory. Hydroxyl condensation predominates at the onset of the process, but water diffusion is the most important process when the transformed fraction is high. The progressive transition between the two transformation stages contrast with the more accentuated transition for a ground muscovite. The activation energy varies weakly (190–214 kJ mol–1) in the whole transformation process that supports the co-existence of hydroxyl condensation and diffusion phenomena. Dehydroxylation kinetic increases strongly with temperature and decreases with the reaction advancement. Exfoliation is correlated with dehydroxylation kinetic and occurs in a narrow transformation and temperature ranges. An in-situ combination process of hydroxyls occurs and water vapor favors the layer expansion.
F. Gridi-Bennadji, P. Blanchart, Journal of Thermal Analysis and Calorimetry, Vol. 90 (2007) 3, 747–753

A1481 – Thermal characterization of the clay binder of heritage Sydney sandstones

Thermal analysis has been employed in a study of the degradation of heritage Sydney sandstone used in St Mary’s Cathedral in Sydney, Australia. TG and DSC have been used to characterise the clay components removed from weathered and unweathered sandstone. Two types of kaolin clays – kaolinite and its polymorph, dickite – have been identified. A higher amount of dickite present in the clay of weathered sandstone indicates that a kaolinite-to-dickite transformation occurs upon weathering. XRD hot stage analysis was also used to demonstrate the presence of a more thermally stable polymorph of the kaolinite.
K.H. Ip, B. H. Stuart, P. S. Thomas, A. S. Ray, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 97–100

A1478 – Thermal behavior and immersion heats of selected clays from Turkey

Four clays (two bentonites and two kaolinites) from Turkey were investigated by X-ray diffraction (XRD), thermal analysis (DTA/TG-DSC) and surface area measurement techniques. Mineralogically bentonite samples were characterized low concentration of montmorillonite and high level of impurities. Both kaolinite samples mainly contained kaolinite and quartz as major mineral. TG-DTA curves of all clay samples were measured in the temperature range 30–1200 °C. The total % weight losses for the bentonite samples (B1 and B2) and the kaolinite samples (K1 and K2) were determined as 14.50, 13.42, 5.55 and 11.85%, respectively. Differential Scanning Calorimeter (DSC) analyses of samples were carried out by heating the samples from 30 to 550 °C. The immersion heats of clay samples were measured using with a Calvet-type C-80 calorimeter. The higher exothermic Qimm values were determined for bentonite samples compared to kaolinite samples.
Meryem Sakizci, Burcu Erdogan Alver, Ertugrul Yörükogullari, J Therm Anal Calorim (2009) 98, 429–436

A1477 – Thermal treatment of zeolitic tuff

In this study, the zeolitic tuffs having clinoptilolite obtained from Bigadic region of western of Anatolia, Turkey were investigated as regards to whether it is possible to be transformed into amorphous phase from them. At first, the zeolite tuffs rich in clinoptilolite were characterized using XRD, DTA, TG, DSC, and FTIR standard methods. All the samples were heated at 110 °C for 2 h and then were expanded within 5 min between the temperatures 1200 and 1400 °C. In addition, porosity and density were determined. The resistance values of all the samples were measured in acidic and basic media. These samples were also analyzed. As a result of this study, zeolitic tuffs in clinoptilolite were transformed into amorphous phase, and especially in chemical industry were found convenient.
E. Yörükogullar?, G. Y?lmaz, S. Dikmen, J Therm Anal Calorim (2010) 100, 925–928

A1476 – Investigation of clinoptilolite rich natural zeolites from Turkey: a combined XRF, TG/DTG, DTA and DSC study

Turkey clinoptilolite-rich tuffs from Gördes and Bigadic¸ regions of western of Anatolia and their exchanged forms (K?, Na?, Mg2? and Ca2?) were characterized by TG/DTG-DTA, DSC and XRF methods and the surface areas were also determined for both tuffs. TG-DTG and DTA curves of all clinoptilolite samples were measured in the temperature range 30–1000 °C. All clin- optilolite samples had major, rapid mass losses between 30 and 200 °C, with slower and less significant mass losses at higher temperatures. The mass loss of the Natural-G is 9.54% while that of the Natural-B sample is 10.50%. Water content increases in the order of KNaCaMg for Bigadic¸ clinoptilolite samples and in the following sequence KNaMgCa for Gördes clinoptilolite samples. One mass loss step for all clinoptilolite samples was observed using differential scanning calorimeter (DSC) in the range of 30–550 °C.
Burcu Erdogan Alver, Meryem Sakizci, Ertugrul Yörükogullari, J Therm Anal Calorim (2010) 100, 19–26

A1473 – Thermal behavior and other properties of Pr(III), Sm(III), Eu(III), Gd(III), Tb(III) complexes with 4,40-bipyridine and trichloroacetates

A novel mixed-ligand complexes with empirical formulae: Ln(4-bpy)1.5(CCl3COO)3 nH2O(where Ln(III) =Pr, Sm, Eu, Gd, Tb; n = 1 for Pr, Sm, Eu and n = 3 for Gd, Tb; 4-bpy = 4,40-bipyridine) were prepared and characterized by chemical, elemental analysis and IR spectroscopy. Conductivity studies (in methanol, dimethylformamide and dimethylsulfoxide) were also described. All complexes are crystalline. The way of metal–ligand coordination was discussed. The thermal properties of complexes in the solid state were studied under non-isothermal conditions in air atmosphere. During heating the complexes decompose via intermediate products to the oxides: Pr6O11, Ln2O3 (for Sm, Eu, Gd) and Tb4O7. TG-MS system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolysis of Pr(III) and Sm(III) compounds in air.
A. Czylkowska, D. Czakis-Sulikowska, A. Kaczmarek, M. Markiewicz, J Therm Anal Calorim (2011) 105, 331–339

A1469 – Thermal dehydration of CeP3O9×3H2O by controlled rate thermal analysis

The aim of this work is to highlight the importance of controlling the residual water vapour pressure above the sample as well as the rate of the thermal decomposition during the thermal dehydration of cerium cyclotriphosphate trihydrate CeP 3O9×3H2O. For this reason, the dehydration of the titled compound was followed by both techniques: the constant rate thermal analysis at PH2O=5 hPa and the conventional TG-DTA in air. It has been shown that the pathway of the thermal dehydration depends strongly on the nature of atmosphere above the sample. However, in air atmosphere CeP3O9×3H2O decomposes in two well defined steps to give first an amorphous, phase in the temperature range 440–632 K, then the cerium polyphosphate Ce(PO3)3 crystallizing in orthorhombic system (C2221) at T>632 K. Whereas decomposition carried out at 5 hPa water vapour pressure, also occurring in two steps, leads first to a crystallized intermediate monohydrate at 259
K. Nahdi, M. Férid, Malika Trabelsi Ayadi, Journal of Thermal Analysis and Calorimetry, Vol. 96 (2009) 2, 455–461

A1464 – Preparation and characterization of uranyl complexes with phosphonate ligands

The preparation, spectroscopic characterization and thermal stability of neutral complexes of uranyl ion, UO22+, with phosphonate ligands, such as diphenylphosphonic acid (DPhP), diphenyl phosphate (DPhPO) and phenylphosphonic acid (PhP) are described. The complexes were prepared by a reaction of hydrated uranyl nitrate with appropriate ligands in methanolic solution. The ligands studied and their uranyl complexes were characterized using thermogravimetric and elemental analyses, ESI-MS, IR and UV–Vis absorption and luminescence spectroscopy as well as luminescence lifetime measurements. Compositions of the products obtained dependent on the ligands used: DPhP and DPhPO form UO2L2 type of complexes, whereas PhP forms UO2L complex. Based on TG and DTG curves a thermal stability of the complexes was determined. The complexes UO2PhP 2H2O and UO2(DPhPO)2 undergo one-step decomposition, while UO2PhP 2H2O is decomposed in a two-step process. The thermal stability of anhydrous uranyl complexes increases in the series: DPhPOPhPDPhP. Obtained IR spectra indicate bonding of P–OH groups with uranyl ion. The main fluorescence emission bands and the lifetimes of these complexes were determined. The complex of DPhP shows a green uranyl luminescence, while the uranyl emission of the UO2PhP and UO2(DPhPO)2 complexes is considerably weaker.
Z. Hnatejko, S. Lis, Z. Stry?a, J Therm Anal Calorim (2010) 100, 253–260

A1463 – Modified Pechini synthesis of Na3Ce(PO4)2 and thermochemistry of its phase transition

Effect of the synthesis conditions of Pechini technique on crystallinity and purity of Na3Ce(PO4)2 compound was investigated. Nano-sized cerium–sodium phosphate obtained when EDTA was used as an additional chelating agent for Ln3+. The total enthalpy change of Na3Ce(PO4)2 phase transition was determined as 14.2 ±0.7 kJ mol–1 for sample synthesized by conventional solid–solid reaction. The phase transition process was confirmed to occur at 1060°C or in temperature range 920–1060°C depending on thermal treatment of powders.
Aleksandra Matraszek, Irena Szczygiel, Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 3, 689–692

A1462 – Thermal properties of tetraethylammonium tetrachloro-, bromotrichloro- and tribromochloroferrates (III)

Thermal decomposition of tetraethylammonium tetrachloro-, bromotrichloro- and tribromochloroferrates(III), of general formula [(C2H5)4N][FeBr4–nCln] (n=1, 3, 4), has been studied using the TG-MS, DTA and DTG techniques. The measurements were carried out in an argon atmosphere over the temperature range 293–1073 K. Solid products of the thermal decomposition were identified by Mössbauer spectroscopy.
D. Wyrzykowski, Agnieszka Pattek-Janczyk, T. Maniecki, Katarzyna Zaremba, Z. Warnke, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 279–284

A1459 – Comparison of thermal properties of lanthanide trimellitates prepared by different methods

By diffusion in gel medium new complexes of formulae: Nd(btc)·6H2O, Gd(btc)·4.5H2O and Er(btc)·5H2O (where btc=(C6H3 (COO)33– ) were obtained. Isomorphous compounds were crystallized in the form of globules. During heating in air atmosphere they lose stepwise water molecules and then anhydrous complexes decompose to oxides. Hydrothermally synthesized polycrystalline lanthanide trimellitates form two groups of isomorphous compounds. The light lanthanides form very stable compounds of the formula Ln(btc)·nH2O (where Ln=Ce–Gd and n=0 for Ce; n=1 for Gd; n=1.5 for La, Pr, Nd; n=2 for Eu, Sm). They dehydrate above 250°C and then immediately decomposition process occurs. Heavy lanthanides form complexes of formula Ln(btc)·nH2O (Ln=Dy–Lu). For mostly complexes, dehydration occurs in one step forming stable in wide range temperature compounds. As the final products of thermal decomposition lanthanide oxides are formed
Renata Lyszczek, Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 3, 833–838

A1458 – Synthesis, characterization and thermal behaviour of hemimellitic acid compexes with lanthanides (III)

The complexes of lanthanides(III) with hemimellitic acid (1,2,3-benzenetricarboxylic acid, H3btc) of the formula Ln(btc)·nH2O, where Ln=lanthanide(III) ion and n=2–6 were prepared and characterized by elemental analysis, infrared spectra, X-ray diffraction patterns and thermal analysis. The IR spectra of the complexes indicate coordination of lanthanides(III) through all carboxylate groups. The complexes of La(III), Ce(III), Pr(III) and Er(III) are amorphous. On heating in air atmosphere all complexes lose water molecules and next anhydrous compounds decompose to corresponding metal oxides.
R. Lyszczek, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 2, 595–599

A1456 – Thermal investigation of strontium acetate hemihydrate in nitrogen gas

The thermal decomposition of strontium acetate hemihydrate has been studied by TG-DTA/DSC and TG coupled with Fourier transform infrared spectroscopy (FTIR) under non-isothermal conditions in nitrogen gas from ambient temperature to 600°C. The TG-DTA/DSC experiments indicate the decomposition goes mainly through two steps: the dehydration and the subsequent decomposition of anhydrous strontium acetate into strontium carbonate. TG-FTIR analysis of the evolved products from the non-oxidative thermal degradation indicates mainly the release of water, acetone and carbon dioxide. The model-free isoconversional methods are employed to calculate the Ea of both steps at different conversion a from 0.1 to 0.9 with increment of 0.05. The relative constant apparent Ea values during dehydration (0.5
Y. Duan, J. Li, X. Yang, X.-M. Cao, L. Hu, Z.-Y. Wang, Y.-W. Liu, C.-X. Wang, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 1, 169–174

A1442 – Low temperature reactivity in agglomerates containing iron oxide. Studies in the Ca(OH)2–C–Fe2O3 system

In this study, we have attempted to explain the complex reactions that occur during the dehydration of Ca(OH)2, in the presence of solid carbon and Fe2O3, in order to clarify their role as eventual precursors to the reduction and high temperature strength characteristics in feedstock agglomerates of iron and steelmaking by-products. A series of simultaneous thermogravimetric (TG), differential thermal analytic (DTA), and mass spectrometric (MS) tests were performed on agglomerated sample mixes of Ca(OH)2, C, and Fe2O3 to test the influence of heating rate and particle size on the transformations occurring below 1,073 K in inert atmosphere. The overall transformation begins with calcium hydroxide dehydration. Nucleation and growth of CaO grains during dehydration, as well as subsequent gasification of solid carbon, are highly dependent on the governing interstitial particle porosity and mildly dependent on the heating rate in and around agglomerates. The reduction of hematite in current agglomerates is, by association to preceding reactions, partly dependent on porosity and heating rate, but the mechanism of reduction was also found to be highly dependent on the particle size of iron oxides. Furthermore, in areas of intimate contact between CaO and iron oxide, a calcium ferrite phase appears in the form of angular and calcium-rich particles.
Ryan Robinson, Fabrice Patisson, Bo Björkman, J Therm Anal Calorim (2011) 103, 185–193

A1441 – Condensation during flue gas cleaning

Nowadays, it is an operational routine to clean the flue gases from glass furnaces to remove noxious air pollutant substances. The established processes are highly effective, however there are failures caused by the condensation of aggressive fluxes inside the large and expensive flue gas filters. To this day, the process control of the flue gas purification equipment is based on empirical data and on experience. Currently available data do not allow to base process design and control on a solid thermodynamic and kinetic foundation. It is the aim of this work to find out under which conditions condensation really takes place. Therefore, first results of collected kinetic data on the condensation from the system Na2O-H2O-SO2-O2-CO2 are shown to estimate the dew points of liquid and solid condensates as a function of flue gas composition and temperature. The measurements are performed in a self-constructed condensation tube. Investigations are particularly focused on the formation of pyrosulfates and bisulfates
A. Neumann, W. Wilsmann, R. Conradt, Advanced Materials Research Vols. 39-40 (2008) pp 647-652

A1435 – Thermogravimetric study of the dehydration reaction of LiCl·H2O

The dehydration of LiCl·H2O was studied under inert helium atmosphere by DTA/TG for different heating rates. The dehydration of LiCl·H2O proceeds through a two step reaction between 99–110 and 160–186°C, respectively. It leads to the formation of LiCl·0.5H2O as intermediate compound. Based on the temperature peak of the DTA signals the activation energies of the two reactions were determined to be 240 kJ mol–1 (step 1) and 137 kJ mol–1 (step 2), respectively.
P. J. Masset, Journal of Thermal Analysis and Calorimetry, Vol. 96 (2009) 2, 439–441

A1433 – Lanthanide complexes of 3-methoxy-salicylaldehyde. Thermal and kinetic investigation by simultaneous TG/DTG–DTA coupled with MS

The reaction of a lanthanide(III) nitrate (Ln = Pr, Nd, Gd, Dy, Er) with 3-methoxy-salicylaldehyde(3-OCH3-saloH), afforded neutral complexes of the general formula [Ln(3-OCH3-salo)3], which were characterized by means of elemental analysis, FT-IR spectra, TG-DTA curves, and magnetic measurements. The released products, due to the thermal decompositionwere analyzed by on-line coupling MS spectrometer to the thermobalance in argon, allowed to prove the proposed decomposition stages. In order to confirm the stability scale provided on the basis of the onset decomposition temperature, a kinetic analysis of the three decomposition stages was made using the Kissinger equation, while the complex nature of the decomposition kinetics was revealed by the isoconvertional Ozawa–Flynn–Wall method.
Christos Papadopoulos, Nikolaos Kantiranis, Stefano Vecchio, Maria Lalia-Kantouri, J Therm Anal Calorim (2010) 99, 931–938

A1429 – Studies on thermal transformation of Na–montmorillonite–glycine intercalation compounds

