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5631 articles

A0613 – Reactivity in air of the Sr3Co2O7-d RP = 2 phase: Formation of the hydrated Sr3Co2O5(OH)2.xH2O cobaltite

A new hydrated oxyhydroxide, Sr3Co2O5(OH)2.xH2O, has been prepared in air. Its structure, determined by combining transmission electron microscopy (TEM) and X-ray powder diffraction, is related to the n = 2 member of the Ruddlesden-Popper series Srn+1ConO3n+1. This compound crystallizes in amonoclinic space group, I2/m, with the following parameters, a = c = 3.7701(8) Å, b = 28.59(1)Å and beta = 90.25(5)°. The introduction of OH- groups, to form (SrOH)+ layers, and the intercalation of additional H2O molecules are found to expand significantly the thickness of the block separating two successive perovskite blocks. As shown by the magnetic measurements, this phase is very unstable for T values beyond RT; this metastable character is also confirmed by the TEM study. Under both vacuum and electron beam, several structural forms have been observed, going from the oxygen deficient RP = 2 phase, Sr3Co2O7-d, to the hydrated oxyhydroxide Sr3Co2O5(OH)2.xH2O, through the anhydrous oxyhydroxide Sr3Co2O5(OH)2. Finally, the topotactic behavior of the hydrolysis process for the Sr3Co2O7-d, phase is also demonstrated.
D. Pelloquin, N. Barrier, A. Maignan, V. Caignaert, Solid State Sciences 7 (2005) 853-860

A0614 – Zeotile-2: A microporous analogue of MCM-48

Ordered mesoporous materials with specific microporosity in the mesopore walls can be assembled by a secondary templating synthesis departing from a clear subcolloidal suspension dedicated to the tetrapropylammonium (TPA) mediated synthesis of colloidal Silicalite-1. A typical member of this material family is Zeotile-2. Zeotile-2 is mesostructurally similar to the cubic MCM-48 material with exceptional long-range order of the mesostructure. Zeotile-2 samples in which the TPA was either left or evacuated were prepared by leaching in boiling ethanolic acetic acid and calcination. The evacuation of the TPA gave rise to a substantial micropore volume revealed with nitrogen adsorption isotherms. The mesoporosity was independent of the presence of the TPA. Molecular separations of isooctane/octane mixtures illustrated the occurrence of molecular shape selectivity similar to MFI-type zeolites.
S.P.B. Kremer, C.E.A. Kirschhock, A. Aerts, C.A. Aerts, K.J. Houthoofd, P.J. Grobet, P.A. Jacobs, O.I. Lebedev, G. Van Tendeloo, J.A. Martens, Solid State Sciences 7 (2005) 861-867

A0616 – Stabilization of a new delta’ polymorph in P-substituted Pb2BiVO6: Single crystal structure of Pb2Bi(V0.84P0.16)O6 and conduction properties of related materials

The single crystal structure of a new polymorph delta'-Pb2Bi(V(1-x)Px)O6 has been investigated; on heating, direct phase transitions alpha --> beta --> delta and alpha --> delta were identified in Pb2Bi(V(1-x)Px)O6 solid solutions for x>0,10, thus avoiding the high-temperature form decomposition noted in the (delta-Pb2BiVO6) mother phase at 480°C, to a mixture of PbBiVO5 and Pb4BiVO8 before recomposition at 650°C. Under a slow cooling process, the delta-Pb2Bi(V(1-x)Px)O6 high-temperature phase transforms into a closely related delta'-Pb2Bi(V(1-x)Px)O6 new polymorph, preserved at room temperature. The structure of delta'-Pb2Bi(V0,84 P0,16)O6 has been solved from a single crystal data in the orthorhombic system, Pbca space group, with a = 5,922(1) Å, b = 18,395(5) Å, c = 11,864(3) Å, Z = 8, and compared to a previous description of delta-Pb2BiVO6 in Pmcn, with b lattice constant halved. Complementary structural investigations of delta'-Pb2Bi(V0,75 P0,25)O6 powder sample by the Rietveld method, and TEM diffraction studies, confirmed the lattice and space group settings. The structural relationship between the alpha, delta and delta' forms is completed for Pb2Bi(V(1-x)Px)O6, and ionic conductivity versus temperature has been measured in the new phase as well as in its related solid solutions.
O. Labidi, P. Roussel, M. Huve, M. Drache, P. Conflant, J.P. Wignacourt, Journal of Solid State Chemistry 178 (2005) 2247-2255

A0615 – Preparation of highly ordered mesoporous AlSBA-15 and its application to isopropylation of m-cresol

Aluminum incorporated SBA-15 mesoporous molecular sieves with different nSi/nAl ratios have been hydrothermally synthesized by adjusting the synthesis gel pH below the isoelectric point of silica (pH?2) using nonionic surfactant as the structure directing agent. All the samples were characterized by X-ray diffraction, N2 adsorption to determine specific pore volume, pore size and specific surface area, FT-IR, TGA-TPD to determine the acid sites and 27Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). Vapor phase alkylation of m-cresol with isopropanol was carried out over large pore AlSBA-15 catalysts with different nSi/nAl ratios. The influence of various reaction parameters such as reaction temperature, reactant feed ratio and space velocity affecting the activity and selectivity of AlSBA-15, were studied. 2-Isopropyl-5-methylphenol (2I-5MP) was obtained as a major product with high selectivity. AlSBA-15 (45) was found to be the most active catalyst in this study. It showed 73.5% m-cresol conversion and a selectivity of 45.68% for 2I-5MP under the optimized reaction conditions. Further, large pore AlSBA-15 (45) catalyst was not deactivated when the reaction was carried out for several hours of reaction time.
A. Vinu, G. Satish Kumar, K. Ariga, V. Murugesan, Journal of Molecular Catalysis A: Chemical 235 (2005) 57-66