Thermogravimetric (TG), differential thermal analysis (DTA) and thermal degradation kinetics, FTIR and X-ray diffraction (XRD) analysis of synthesized glycine–montmorillonite (Gly–MMT) and montmorillonite bound dipeptide (Gly–Gly–MMT) along with pure Na–MMT samples have been performed. TG analysis at the temperature range 25–250 °C showed a mass loss for pure Na– MMT, Gly–MMT and Gly–Gly–MMT of about 8.0%, 4.0% and 2.0%, respectively. DTA curves show the endothermic reaction at 136, 211 and 678 °C in pure Na–MMT whereas Gly–MMT shows the exothermic reaction at 322 and 404 °C and that of Gly–Gly–MMT at 371 °C. The activation energies of the first order thermal degradation reaction were found to be 1.64 and 9.78 kJ mol-1 for Gly–MMT and Gly–Gly–MMT, respectively. FTIR analyses indicate that the intercalated compounds decomposed at the temperature more than 250 °C in Gly–MMT and at 250 °C in Gly–Gly–MMT.
A. H. Khan, M. Nurnabi, P. Bala, J Therm Anal Calorim (2009) 96, 929–935

A1414 – Pyrolysis study of a hydride sol-gel silica. Part II. Kinetic aspects

The thermal behaviour of a sol–gel prepared hydride silica gel (HSiO sample) in the 20–1000°C interval was studied by coupled thermogravimetric-mass spectrometric (TG-MS) analyses carried out at various heating rates. Thermogravimetric curve elaboration allowed the determination of the flex temperatures, corresponding to the maximum release rate of gas-evolved compounds, and to calculate the activation energy of the overall process. The mass spectrometric data, registered in the TG-MS measurements, were treated to discriminate the single reactions accounting for the release of each compound, among which water, dihydrofuran and various silane- and siloxane-derived species. These results were used to calculate the comprehensive activation energy and also those of each of the released species. Different methods of data processing were used to achieve better reliability of calculated activation energies. The discussion focuses on the high extension of kinetic information arising from MS data processing and on the advantage of identifying the contribution of single reactions, although they occur simultaneously during the heating process. In this respect, good agreement was found between the activation energies of the overall process calculated by separately processing TG and MS data. By processing MS data, the same agreement was observed in the comparison between the activation energy calculated for the overall thermal process and in the sum of the weighed activation energies of the reaction of each released compound.
R. Campostrini, A. Sicurelli, M. Ischia and G. Carturan, Journal of Thermal Analysis and Calorimetry, Vol. 90 (2007) 1, 179–184

A1413 – Pyrolysis study of a hydride sol-gel silica. Part I. Chemical aspects

A homogeneous silica gel sample bearing Si–H groups was prepared, via sol–gel method, by hydrolysis of trimethoxysilane under acid condition in tetrahydrofuran. Preliminary NMR experiments in liquid phase indicated an immediate and complete hydrolysis of Si–OCH3, followed by a slower condensation of the Si–OH groups, with maintenance of Si–H bonds. The crude-gel, and samples heated to various temperatures, were characterized by different instrumental methods, including FTIR, density, porosity, and specific surface area. These data indicate that the crude-gel was a dense material which, on heating, increases porosity and surface area up to ca. 500°C. The thermal behavior was studied in inert atmosphere by means of coupled thermogravimetric, gas chromatographic, mass spectrometric analyses. The pyrolysis process was described by the fundamental chemical reactions occurring among the siloxane chains of the gel network and by the qualitative and semiquantitative chemical analysis of the compounds released in gas-phase. The proposed pyrolysis mechanism was discussed and interpreted in agreement with the change of the morphological properties of the gel. The pyrolysis data and the mass balance between the compounds released in gas-phase and the solid residue at 1000°C allowed the determination of a nominal chemical formula to describe the crude-gel composition.
R. Campostrini, A. Sicurelli, M. Ischia and G. Carturan, Journal of Thermal Analysis and Calorimetry, Vol. 89 (2007) 2, 633–641

A1409 – Heating rate effect on the thermal behavior of ammonium nitrate and its blends with limestone and dolomite

The effect of heating rate on the thermal behavior of ammonium nitrate (AN) and on the kinetic parameters of decomposition of AN and its blends with limestone and dolomite was studied on the basis of commercial fertilizer-grade AN and several Estonian limestone and dolomite samples. Experiments were carried out under dynamic heating conditions up to 900 °C at heating rates of 2, 5, 10 and 20 °C min-1 in a stream of dry air using Setaram Labsys 2000 equipment. For calculation of kinetic parameters, the TG data were processed by differential isoconversional method of Friedman. The variation of the value of activation energy E along the reaction progress a showed a complex character of decomposition of AN—interaction of AN with limestone and dolomite additives with the formation of nitrates as well as decomposition of these nitrates at higher temperatures.
T. Kaljuvee, I. Rudjak, E. Edro, A. Trikkel, J Therm Anal Calorim (2009) 97, 215–221

A1408 – Thermal behaviour of ammonium nitrate prills coated with limestone and dolomite powder

The thermal behaviour of ammonium nitrate (AN) and its prills coated with limestone and dolomite powder was studied on the basis of commercial fertilizergrade AN and six Estonian limestone and dolomite samples. Coating of AN prills was carried out on a plate granulator and a saturated solution of AN was used as a binding agent. The mass of AN prills and coating material was calculated based on the mole ratio of AN/(CaO ? MgO) = 2:1. Thermal behaviour of AN and its coated prills was studied using combined TG-DTA-FTIR equipment. The experiments were carried out under dynamic heating conditions up to 900 °C at the heating rate of 10 °C min-1 and for calculation of kinetic parameters, additionally, at 2, 5 and 20 °C min-1 in a stream of dry air. A model-free kinetic analysis approach based on the differential isoconversional method of Friedman was used to calculate the kinetic parameters. The results of TG-DTA- FTIR analyses and the variation of the value of activation energy E along the reaction progress a indicate the complex character of the decomposition of neat AN as well as of the interactions occurring at thermal treatment of AN prills coated with limestone and dolomite powder.
I. Rudjak, T. Kaljuvee, A. Trikkel, V. Mikli, J Therm Anal Calorim (2010) 99, 749–754

A1407 – Temperature-induced changes in crystal lattice of bioaragonite of tapes decussatus linnaeus (mollusca bivalvia)

The characteristics of bioaragonite of shells of recent T. decussatus during heating were studied by the means of TG-DTA-EGA (FTIR), XRD, XRF and FTIR. The mass loss recorded up to 2.5% appeared with the higher rates at 110–150, 200–250, 295–300, and 390–415°C at heating of 10°C min–1 up to 500°C. IR analysis of the evolved gases revealed the emission of water and CO2. The lattice constants tend to change with anisotropy character (parameters a and c diminish whilst b tends to grows) and with an overall contraction of cell volume (from 227.36 to 226.84 ?3) during heating was established. The peculiarity of bioaragonite was explained by substitution of H2O and sulphate ion into the lattice. In spite of those substitutions, bioaragonite reveals an orthorhombic structure, which is preserved during the changes up to calcite formation above 380°C.
J. Nemliher, K. Tonsuaadu, T. Kallaste, Journal of Thermal Analysis and Calorimetry, Vol. 97 (2009) 1, 27–32

A1390 – Equilibrium desorption isotherms of water, ethanol, ethyl acetate, and toluene on a sodium smectite clay

Desorption isotherms for water, ethanol, ethyl acetate and toluene from a sodium smectite clay have been determined by both dynamic vapor sorption (DVS) measurements and Knudsen thermogravimetry (KTGA), at the exception of toluene that was measured only by the DVS method. The results obtained using these two methods were in satisfactory agreement, providing reliable insight into the desorption process, with certain lack of precision for ethyl acetate. The observed desorption behaviour suggests a liquid like phase at high volatile load, and a sorbed state in which molecules interact with the counter ions, at low volatile contents. However, the isotherms for water determinedat various temperatures nearly superposed when plotted as a function of water activity, indicating the strength of the interactions in the clay–water system to remain of the same order of magnitude as that in bulk water, consistent with previous ab initio calculations.
Pascal Clausen, Marco Signorelli, Andreas Schreiber,,Eric Hughes,,Christopher J. G. Plummer, Dimitrios Fessas,,Alberto Schiraldi, Jan-Anders E. Manson, J Therm Anal Calorim, 2009

A1353 – Investigation of surface properties of lunar regolith Part III

We investigated lunar regolith collected during the Apollo 11, 12 and the Apollo 16 missions. The Apollo 11 and the Apollo 12 samples come from the lunar mare, whereas the Apollo 16 expedition brought back material from a highland region of the near side of the Moon. In paper series we summarise in brief the results of measurements using photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), nitrogen adsorption, thermal analysis (TG, DTA) and temperature-programmed reduction and oxidation (TPRO) method. Parts of samples were examined by means of scanning electron (SEM/EDS) and atomic force microscopy (AFM).
A. Dabrowski, E. Mendyk, E. Robens, K. Skrzypiec, J. Goworek, Mariola Iwan and Zofia Rzaczynska, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 3, 633–639

A1352 – Thermal behavior and water adsorption of natural and modified sepiolite having dolomite from Turkey

The water adsorption properties of sepiolite having dolomite supplied from Eskisehir region and their exchanged forms (K+, Na+, Mg2+ and Ca2+) were investigated. The sepiolite samples were characterized using XRD, TG-DTA, DSC and nitrogen adsorption methods. The temperature ranges were determined for the dehydrations of hydroscopic and zeolitic water as 30–200°C, for the dehydration of the bound water as 250–750°C and for the dehydroxylation of hydroxyls as 810–850°C in the sample. It was observed that the value of percent mass loss for natural and modified samples varied in the range from 36.70 to 39.05%. Two mass loss steps for all samples were observed using a differential scanning calorimetry (DSC) in the range of 30–550°C. Adsorption isotherms for water on natural and modified forms were obtained at pressures up to 2.39 kPa. Uptake of water increased as K-SEP.
B. Erdogan Alver, M. Sakici, E. Yörükogullari, Y. Yilmaz and M. Güven, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 3, 835–840

A1336 – Upgrading of carbonaceous phosphate rocks by direct carbonation with CO2-water solutions

This work is an investigation of a relatively new process to upgrade carbonaceous phosphate rocks via direct carbonation with CO2-water solution. The process is mainly based on the reaction of the CaCO3 present in the phosphate ore with CO2-water solutions to convert the former to a water-soluble compound (i.e. calcium bicarbonate). The carbonation experiments were carried out in a 0.054m inner diameter column and 1.7m high. The parameters that may affect the dissolution of CaCO3 in the CO2-water solution such as column pressure and temperature, CO2-bubbler perforation diameter, CO2 flow rate, phosphate particles size, solid/liquid ratio in the slurry mixture, and the slurry height in the column were investigated. The effects of before-carbonation phosphate ore preheating as well as multiple carbonations were also examined. It was found out that the rate of dissolution of CaCO3 increased with the increase of pressure inside the column, CO2-bubbler perforation diameter, and CO2 flow rate. Furthermore, it increased with the decrease of phosphate ore particles size, slurry height in the column, and temperature. Low solid/liquid ratio of 30-50 g phosphate ore per liter of CO2-water solution were found to give better dissolution rates. The heating of the phosphate ore to 150°C for 15 min (before carbonation) gave better dissolution than other preheating temperatures and time intervals. By multiple carbonation, it was possible to remove about 90% of the CaCO3 present in the phosphate ore in 10 stages. The recovery of CO2 and production of CaCO3 precipitate is possible and can be easily handled by heating the calcium bicarbonate solution under vacuum.
S.I. Abu-Eishah, M.J.J. Anabtawi, S.L. Isaac, Chemical Engineering and Processing 43 (2004) 1085-1094

A1329 – Characterization of lalithe, a new bentonite-type Algerian clay, for intercalation and catalysts preparation

Iron-intercalated clay has been obtained starting from a natural bentonite-type clay sample from Maghnia (Algeria). The natural compound contained, besides the clay material, impurities such as quartz, beta-cristobalite and calcite. The quartz phase was removed by applying a purification protocol based on sedimentation. The two other phases remained in the solid but did not apparently affect the intercalation process. The intercalation process has been optimized to lead a microporous solid with a reticular distance of 16 Å and a specific surface area of 260m2 g-1. High-resolution electron microscopy with EDX analyses showed that the sample had a relatively inhomogeneous composition with a typical delaminated structure. It confirmed the pillaring but also showed some goethite particles. These particles certainly formed because of the delamination are few and small and do not affect the Mössbauer spectra showing only one ferric iron species and confirming that most of the iron was in the pillars. The thermal stability of the iron-pillared clay has been studied. It was shown that the structure started to collapse before 773K which is rather low for polyoxocations-intercalated clay but comparable for other iron-intercalated clays.
L.S. Belaroui, J.M.M. Millet, A. Bengueddach, Catalysis Today 89 (2004) 279-286

A1321 – Poly(ethylene oxide)-based surfactants as templates for the synthesis of mesoporous silica materials

Various mesoporous silica solids were prepared by using poly(ethylene oxide)-based surfactants as templates in a neutral, fluoride, or moderately acidic medium, and their properties examined by different physical techniques. Precipitation in an acid or neutral medium provided materials of pore size in between those of micropores and mesopores irrespective of the molecular size of the surfactant. On the other hand, syntheses in a fluoride-containing medium yielded mesoporous materials with pore diameters over the range 36-84 Å that increased with increasing surfactant size. All materials possessed specific surface areas above 650 m2 g-1 and high pore volumes-particularly those obtained in a fluorinated medium. The conditions used in the syntheses and the fact that all produced highly disordered porous materials suggest that their mechanism of formation is essentially of the N°I° neutral type. The materials obtained in the presence of fluoride ion, which promote the condensation of siliceous species, retain greater amounts of surfactant and exhibit increased cross-linking and decreased particle sizes, which results in textural mesoporosity.
M.A. Aramendia, V. Borau, C. Jiménez, J.M. Marinas, and F.J. Romero, Journal of Colloid and Interface Science 269 (2004) 394-402

A1319 – Effect of the support on the basic and catalytic properties of KF

KF supported by various supports was characterized by DTG-DTA coupled with mass spectral analysis of the gases evolved by the solid, in situ XRD, calorimetry, 19F NMR spectroscopy, and tested in the Michael addition of cyclohexene-2-one with nitroalkanes. After dehydration at low temperatures, from 19F NMR spectroscopy F is in part as KF when the support is alpha-alumina but only as K3AlF6 when the support is gamma-alumina. During activation no fluorine is lost. On alpha-alumina KF is detected by XRD only after calcination at about 723 K and results in part of the decomposition of K3AlF6; it disappears with formation of K2AlF5 and KAlO2 at higher temperatures. A comparison of the results obtained by XRD and NMR suggests that KF is well dispersed on alpha-alumina. KF/alpha-alumina is a strong base, stronger than KF on gamma-alumina, and more active for Michael reactions. On KF/alpha-alumina the Michael condensation of 2-cyclohexen-1-one with nitroalkanes can be achieved in 5 min with an equimolar mixture of reactants. Solvent-free reactions can also be achieved reaching 75% yield in adduct after 8 h, and KF/alpha-alumina is also active after simple drying at 393 K, avoiding the usual activation at higher temperatures.
J-M. Clacens, D. Genuit, L. Delmotte, A. Garcia-Ruiz, G. Bergeret, R. Montiel, J. Lopez, and F. Figueras, Journal of Catalysis 221 (2004) 483-490

A1318 – Standard molar enthalpies of formation of Ln(C9H6NO)2(C2H3O2) (Ln: Nd, Sm)

Using an on-line solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction: LnCl3.6H2O(s) + 2C9H7NO(s) + CH3COONa(s) = Ln(C9H6NO)2(C2H3O2)(s) + NaCl(s) + 2HCl(g) + 6H2O(l) (Ln: Nd, Sm), were determined at T = 298.15 K, as -(56.9 ± 1.4) and - (67.9 ± 1.5) kJ mol-1, respectively. From the mentioned standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of Ln(C9H6NO)2(C2H3O2)(s) (Ln: Nd, Sm), at T = 298.15 K, have been derived to be: -(1494.7 ± 3.3) and -(1501.5 ± 3.4) kJ mol-1, respectively.
H-G. Yu, Y. Liu., S-S. Zhao, X-F. Guo, S-S. Qu, Thermochimica Acta 409 (2004) 195-199

A1317 – Hydrothermal syntheses and crystal structures of novel one- and two-dimensional organic-inorganic hybrid materials composed of paradodecatungstate-B clusters and [Cu(en)2]2+ complex groups

Novel one- and two-dimensional solids consisting of paradodecatungstate-B units linked via [Cu(en)2]2+ and/or [Cu(H2O)2]2+ bridging groups have been synthesized by the hydrothermal method and structurally characterized by X-ray crystallography, IR and chemical analysis.
B.Yan, N.K. Goh, L.S. Chia, Inorganica Chimica Acta 357 (2004) 490-494

A1310 – Synthesis and characterization of a new organic dihydrogenomonophosphate [3,5-(CH3O)2C6H3NH3]2(H2PO4)2