A0617 – Structural and thermal investigation of gadolinium gallium mixed oxides obtained by coprecipitation: Observation of a new metastable phase

Polycrystalline gadolinium gallium mixed oxides were prepared by coprecipitation and annealing at various temperatures below 1000°C. The oxide materials appear to be X-ray amorphous after a heat treatment at 500°C for 30 h, but after 30 h at 800 and 900°C a major, unreported, hexagonal phase, isostructural with TAlO3 compounds (where T = Y, Eu, Gd, Tb, Dy, Ho, Er) appears to crystallize. On the other hand, a highly energetic mechanical treatment of the amorphous powder previously annealed at 500°C changes considerably the shape and position of exothermal events occurring in the range from 700 up to 900°C. Subsequent annealing at 900°C of the mechanically treated powder gives rise to the complete formation of the Gd3Ga5O12 garnet structure at the expense of the hexagonal phase and of the minor Gd4Ga2O9 oxide phase. However, a 7.0wt% contamination is found to be due to tetragonal zirconia coming from vials and balls colliding media. The garnet phase may have strong deviations from the nominal stoichiometry of the garnet, as suggested by the refined lattice parameter obtained from the powder diffraction patterns and by the remarkable absence of intensity relative to the (220) Bragg peak position.
M. Bazzoni, M. Bettinelli, M. Daldosso, S. Enzo, F. Serra, A. Speghini, Journal of Solid State Chemistry 178 (2005) 2301-2305

A0618 – Preparation and characterization of electrolytic alumina deposit on austenitic stainless steel

Conversion coating modified by alumina has been studied as a way for improving the resistance to thermal oxidation of an austenitic stainless steel. Conversion coating, characterized by a particular morphology and strong interfacial adhesion with the substrate, facilitate the electrochemical deposition of ceramic layers and enhance their adhesion to the substrate. The influence of the current density and treatment time on alumina deposit was studied using statistical experimental designs like Doehlert uniform shell design. After heating, coatings present a continuous composition gradient with refractory compounds at the surface. The behavior at high temperature (1000°C) of the alumina coating was investigated. The presence of alumina increases the oxidation resistance of an austenitic stainless steel at 1000°C. The morphology and the chemical composition of the deposit are analyzed. Results on the thermal stability of coating on austenitic stainless steel are presented.
S. El Hajjaji, M. El Alaoui, P. Simon, A. Guenbour, A. Ben Bachir, E. Puech-Costes, M.-T. Maurette, L. Aries, Science and Technology of Advanced Materials 6 (2005) 519-524

A0619 – Synthesis, characterization and structure determination of two isotypes of a layered aluminophosphate with a new 2D network topology

Two isotypes of a new layered aluminophosphate, further denoted MDAP-3 and MDAE-1, have been synthesized under hydrothermal conditions using N-methyl-1,3-propanediamine and N-methyl-ethylenediamine, respectively. MDAP-3, with the empirical formula [Al2(HPO4)(PO4)2](C4N2H14)(H2O), crystallizes in the orthorhombic space group Pna2(1) (No. 33) with a = 9,602(16) Å, b = 9,26(2) Å, c = 16,03(3) Å, Z = 4, R1 = 0,0498 and wR2 = 0,1217. The second solid, MDAE-1, with the empirical formula [Al2(HPO4)(PO4)2](C3N2H12)(H2O), crystallizes in the same space group with a = 9,4250(19) Å, b = 9,3170(19) Å, c =15,907(3) Å, Z = 4, R1 = 0,0407 and wR2 = 0,0954. The two compounds possess the same layer topology. Inorganic layers contain PO3 = O, PO3OH, AlO4 and AlO6 polyhedra, linked together to generate a new4 8 net. MDAP-3 and MDAE-1 represent the first examples of two-dimensional layered aluminophosphates with the Al2P3O12 stoichiometry, and containing AlO6 octahedra.
A. Tuel, Ch. Lorentz, V. Gramlich, Ch. Baerlocher, Journal of Solid State Chemistry 178 (2005) 2322-2331

A0620 – Crystal structure and thermal behavior of two new organic monosulfates NH3(CH2)5NH3SO4 1.5H2O and NH3(CH2)9NH3SO4 H2O

The chemical preparation, the calorimetric studies and the crystal structure are given for two new organic sulfates NH3(CH2)5NH3SO4 1.5H2O (DAP-S) and NH3(CH2)9NH3SO4.H2O (DAN-S). DAP-S is monoclinic P21/n with unit cell dimensions: a=11.9330(2) Å ; b= 10.9290(2) Å ; c=17.5260(2) Å ; beta=101.873(1)°; V=2236.77(6) Å3; and Z=8. Its atomic arrangement is described as inorganic layers of (SO4)2- units and water molecules separated by organic chains. DAN-S is monoclinic P21/c with unit cell parameters: a=5.768(2) Å ; b= 25.890(10) Å ; c=11.177(5) Å ; beta=115.70(4)°; V=1504.0(11) Å3 and Z=4. Its structure exhibits infinite chains, parallel to the [100] direction where the organic cations are interconnected. In both structures a network of strong and weak hydrogen bonds connects the different components in the building of the crystal.
M. Belhouchet, J.M. Savariault, T. Mhiri, Journal of Physics and Chemistry of Solids 66 (2005) 1294-1301