Chemical preparation, crystal structure, calorimetric studies and spectroscopic investigation are given for a new organic cation dihydrogenomonophosphate [3,5-(CH3O)2C6H3NH3]2(H2PO4)2. This compound is triclinic P1 with the following unit cell parameters: a = 9.030(6) Å , b = 16.124(5) Å , c = 8.868(3) Å , alpha = 75.04(3)8°, beta = 110.71(4)°, gamma = 104.61(1)°, Z = 4, V = 1148.0(1) Å3, Z = 2 and ?cal. = 1.454 g cm-3. Crystal structure was solved and refined to R = 0.04, 2752 independent reflections. The atomic arrangement can be described as inorganic layers of (H2PO4)- anions parallel to y = 1/2 planes, between which are located the organic groups. Solid-state 13C and 31P MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of the phosphorous and carbon signals to the independent crystallographic sites and to the various atoms of the organic groups.
K. Kaabi, C. Ben Nasr, F. Lefebvre, Materials Research Bulletin 39 (2004) 205-215

A1306 – Lattice thermal expansion of LaCo(1-x)CuxO3

Lattice thermal expansion studies on LaCo(1-x)CuxO3 (x = 0, 0.02, 0.05, 0.1, 0.3 and 0.5) were carried out by high temperature XRD from room temperature to 1173 K.Alinear increase in lattice parameterwas observed with increase in copper concentration indicating the substitution of copper in the lattice. The % volume thermal expansion (?V?100/V) increases with temperature. As the copper concentration increases from 0.0 to 30 mol.%, the % volume thermal expansion decreases from 5.98 to 4.522. The lattice and volume thermal expansion coefficients (TEC), alpha(a), alpha(c), and alpha(v) averaged between 298 and 1023 K are calculated using the HTXRD data. alpha(a), alpha(c), and alpha(v) decreased from 26.78 x x10^(-6) to 18.27 x 10^(-6) K-1, 27.81 x 10^(-6) to 24.56 x 10^(-6) K-1 and 82.45 x 10^(-6) to 72.9 x 10^(-6) K-1, respectively, as the copper concentration increased from 0 to 30 mol.%. The decrease in TEC with copper loading is due to the introduction of the covalent character of the Cu-O bond in the otherwise ionic nature of the La-O bond in LaCoO3. The larger decrease in alpha(a) as compared to alpha(c) confirms the substitution of more copper in the a-b plane rather than in the c-axis.
V. Ramaswamy, P. Awati, A.K. Tyagi, Journal of Alloys and Compounds 364 (2004) 180-185

A1295 – Characterization of the pores in hydrous ferric oxide aggregates formed by freezing and thawing

Hydrous ferric oxides (HFO) are efficient sorbents for inorganic and organic pollutants and therefore have great potentials in environmental science and engineering applications. Freezing and thawing of HFO suspensions leads to the formation of dense HFO aggregates. It facilitates the handling and increases the drying rate of HFO. In this study, we used a combination of pycnometry, gas adsorption (N2 gas, water vapor), and small-angle neutron scattering (SANS) to characterize the porosity and pore size distribution of dense HFO aggregates formed by freezing dialyzed HFO suspensions at -25°C and thawing them at room temperature. The crystallinity of the HFO, which was a 2-line ferrihydrite, was not affected by this treatment. Wet sieving and laser diffraction analysis showed that the dense HFO aggregates had a unimodal size distribution with an average diameter of 235 ± 35 µm. Increasing the freezing rate by cooling with liquid N2 (-196°C) resulted in much smaller aggregates with an average diameter of 20 µm. Adding NaNO3 electrolyte to the HFO suspensions prior to freezing also resulted in the formation of smaller aggregates. The dense HFO aggregates formed at -25°C had a porosity of 0.73 ± 0.02 11^(-1). SANS revealed a unimodal size distribution of pores, with an average pore diameter of 2.0 nm. The diameter of the HFO crystallites was estimated by transmission electron microscopy to be 1.9 ± 0.5 nm. Geometrical considerations taking into account the unit particle and average pore size suggest that the crystallites retain 1-2 layers of hydration water during the coagulation induced by freezing. Analysis by N2 gas adsorption showed that drying the dense HFO aggregates induced a reduction in porosity by about 25% and shifted the pore size distribution to smaller diameters. Rewetting during water vapor adsorption did not induce significant changes of the aggregate structure. The specific surface area of the dry HFO aggregates was between 320 and 380 m2 g-1.
A. Hofmann, M. Pelletier, L. Michot, A. Stradner, P. Schurtenberger, and R. Kretzschmar, Journal of Colloid and Interface Science 271 (2004) 163-173

A1284 – Structure and phase transitions in [(CH3)4P]3[Sb2Br9] and [(CH3)4P]3[Bi2Br9]

Two new phosphonium bromoantimonate(III) and bromobismuthate(III) [(CH3)4P]3[Sb2Br9] (PBA) and [(CH3)4P]3[Bi2Br9] (PBB) crystals have been synthesized and their structure determined by single-crystal X-ray diffraction. Both compounds are isomorphous in the room temperature phase and crystallize in the trigonal space group (polar), P31c: The structure consists of discrete [M2X9]3- anions and [(CH3)4P]+ cations. A sequence of structural phase transitions in PBA and PBB is established on the basis of differential scanning calorimetry and dilatometric studies. Two reversible phase transitions are found: (I <-> II) at 540/540 K and (II <-> III) at 193/195 K for PBA and (I <-> II) at 550/550 K and (II <-> III) at 205/207.5 K for PBB (on cooling/heating). The pyroelectric measurements of both compounds have confirmed the polar nature of phases (II) and (III). Proton spin-lattice relaxation time of polycrystalline PBA have been studied in temperatures 77-400 K. A dynamic inequivalence of two tetramethylphosphonium cations has been detected. A ferroelastic domain structure was found over the lowest temperature phase (III) of both crystals studied. The possible mechanisms of the phase transitions are discussed on the basis of the presented results.
M. Wojtas, R. Jakubas, Z. Ciunik, and W. Medycki, Journal of Solid State Chemistry 177 (2004) 1575-1584

A1278 – Synthesis and structural characterization of a new layered chlorozincophosphate, Zn(HPO4)Cl.[H3N(CH2)6NH3]0.5

A new layered zinc-phosphate Zn(HPO4)Cl [H3N(CH2)6NH3]0.5 was synthesized in acidic conditions at room temperature. It crystallizes in monoclinic space group C2/c (No. 15) with the lattice parameters a = 21.826(3) Å, b = 9.452(7) Å, c = 8.780(1) Å, beta = 109.36(8)°, V = 1708.83(1) Å3, Z = 8, R = 0.036, Rw = 0.047. The structure of this compound is determined by X-ray diffraction and characterized with IR, TGA-DTA/DSC and NMR. The structure consists of inorganic layers, built by PO4 and ZnO3Cl tetrahedra interconnected by common oxygen atoms. The organic entities, located between these layers, perform the 3D cohesion through N-H...O or N-H...Cl hydrogen bonds.
A. Rayes, C. Ben Nasr, M. Rzaigui, Materials Research Bulletin 39 (2004) 571-580

A1271 – Synthesis and characterization of metal carboxyalkylphosphonates hybrid materials

Several carboxyalkylphosphonate hybrid materials have been prepared under hydrothermal conditions: Mn2(OH)(O3PCH2CO2).1/2H2O, Mn2(OH)(O3PCH2CO2), Al3(OH)3(O3PCH2CH2CO2)2.3H2O, Pb5(O3PCH2CH2CO2)2(O3PCH2CH2COOH)2 and Pb3(O3PCH2CH2- CO2)2. The influence of some variables in the syntheses such as pH or metal/phosphonic acid molar ratios have been examined. Mn2(OH)(O3PCH2CO2).1/2H2O crystallizes in a triclinic cell with parameters a = 8.405 Å, b = 8.789 Å, c = 4.910 Å, alpha = 90.71°, beta = 98.58°, gamma = 103.68° and V = 348.6 Å3. Its dehydration lead to Mn2(OH)(O3PCH2CO2), which unit cell has also been determined: a = 8.307 Å, b = 8.322 Å, c = 4.940 Å, alpha = 103.31°, beta = 98.81°, gamma = 80.79° and V = 325.6 Å3. The diffraction data suggest a layered structure. Al3(OH)3(O3PCH2CH2CO2)2.3H2O crystallizes in a monoclinic unit cell with a = 10.534 Å, b = 7.880 Å, c = 10.320 Å, beta = 109.86° and V = 805.7 Å3. Its X-ray powder pattern and the spectroscopic data are consistent with a pillared layered structure. Finally, Pb5(O3PCH2CH2CO2)2(O3PCH2CH2COOH)2 is monoclinic with a = 11.889(1) Å, b = 12.746(1) Å, c = 9.835(1) Å, beta = 114.081(2)°, V = 1360.6(2) Å3, Z = 2, space group P21/c. Its structure has been solved from single crystal data, R1 = 0.069, and shows a pillared layered framework. There are two types of carboxyethylphosphonate chains, one being protonated which is pillaring the layers and the other chain is twisted and bonded to a unique inorganic layer through both carboxylate and phosphonate moieties. Thermal and IR data for these compounds are reported and discussed.
M.M. Gomez-Alcantara, A. Cabeza, M.A.G. Aranda, A. Guagliardi, J.G. Mao, A. Clearfield, Solid State Sciences 6 (2004) 479-487

A1270 – Synthesis of nanocrystalline Y2O3/Pr3+ from heterometallic alkoxide via sol-gel process

Y2O3/Pr3 + nanoparticulate powder has been prepared through a one-step hydrolytic sol-gel process using an yttrium praseodymium heterometallic alkoxide. The powder was characterized by TGA/TDA, XRD, TEM, XPS and photoluminescent experiments, which showed that a homogeneous and a highly crystalline material was obtained by calcination as low as 500°C.
S. Daniele, L.G. Hubert-Pfalzgraf, Materials Letters 58 (2004) 1989-1992

A1268 – Synthesis and crystal structure of [3,5-(CH3)2C6H3NH3]4P4O12.3H2O

Chemical preparation and crystal structure are given for a new cyclotetraphosphate: [3,5-(CH3)2C6H3NH3]4P4O12.3H2O. This compound is triclinic P1 with the following unit-cell parameters: a = 8.298(3); b = 8.299(3); c = 17.242(7) Å , alpha= 97.13(3); beta= 102.72(3); gamma= 64.55(3)°; Z = 1 and V = 1045.2(8) Å3. The crystal structure has been solved and refined to R = 0.040 using 6086 independent reflections. The atomic arrangement can be described as layers organization. Layers built by P4O12 ring anions, ammonium groups and water molecules parallel to the plan (001), between which the organic groups are located. Characterization by X-ray diffraction, IR absorption, and thermal analysis are described.
Z. Aloui, S. Abid, M. Rzaigui, Journal of Physics and Chemistry of Solids 65 (2004) 923-926

A1267 – Structure, phase transitions and molecular dynamics in 4-methylpyridinium tetrachloroantimonate(III), [4-CH3C5H4NH][SbCl4]

Crystal structure of the 4-methylpyridinium tetrachloroantimonate(III), [4-CH3C5H4NH][SbCl4], has been determined at 240 K by X-ray diffraction as monoclinic, space group, P21=n; Z = 8. Differential scanning calorimetry and dilatometric studies indicate the presence of two reversible phase transitions of first order type, at 335/339 and 233/289 K (cooling/heating) with ?S = 0.68 and 2.2 J mol-1 K-1, respectively. Crystal dynamics is discussed on the basis of the temperature dependence of the 1H NMR spin-lattice relaxation time T1 and infrared spectroscopic studies. The low temperature phase transition at 233 K of an order-disorder type is interpreted in terms of a change in the motional state of the 4-methylpyridinium cations. The phase transition at 335 K, probably of a displacive type, is characterised by a complex mechanism involving the dynamics of both the cationic and anionic sublattice. The 1H NMR studies show that the low temperature phase III is characterised only by the dynamics of the CH3 groups.
B. Kulicka, R. Jakubas, Z. Ciunik, G. Bator, W. Medycki, J. Swiergiel, J. Baran, Journal of Physics and Chemistry of Solids 65 (2004) 871-879

A1263 – From molecules to materials: some examples in yttrium and lanthanide chemistry

Hydrolytic and hydrothermal transformations were applied to yttrium alkoxides, namelyY5O(OiPr)13, Y3(OtBu)9(tBuOH)2 and [Y8O6(OtBu)12]m. The resulting powders were characterized by XRD, TGA and transmission electron microscopy (TEM). Hydrolysis of the octanuclear oxo species gave nanocrystalline (5-6 nm) cubicY2O3 at 400°C by annealing of an oxohydroxide. Hydrothermal transformation in basic media (200°C, 10 h, 17 atm) of Y5O(OiPr)13 gave amorphousY2O3 as well as crystalline platelets and nanowires of Y(OH)3. Transformation into cubic yttria was achieved at 300°C. The lability of the M-OR bond allows easy formation of mixed-metal species, giving access to doped materials of high homogeneity and crystallinity, as shown by a Y2O3 matrix doped by Pr2O3. Modification of Y5O(OiPr)13 by polymerisable ligands provided molecular oxohydroxide aggregates that can be used for access to organic-inorganic materials by copolymerisation reactions.
L.G. Hubert-Pfalzgraf, S. Daniele, C. R. Chimie 7 (2004) 521-527

A1262 – X-ray diffraction, Raman study and electrical properties of the new mixed compound [Rb0.44(NH4)0.56]2HgCl4.H2O

Differential scanning calorimetry of [Rb0.44(NH4)0.56]2HgCl4.H2O material showed three anomalies at 340, 355 and 424 K, respectively. The room temperature phase has space group Pcma (a = 8.433(1) Å, b = 9.1817(9) Å and c = 11.954(1)). Phase II (T = 350 K) is disordered and exhibits orthorhombic symmetry (a = 8.456(13), b = 9.202(9) and c = 12.011(10) Å). Hydrogen bonding, the nature and the degree of structure (dis)order and the mechanisms of the transitions are discussed. The dielectric constant ?' at different frequencies and temperature revealed a phase transition at T = 340 K related to (NH4)+ reorientation and H+ diffusion, and a characteristic increase above 355 K, which might be due to loss of water of crystallization. Transport properties in this compound appear to be due to an Rb+ / (NH4)+ and H+ ions hopping mechanism.
M. Loukil, A. Kabadou, Ph. Salles, A. Ben Salah, Chemical Physics 300 (2004) 247-251

A1260 – Characterization of perovskite systems derived from Ba2In2O5 Part II: The proton compounds Ba2In2(1-x)Ti2xO(4+2x)(OH)y [0

The proton compounds Ba2In2(1-x)Ti2xO(4+2x)(OH)y [0
V. Jayaraman, A. Magrez, M. Caldes, O. Joubert, F. Taulelle, J. Rodriguez-Carvajal, Y. Piffard, L. Broh, Solid State Ionics 170 (2004) 25-32

A1251 – Synthesis and characterization of Sr(1-x)LnxCoO(3-d), Ln = Y, Sm-Tm, 0.1< x < 0.5

Different perovskite-related phases have been found in an X-ray powder diffraction (XRD) and transmission electron microscopy study of the Sr(1-x)LnxCoO(3-d), Ln = Y, Sm-Tm, 0.1 < x < 0.5 systems. For the compositions Sr0.7Ho0.3CoO(3-d); Sr(1-x)EuxCoO(3-d) , 0.3 < x < 0.4; Sr(1-x)GdxCoO(3-d), 0.3 < x < 0.5; Sr(1-x)TbxCoO(3-d), 0.3 < x < 0.4; Sr(1-x)DyxCoO(3-d), 0.2 < x < 0.3 the formation of phases isostructural with the recently discovered perovskite related Sr0.7Y0.3CoO2.62, a ? 2 x aper, c ? 4 x aper (aper perovskite subcell) was observed. The crystal and magnetic structures of Sr0.7Dy0.3CoO2.62 were refined using neutron diffraction data (I4/mmm, a = 7.6280(8), c = 15.338(2) Å, Rp = 0.0332, RF2= 0.0447, X2 = 1.19). For x = 0.1 the XRD study indicates formation of cubic perovskites with all rare-earth cations. Electron diffraction and high resolution electron microscopy studies performed on Sr0.9Ln0.1CoO(3-d), Ln = Y, Eu, Dy, Ho revealed the presence of crystallites with brownmillerite (a ? ?2 x aper, b ? 4 x aper, c ? ?2 x aper), tetragonal perovskite (a ? aper, c ? 2 x aper) and Sr0.7Ln0.3CoO2.62 type (a ? 2 x aper, c ? 4 x aper) structures. For Ln = Sm, only XRD cubic perovskite phases were observed for all compositions, 0.1< x < 0.5. In the Sr0.5Eu0.5CoO(3-d) sample, crystallites of perovskite, tetragonal perovskite and Sr0.7Ln0.3CoO2.62 type were observed in the TEM study.
S.Ya. Istomin, O.A. Drozhzhin, G. Svensson, E.V. Antipov, Solid State Sciences 6 (2004) 539-546

A1249 – The phase diagram and tetragonal superstructures of the rare earth cobaltate phases Ln(1-x)SrxCoO(3-d) (Ln=La3+, Pr3+, Nd3+, Sm3+, Gd3+, Y3+, Ho3+, Dy3+, Er3+, Tm3+ and Yb3+)

Single phase perovskite-based rare earth cobaltates (Ln(1-x)SrxCoO3 d) (Ln=La3+, Pr3+, Nd3+, Sm3+, Gd3+, Dy3+, Y3+, Ho3+, Er3+, Tm3+ and Yb3+; 0:67pxp0:9) have been synthesized at 1100°C under 1 atmosphere of oxygen. X-ray diffraction of phases containing the larger rare earth ions La3+, Pr3+ and Nd3+ reveals simple cubic structures; however electron diffraction shows orientational twinning of a local, tetragonal (I4/mmm; ap x ap x 2ap) superstructure phase. Orientational twinning is also present for Ln(1-x)SrxCoO(3-d) compounds containing rare earth ions smaller than Nd3+. These compounds show a modulated intermediate parent with a tetragonal superstructure (I4=/mmm; 2ap x 2ap x 4ap). Thermogravimetric measurements have determined the overall oxygen content, and these phases show mixed valence (3+/4+) cobalt oxidation states with up to 50% Co(IV). X-ray diffraction data and Rietveld techniques have been used to refine the structures of each of these tetragonal superstructure phases (Ln=Sm3+-Yb3+). Coupled Ln/Sr and oxygen/vacancy ordering and associated structural relaxation are shown to be responsible for the observed superstructure.
M. James, D. Cassidy, D.J. Goossens, and R.L. Withers, Journal of Solid State Chemistry 177 (2004) 1886-1895

A1248 – Anomalous temperature effect on the hydrogen bond strength and phase transition in 2,4,6-trimethylpyridinium pentachlorophenolate.