A0622 – Synthesis and characterization of a new organic dihydrogen phosphate-arsenate: [H2(C4H10N2)][H2(As, P)O4]2

Chemical preparation, crystal structure, calorimetric and spectroscopic investigations (IR and RMN) are given for a new non-centrosymmetric organic-cation dihydrogen phosphate-arsenate [H2(C4H10N2)][H2(As, P)O4]2. This compound is triclinic P1 with the following unit-cell parameters: a = 7.082(2) Å , b = 7.796(1) Å , c = 12.05(3) Å , alpha = 95.37(2)°, beta = 98.38(3)°, gamma = 62.98(1)°, Z = 2, V = 586.2(1) Å3 and Dx = 1.836 g cm-3. The crystal structure has been solved and refined to R = 0.03 using 2328 independent reflections. The structure can be described as infinite (H2XO)n chains spreading parallel to the b direction. These chains are themselves interconnected by a set of N-H...O hydrogen bonds generated by the organic entities, alternating with the chains. Solid-state 13C, 15N and 31P MAS NMR spectroscopies are in agreement with the X-ray structure.
A. Oueslati, C. Ben Nasr, A. Durif, F. Lefebvre, Materials Research Bulletin 40 (2005) 970-980

A0621 – Oxidation kinetics of ZrNbO in steam: Differences between the pre- and post-transition stages

The oxidation by water vapour of a zirconium based alloy, a ZrNbO alloy containing 1% of Nb, has been studied between 500 and 550°C, the water vapour partial pressure ranging in 13-80 h Pa, using isothermal and isobaric thermogravimetry, and calorimetry. During gravimetry experiments, sudden changes (jumps) in temperature or water vapour pressure have also been performed. It comes out that the kinetic behaviour is different before and after the transition, even though the approximations of steady-state and rate-limiting step are justified in both stages: the influence of temperature jumps is greater in pre-transition, whereas the effect of water vapour partial pressure is more pronounced in post-transition (nevertheless, an accelerating effect is also observed before the transition). No influence of hydrogen partial pressure has been observed. Besides, the higher the Nb content in the alloy, the higher the oxidation rate (in pretransition). A mechanism has been proposed to account for the results obtained in pre-transition, involving the diffusion of adsorbed species in the porous part of the oxide layer as rate-determining step. The transition is accompanied by a change in the oxidation mechanism: in the post-transition stage, the kinetic curves being linear, the oxidation may be controlled by an interface step, which is probably different from the steps proposed for the pre-transition mechanism.
M. Tupin, M. Pijolat, F. Valdivieso, M. Soustelle, Journal of Nuclear Materials 342 (2005) 108-118

A0624 – Hydrotalcite like compounds with low Mo-loading active catalysts for selective oxidation of cyclohexene with hydrogen peroxide

Several Mo-containing hydrotalcite-like compounds (HTlcs-Mo) were prepared by different ionic exchange procedures using as parent a synthetic hydrotalcite Mg3Al(OH)8(CO3)0.5 2H2O with a composition similar to the natural occurring mineral. Their physico-chemical properties determined by chemical and TG-DTA analyses, XRD, BET, FTIR, SEM-EDX, DR-UV-vis and Raman spectroscopy, were compared to those of two HTlcs-Mo prepared by direct synthesis at constant pH = 10 and low or respectively high supersaturation. The catalytic activity of these solids towards cyclohexene oxidation with hydrogen peroxide was investigated. The catalytic activity was mainly influenced by the basic properties of the catalysts, which varied depending on the preparation procedure. The best catalysts for hydroperoxidation were found to be those having a low Mo content (about 2.5-2.8%) in the form of MoO4 2 species, and higher Mg concentration in the brucite layer. The catalysts containing also Mo7O24 6 species were more active for epoxidation.
R. Zavoianu, R. Birjega, O.D. Pavel, A. Cruceanu, M. Alifanti, Applied Catalysis A: General 286 (2005) 211-220

A0623 – Oxygen vacancy ordering in strontium doped rare earth cobaltate perovskites Ln1-xSrxCoO3-d (Ln = La, Pr and Nd; x > 0.60)

A family of Sr-doped perovskite compounds Ln1 xSrxCoO3 d (Ln = La3+, Pr3+ and Nd3+; x > 0.60), were prepared by sol-gel chemistry and reaction at 1100°Cunder 1 atm of oxygen. This structural family has been shown to be present only for rare earth ions larger than Sm3+ and an upper limit of Sr2+ solubility in these phases was found to exist between x = 0.90 and 0.95. X-ray diffraction shows oxygen-deficient, simple cubic (Pm-3m) perovskite crystal structures. The combination of electron and powder neutron diffraction reveals that oxygen vacancy ordering occurs, leading to a tetragonal (P4/mmm) superstructure and a doubling of the basic perovskite unit along the crystallographic c-axis. No additional Ln3+/Sr2+ cation ordering was observed.
M. James, T. Tedesco, D.J. Cassidy, R.L. Withers, Materials Research Bulletin 40 (2005) 990-1000

A0625 – Iron oxide modified mesoporous carbons: Physicochemical and catalytic study

Series of iron oxide supported on CMK-1 and CMK-3 materials obtained by impregnation from aqueous or organic media are studied by TPR, XAFS, Moessbauer spectroscopy and methanol decomposition as a catalytic test. More highly dispersed iron oxide particles are obtained using ethanolic impregnation medium, but their dispersion is affected to a low extent by the support pore structure. On the basis of the combined results on the state and reductive phase transformations of the loaded iron oxide particles, more accessible CMK-3 in comparison with CMK-1 pore structure is assumed.
C. Minchev, H. Huwe, T. Tsoncheva, D. Paneva, M. Dimitrov, I. Mitov, M. Froba, Microporous and Mesoporous Materials 81 (2005) 333-341

A0628 – Calorimetric study of reactions occurring between impregnated activated fibres and hydrogen sulphide

Activated carbon fibres, which exhibit high specific area and numerous active surface sites constitute very powerful adsorbents and are widely used in filtration to eliminate pollutants from liquid or gaseous effluents. The fibres studied in this work are devoted to the filtration of gaseous effluents containing very small amounts (few vpm) of hydrogen sulphide. To improve their fixation capacity towards H2S the activated fibres are impregnated in an aqueous solution of potassium hydroxide and then thermally treated. The treatment leads to the deposition of crystallites of K2CO3 showing a great activity for H2S gas in the presence of water vapour. The H2S fixation mechanism proposed can be summarised as follow: K2CO3 and H2S dissolve in a liquid aqueous solution formed on the fibre surface. Then carbonate ions and H2S molecules react together almost completely to yield HS species. This mechanism has been validated and completed by the study of the thermal effects induced when the treated fibres are in contact with H2S together with water vapour. The study has been carried out using a calorimetric method. The variations of standard enthalpy of reactions involved in the fixation mechanism are measured and compared to the data given by the thermodynamic tables for bulk solutions.
L. Meljac, L. Perier-Camby, G. Thomas, Carbon 43 (2005) 1407-1415

A0627 – Ferromagnetism and metallicity in the modulated Sr1KxThxCoO3Kd oxygen deficient perovskites with x~0.1

The Th4C for Sr2C substitution in SrCoO3Kd is found to be an efficient way to stabilize an oxygen deficient perovskite. The structural study reveals a Th4C solubility limited to w10% so that the chemical formula, Sr0.9Th0.1CoO2.79, is obtained. The comparison to the Y3C for Sr2C substitution shows that a lower oxygen content is obtained for the former according to the Sr0.75Y0.25CoO2.55 formula. The higher oxygen content reached with Th4C has a strong impact on the physical properties: Sr0.9Th0.1CoO2.79 is an itinerant ferromagnet (TCw200 K, r5 KZ2 mU cm) whereas Sr0.75Y0.25CoO2.55 is a robust insulating antiferromagnet (TNw320 K, r5 KZ105 U cm). Clearly, the substitution of a tetravalent cation for Sr2C appears to be a promising route to synthesize SrCoO3Kd itinerant ferromagnets without the use of high oxygen pressure nor electrochemical oxidation
S. Hébert, A. Maignan, V. Caignaert, V. Pralong, D. Pelloquin, B. Raveau, Solid State Communications 134 (2005) 815-820

A0626 – Synthesis, spectroscopy, structure and photophysical properties of dinaphthylmethylarsine complexes of palladium(II) and platinum(II)

Dinaphthylmethylarsine complexes of palladium(II) and platinum(II) with the formulae [MX2L2] (M = Pd, Pt; L = di(1-naphthyl) methylarsine = Nap2AsMe and X = Cl, Br, I), [M2Cl2(l-Cl)2L2], [PdCl(S2CNEt2)L], [Pd2Cl2(l-OAc)2L2] and [MCl2(PR3)L] (PR3 = PEt3, PPr3, PBu3, PMePh2) have been prepared. These complexes have been characterized by elemental analyses, IR, Raman, NMR (1H, 13C, 31P) and UV-vis spectroscopy. The stereochemistry of the complexes has been deduced from the spectroscopic data. The crystal structures of trans-[PdCl2(PEt3)(Nap2AsMe)] and of [Pd(S2CNEt2)2], a follow-up product, were determined. The UV-vis spectra of [MX2L2] complexes show a red shift on going from X = Cl to X = I. The complexes [PdX2L2] and [PtX2L2] are strongly luminescent in fluid solution and in the solid at ambient temperature.
P.P. Phadnis, V.K. Jain, T. Schurr, A. Klein, F. Lissner, T. Schleid, W. Kaim, Inorganica Chimica Acta 358 (2005) 2609-2617

A0629 – Kinetic behaviour of iron oxide sorbent in hot gas desulfurization

Although a number of reports on sorbents containing ZnO for H2S removal from coal-derived gases can be found in the literature, it is shown in our study that a special sorbent containing Fe2O3.FeO (SFO) with minor promoters (Al2O3, K2O, and CaO) as the main active species is more attractive for both sulfidation and regeneration stages, also under economic considerations. This paper presents the kinetic behaviour of SFO in a hot gas desulfurization process using a thermogravimetric analysis under isothermal condition in the operating range between 500 and 800°C. The gas stream was N2 with a 2% wt of H2S. Experiences carried out on sorbent sulfidation with SFO (particle sizes in the range of 0.042-0.12 mm) indicate that the sorbent sulfidation capacity sharply increases with temperature in the range of 500-600°C. It is also shown that the sample weight reaches its maximum absorption capacity, near saturation, at 600°C so that it makes no sense to increase the sulfidation temperature from this point. To make a comparison between SFO and a zinc titanate based sorbent, a set of sulfidation tests was carried out at 600°C during 7200 s using the same sieve range for both sorbents between 42 and 90 mm. Results show that the sulfidation capacity of SFO is 1.9 times higher than that of zinc titanate.
Y.G. Pan, J.F. Perales, E. Velo, L. Puigjaner, Fuel 84 (2005) 1105-1109