The phase transition in 2,4,6-trimethylpyridinium pentachlorophenolate has been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dielectric method as well as theoretical calculations. The crystal undergoes a first order phase transition of order-disorder type at 376 K. The transition to the high temperature phase causes anomalous hydrogen-bond shortening. Experimental and theoretical results show that the change in the mutual orientation of the phenol and pyridine rings is connected with the change of the hydrogen bond. Such an effect, which appears in the present simple hydrogen-bond complex, may be common also for the other hydrogen-bond complexes.
I. Majerz, R. Jakubas, Journal of Molecular Structure 694 (2004) 45-53

A1239 – Synthesis and crystal structures of a new (2,3-(CH3)2C6H3NH3)H2XO4 (X = P, As)

The aim of encapsulation of 2,3-dimethylanilinium cation in (H2XO4)n polymeric anion chains is to build acentric frameworks that are efficient for non-linear optical (NLO) applications. The synthesis and structures of two new inorganic-organic NLO crystals with general formula (2,3-(CH3)2C6H3NH3)H2XO4 (X = P, As) are reported. The magnitude of their second harmonic generations (SHG) responses was found to be between the KDP and urea. They crystallize with monoclinic unit-cells and are isotopic. We have determined the structure of phosphoric salt. The following unit-cell parameters were found: a = 8.866(3) Å, b = 5.909(6) Å, c = 10.644(5) Å, beta = 112.44(1)°, V = 515.5(5) Å3 and Dx = 1.412 g cm-3. The space group is P21 with Z = 2. The structure was refined with R = 0.041 (Rw = 0.057) for 1652 reflections with I > 3?(I). It exhibits infinite ((H2PO4)n)n- chains. The organic groups (2,3-(CH3)2C6H3NH3)+ are anchored between adjacent polyanions through multiple hydrogen bonds. Chemical preparation, crystal structure, calorimetric and spectroscopic investigation are described.
A. Rayes, C. Ben Nasr, M. Rzaigui, Materials Research Bulletin 39 (2004) 1113-1121

A1238 – Synthesis and crystal structure of a new o-ethylphenylammonium triphosphate [2-C2H5C6H4NH3]3H2P3O10

Chemical preparation and characterization by X-ray diffraction, IR, and NMR spectroscopies and thermal analysis of a new o-ethylphenylammonium triphosphate [2-C2H5C6H4NH3]3H2P3O10 are reported. This compound crystallizes in a monoclinic unit cell P21/n with the parameters: a = 17.670(1) Å , b = 8.558(8) Å , c = 20.100(2) Å , beta = 100.39(6)° , Z = 4, and V = 2990(4) Å3. Crystal structure has been solved and refined to R = 0.041 using 6857 independent reflections. In this atomic arrangement, layers built by (H2P3O10)3- groups are developed along (1 0 -1) direction. Between these layers are located the o-ethylphenylammonium entities which form hydrogen bonds with some external oxygen atoms of phosphoric groups.
W. Smirani, C. Ben Nasr, M. Rzaigui, Materials Research Bulletin 39 (2004) 1103-1111

A1235 – Low-temperature heat capacity and thermal decomposition of crystalline [Er2(His.H+)(H2O)8](ClO4)6.4H2O

The heat capacities of rare earth complex with amino acid histidine, [Er2(His.H+)(H2O)8](ClO4)6.4H2O, were measured with an automatic adiabatic calorimeter from 79 to 320 K. Itwas found that therewas a sudden increment in heat capacity within the temperature range 182-190 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis, and a possible decomposition mechanism was suggested according to TG-DTG results.
X. Lan, Z-C. Tan, B. Liu, Z. Nan, L. Sun, F. Xu, Thermochimica Acta 416 (2004) 55-58

A1225 – New binuclear vanadium(III) and (IV) squarate species: synthesis, structure and characterization of [V(OH)(H2O)2(C4O4)]2 . 2H2O and (NH4)[(VO)2(OH)(C4O4)2(H2O)3] . 3H2O

Two new vanadium squarates have been synthesized, characterized by infrared and thermal behavior and their structures determined by single crystal X-ray diffraction. Both structures are made of discrete, binuclear vanadium entity but in 1, [V(OH)(H2O)2(C4O4)]2 . 2H2O the vanadium atom is trivalent and the entity is neutral while in 2, (NH4)[(VO)2(OH)(C4O4)2 (H2O)3] . 3H2O, the vanadium atom is tetravalent and the entity is negatively charged, balanced by the presence of one ammonium ion. Both molecular anions are bridged by two terminal m2 squarate ligands. 1 crystallizes in the triclinic system, space group P-1, with lattice constants a = 7.5112(10) Å , b = 7.5603(8) Å , c = 8.2185(8) Å , alpha = 106.904(8)° ; beta = 94.510(10)° ; gamma = 113.984(9)° while 2 crystallizes in the monoclinic system, space group C2=c; with a = 14.9340(15) Å , b = 6.4900(9) Å , c = 17.9590(19) Å and beta = 97.927(12)° : From the magnetic point of view, V(III) binuclear species show ferromagnetic interactions at low temperatures. However, no anomalies pointing to magnetic ordering are observed down to 2K.
C. Brouca-Cabarrecq, A. Mohanu, P. Millet, and J.C. Trombe, Journal of Solid State Chemistry 177 (2004) 2575-2583

A1217 – Synthesis and spectroscopic characterisation of chosen heteropolyanions and their Ln(III) complexes containing tetrabutylammonium counter ion

Synthesis and spectroscopic characterisation of tetrabutylammonium salts of heteropolyanions (NBu4HPAS) of Keggin's (NBu4)5H2PW11O39, (NBu4)6HPMo2W9O39, (NBu4)6H2SiMo2W9O39, (NBu4)4H3PMo2W9O39, (NBu4)6HPMo2W9O39, Dawson's type (NBu4)9HP2W17O61 and Preyssler heteropolyanion (NBu4)12[(Eu)P5W30O110] are presented. Extraction procedure has been selected as the best method for synthesis of compositions containing an organic counter anion. Elemental and thermogravimetric analysis, spectrophotometric determination of W and Mo, and FTIR spectra have been applied for analysis of the compositions obtained. The complexation studies were carried out with the use of Nd(III) and Er(III) absorption spectra (in the range of their hypersensitive transitions) and Eu(III) luminescence lifetime measurements. Threshold bootstrap computer-assisted target factor analysis (TB CAT) has been applied to evaluate the Nd(III) and Er(III) spectra in DMF and DMSO solutions and to estimate conditional formation constants for Ln(III)(NBu4HPAS)2 sandwich species (Ln(III)=Nd(III), Er(III)). Luminescence characterisation of the NBu4EuHPAS compounds concerning their intensity, quantum yield and luminescence lifetime of Eu(III) ion in non-aqueous solutions and solid are discussed.
S. Lis, S. But, G. Meinrath, Journal of Alloys and Compounds 374 (2004) 366-370

A1195 – Online evolved gas analyses (EGA by TG-FTIR and TG/DTA-MS) and solid state (FTIR, XRD) studies on thermal decomposition and partial reduction of ammonium paratungstate tetrahydrate

Ammonium paratungstate tetrahydrate (NH4)10[H2W12O42].4H2O (APT), a starting material in powder metallurgy of tungsten, has been subjected to a complex thermoanalytical study. The weight loss stages and the various heat effects have been followed by simultaneous thermogravimetry and differential thermal analysis (TG/DTA) in flowing 10% H2/Ar and 10% H2/He atmospheres up to 600°C. Meanwhile evolution of gaseous products has also been analyzed and monitored by both on-line coupled mass spectrometer (TG/DTA-MS) and infrared gas cell (TG-FTIR). In atmospheres containing 10% H2, the evolution courses of H2O and NH3 traced by these EGA-methods and the TG/DTA curves up to 380°C have been found quite similar to those of measured in air or in pure He. Effect of the reductive medium occurred above 380°C, where solid products of intermediate temperatures have been structurally evaluated by both FTIR spectroscopy and powder X-ray diffraction (XRD). Based on significant changes in XRD patterns, the only small exothermic heat effect observed at 420-440°C is assigned to the crystallization heat of a mixture of partially reduced tungsten oxide bronzes.
I.M. Szilagyi, J. Madarasz, F. Hange, G. Pokol, Solid State Ionics 172 (2004) 583-586

A1194 – Synthesis, crystal structures and properties of the bis-(trimetaphosphimato)-metallates Na4{Co[(PO2NH)3]2}.12H2O and Na4{Ni[(PO2NH)3]2}.12H2O

Tetrasodium-bis-(trimetaphosphimato)-cobaltate(II) dodecahydrate, Na4{Co[(PO2NH)3]2}.12H2O (1), and tetrasodium-bis-(trimetaphosphimato)- nickelate(II) dodecahydrate, Na4{Ni[(PO2NH)3]2}.12H2O (2), were obtained by the stoichiometric reaction of an aqueous solution of Na3(PO2NH)3.4H2O with the respective metal nitrate or halide. The structures of 1 and 2 were found to be isomorphous and were solved by single-crystal X-ray methods (1a: C2/c, a = 888.9(1) pm, b = 1901.8(2) pm, c = 1711.2(2) pm, beta = 104.59(1)°, Z = 4; 2a: C2/c, a = 894.4(1) pm, b = 1890.6(1) pm, c = 1723.6(1) pm, beta = 104.49(1)°, Z = 4). At low temperature a reversible phase transition occurs and the symmetry of the structure changes from C2/c to P21/n (1b: P21/n, a = 887.1(2) pm, b = 1900.1(4) pm, c = 1707.2(3) pm, beta = 104.59(2)°, Z = 4; 2b: P21/n, a = 890.3(1) pm, b = 1890.2(2) pm, c = 1713.3(2) pm, beta = 104.62(1)°, Z = 4). The phase transition is caused by a structural ordering of Na+ and H2O at low temperature. The P3N3 rings of the trimetaphosphimate ions exhibit a chair conformation. The trimetaphosphimate ions act as tridentate ligands. Thus, anionic complexes {M[(PO2NH)3]2}4- (M = Co, Ni) are formed. These structural elements are interconnected in the crystal by N-H...O and O-H...O hydrogen bonds and by coordination to Na+ forming a three-dimensional network. Upon heating, 1 and 2 loose their crystal water around 100°C and above 400°C new crystalline phases are formed, which have not been identified so far.
S. Correll, N. Stock, W. Schnick, Solid State Sciences 6 (2004) 953-965

A1179 – Synthesis and calorimetric study of rare earth complexes [RE(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3 (RE: Sm, Eu, Dy, Er)

The crystals of four complexes of rare earth perchlorate with DL-alpha-alanine and imidazole were synthesized and characterized. The components of them were determined to be [RE(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3 (RE: Sm, Eu, Dy, Er) by FT-IR, chemical, elemental and thermal analysis. The enthalpies of dissolution of [2C3H7NO2(s) + 3NaClO4(s)], [C3H4N2(s) + RECl3.6H2O(s)] and [3NaCl(s)], {[RE(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3(s)} were determined by a solution-reaction isoperibol calorimeter at T = 298.15 K, respectively. According to Hess's law, the standard molar enthalpies of reaction of four reactions, RECl3.6H2O(s)+ 2C3H7NO2(s)+ C3H4N2(s)+ 3NaCl(s) = [RE(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3(s) + 3NaCl(s) + 5H2O(l) (RE: Sm, Eu, Dy, Er) were determined to be 4.87 ± 0.20, 7.23 ± 0.19, 0.96 ± 0.27 and 12.88 ± 0.32 kJ mol-1, respectively. The standard molar enthalpies of formation of the four complexes at T = 298.15 K, ?fHm° {[Re(C3H7NO2)2(C3H4N2)(H2O)](ClO4)3(s)} (RE: Sm, Eu, Dy, Er), were determined to be -(2448.1 ± 3.3), -(2360.3 ± 3.3), -(2451.8 ± 3.3) and -(2444.3 ± 3.3) kJ mol-1, respectively.
Y-M. Dan, H-G. Yu, Q. Long, A-X. Hou, Y. Liu, S-S. Qu, Thermochimica Acta 419 (2004) 169-172

A1173 – Oxygen isotopic effect on the IR reflectivity spectra of a La2NiO4.14 single crystal

Infrared reflectivity spectra measurements have been realised at T = 300 K on the oxygen-isotope exchanged single crystals (16O and 18O) of La2NiO(4+d) with d = 0.14. One of the main results lies on transfer of the spectral weight from the mid-infrared spectral range to the far-infrared range upon 18O substitution. This striking effect is studied in the framework of the harmonic oscillator concept by simulating the experimental data with a dielectric function model based on the generalisation of the Lyddane-Sachs-Teller relationship. It suggests that the lattice strongly influences the behaviour of the charge carriers in such 3d transition metal oxides.
B. Rousseau, J.M. Bassat, A. Blin, M. Silva de Oliveira, P. Odier, C. Marin, P. Simon, Solid State Sciences 6 (2004) 1131-1137

A1150 – Time-resolved photoluminescence analysis of distribution and migration ofterbium ions in zeolites X

The photoluminescence (PL) dynamics ofterbium-exchanged zeolites X was investigated upon laser excitation at 355 nm. The results evidenced the presence ofat least two terbium main environments with PL lifetimes varying between 391-411 and 753-770 ms. The two-site nature ofterbium distribution in zeolites X permitted a quantitative analysis ofthe migration process of terbium ions inside the pores and cavities upon dehydration in air at 200°C. Besides the increase ofthe PL lifetimes with about 30% and 80% compared to those ofthe hydrated zeolite, a fraction of almost 30% of terbium ions was estimated to migrate from the supercages to the neighboring sodalites or hexagonal prisms. Our results evidenced for the first time the capability of time-resolved luminescence spectroscopy in quantitatively tracking for the intrazeolitic migration of lanthanides.
C. Tiseanu, L. Frunza, M. Kumke, Physica B 352 (2004) 358-365

A1149 – Crystal structure, thermal, dielectric and vibrational studies of the [4-C2H5PyH]4[Sb2Cl10] crystal

Crystal structure of tetra(4-ethylpyridinium) decachlorodiantimonate(III), [4-C2H5PyH]4[Sb2Cl10], has been determined at 245 K by X-ray diffraction (tetragonal, space group P41212). DSC and dilatometric studies indicate a presence of two reversible phase transitions of the first order type, at 370/373 and 233/238 K (cooling/heating) with S = 4.0 and 10.1 J mol-1 K-1, respectively. Infrared spectra of polycrystalline [4-C2H5PyH]4[Sb2Cl10] have been studied in the temperature range 20-306 K. Substantial changes in the temperature evolution of frequencies of internal modes of the 4-ethylpyridinium cations near 233 K are due to the ordering of the cationic sublattice. The experimental results indicate that both phase transitions may be classified as the order-disorder ones.
B. Kulicka, R. Jakubas, A. Pietraszko, G. Bator, J. Baran, Solid State Sciences 6 (2004) 1273-1286

A1148 – [Zn(3+x)V(2-x)O(7-3x)(OH)(2+ 3x)].2H2O and M[Zn(3-x)V2O7(OH)2]Cl(1-2x).(1+2x)H2O two families of zinc vanadates with structures related to the hexagonal structure of [Zn3V2O7(OH)2].2H2O