A0630 – Mixed conductivity, thermal expansion, and oxygen permeability of Ce(Pr,Zr)O2- d

The use of PrxCe(1-x)O(2-d) fluorites in electrochemical devices is hindered by several fundamental problems, one of which is the high thermal expansion coefficients (TECs), which have been shown to vary in the range (10-40) x 10^(-6) K-1 between the temperatures 0 and 1000°C. Thermogravimetric study shows that such a fluctuation of TECs, and non-linear lattice expansion on heating, are related to oxygen losses and can be controlled, to a substantial extent, by compositional selection. The influence of composition upon resultant mixed conductivity and oxygen permeability values is analysed for the compositions Zr0.1Ce(0.9-x)Prx(O2-d) and Ce(1-x)PrxO(2-d) (x =0.2-0.3). Zr substitution leads to a decrease in total conductivity and an increase in average grain size. Oxygen permeability in these materials is controlled by both ambipolar bulk conductivity and oxygen surface exchange rates. Typical values of specific oxygen permeability are approximately 3 x 10^(-8) mol/s cm at 1000°C and compare well with other phases that are promising as oxide catalyst supports and precursors, such as La(Fe,Ni)O(3-d) perovskites. A decrease in both ionic and electronic conductivities is observed with decreasing p(O2) by measurements of oxygen concentration cell emf combined with impedance spectroscopy. Ion transference numbers show a positive temperature dependence, with typical values to=0.8 at 950°C under oxidizing conditions.
D.P. Fagg, V.V. Kharton, A. Shaula, I.P. Marozau, J.R. Frade, Solid State Ionics 176 (2005) 1723 - 1730

A0631 – Influence of talc physical properties on the fire retarding behaviour of (ethyleneevinyl acetate copolymer/magnesium hydroxide/talc) composites

The present work focuses on the fire retarding behaviour of (ethyleneevinyl acetate (EVA) copolymer/magnesium hydroxide (MH)/talc) composites. Talc particles of different lamellarity and specific surface area have been tested, leading to the conclusion that for highly lamellar talc particles, the fire retarding behaviour becomes similar to that of (EVA/MH/organomodified montmorillonite (oMMT)) composites, with a significant intumescence. This intumescence, which occurs during the pre-ignition period in cone calorimeter tests, seems to be related to three phenomena caused by the presence of the lamellar particles (oMMT or talc): heterogeneous bubble nucleation, increased viscosity and charring promotion.
L. Clerc, L. Ferry, E. Leroy, J-M. Lopez-Cuesta, Polymer Degradation and Stability 88 (2005) 504e511

A0634 – 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 (G0.13)ZK22599.1/TC35.21 (774%T (K)%952) for Gd2O2CO3 decomposition and ln pCO2/Pa (G0.19)ZK23824.7/TC33.14 (775%T (K)%1105) for Nd2O2CO3 decomposition. From the above vapor pressure expressions, the median enthalpy and entropy of the decomposition of the oxycarbonates were calculated by the second law analysis and their thermodynamic stabilities were derived. The results are discussed in the light of available thermochemical data of the compounds.
A.N. Shirsat, K.N.G. Kaimal, S.R. Bharadwaj, D. Das, Journal of Physics and Chemistry of Solids 66 (2005) 1122-1127

A0633 – Synthesis and electrical characterization of Li0.30Ca0.35TaO3 perovskite synthesized via a polymerized complex route

The synthesis of Li0.30Ca0.35TaO3 perovskite by a Pechini-type polymerizable precursor method is carefully described. The thermal decomposition of the precursor and the formation of a pure perovskite phase were investigated by means of differential thermal analysis-thermogravimetric analysis (DTA-TGA) and XRD techniques. A pure and well-crystallized phase has been obtained at a lower temperature and with a much shorter synthesis time than the phase obtained by conventional solid-state reaction method. The morphology of the powder after heating at 1300°Cwas observed by laser granulometry, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Impedance spectroscopy data allowed us to determine the electrical properties, i.e., permittivity and dc-conductivity, of the bulk and grain boundaries. The results are discussed on the assumption of the brick layer model.
Q.N. Pham, M. Vijayakumar, C. Bohnke, O. Bohnke, Journal of Solid State Chemistry 178 (2005) 1915-1924

A0632 – [Zn(H2PO4)4]2 clusters and N[Zn2(HPO4)3(H2PO4)2]4 layers in two new zinc phosphates templated by [H2(4-amino-]2+ cations