[Zn(3 +x)V(2-x)O(7-3x)(OH)(2+ 3x)].2H2O (I), with 0 < x < 0.66 and M[Zn(3-x)V2O7(OH)2]Cl(1-2x).(1 + 2x)H2O (II), with 0.15 < x <0.5, were obtained by hydrothermal synthesis at 170°C (24 h) from gels with the molar composition ZnCl2; aV2O5; bMOH; 228H2O, with M= Li, Na, NH4 or K for (I) and NH4 or Rb for (II); 0.2 < a <0.5 and 0.5 < b<6. The compounds of both families crystallize in the hexagonal system with a structure which can be related to the structure of [Zn3V2O7(OH)2].2H2O. Their Zn/V molar ratio can be determined from to the unit-cell parameter a0 by the linear relations Zn/V = 4.896 a0 - 28.124 (R = 0.988) for (I) and Zn/V = 15.302 a0 - 91.027 (with R2 = 0.992) for (II). In (I) the negative charges created by the substitution of vanadium with zinc in the tetrahedra of the pyrovanadate pillars connecting the octahedral sheets containing the zinc, are compensated by protonation of framework oxygen atoms. In (II) the negative charges, created by the removal of zinc in the octahedral sheet, are compensated by cations (NH4+ or Rb+) located between the pyrovanadate pillars. But in order to fill more completely the space, additional cations (NH4+ or Rb+) are incorporated in form of the chloride salt.
D. Hoyos, L. A. Palacio, J-L. Paillaud, A. Simon-Masseron, J-L. Guth, Solid State Sciences 6 (2004) 1251-1258

A1119 – Kinetic study of the thermal dehydration of borogypsum

In Turkey, a large amount of borogypsum waste is discharged by the economically important boric acid industry. Calcination of this waste provides a promising technique not only for recovering an economic value but also for reducing its environmental impact. The aim of this work is to study the thermal behavior of borogypsum, which contains gypsum crystals, boron oxide and some impurities under nonisothermal conditions in air atmosphere by using thermogravimetry and differential thermal analysis techniques (TG-DTA). Experiments were carried out at temperatures ranging from ambient to 773K at different heating rates. The temperatures of conversion from gypsum to hemihydrate and anhydrite states were determined. Various methods were used to analyze the TG and DTA data for determination of reaction kinetics. The activation energy and frequency factor were calculated for dehydration of borogypsum. Activation energy values of the main dehydration reaction of borogypsum were calculated to be approximately 95-114 kJ mol-1.
I.Y. Elbeyli, S. Piskin, Journal of Hazardous Materials B116 (2004) 111-117

A1096 – Synthesis and characterization of a new (2-NH2-6-CH3C5H4N)H2XO4 (X = P, As)

Crystals of 2-amino-6-methylpyridinium dihydrogenmonophosphate (denoted as 2A6MPP) and 2-amino-6-methylpyridinium dihydrogenmonoarsenate (denoted as 2A6MPAs), have been prepared and grown at room temperature. They crystallize with triclinic unit cells and are isotopic. The following unit cell parameters were found, (2-NH2-6-CH3C5H4N)H2PO4: a = 7.5165(6), b = 8.2640(5), c = 8.5674(7) Å , alpha = 64.845(5), beta = 80.156(3), gamma = 85.783(5), Z = 2, V = 474.61(6) Å3; (2-NH2-6- CH3C5H4N)H2AsO4: a = 7.6011(4), b = 8.4261(6), c = 8.7074(6) Å , alpha = 64.228(3), beta = 81.047(4), gamma = 85.972(4), Z = 2, V = 496.09(6) Å3. The common space group is P¯1. We have determined the structure of the phosphate. It exhibits infinite (H2PO4)n n chains. The organic groups (2-NH2-6-CH3C5H4N)+ are anchored between adjacent polyanions through multiple hydrogen bonds. The thermal property of the compound was investigated as well as was the IR property supported by group theoretical analyses.
A. Chtioui, A. Jouini, Materials Research Bulletin 41 (2006) 569-575

A1090 – Dimeric allylpalladium(II) complexes with pyrazolate bridges: Synthesis, characterization, structure and thermal behaviour

The synthesis, characterization and thermal behaviour of some new dimeric allylpalladium (II) complexes bridged by pyrazolate ligands are reported. The complexes [Pd(µ-3; 5-R2'pz)(?3-CH2C(R)CH2)]2 [R = H, R' = CH(CH3)2 (1a); R=H, R' = C(CH3)3 (1b), R = H, R' = CF3 (1c); R = CH3, R' = CH(CH3)2 (2a); R = CH3, R' = C(CH3)3 (2b); and R = CH3, R' = CF3 (2c)] have been prepared by the room temperature reaction of [Pd(?3-CH2C(R)CH2)(acac)](acac = acetylacetonate) with 3,5-disubstituted pyrazoles in acetonitrile solution. The complexes have been characterized by NMR (1H, 13C{1H}), FT-IR, and elemental analyses. The structure of a representative complex, viz. 2c, has been established by single-crystal X-ray diffraction. The dinuclear molecule features two formally square planar palladium centres which are bridged by two pyrazole ligands and the coordination of each metal centre is completed by allyl substituents. The molecule has non-crystallographic mirror symmetry. Thermogravimetric studies have been carried out to evaluate the thermal stability of these complexes. Most of the complexes thermally decompose in argon atmosphere to give nanocrystals of palladium, which have been characterized by XRD, SEM and TEM. However, complex 2c can be sublimed in vacuo at 2 mbar without decomposition. The equilibrium vapour pressure of 2c has been measured by the Knudsen effusion technique. The vapour pressure of the complex 2c could be expressed by the relation: ln (p/Pa)(±0.06) = 18047.3/T + 46.85. The enthalpy and entropy of vapourization are found to be 150.0 ± 3 kJ mol-1 and 389.5 ± 8 J K-1 mol-1, respectively.
A. Singhal, R. Mishra, S.K. Kulshreshtha, P.V. Bernhardt, E.R.T. Tiekink, Journal of Organometallic Chemistry 691 (2006) 1402-1410

A1083 – 3-Dimethylaminopropyl chalcogenolate complexes of palladium(II): Syntheses and characterization, including the crystal structures of [Pd(OAc)(ECH2CH2CH2NMe2)]2 . H2O (E = S, Se) and [PdCl(TeCH2CH2CH2NMe2)]2

The reactions of the sodium salts of 3-dimethylamino-1-propylchalcogenolates, prepared by sodium borohydride reduction of (Me2NCH2CH2CH2E)2 in methanol, with Na2PdCl4 yielded homoleptic [Pd(ECH2CH2CH2NMe2)2]6 (1) (E=S (1a); Se (1b); Te (1c)). When treated with [Pd(OAc)2]3 or Na2PdCl4, compounds 1 readily gave binuclear redistribution products [PdX(ECH2CH2CH2NMe2)]2 where X = OAc (2) (E=S (2a); Se (2b); or Cl (3)) (E = S (3a); Se (3b); Te (3c)), respectively. The terminal acetate/chloride ligands in 2b/3b can be substituted by other ionic ligands like PhSe . The complexes were characterized by elemental analysis, UV-Vis, IR and NMR spectroscopy. The structures of 2a, 2b and 3c were established by X-ray crystallography. Each molecule has a dimeric structure in which there are two chalcogenolate bridges from the chelating 3-dimethylamino-1-propylchalcogenolate ligands. On pyrolysis, compound 2b affords Pd17Se15.
S. Dey, V.K. Jain, B. Varghese, T. Schurr, M. Niemeyer, W. Kaim, R.J. Butcher, Inorganica Chimica Acta 359 (2006) 1449-1457

A1054 – Hybrid organic-inorganic materials: Layered hydroxy double salts intercalated with substituted thiophene monomers

The present paper describes the synthesis and characterization of Layered Hydroxy Double Salts (HDSs) containing substituted thiophene anions (2-thiophenecarboxylate, 3-thiophenecarboxylate, and 3-thiopheneacetate). The HDSs host was synthesized via hydrothermal method and the organic anions were incorporated between the sheets by anion-exchange reaction. The materials were characterized by powder X-ray diffraction (PXRD), thermal gravimetric (TG) analysis and electron spin resonance (ESR) spectroscopy. For the 2D-hybrid materials, the basal spacing is found to be consistent with the formation of bilayers of the intercalated organic monomers. For the hybrid material formed after intercalation of 3-thiopheneacetate anion, the ESR signals suggest that the monomers connect each other directly forming small oligomers, whereas this process is not occurring for the two other monomers presenting short alkyl chain. The TG analyses show different stages of thermal decomposition between HDSs host and 2D-hybrid materials, underlining the enhanced thermal stability of the hybrid assembly.
J. Tronto, F. Leroux, M. Dubois, C. Taviot-Gueho, J. Barros Valim, Journal of Physics and Chemistry of Solids 67 (2006) 978-982

A1035 – Thermal decomposition of HfCl4 as a function of its hydration state

The thermogravimetric behavior of HfCl4 powders with different hydration states has been compared. Strongly hydrated powders consist of HfOCl2 . nH2O with n>4. Partially hydrated powders consist of particles with a HfCl4 core and a hydrated outerlayer of HfOCl2 . nH2O with n in the range of 0-8. Hydrated powders decomposed at temperature lower than 200°C whereas the decomposition of partially hydrated powders was completed at a temperature of around 450°C. The observed differences in decomposition temperature is related to the structure of HfOCl2 . nH2O, which is different if n is higher or smaller than 4 and leads to intermediate compounds, which decompose at different temperatures.
E. Barraud, S. Bégin-Colin, G. Le Caër, F. Villieras, O. Barres, Journal of Solid State Chemistry 179 (2006) 1842-1851

A1020 – Soft chemistry synthesis, structure and electrochemical characterization of iron phosphates Fe(H2PO4)3 and Fe(PO3)3

The iron phosphate, Fe(H2PO4)3, was synthesized through a precipitation route by means of acidic media. As the compound is highly hygroscopic, the structure was solved ab initio by powder X-ray diffraction under nitrogen flow at room temperature and 200°C. This phase is antiferromagnetic below 30 K. It converts into Fe(PO3)3 at 550°C, after dehydration. Electrochemical characterizations, performed on the last compound, show irreversible decomposition into metallic iron.
R. Baies, V. Pralong, V. Caignaert, B. Raveau, Materials Research Bulletin 41 (2006) 1170-1177

A1004 – Adsorption of pesticides Carbetamide and Metamitron on organohydrotalcite

This paper reports on the adsorption of low polarity pesticides Carbetamide and Metamitron on hydrotalcite [Mg3Al(OH)8]2 CO3.nH2O and organohydrotalcites [Mg3Al(OH)8]2DDS.nH2O with different degree of dodecyl sulphate (DDS) saturation. The adsorbents and the adsorption products were characterized by X-ray diffraction method and FT-IR spectroscopy. Both pesticides were better adsorbed on organohydrotalcite with higher DDS saturation, while their adsorption on inorganic hydrotalcite was very low. The results indicate that the adsorption capacity of different materials depends on their nature as well as structure and polarity of the pesticides and suggest the possibility of use of organohydrotalcite to uptake the Carbetamide and Metamitron from contaminated waters. The results also showed that the recyclability of organohydrotalcite and their reutilization as adsorbent is possible.
F. Bruna, I. Pavlovic, C. Barriga, J. Cornejo, M.A. Ulibarri, Applied Clay Science 33 (2006) 116-124

A1003 – Study on the potential use of Tunisian clays as pozzolanic material

Samples of Tunisian clays from different locations are calcined at 600, 700 and 800°C. Geotechnical, chemical and physical properties of both untreated and calcined samples are studied. The pozzolanic activity of the calcinated clays is evaluated by compressive strength performed on calcinated clay-calcium hydroxide mini-cylinders. The geotechnical study associated with the chemical analysis was found to be useful to predict the pozzolanic activity of the clays. Clays rich in kaolinite were shown to have the highest strength and therefore the best pozzolanic activity. The presence of some mineral clays such as illite, montmorillonite and muscovite does not improve the pozzolanic activity despite their relatively high level of silica, alumina and iron.
A. Chakchouk, B. Samet, T. Mnif, Applied Clay Science 33 (2006) 79-88

A1001 – Photoluminescence and microstructure of Mn-doped ZnS phosphor powder co-fired with ZnS nanocrystallites

In this study, we correlated the photoluminescence (PL) with the microstructure of ZnS:Mn phosphor powders prepared by firing ZnS with MnO (1 mol%), NaCl (1 mol%) and ZnS nanocrystallites (NCs) in the range of 0-100 wt% at 600-1000°C for 2 h in the atmosphere of 3%H2/Ar. ZnS NCs of 10-30 nm in size were produced by co-precipitation of zinc nitrate and sodium sulfide solutions at room temperature. Thermal analysis (DTA/TG) and X-ray diffraction (XRD) results indicated that the cubic-hexagonal transformation temperature of ZnS NCs was lowered to approximately 600°C, which was much lower than that of bulk ZnS (1020°C). PL measurements revealed that ZnS:Mn fired with 1 wt% ZnS NCs showed the optimal luminescence intensity when compared to those without or with higher ZnS NCs (>1 wt%). An appropriate amount of ZnS NCs (1 wt%) acting as the flux in the firing process was inferred to avoid the inhomogeneous distribution of Mn2+ as well as the migration of excitation energy to quenching sites and therefore to result in the enhanced PL intensity.
Y-T. Nien, H-S. Hsu, I-G. Chen, C-S. Hwang, S-Y. Chu, Journal of Non-Crystalline Solids 352 (2006) 2539-2542

A1000 – Synthesis of all-silica BEA-type material in basic media

Previous investigations have shown that an all-silica BEA-type (Si-BEA) material is difficult to be nucleated in basic media and that the fluorosilicic precursors formed in near neutral media play an important role in its formation. The present study reports on the synthesis of this microporous material under basic conditions by using TEA2SiF6 as an additional silica source that provides preformed fluorosilicate species. The effect of the amount of TEA2SiF6 on the purity of the final product, crystallization kinetics and morphological features of Si-BEA were systematically studied. The investigation showed that above a certain concentration corresponding to TEA2- SiF6/SiO2 = 0.07 pure Si-BEA was obtained and further increase in the concentration improved substantially the crystallization kinetics. The increase in TEA2SiF6 content led also to a gradual increase of the size of the pyramidal (h0l) face coupled with the decrease of pinacoidal (001) one. Thus, the morphology of the zeolite crystals can be varied from well developed truncated bipyramids to plate-like crystals with dominating pinacoidal faces. A consequence of this morphological changes is the number the pore openings of the channel systems running along the a- and c-axes per total external surface. The framework defectness and water content in the synthesized materials were studied by 29Si NMR spectroscopy and TG analysis, respectively. This combined study revealed that materials with a high level of hydrophobicity, due to the specific effect of fluorine anions, have been synthesized under basic conditions.
O. Larlus, V. Valtchev, Microporous and Mesoporous Materials 93 (2006) 55-61

A0995 – Laser-induced fluorescence and thermoluminescence response of a Na-Ca rich silicate

Pectolite (NaCa2Si3O8(OH)) is an inosilicate of hydrothermal origin hosted in Cretaceous basalt with calcite and iron oxides and is almost always associated with zeolites. The emission of this silicate was studied by laser-induced fluorescence (LIF) and thermal stimulated luminescence (TL). The fluorescence spectra of different areas of the sample induced by exposition to 266 nm UV laser light (5 nm of spectral resolution, FWHM) give rise to two peaks at 550 and 830 nm that can be, respectively, linked to the presence of Mn2+ and Cr3+ emission centres. The stability tests at different temperatures show clearly that the TL glow curves at 400 nm in natural pectolite samples, track the typical pattern of a system produced by a continuous trap distribution, well defined in other silicates. This process could be mainly associated to dehydroxylation effect, as observed by differential thermal analysis (DTA), and probably is also linked to chromophore oxidation.
V. Correcher, J. Garcia-Guinea, M. Castillejo, M. Oujja, E. Rebollar, P. Lopez-Arce, Radiation Measurements 41 (2006) 971-975

A0994 – Nickel and cobalt precipitation from sulphate leach liquor using MgO pulp as neutralizing agent

The research work presented in this paper determined the conditions at which nickel and cobalt can be recovered, as easily filterable precipitates, from leach liquors, which are produced by sulphuric acid leaching of nickel oxide ores, at atmospheric pressure. More specifically, nickel and cobalt were precipitated as hydroxides at pH = 9, using MgO pulp as a neutralizing agent, by 99.9% and 99.0%, respectively. At this pH value, manganese, which was contained in the leach liquor, was precipitated having a concentration of about 3% in the final mixed precipitate. Statistical design and analysis of experiments were used in order to determine the main effects and interactions of the precipitation factors, which were the pH at equilibrium and the addition of seed material. The characterization of the produced mixed precipitate was carried out by X-ray diffraction, TG-DTA, scanning electron and optical microscopy and particle size distribution analyzer. The main mineralogical phases in the precipitate were theophrastite (Ni(OH)2) and brucite (Mg(OH)2). The microscopic observation revealed that the presence of brucite was, mainly, due to the un-reacted MgO pulp, during the precipitation process. This brucite content acted as seed material for nickel precipitation.
P. Oustadakis, S. Agatzini-Leonardou, P.E. Tsakiridis, Minerals Engineering 19 (2006) 1204-1211

A0988 – Iron oxide modified diamond blends containing ultradispersed diamond

Iron oxide modified diamond blends containing different amounts of ultradispersed diamond were prepared and characterized by nitrogen physisorption, X-ray diffraction, temperature programmed reduction, Mössbauer and IR spectroscopy. The catalytic behavior of these composite materials inmethanol decomposition to hydrogen, carbon monoxide, and methane has been also studied. The initial state and phase transformations of the supported highly dispersed iron oxide particles in various pretreatment media, as well as their reductive and catalytic properties, strongly depend on the ultradispersed diamond content in the diamond blends.
T. Tsoncheva, M. Dimitrov, L. Ivanova, D. Paneva, D. Mitev, B. Tsintsarski, I. Mitov, S. Stavrev, C. Minchev, Journal of Colloid and Interface Science 300 (2006) 183-189

A0979 – Crystal structure and physicochemical properties of a new organic condensed phosphate (C7H10NO)3P3O9.4H2O

Chemical preparation, X-ray characterization, IR spectroscopy and thermal analysis of a new cyclotriphosphate: (C7H10NO)3- P3O9.4H2O abbreviated as OACTP, are reported. This mixed organo-mineral compound crystallizes in the monoclinic system with P21/n space group, the unit cell dimensions are: a = 6.605(3) Å , b = 26.166(3) Å , c = 18.671(8) Å , beta = 91.95(3)°, Z = 4 and V = 3255(2) Å3. The structure was solved using a direct method and refined to a reliability R-factor of 0.043 using 3931 independent reflections (I > 2?I). Atomic arrangement exhibits infinite (P3O9 2H2O)n 3n- chains connected by organic cations. The thermal behavior and the IR spectroscopic studies of this new compound are discussed.
L. Guelmami, T. Guerfel, A. Jouini, Materials Research Bulletin 42 (2007) 446-455

A0970 – Thermochemistry of NaRb[B4O5(OH)4].4H2O

The enthalpies of solution of NaRb[B4O5(OH)4].4H2O in approximately 1 mol dm-3 aqueous hydrochloric acid and of RbCl in aqueous (hydrochloric acid + boric acid + sodium chloride) were determined. From these results and the enthalpy of solution of H3BO3 in approximately 1 mol dm-3 HCl(aq) and of sodium chloride in aqueous (hydrochloric acid + boric acid), the standard molar enthalpy of formation of -(5128.02±1.94) kJ mol-1 for NaRb[B4O5(OH)4].4H2O was obtained from the standard molar enthalpies of formation of NaCl(s), RbCl(s), H3BO3(s) and H2O(l). The standard molar entropy of formation of NaRb[B4O5(OH)4].4H2O was calculated from the Gibbs free energy of formation of NaRb[B4O5(OH)4].4H2O computed from a group contribution method.
J. Zhou, F. Zhao, Q. Yang, Y. Lu, S. Xia, S. Gao, Thermochimica Acta 448 (2006) 52-55

A0969 – Synthesis and crystal structure of a new adduct of dihydrogenphosphate phosphoric acid monohydrate with 8-aminoquinolinium (8-NH2-C9H6NH)2(H2PO4)2H3PO4.H2O

The synthesis and structure of a new adduct with formula: (8-NH2-C9H6NH)2(H2PO4)2H3PO4.H2O is reported. It crystallizes with triclinic unit cell. The following unit cell parameters were found: a = 9.371(2), b = 11.442(2), c = 13.340(2) Å, alpha = 96.78(6)°, beta = 97.34(5)°, gamma = 113.90(3)°, V = 1273.7(6) Å3 and ?cal. = 1.565 gcm-3. Crystal structure was solved with a final R = 0.041 for 3982 independent reflections. The space group is P-1 and Z = 2. The atomic arrangement can be described as wide pseudo-hexagonal channels including the organic entities. Solid-state 13C and 31P MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of the phosphorous signals to the three independent crystallographic sites.
J. Oueslati, A. Oueslati, C. Ben Nasr, F. Lefebvre, Solid State Sciences 8 (2006) 1067-1073

A0964 – Reduction roasting of limonite ores: effect of dehydroxylation

The effect of pre-calcination in the reducibility of tropical limonite ore, obtained from New Caledonia, was investigated in this study. A series of reduction tests were carried out with pre-calcined and raw limonite ores. The extent of metallisation was determined from nickel and iron which dissolved in ammoniacal solution. Mineralogical transformations that occurred during reduction were analysed using thermal gravimetric, differential thermal analysis (TGA/DTA) and in situ high temperature synchrotron based X-ray diffraction. Bulk mineral analysis of the raw ore was also obtained using neutron diffraction. This study suggests that there is benefit in the pre-calcination of limonite ores. Pre-calcination of the ores which opens the main gangue mineral structure, goethite, allows a rapid interaction between the reductant gases and the nickel species during reduction. The greater nickel metallisation achieved in reduction of pre-calcined ores resulted in higher dissolved nickel whilst reduced raw limonite showed poorer nickel recovery. Reduction of metal minerals was also accompanied by diffusion of nickel into the reduced iron matrix that resulted in the formation of ferro-nickel alloy (Ni3Fe). The formation of this solid solution was monitored by in situ synchrotron based X-ray diffraction and was also reflected by the lower nickel leachability in ammoniacal solution. It was found that incorporation of nickel into the reduced iron oxide resulting from pre-calcination is significantly less in comparison to the diffusion occurring in reduced raw or uncalcined limonite ores. This effect is prevalent in prolonged reduction periods (greater than 20 min), at higher temperatures (>500°C) and highly reducing conditions (H2/CO2=1:1). This study showed that optimal nickel recovery can be achieved by controlling the incorporation of nickel into the reduced iron structure by pre-calcination of the limonite ore.
F. O'Connor, W.H. Cheung, M. Valix, Int. J. Miner. Process. 80 (2006) 88- 99

A0951 – Synthesis and characterisation of a new stable organo-mineral hybrid nanomaterial: 4-Chlorobenzenesulfonate in the zinc-aluminium layered double hydroxide

4-Chlorobenzenesulfonate (4-CBS) was intercalated between layers of Zn-Al layered double hydroxides (LDHs). Two methods of incorporation were applied: (1) direct synthesis by coprecipitation of metal nitrates and sodium 4-CBS and (2) ion exchange of the LDH nitrate with the organic ion. The solids were characterized by X-ray diffraction and infrared spectroscopy. The direct method, effected at different pH values, led to a hybrid material with good degree of intercalation. In order to optimise the exchange conditions, particular attention was given to the effect of solution pH, 4-CBS/NO3 ratio and exchange temperature. The total exchange was successful and a new stable hybrid nanostructured material was obtained at pH 8 and with a 4-CBS concentration of 0.0028 M. This solid was further characterised by chemical and thermal analyses.
M. Lakraimi, A. Legrouri, A. Barroug, A. De Roy, J.P. Besse, Materials Research Bulletin 41 (2006) 1763-1774

A0949 – Influence of sulfate ions on the interaction between fatty acids and calcite surface

The effect of sulfate ions on adsorption/displacement of long chain fatty acids onto/from calcite surface is investigated. The fatty acids used in this work are stearic acid (SA), oleic acid (OA) and 18-cyclohexyl-octadecanoic acid (CHOA). The main methods are thermogravimetric analysis for determining the extent of surface modification and vapour adsorption isotherm to evaluate the wetting behaviour. An appreciable reduction of adsorbed amount of fatty acids is observed in presence of sulfate ions. This is interpreted by the high affinity of the sulfate ions for the active sites of the calcite. In addition, they modify the calcite surface to a negative charge, as indicated by zeta potential measurements, hence reducing the availability of the active sites for carboxylate ions. The ability of sulfate ions to displace the pre-adsorbed fatty acids from the calcite surface is also demonstrated. It is mostly related to the molecular structure of the fatty acids, where the percentage of displacement by 0.1M sulfate is found to be 7 and 10 for stearic acid and oleic acid, respectively. This work shows that the sulfate ions changed the wettability of calcite to more water-wet as indicated by water vapour adsorption isotherms.
K.A. Rezaei Gomari, A.A. Hamouda, R. Denoyel, Colloids and Surfaces A: Physicochem. Eng. Aspects 287 (2006) 29-35

A0947 – Synthesis of MCM-41 from coal fly ash by a green approach: Influence of synthesis pH

The present study reports a green synthesis method for preparing pure (free of fly ash) and ordered MCM-41 materials from coal fly ash at room temperature (25°C) during 24 h of reaction. It was shown that the impurities in the coal fly ash were not detrimental to the formation of MCM-41 at the tested conditions. The influence of initial synthesis pH on material properties of calcined MCM-41 samples was investigated by various techniques such as XRF, XPS, XRD, FTIR, DR-UV-vis, solid state NMR, N2 physisorption, TG-DTA, SEM and TEM. The experimental results showed that the amount of trace elements such as Al, Na, Ti and Fe incorporated into the sample increased with synthesis pH value. More aluminum species were incorporated with tetrahedral coordination in the framework under a high pH value. The particle size of the sample decreased with the synthesis pH value. Samples synthesized at high pH values had a larger pore size and were more hydrothermally stable than those at low pH values. From thermal analysis, it was observed that the synthesized MCM-41 samples showed a high thermal stability. These properties made the synthesized MCM-41 suitable for further processing into more useful materials in a wide range of applications.
K.S. Hui, C.Y.H. Chao, Journal of Hazardous Materials B137 (2006) 1135-1148

A0936 – Structural characterization and properties of [4-CH3C5H4NH][SbBr4]. The mechanism of phase transitions in 4-methylpyridinium bromoantimonates(III)

The crystal structure of [4-CH3C5H4NH][SbBr4] is determined at 297 K. The compound crystallizes in the monoclinic space group: P21/c. The structure consists of SbBr4- ions which form infinite chains through the crystal via halogen linkages. The anions are connected with the 4-methylpyridinium via weak N-H...X hydrogen bonds. The phase situation was studied on two methyl-substituted pyridinium analogous: [4-CH3C5H4NH][SbBr4] and [4-CH3C5H4NH]2[SbBr5] with the differential scanning calorimetry and dilatometric methods. The former derivative undergoes two structural phase transitions: at 351/349 K (heating-cooling) and at 385/381. [4-CH3C5H4NH]2[SbBr5] reveals one phase transition at 426/419 K. The dielectric relaxation studies on [4-CH3C5H4NH]2[SbBr5] in the frequency range between 800 Hz and 6 MHz indicate a presence of relaxation process below room temperature. The dielectric response is well explained in terms of an existence of two dielectric relaxators. The mechanism of the phase transitions in the studied crystals is discussed.
B. Kulicka, R. Jakubas, Z. Ciunik, Solid State Sciences 8 (2006) 1229-1236

A0935 – Polycationic disorder in [Bi6O4(OH)4](NO3)6: Structure determination using synchrotron radiation and microcrystal X-ray diffraction

The bismuth basic nitrate [Bi6O4(OH)4](NO3)6 crystallizes in a rhombohedral hexagonal unit cell with parameters a = 15.1332(6) Å, c = 15.7909(9) Å, V = 3131.8(3) Å3, Z = 6, space group R-3. The synthesis, formula determination, thermogravimetric analysis and nitrate assay, and finally, its crystal structure refinement determined at 150(2)K by synchrotron X-ray microcrystal diffraction are reported. Its structure is built from [Bi6O4(OH)4]6+ polycations, six per unit cell, disordered over two positions. Two oxygen atoms are common to the two antagonist polycations (full occupancy) while the remaining six are partially occupied. The [Bi6O4(OH)4]6+ hexanuclear clusters form columns along the c-axis. The cohesion between polycationic entities is effected by nitrate anions through either OH-ONO2 hydrogen bonds or Bi-ONO2 bonds. One of the two independent [NO3]- groups is also disordered over two positions. Only a local order in the columns is obtained by formation of pairs of ordered [Bi6O4(OH)4]6+ polycations.
N. Henry, O. Mentré, F. Abraham, E.J. MacLean, P. Roussel, Journal of Solid State Chemistry 179 (2006) 3087-3094

A0928 – Indigo chemisorption in sepiolite. Application to Maya blue formation

Having first studied the loss of water in sepiolite via TGA, we then observed through FTIR the evolution of the indigo/sepiolite chemical bonds during the Maya blue formation process. Three stages, corresponding to three different temperature domains, were observed. They explain the peculiar properties of this pigment.
S. Ovarlez, A-M. Chaze, F. Giulieri, F. Delamare, C. R. Chimie 9 (2006) 1243-1248

A0923 – Synthesis, structure and thermal behaviour of a barium-glutarate framework

A hybrid framework material has been synthesized via a gel diffusive technique. Its X-ray single crystal structure has been determined at 120 K, in the tetragonal space group P4 2/mbc. The ligand is partially deprotonated giving interesting supramolecular bonding formed by hydrogenoglutarate anion, which can act as a building synthon. The layer-type polymeric structure is built up from isolated polyhedra linked via conventional carboxylate bridges and forming inorganic layers in the plane (001). Along [001], layers consisting of the methylene spacers of the ligands, complete the three-dimensional framework. The thermal analysis performed by TGA and DSC in air and under N2, respectively, revealed the high stability of the non-templated framework (up to 210°C) and showed several phase transitions and one solid-state reaction detected by an exothermic peak at 500°C.
K. Aliouane, A. Djeghri, A. Guehria-Laidoudi, S. Dahaoui, C. Lecomte, Journal of Molecular Structure 832 (2007) 150-155

A0916 – Crystal structure of a new organic dihydrogenomonophosphate (C6H8N3O)2(H2PO4)2

Chemical preparation, X-ray single-crystal, thermal behavior, and IR spectroscopy investigations are given for a new organic cation dihydrogenomonophosphate (C6H8N3O)2(H2PO4)2 (denoted IAHP) in the solid state. This compound crystallizes in the orthorhombic space group P212121. The unit cell dimensions are: a = 7.422(3) Å , b = 12.568(5) Å , c = 20.059(8) Å with V = 1871.1(13) Å3 and Z = 4. The structure has been solved using direct method and refined to a reliability R factor of 0.029. The atomic arrangement can be described as inorganic layers of (H2PO4)- anions between which are located the organic groups (C6H8N3O)+ through multiple hydrogen bonds.
L. BenHamada, A. Jouini, Materials Research Bulletin 41 (2006) 1917-1924

A0864 – Synthesis and characterization of two new photochromic organic-inorganic hybrid materials based on isopolyoxomolybdate: (HDBU)3(NH4)[beta-Mo8O26].H2O and (HDBU)4[delta-Mo8O26]

Two new organic-inorganic hybrid compounds of molybdenum(VI) (HDBU)3(NH4)[beta-Mo8O26].H2O 1 and (HDBU)4[delta-Mo8O26] 2 have been synthesized and characterized by elemental analyses, FT-IR and UV-vis spectroscopies, and single-crystal X-ray diffraction (at 293 and 100 K, respectively). Compound 1 is obtained at room temperature by adding 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on aqueous molybdate solution at pH = 5.7. Compound 2 is obtained hydrothermally from 1 (110°C, 24 h, autogenous pressure). Compound 1 crystallizes in the triclinic crystal system, space group P1, with a = 11.2492(9), b = 14.1907(10), c = 16.7498(10) Å , alpha = 80.993(4), beta = 72.272(6), gamma = 71.696(7)°, V = 2412.5(3) Å3 at T = 20°C and Z = 2. The refinement of the structure leads to a residual factor R = 0.0697 for 10234 independent observed reflections [I/s(I)>2] and 623 parameters. Compound 2 crystallizes in the triclinic crystal system, space group P1, with a = 11.3158(9), b = 11.3773(8), c = 13.2884(17) Å , alpha = 92.110(8), beta = 112.127(9), gamma = 117.581(7)°, V = 1357.4(3) Å3 at T = 173°C and Z = 2. The refinement of the structure leads to a residual factor R = 0.0226 for 11812 independent observed reflections [I/s(I)>2] and 354 parameters. The structure of 1 consists of beta-[Mo8O26]4- anions with HDBU+ and (NH4)+ cations connected to the mineral parts by hydrogen bonds and the structure of 2 contains delta-[Mo8O26]4- anions with HDBU+ counter-cations. Both the thermal and chemical isomerizations of the two [Mo8O26]4- isomers are highlighted and discussed. Photochromic behaviors of compounds 1 and 2 are also reported.
V. Coué, R. Dessapt, M. Bujoli-Doeuff, M. Evain, S. Jobic, Journal of Solid State Chemistry 179 (2006) 3615-3627

A0863 – Diffuse reflectance infrared Fourier transform spectroscopy as a tool to characterise water in adsorption/confinement situations