Two zinc phosphates (ZnPO), [H2(N2C9H20)] [Zn(H2PO4)4] (I) and [H2(N2C9H20)]2 [Zn2(HPO4)3(H2PO4)2] H2O (II), are synthesized under hydrothermal conditions using 4-amino- as organic template. I crystallizes in P1 space group with a = 8,7398(3) Å, b = 9,0417(3) Å, c = 15,3822(1) Å, alpha = 92,57(1)°, beta = 89,76(1)°, gamma = 102,16(2)°, V = 1187,1(1) Å3 and Z = 2. Its structure, refined to R = 0,029 and Rw = 0,076 for 4279 independent reflections, consists of [Zn(H2PO4)4]2 clusters held together through strong hydrogen bonds to form pseudo-layers between which the doubly protonated amine molecules are inserted. II is monoclinic, C2, with a = 27,57(2) Å, b = 9,745(5) Å, c = 14,08(1) Å, b = 103,72(5)°, V = 3675(4) Å3 and Z = 4 (R = 0:079, Rw = 0:268, 2477 independent reflections). The structure of II consists of N[Zn2(HPO4)3(H2PO4)2]4 inorganic (2D) layers built up from vertex-sharing [ZnO4] and [(H2/H)PO4] tetrahedra. Organic cations and water molecules ensure the connection between these layers via hydrogen bonds. It is shown that numerous (1D), (2D), e.g., [H2(N2C9H20)]2 [Zn2(HPO4)3(H2PO4)2] H2O, and (3D) (ZnPO) result from the condensation of the [Zn(H2PO4)4]2 clusters.
A. Dakhlaoui, V. Maisonneuve, M. Leblanc, L.S. Smiri, Journal of Solid State Chemistry 178 (2005) 1880-1887

A0635 – Investigation of nucleation and crystal growth kinetics of nickel manganese oxalates

The nucleation andthe crystal growth rates of mixednickel manganese oxalates have been determined from the changes of the ionic concentration of the solution and the crystal size distribution during the precipitation process within a supersaturation range 0-0.1 M. Thermodynamic solubility calculations have been used to identify the different species contributing the precipitation reaction and for estimation of the thermodynamic constant. Experimental data show that the nucleation rate of mixednickel manganese oxalate in this supersaturation range is consistent with a primary heterogeneous mechanism andwas foundto obey to an exponential law. The crystal growth rates indicate a surface-integration-controlledmechanism with a first-order law with respect to the supersaturation.
M. Aoun-Habbache, S. Guillemet-Fritsch, J. Lemaitre, A. Jones, Journal of Crystal Growth 279 (2005) 531-539

A0636 – Synthesis and conductivity of Yb2Ti2O7 nanoceramics

The ordering processes in Yb2Ti2O7 ceramics are studied by thermal analysis, IR spectroscopy, X-ray diffraction, SEM and electrical conductivity measurements. Yb2Ti2O7 was obtained by a co-precipitation method followed by freeze drying and thermal annealing at 350- 1670°C. The existence of the fluorite-pyrochlore low-temperature transition near 800°C and the pyrochlore-fluorite high-temperature transition near 1700°C was established. The conductivity of Yb2Ti2O7 sintered at 1670°C seems to be ionic in the range of 300-950°C, with a bulk activation energy of 0.81 eV. Yb2Ti2O7 ceramics had a grain size of about 30 nm over a wide range of sintering temperatures (1400-1670°C).
A.V. Shlyakhtina, J.C.C. Abrantes, L.L. Larina, L.G. Shcherbakova, Solid State Ionics 176 (2005) 1653 - 1656

A0637 – Dispersive surface properties of glass-ionomer cements determined by inverse gas chromatography

The surface properties of several glass-ionomer cements (GIC), restorative dental materials, (GC-Fuji, Chemadent G-J, Ketac Fil and Ketac Molar) were investigated for the first time by means of inverse gas chromatography. This method enables characterization of surface activity in dispersive (non-polar) and acid-base interactions. The ability of the surface of glassionomers to participate in dispersive interactions was expressed by the use of the dispersive component of surface free energy gds . This parameter was determined with satisfactory precision, meaning that the values of gds can be further used in the discussion of the influence of the type of GIC, its preparation and the storage time on the surface properties. The greatest capacity for dispersive interactions was revealed by Ketac Molar and the lowest by GC-Fuji. Dispersive interactions in the surface activity of glass-ionomers increased with increasing storage time after cement preparation.
E. Andrzejewska, A. Voelkel, M. Andrzejewski, H. Limanowska-Shaw, Applied Surface Science 245 (2005) 135-140

A0638 – Intermolecular interaction and properties of cross-linked materials from poly(ester-urethane) and nitrochitosan

Two series of semi-interpenetrating polymer network (semi-IPN) films, coded as PUNT and PUN, have been prepared from amorphous nitrochitosan (NCH) and semicrystalline poly(ester-urethane) (PU) cross-linked to the hydroxy groups of tris(hydroxymethyl)propane (TMP) and NCO groups of PU prepolymer, respectively, by a casting method. The effects of different cross-linking methods and NCH content on the crystallization and hydrogen bonding strengths of the films were studied by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) with the curve fitting method and wide angle X-ray diffraction (WAXD). The miscibility and mechanical properties of the films were measured by dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), density measurement, thermogravimetric analysis (TGA), tensile testing and solvent swelling testing. The results revealed that the degree of crystalline for the semi-IPN films was lower than that of PU, because of the addition of amorphous NCH to destroy the original ordered structure in the PU film. Moreover, the crystal domain formation for the PUNT films cross-linked with TMP can be more easily interrupted than to other selfcrosslinked PUN films without TMP, resulting in a new disordered hydrogen bonded band in ATR-FTIR spectra. The PUNT films exhibited better miscibility as well as higher density, thermal stability, tensile strength and water resistance than the PUN films, suggesting an effective interpenetration and dense network structure. The differences between the two series of the films can be attributed to a relatively dense crosslinking network and strong intermolecular hydrogen bonding occurred between NCH and PU in the PUNT films as a result of the reaction cross-linked with TMP. It is noted that with an increase of NCH from 5 to 30% w/w, the thermal stability, tensile strength and water resistance of the PUNT films increased.
M. Zeng, L. Zhang, J.F. Kennedy, Carbohydrate Polymers 60 (2005) 399-409

A0639 – Physical and chemical characterisation of crude meat and bone meal combustion residue: “waste or raw material?”