We present experimental data acquired by diffuse reflectance infrared spectroscopy in the mid-IR (4000-400 cm-1), on micrometric-sized mineral grain powders. The spectral evolution of the OH-stretching band is followed when the adsorbed water film is thinned under dry conditions, from high to low hydration states. The IR bands are found to be characteristic of the degree of adsorption/confinement of the liquid water. The OH-stretching band is shifted toward shorter wavenumbers than in bulk water, showing that a significant portion of adsorbed water has a higher intermolecular bonding energy. Complementary treatment of the kinetics of water desorption, varying with the surface forces in the water film, confirms the relationships of these bands with the constrained water state. We distinguish different water types obeying liquid-liquid interactions (free and capillary water) or dominated by solid-water interactions (confined and adsorbed water). Part of this study is devoted to mesoporous silica MCM-41, of interest due to the restricted geometries of its mesopores (4.7 nm) favouring the confined water state. The methodology allows us to distinguish bulk and adsorbed/confined water, using spectral analysis coupled with an understanding of the dynamic behaviour of the desorption process.
T. Richard, L. Mercury, F. Poulet, L. d'Hendecourt, Journal of Colloid and Interface Science 304 (2006) 125-136

A0857 – Cr(VI) adsorption on functionalized amorphous and mesoporous silica from aqueous and non-aqueous media

A mesoporous silica (SBA-15) and amorphous silica (SG) have been chemically modified with 2-mercaptopyridine using the homogeneous route. This synthetic route involved the reaction of 2-mercaptopyridine with 3-chloropropyltriethoxysilane prior to immobilization on the support. The resulting material has been characterized by powder X-ray diffraction, nitrogen gas sorption, FT-IR and MAS NMR spectroscopy, thermogravimetry and elemental analysis. The solid was employed as a Cr(VI) adsorbent from aqueous and non-aqueous solutions at room temperature. The effect of several variables (stirring time, pH, metal concentration and solvent polarity) has been studied using the batch technique. The results indicate that under the optimum conditions, the maximum adsorption value for Cr(VI) was 1.83 ± 0.03 mmol/g for MP-SBA-15, whereas the adsorption capacity of the MP-SG was 0.86 ± 0.02 mmol/g. On the basis of these results, it can be concluded that it is possible to modify chemically SBA-15 and SG with 2-mercaptopyridine and to use the resulting modified silicas as effective adsorbents for Cr(VI).
D. Pérez-Quintanilla, I. del Hierro, M. Fajardo, I. Sierra, Materials Research Bulletin 42 (2007) 1518-1530

A0849 – Selective mesoporous adsorbents for (Cr2O7)2- and Cu2+ separation

NH2-MCM-41 and COONa-MCM-41 were prepared by grafting aminopropyls and propionates on the pore wall of the mesoporous silica MCM-41 for the separation of (Cr2O7)2- and Cu2+. Single and binary component adsorptions show that (NH3+)-MCM-41 has a 100% selectivity for (Cr2O7)2- adsorption at low pH (<3.5 i.e., point of zero charge, p.z.c.), while COO Na+-MCM-41 adsorbs only Cu2+ over the entire pH range of the study (i.e., pH 1.5-5.5). Adsorption uptakes were rapid on both adsorbents reaching equilibrium in less than 3 h and in most cases less than 10 min. The adsorption capacity of (NH3+)-MCM-41 for (Cr2O7)2- is high, approaching the theoretical values of two aminopropyls for one (Cr2O7)2- , the Cu2+ adsorption on COO Na+-MCM-41 was less efficient requiring five propionates to adsorb one Cu2+. High purity hydrogen dichromate and copper chloride solutions were respectively recovered by a simple acid wash and the regenerated adsorbents were reused without a loss of performance.
K.F. Lam, K.L. Yeung, G. Mckay, Microporous and Mesoporous Materials 100 (2007) 191-201

A0835 – Encapsulation of direct blue dye into mesoporous silica-based materials

Mesoporous hexagonal silica CMI-1, MCM-41,SBA-15 and Al-incorporated silica AlCMI-1 with pore sizes of 2, 2.7, 3.8 and 3.6 nm, respectively, have been synthesized and used as host materials for the fabrication of optical materials by the encapsulation of direct blue 71 dye. The surface silanol groups of these mesoporous silicas were functionalized by silylation with 3-(aminopropyl)-triethoxysilane or methyltrimethoxylsilicate, which allow a successful doping of organic dye molecules. X-ray diffraction, N2 adsorption, thermogravimetric analysis, infrared, UV-vis diffuse reflectance and solid-state NMR spectroscopy were used to structurally characterize these composite products. It is found that the dye molecules of direct blue 71 have been encapsulated in the pores of MCM-41, SBA-15 and AlCMI-1, whereas attached on the external surface of CMI-1. The steric effect from the pore size of the host materials is significant. Moreover, Al-species in the AlCMI-1 were believed to take an important role in the dye encapsulation, resulting in a larger blue-shift of 21 nm than other mesoporous dye/silica composites.
T-Z. Ren, Z-Y. Yuan, B-L. Su, Colloids and Surfaces A: Physicochem. Eng. Aspects 300 (2007) 79-87

A0810 – Structure, phase transitions, dielectric and spectroscopic studies of the 2-aminopyrimidinium salts: [(2-NH2C4N2H3)2H][ClO4] and [2-NH2C4N2H4][BF4]

Crystal structure of the 2-aminopyrimidinium derivatives: [(2-NH2C4N2H3)2H][ClO4] (I) and [2-NH2C4N2H4][BF4] (II) has been determined at 100 K (I) and 293 K (II) by means of single crystal X-ray diffraction as monoclinic space group, P2/c and P21/n, respectively. The asymmetric part of the unit cell of (I) contains two symmetry independent 2-aminopyrimidine forming one dimeric cation and one disordered perchlorate anion. The structure of (II) consists of 2-aminopyrimidinium cation, [2-NH2C4N2H4]+, protonated at a pyrimidine ring-N atom and [BF4]- anion. Differential scanning calorimetry (DSC) on perchlorate derivative (1 : 1), [2-NH2C4N2H3][ClO4] (III)-being isomorphic to tetrafluoroborate one (I) at room temperature, reveals two phase transitions of first order: at 250/275 K and 390/410 K (cooling-heating, respectively), whereas the analog (II) only one transition at high temperatures-343/385 K. The dielectric studies in the frequency range 75 kHz - 10 MHz disclose relaxation process at high temperatures in salt (I). Infrared spectra of polycrystalline [2-NH2C4N2H4][BF4] have been studied in the temperature range 300-420 K. Substantial changes in the temperature evolution of frequencies of internal modes of the 2-aminopyrimidinium cations and [BF4]- anions near 390 K are due to the variations in the motion of both moieties and hydrogen bond configuration. The experimental studies indicate that all phase transitions taking place in studied 2-aminopyrimidinium derivatives are classified as an order-disorder.
O. Czupinski, M. Wojtas, Z. Ciunik, R. Jakubas, Solid State Sciences 8 (2006) 86-96

A0796 – Hydration of hydratable alumina in the presence of various forms of MgO

This work investigates hydration behavior of hydratable alumina in the presence of several forms of magnesia used for production of refractory castables. The mixtures of hydratable alumina with reactive magnesia, fused magnesite and deadburnt magnesite were hydrated at 20°C and 110°C. The hydration products were determined with X-ray diffractometer and the hydration extent was calculated from thermogravimetric analysis. The results revealed significant difference in the hydration products between the hydratable alumina-reactive magnesia mixture and the hydratable alumina-fused magnesite or deadburnt magnesite mixtures under the hydration conditions. The relationships of the compositions of hydrotalcite-like hydrates with different types of magnesias are elucidated. The bonding formed between hydratable alumina and magnesite aggregate in castables and its effect on the strength of the castables dried at 110°C and fired at 816°C was discussed.
G. Ye, T. Troczynski, Ceramics International 32 (2006) 257-262

A0782 – Microporous aluminum bisphosphonates

Several bisphosphonates of trivalent elements (Al, Ga and La) have been prepared under different synthetic conditions in order to induce microporosity. Two bisphosphonic acids, 4,40-biphenylenebis(phosphonic acid), [H2O3P-C6H4]2, and 4-(4-phosphonophenoxy) phenyl phosphonic acid, [H2O3P-C6H4]2-O, have been used as crosslinking agents. The materials have been characterized by a number of techniques including N2 adsorption-desorption isotherms and temperature-programmed desorption of ammonia to characterize the specific surface and acid properties, respectively. Crosslinked hybrid materials with surface areas ranging between 100 and 400 m2/g and textural properties varying from non-porous to mainly microporous can be isolated. The use of inexpensive phenylphosphonic acid as a spacer group has also been studied. The experimental conditions to get microporous solids with specific surface areas as high as 400 m2/g are described. Usually, the compounds contain both mesopores and micropores. The micropore size distributions are centered between 7 and 20 A ? .
M. del Mar Gomez-Alcantara, A. Cabeza, L. Moreno-Real, M.A.G. Aranda, A. Clearfield, Microporous and Mesoporous Materials 88 (2006) 293-303

A0775 – Structure, phase transitions and molecular dynamics in 4-aminopyridinium hexachloroantimonate(V), [4-NH2C5H4NH][SbCl6]

4-Aminopyridinium hexachloroantimonate(V), [4-NH2C5H4NH][SbCl6], abbreviated to 4APCA, crystallizes at room temperature in the monoclinic system, space group P21/c (phase III). The crystal undergoes two reversible phase transitions of first order type at 386/346 K (II4III) and at 467/466 K (I4II) on heating-cooling runs. Dielectric studies suggest the plastic crystal's behavior above 386 K (phase II). The proton NMR second moment (M2) and the1H NMR spin-lattice relaxation time (T1) for 4APCA measured between 77 and 420 K revealed the C2 reorientation of the 4-aminopyridinium cations. The mechanism of the phase transitions in 4APCA at 386 K is discussed.
B. Kulicka, R. Jakubas, A. Pietraszko, W. Medycki, J. S wiergiel, Journal of Molecular Structure 783 (2006) 88-95

A0774 – Spectroscopic characterization of chosen Ln(III) polyoxometalate complexes with organic counter cations in solid and in non-aqueous solutions

Polyoxometalate (POM) compositions containing organic counter cations and SiMo2W9O39 8- polyanion have been synthesized using extraction. Several compounds with counter ions containing phosphorus such as: Ph3P+CPh3, Ph3P+Et, Ph3P+C16H33, Ph4P+, Bu4P+ were obtained and their Eu(III) complexes synthesized. Luminescence characterization of the europium complexes concerning their intensities, quantum yields and luminescence lifetimes of Eu(III) ion both in DMF solutions and solid are discussed. The complexation study has been carried out analyzing absorption spectra of Nd(III) ion in the range of its hypersensitive transition (4I9/2 => 2H9/2). Results indicated formation of the Ln(POM)2 sandwich complexes. Computer-assisted target factor analysis has been applied to evaluate the spectra of Nd(III) in DMSO solutions containing varying amounts of the POM. The conditional formation constants with lg beta12 = 8.6±0.5, lg beta12 = 8.2±0.4 and lg beta12 = 9.6±0.7 were obtained for (Ph3PEt)5H3SiMo2W9O39, (Ph3PC16H33)7HSiMo2W9O39 and (Ph3PCPh3)6H3SiMo2W9O39, respectively. Studies have shown significant influence of the counter ion structure on the luminescence properties of Eu(III) in the systems studied. The most intensive luminescence and the highest value of quantum yield were observed in the case of the complex (Ph3PCPh3)7H6Eu(SiMo2W9O36)2, containing six phenyl groups in the organic counter cation.
S. Lis, S. But, G. Meinrath, Journal of Alloys and Compounds 408-412 (2006) 958-961

A0769 – Mesoporous silica functionalized with 2-mercaptopyridine: Synthesis, characterization and employment for Hg(II) adsorption

Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl-SBA-15 or Cl-MCM-41. In a second reaction a multifunctionalized N, S donor compound (2-mercaptopyridine, MP) was incorporated to obtain the functionalized silicas denoted as MP-SBA-15-Het or MP-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MP-SBA-15-Hom or MP-MCM-41-Hom. When the functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions contaminated with Hg(II), mercury adsorption was higher in the mesoporus silicas prepared by the homogeneous method. The modified mesoporous silica MP-SBA-15-Hom displayed the best mercury adsorption efficiency.
D. Pérez-Quintanilla, I. del Hierro, M. Fajardo, I. Sierra, Microporous and Mesoporous Materials 89 (2006) 58-68

A0768 – Nitridation under ammonia of high surface area vanadium aerogels

Vanadium pentoxide gels have been obtained from decavanadic acid prepared by ion exchange on a resin from ammonium metavanadate solution. The progressive removal of water by solvent exchange in supercritical conditions led to the formation of high surface area V2O5, 1.6H2O aerogels. Heat treatment under ammonia has been performed on these aerogels in the 450-900°C temperature range. The oxide precursors and oxynitrides have been characterized by XRD, SEM, TGA, BET. Nitridation leads to divided oxynitride powders in which the fibrous structure of the aerogel is maintained. The use of both very low heating rates and high surface area aerogel precursors allows a higher rate and a lower threshold of nitridation than those reported in previous works. By adjusting the nitridation temperature, it has been possible to prepare oxynitrides with various nitrogen enrichment and vanadium valency states. Whatever the V(O,N) composition, the oxidation of the oxynitrides in air starts between 250 and 300°C. This determines their potential use as chemical gas sensors at a maximum working temperature of 250°C.
O. Merdrignac-Conanec, K. El Badraoui, P. L'Haridon, Journal of Solid State Chemistry 178 (2005) 218-223

A0767 – Crystal structure, conductivity and reversible water uptake of new layered potassium antimonates K(x)L((1+x)/3)Sb((2-x)/3)O2 (L = Ni2+, Mg2+, Co2+)

Novel mixed potassium antimonates K0.59Mg0.53Sb0.47O2, K0.5Ni0.5Sb0.5O2, K0.5Co0.5Sb0.5O2 (rhombohedral P3-type structure), K0.56Ni0.52Sb0.48O2 and K0.86Co0.62Sb0.38O2 (hexagonal P2 type) have layered structures based on brucite-like (L,Sb)O6/3 sheets of edge-shared octahedra and interlayer K+ cations in trigonal prismatic coordination. The preference to form P2 and P3 structures rather than closely related O3 type is dictated by the large radius of K+ and the value of unit cell parameter a, restricted by average size of the cations randomly distributed in the octahedral sites within (L,Sb)O6/3 layer. The new phases reversibly absorb atmospheric moisture leading to the formation of hydrates with ca. 11% larger interlayer distances. The impedance spectroscopy of P2-type K0.56Ni0.52Sb0.48O2 and P3-type K0.59Mg0.53Sb0.47O2 ceramics shows relatively high ionic conductivity, presumably due to potassium cationic transport, with activation energies of 3572 and 3371 kJ/mol, respectively. At 573 K, the conductivity values are 0.016 S/cm for K0.56Ni0.52Sb0.48O2 and 0.021 S/cm for K0.59Mg0.53Sb0.47O2. Interaction with water vapor leads to increasing total conductivity.
O.A. Smirnova, V.B. Nalbandyan, M. Avdeev, L.I. Medvedev, B.S. Medvedev, V.V. Kharton, F.M.B. Marques, Journal of Solid State Chemistry 178 (2005) 172-179

A0763 – Synthesis of a new microporous gallophosphate obtained by in situ generation of cyclohexylamine

A novel gallophosphate [Ga13(PO4)18(C6H14N)13(C6H13N).2H3O+ .3H2O] was synthesized using cyclohexylformamide as main solvent. The structure-directing agent is the cyclohexylamine which is generated in situ by thermal decomposition of the solvent. The structure was solved by single-crystal X-ray diffraction (space group P-3, a = 16.605(14) Å, c = 17.22(2) Å, Z = 1, V = 4112(6) Å3). The 2D structure of Mu-30 is built up from (4,6) layers constituted of PO4 tetrahedra sharing three of their oxygen atoms with one GaO6 octahedron and two GaO4 tetrahedra. Monoprotonated cyclohexylamine, water molecules and H3O+ ion are intercalated between the layers. Characterizations of this new gallophosphate by bulk chemical analysis, scanning electron microscopy, thermal analysis, and 13C and 31P solid state NMR spectroscopies are also reported.
L. Lakiss, A. Simon-Masseron, V. Gramlich, J. Patarin, Solid State Sciences 7 (2005) 141-148

A0744 – Influence of spectator ions on the reactivity of divalent metal salts in molten alkali metal nitrates. Morphology of the resulting metal oxides

This work focuses on the investigation of the reaction of alkali metal nitrates (LiNO3, NaNO3 and KNO3) with divalent metal salts (Cu2+, Ni2+ and Zn2+). Thermogravimetric analysis (TGA) was employed to study the kinetics and mechanisms of the above reactions, which led to the formation of the corresponding metal oxides. The reaction temperature was found to depend not only on the alkali metal but also on the metal salt (MCl2 or M(NO3)2) involved in the reaction. SEM observations show that the spectator ions present in the reacting medium have varying degrees of influence on the morphology of the powder; the growth directions, sizes and the homogeneity of their distribution, are modified. KNO3 generates the most significant differences compared to LiNO3 and NaNO3.
P. Marote, C. Matei, C. Sigalac, J.P. Deloume, Materials Research Bulletin 40 (2005) 1-11