As a result of the recent bovine spongiform encephalopathy (BSE) crisis in the European beef industry, the use of animal by-product is now severely controlled. Meat and bone meal (MBM) production can no longer be used to feed cattle and must be safely disposed of or transformed. Main disposal option is incineration, producing huge amounts of ashes the valorisation of which becomes a major concern. The aim of this work is to characterise MBM combustion residue in order to evaluate their physical and chemical properties to propose new valorisation avenues. The thermal behaviour of crude meat and bone meal was followed by thermogravimetric analysis (TGA) and (24 wt.%) inorganic residue was collected. The resulting ashes were characterised by powder X-ray diffraction (XRD), particle size distribution, specific surface area (BET), scanning electron microscopy (SEM) couple with energy disperse X-ray analysis (EDX). Elemental analysis revealed the presence of chloride, sodium, potassium, magnesium with high level of phosphate (56 wt.%) and calcium (31 wt.%), two major constituents of bone, mainly as a mixture of Ca10(PO4)6(OH)2 and Ca3(PO4)2 phases. The impact of combustion temperature (from 550 to 1000°C) on the constitution of ashes was followed by TGA, XRD and specific surface measurements. We observed a strong decrease of surface area for the ashes with crystallisation of calcium phosphates phases without major changes of chemical composition.
E. Deydier, R. Guilet, S. Sarda, P. Sharrock, Journal of Hazardous Materials B121 (2005) 141-148

A0641 – Sintering characterization of Li2TiO3 ceramic breeder powders prepared by the solution combustion synthesis process

A new approach, the solution combustion synthesis process (SCSP), has been developed to produce high purity and fine-grained Li2TiO3. The synthesis using glycine as a fuel was studied in order to prepare the powders that could be sintered to the 80% TD at relatively low temperature (<1100°C) and short sintering time (<4 h). Systematic studies were carried out to optimize various parameters such as sintering temperature, time and the microstructure of the sintered pellets. The SCSP was shown to be a practically viable process to prepare highly pure and sinterable Li2TiO3 powders.
Choong-Hwan Jung, Journal of Nuclear Materials 341 (2005) 148-152

A0640 – Bifunctional mechanism for the selective catalytic reduction of NOx on Rh/sulfated titania

The selective catalytic reduction of NO by propene has been investigated on a series of Rh catalysts supported by sulfated titanias. The dispersion of Rh oxide was measured by FTIR, from the observation of NO adsorption, and the number of acid sites by gravimetry, from the observation of NH3 adsorption. The addition of sulfated titania to Rh/SiO2 as a mechanical mixture increased the rate of N2 formation, and a higher rate was observed when Rh was supported on sulfated titania. A quantitative analysis of the influence of the acidity of the support shows that the activity for N2 increases with the number of acid sites. An increase in the surface of Rh oxide also leads to an increase in rate up to a plateau, at which point the rate is limited by an acid-catalysed reaction. This behaviour is attributed to a bifunctional mechanism for the reaction. In the presence of 25 ppm of SO2 and 3% water, these catalysts reach 40% yield in N2 at a GHSV = 35,000 h-1 with no loss of properties.
F. Figueras, J.L. Flores, G. Delahay, A. Giroir-Fendler, A. Bourane, J.-M. Clacens, A. Desmartin-Chomel, C. Lehaut-Burnouf, Journal of Catalysis 232 (2005) 27-33

A0642 – Synthesis and structural analysis of lithium nickel vanadate

The compound LixNiVO4 (x = 0.8; 1.0; 1.2) has been prepared by a solid state reaction method at 800°C. The X-ray diffraction pattern of Li1.2NiVO4 shows the absence of the (1 1 1) line, indicating the occupation of more vanadium ions on the tetrahedrally coordinated interstices. The averaged size of the particles and the grain size have been found to be around 2-10 µm. The grain interior and grain boundary resistance values are found to be 4.08 x 10^5 and 1.45 x 10^6 cm-1 at 573 K. The formal activation energy, describing the temperature dependence of conductivity of Li0.8NiVO4, was found to be 0.64 eV.
M.S. Bhuvaneswari, S. Selvasekarapandian, O. Kamishima, J. Kawamura, T. Hattori, Materials Chemistry and Physics 91 (2005) 94-98

A0644 – Characterization and photooxidative behaviour of nanocomposites formed with polystyrene and LDHs organo-modified by monomer surfactant

Layered double hydroxide (LDH) organo-modified by a surface-active monomer, 3-sulfopropyl methacrylate (SPMA) was used as filler for polystyrene (PS). Different nanocomposites SPMA/LDH:PS were prepared by bulk polymerization process using low amount of initiator. The two components, filler and polymer, as well as the degree dispersion of the reactive filler as a function of its loading in PS were characterized by a combination of several techniques: X-ray diffraction, high resolution 13C CP-MAS NMR, FTIR, UV-visible, thermal analysis, SEC and MET. The nanocomposites were submitted to UV-light exposures in the presence of oxygen. The oxidation photoproducts and the rates of oxidation were compared for the various samples. It was shown that the filler was not modifying the oxidation mechanism of the polymer, but had a slight effect on the oxidation rate.
F. Leroux, L. Meddar, B. Mailhot, S. Morlat-Thérias, J-L. Gardette, Polymer 46 (2005) 3571-3578