A0740 – The effect of varying synthesis conditions on zinc chromium hydrotalcite: a spectroscopic study

Zn/Cr hydrotalcites were synthesised by coprecipitation, with varying pH values and divalent/trivalent metal ion ratio. Depending on the pH conditions, two 3R rhombohedral varieties were synthesised with different layer spacings of 7.8 and 8.9 Å, at room temperature. More carbonate was incorporated in the interlayer of samples prepared at low pH values, increasing the interlayer distance and the unit cell. Preparation under acidic conditions lead to a more crystalline, pure and thermally stable compound. Spectroscopy was used to determine the effect of varying the ratio of divalent/trivalent metal ion ratio. It was shown that although ratios >2 yield crystalline compounds a ratio of 3 was preferred for both phases.
J.T. Kloprogge, L. Hickey, R.L. Frost, Materials Chemistry and Physics 89 (2005) 99-109

A0732 – Phase equilibria in the system CePO4-K3PO4-K4P2O7

The phase diagram with liquids isotherms and isothermal section at room temperature of the system CePO4-K3PO4-K4P2O7 has been determined by thermal analysis, K4P2O7 powder X-ray diffraction and IR spectroscopy. The system contains two double phosphates: K3Ce(PO4)2 and K4Ce2P4O15. The first one melts incongruently at 1500°C. The other exists only in solid state (below 880°C). Two systems: CePO4-K4P2O7 and K3Ce(PO4)2-K4P2O7, which are binary only in the subsolidus region, have been found.
I. Szczygiel, Solid State Sciences 7 (2005) 189-194

A0726 – Metal organic frameworks based on Cu2+ and benzene-1,3,5-tricarboxylate as host for SO2 trapping agents

Metal organic framework materials with Cu2+ as central cation and benzene-1,3,5-tricarboxylate (BTC) as linker were prepared via hydrothermal synthesis and impregnated with barium salts (chloride, nitrate, acetate) to explore the role of the Ba2+ counter ion on the SO2 uptake. The impregnation of the metal organic framework materials with barium salts led to a decrease of pore volume through the (intra pore) formation of small Ba salt crystals. The structure of the Cu-BTC material was preserved after the impregnation with acetate and nitrate, but partially destroyed during impregnation with chloride. The complete loss of the BTC structure occurred through thermal decomposition at temperatures around 573 K. The sample impregnated with BaCl2 showed a higher fraction of Cu2+ species compared to the other Ba/Cu-BTC samples. The SO2 uptake capacity of the Ba/Cu- BTC(Cl-) sample was the highest at temperatures below 673 K among all materials prepared and even higher compared to BaCO3/Al2O3/Pt based material. The comparison of the theoretical uptake (based on the stoichiometric formation of BaSO4) with the maximum SOx uptake achieved on the Ba/Cu-BTC samples clearly points out that a fraction of the SOx is stored on the Cu species being part of the metal organic framework structure.With increasing temperature the framework is (partially) decomposed and highly dispersed Cu species are released, which act as additional SOx storage sites in the high temperature region.
H. Dathe, E. Peringer, V. Roberts, A. Jentys, J.A. Lercher, C. R. Chimie 8 (2005) 753-763

A0722 – Crystallization, stability and possible application of the molecular sieve cloverite

Experiences on crystallization, stability and application fields of the molecular sieve cloverite are summarized, with focus on the achievable stability improvements by silanation of the surface to shield the framework from bond-rupture by interacting small polar molecules like water and ammonia. Benefits of applying microwave-assisted syntheses routines are outlined, and the morphology of crystallization products as revealed by SEM images is discussed.
R. Fricke, H-L. Zubowa, M. Richter, H. Kosslick, C. R. Chimie 8 (2005) 549-559

A0720 – AlPO-ERI, an aluminophosphate with the ERI framework topology: characterization and structure of the as-made and calcined rehydrated forms

An aluminophosphate with the ERI framework topology, further denoted AlPO-ERI, has been synthesized in the presence of N,N,N',N'-tetramethyl-1,6-hexanediamine and its structure was solved by single crystal X-ray diffraction. It crystallizes in the monoclinic space group P2(1) (No. 4) with a = 13.163(14) Å, b = 14.793(15) Å, c = 13.215(14) Å, b = 119.74(8)°. As compared to similar materials prepared with piperidine as template, extraframework hydroxyl groups are locally ordered in the structure. After calcination and rehydration, the aluminophosphate remains monoclinic and crystallizes in space group P2(1)/n (No. 14) with a = 13.283(17) Å, b = 14.910(14) Å, c = 22.76(3) Å and b = 90.19(10)°. Both the as made and calcined rehydrated forms of AlPO-ERI have been characterized by multidimensional solid state NMR. To cite this article: A. Tuel et al., C. R. Chimie 8 (2005).
A. Tuel, C. Lorentz, V. Gramlich, C. Baerlocher, C. R. Chimie 8 (2005) 531-540

A0709 – Crystal structure and physicochemical properties of a new organic monohydrogen monophosphate hydrate

Crystals of 2(2-ammonium ethyl ammonium) ethanol monohydrogenmonophosphate monohydrate: (C4H14N2O)HPO4 H2O abbreviated as AEEHP, were prepared and grown at room temperature. The AEEHP crystallizes in the monoclinic system with the P21/a space group. Its unit cell dimensions are: a = 4.8236(2), b = 28.429(2), c = 7.0711(6) Å , and b = 94.881(4)8 with V = 966.14(11) Å 3 and Z = 4. The structure of this compound was determined by using X-ray data collection on single-crystal. The AEEHP structure is built up from infinite inorganic HPO4 2 chains parallel to the alpha-axis, alternating with infinite chains of H2O molecules. These chains are interconnected by organic groups so as to build a three dimensional arrangement. In the present work, we describe the crystal structure, thermal behavior and IR analysis of this new compound.
L. Ben Hamada, A. Jouini, Materials Research Bulletin 40 (2005) 459-468

A0694 – Preparation and characterization of high surface area mesoporous anatase obtained from TiCl3 hydrothermally

Samples of titania (anatase) were prepared via precipitation by ammonia from TiCl3 aqueous solutions at pH = 4.7. Autoclaving of precipitates, after pre-drying, was effected at 8 atmospheres for 2 or 6h. Two pre-drying temperatures were assayed (100°C and 300°C). The synthetic mesoporous anatase possessed a specific surface area of 160m2/g, and resisted rutilation up to 800°C. Autoclaving resulted in fully hydroxylated surfaces (as determined by TGA), and the pre-drying at 300°C produced a greater number of acidic hydroxyls as determined by equilibrium adsorption of NaOH. Texture analysis via adsorption of N2 at 77K indicated that pre-drying at 100°C produced network-pore structure, and fractal analysis (by FHH equation) indicated that the pore network is constituted by channels with a variable distribution of hydraulic radii, and rough walls. On the other hand, pre-drying at 300°C resulted in plate-like particles in which the pore system is slit-shaped. The different pore structure caused the samples to respond differently to temperature, where the samples pre-dried at 100°C showed a decrease in fractal dimension implying a decrease in the participation of pores of small volume. On the other hand, no detectable change in fractal dimension was noted in case of the sample pre-dried at 300°C when calcined at temperatures up to 550°C. In no case was a specific surface area or less than 100m2/g obtained upon calcination at 550°C.
G.M.S. El Shafei, C.A. Philip, N.A. Moussa, Microporous and Mesoporous Materials 79 (2005) 253-260

A0674 – Determination of thermodynamic stability of CdMoO4 by knudsen effusion vapor pressure measurement method

Thermodynamic stability of CdMoO4 was determined by measuring the vapor pressures of Cd and MoO3 bearing gaseous species. Th vaporization reaction could be described as CdMoO4(s)+MoO2(s) =Cd(g)+2/n(MoO3)n (n=3, 4 and 5). The vapor pressures of the cadmium (pCd) and trimer (p(MoO ) 3 3 ) measured in the temperature range 987 T/K 1111 could be expressed, respectively, as ln (pCd/Pa) = -32643.9/T+29.46 0.08 and ln(p(MoO ) 3 3 /Pa) = -32289.6/T+29.28 0.08. The standard molar Gibbs free energy of formation of CdMoO4(s), derived from the vaporization results could be expressed by the equations: f CdMoO s G 4 0 ( )= -1002.0+0.267T 14.5 kJ mol-1 (987 T/K 1033) and f CdMoO s 4 G ( ) 0 = -1101.9+0.363T 14.4 kJ mol-1 (1044 T/K 1111). The standard enthalpy of formation of CdMoO4(s) was found to be -1015.4 14.5 kJ mol-1.
R. Mishra, S. R. Bharadwaj and D. Das, Journal of Thermal Analysis and Calorimetry 86 (2006) 547-552

A0672 – Iron oxide pigmenting powders produced by thermal treatment of iron solid wastes from steel mill pickling lines

Phase changes of iron containing solid wastes from steel mill pickling lines after thermal treatments were investigated aiming the determination of the appropriate conditions for its transformation to be useful for industrial raw materials. Above 275°C, the thermally treated wastes contain a mixture of -Fe2O3 (hematite) and -Fe2O3 (maghemite) in different proportions, depending on the maximum heating temperature of the thermal treatment. Increasing the maximum temperature the maghemite participation is decreased through its transformation to hematite. Above 850°C hematite is the main constituent, suggesting that thermal treatment of the wastes in this temperature will give a product that could be used as red iron pigment.
C. Sikalidis, T. Zorba, K. Chrissafis and K.M. Paraskevopoulos, Journal of Thermal Analysis and Calorimetry 86 (2006) 411-415

A0671 – Thermal, spectral and magnetic characterization of Co(II), Ni(II) and Cu(II) 4-chloro-2-nitrobenzoates

Physico-chemical properties of 4-chloro-2-nitrobenzoates of Co(II), Ni(II), and Cu(II) were studied. The complexes were obtained as mono- and trihydrates with a metal ion to ligand ratio of 1:2. All analysed 4-chloro-2-nitrobenzoates are polycrystalline compounds with colours depending on the central ions: pink for Co(II), green for Ni(II), and blue for Cu(II) complexes. Their thermal decomposition was studied only in the range of 293-523 K, because it was found that on heating in air above 523 K 4-chloro-2-nitrobenzoates decompose explosively. Hydrated complexes lose crystallization water molecules in one step and anhydrous compounds are formed. The final products of their decomposition are the oxides of the respective transition metals. From the results it appears that during dehydration process no transformation of nitro group to nitrite takes place. The solubilities of analysed complexes in water at 293 K are of the order of 10^(-4)--10^(-2) mol dm-3. The magnetic moment values of Co2+, Ni2+ and Cu2+ ions in 4-chloro-2-nitrobenzoates experimentally determined at 76-303 K change from 3.89 to 4.82 B for Co(II) complex, from 2.25 to 2.98 B for Ni(II) 4-chloro-2-nitrobenzoate, and from 0.27 to 1.44 B for Cu(II) complex. 4-chloro-2-nitrobenzoates of Co(II), and Ni(II) follow the Curie-Weiss law. Complex of Cu(II) forms dimer.
W. Ferenc, A. Walkow-Dziewulska, M. Wojciechowska and J. Sarzynski, Journal of Thermal Analysis and Calorimetry 86 (2006) 359-364

A0670 – New complexes of Mn(II), Co(II), Ni(II) and Cu(II) with 2,2′- or 2,4′-bipyridine and formates : Synthesis, thermal and other properties

New mixed-ligand complexes with empirical formulae: Mn(2-bpy)1.5L2.2H2O, M(2-bpy)2L2.3H2O (M(II)=Co, Cu), Ni(2-bpy)3L2.4H2O and M(2,4'-bpy)2L2.2H2O (where 2-bpy=2,2'-bipyridine, 2,4'-bpy=2,4'-bipyridine; L=HCOO-) have been obtained in pure solid-state. The complexes were characterized by chemical and elemental analysis, IR and VIS spectroscopy, conductivity (in methanol and dimethylsulfoxide). The way of metal-ligand coordination discussed. The formate and 2,4'-bpy act as monodentate ligands and 2-bpy as chelate ligand. The new complexes with ligand isomerism were identified. During heating the complexes lose water molecules in one or two steps. Thermal decomposition after dehydration is multistage and yields corresponding metal oxides as final products. A coupled TG-MS system was used to analysis principal volatile thermal decomposition (or fragmentation) products of Ni(2,4'-bpy)2(HCOO)2.2H2O under dynamic air or argon atmosphere.
D. Czakis-Sulikowska, J. Radwanska-Doczekalska, A. Czylkowska, M. Markiewicz and A. Broniarczyk, Journal of Thermal Analysis and Calorimetry 86 (2006) 327-335

A0667 – Synthesis and characterization of a new sulfate K4H2(SO4)3

The formation of a new sulfate compound K4H2(SO4)3 is obtained by evaporation at 25°C of an aqueous solution, which was formed by a mixture of K2SO4 and H2SO4. The characterization of this solid is carried out by X-ray diffraction, thermal and infrared analyzes. The heat treatment was carried out in interval 25-700°C; the end product of the thermal evolution is K2SO4. The vibration bands relating to SO4 and OH groups were highlighted by the infrared spectroscopy.Moreover, one study of ionic conductivity on this solid compound was carried out according to the temperature in interval 25-80°C. Its activation energy is 0.47 eV. The X-ray intensities collection obtained on a monocrystal of K4H2(SO4)3 gives the following cell parameters: a=7.035(5), b=19.751(4), c=23.466(2) , =95.25(1)°.
A.H. Hamzaoui, K. Ben-Saâd, M. Férid and A. M'Nif, Journal of Thermal Analysis and Calorimetry 86 (2006) 169-172

A0664 – Microwave-assisted synthesis of nanocrystalline MWO4 (M: Ca, Ni) via water-based citrate complex precursor

Nano-sized MWO4 (M: Ca, Ni) powders, which have scheelite and wolframite type structure, were successfully synthesized at low temperatures by a modified citrate complex method assisted by microwave irradiation. The citrate complex precursors were heat-treated at temperatures from 300 to 500°C for 3 h. Crystallization of the CaWO4 and NiWO4 nano-sized powders were detected at 300 and 350°C, respectively, and completed at a temperature of 400°C. Most of the CaWO4 and NiWO4 powders heat-treated between 350 and 450°C showed primarily spherical and homogeneous morphology. The average crystallite sizes of CaWO4 and NiWO4 were between 12 and 35 nm and between 14 and 29 nm, respectively, showing an ordinary tendency to grow with temperature.
J.H. Ryu, J-W. Yoon, C.S. Lim, W-C. Oh, K.B. Shim, Ceramics International 31 (2005) 883-888

A0663 – Blue luminescence of nanocrystalline PbWO4 phosphor synthesized via a citrate complex route assisted by microwave irradiation

Nanocrystalline PbWO4 phosphor powders, which have scheelite structure, were successfully synthesized at low temperatures via a modified citrate complex route assisted by microwave irradiation. Crystallization of the PbWO4 precursor were detected at 400°C, and entirely completed at 500°C. Prepared PbWO4 nanocrystallites showed primarily spherical and disperse morphology. The average crystallite sizes were between 18 and 29 nm, showing an ordinary tendency to increase with temperature. The nanocrytalline PbWO4 phosphor powders exhibited spread-eagle shape of blue luminescence. Especially the PbWO4 phosphor powders prepared at 600°C showed the strongest luminescent intensity, which was due to the higher crystallinity and homogeneous particle morphology.
J.H. Ryu, J-W. Yoon, K.B. Shim, Solid State Communications 133 (2005) 657-661

A0662 – Microwave-assisted synthesis of CaMoO4 nano-powders by a citrate complex method and its photoluminescence property

Nano-sized CaMoO4 powders, which have scheelite type structure, were successfully synthesized at low temperatures by a modified citrate complex method using microwave irradiation. The citrate complex precursors were heat-treated at temperatures from 300 to 700°C for 3 h. Crystallizations of the CaMoO4 nano-sized powders were detected at 400°C, and entirely completed at a temperature of 500°C. Almost nano-powders of CaMoO4 heat-treated between 400 and 600°C showed primarily spherical and homogeneous morphology. The average crystalline sizes of CaMoO4 were 12-27 nm at temperatures of 400-700°C, showing an ordinary tendency to increase with the temperatures. The CaMoO4 powders prepared at 600°C showed the strongest photoluminescence intensity.
J.H. Ryu, J-W. Yoon, C.S. Lim, W-C. Oh, K.B. Shim, Journal of Alloys and Compounds 390 (2005) 245-249

A0661 – Microwave-assisted synthesis of barium molybdate by a citrate complex method and oriented aggregation

BaMoO4 powders, which have scheelite type structure, were successfully synthesized at low temperatures by a modified citrate complex method assisted by microwave irradiation. The citrate complex precursors were heattreated at temperatures from 300 to 500°C for 3 h. Crystallization of the BaMoO4 powders were detected at 350°C, and completed at a temperature of 400