A0643 – Thermal and luminescent properties of polymeric acidic organophosphorus complexes of Eu(III) and Tb(III) undoped and doped with 1,10-phenanthroline

Complexes of Eu(III) and Tb(III) with acidic organophosphorus compounds, di(2-ethylhexyl)phosphate (DEHP) and 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (EHEP), were prepared and their thermal and luminescent properties were studied. The thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses of the complexes revealed that they are very stable up to 300°C, and that the thermal decomposition mechanisms of theDEHPand the EHEP complexes differ significantly from each other. To obtain highly efficient luminescence, 1,10-phenanthroline (phen)was introduced as a sensitizer. The element analysis proved that the complex only accommodated phen as a dopant. The photoluminescence (PL) and excitation spectra of Eu(III) and Tb(III) complexes, undoped and doped with phen, are reported. The Eu(III) and Tb(III) complexes excited by UV light produce very bright red and green emissions, respectively, via non-radiative energy transfer from phen to the metals. The quantum yields of the sensitized luminescence of thin films of the complexes are much greater than those of the non-sensitized complexes. The luminescence decay rate was also determined in the powdered state.
J-G. Kang, H-G. Cho, J-G. Kim, K-S. Choi, Materials Chemistry and Physics 91 (2005) 172-179

A0645 – Homopolymerization of 5-alkyl-2-norbornenes and their copolymerization with norbornene over novel Pd(acac)2/PPh3/BF3OEt2 catalyst system

The homopolymerization of 5-alkyl-2-norbornenes and their copolymerization with norbornene have been successfully carried out employing Pd(acac)2/PPh3/BF3OEt2 catalyst system. The activity of the catalyst system is comparable to that of most active late-transition metal catalysts described in the literature. The molecular weight distributions of homo- and copolymers indicate a single-site, highly homogeneous character of the active catalyst species. The incorporation of flexible alkyl groups onto the main chain of norbornene as well as copolymerization of 5-alkyl-2-norbornenes with norbornene represent useful methods for lowering the glass transition temperature (Tg), i.e. improving the processability. The simplicity of catalytic system composition might be of industrial importance.
G. Myagmarsuren, K-S. Lee, O-Y. Jeong, S-K. Ihm, Polymer 46 (2005) 3685-3692

A0646 – Synthesis, crystal structure and thermal stability of tetrahydroborate sodalite Na8[AlSiO4]6(BH4)2

Tetrahydroborate sodalite formation was investigated in the system Na2O-SiO2-Al2O3-NaBH4-H2O under mild hydrothermal conditions. Due to the high degree of decomposition of hydroborates in aqueous solutions synthesis conditions were tuned by variation of the parameters alkalinity, liquid/solid ratio, reaction temperature and reaction time. The insertion of 8-16 molar NaOH solution was crucial for the higher stability of pure tetrahydroborate salt under strong alkaline conditions. Synthesis at 393 K and 24 h reaction time reveal tetrahydroborate sodalite Na8[AlSiO4]6(BH4)2 beside a small amount of amorphous material within the total batch. Structure, composition and thermal stability of this new sodalite was investigated using XRD, NMR, infrared and TG/DTA methods. The crystal structure of tetrahydroborate sodalite has been refined in the space group P-43n with a = 891.61(2) pm. The Si- and Al-atoms of the aluminosilicate framework are completely ordered. The boron atoms of the tetrahydroborate anions are located at the centre of the sodalite cage whereas the hydrogen atoms are positionally disordered. Na8[Al- SiO4]6(BH4)2 shows a high stability under inert gas conditions. At atmospheric conditions the BH 4 group can be oxidized to borate and boroxide anions suggesting the formation of hydrogen which leaves the sodalite cages. Future investigation of reloading properties of the oxidized form could be highly interesting for the hydrogen storage capabilities of these sodalites.
J.-Ch. Buhl, Th.M. Gesing, C.H. Ruscher, Microporous and Mesoporous Materials 80 (2005) 57-63

A0648 – Benzylation of benzene and other aromatics by benzyl chloride over mesoporous AlSBA-15 catalysts

Aluminum-containing mesoporous molecular sieves AlSBA-15 with different nSi/nAl ratios and AlMCM-41 have been synthesized hydrothermally and characterized in detail by physicochemical methods, viz. XRD, N2 adsorption and 27Al NMR spectroscopy. The low angle XRD and N2 adsorption measurements reveal that the structural order of SBA-15 was retained after the incorporation of Al. The increase of the unit cell parameter with increasing aluminum content and 27Al MAS NMR spectroscopy confirm the incorporation of aluminum in the framework. Benzylation of benzene and substituted benzenes reaction employing benzyl chloride as the alkylating agent over AlSBA-15 and AlMCM-41 have been investigated. The influence of various reaction parameters such as reaction temperature, reactant feed ratio and catalyst amount affecting the activity and selectivity of AlSBA-15, have been studied. Among the mesoporous catalysts studied, AlSBA-15(45), where the number in parentheses indicates the molar nSi/nAl ratio, shows both high conversion and high selectivity for the benzylation of benzene. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene > toluene > p-xylene > mesitylene > anisole. Kinetics of the benzene benzylation over different catalysts have also been investigated.
A. Vinu, Dhanashri P. Sawant, K. Ariga, M. Hartmann, S.B. Halligudi, Microporous and Mesoporous Materials 80 (2005) 195-203

A0647 – Pore structure modification of pitch-based activated carbon by NaOCl and air oxidation/pyrolysis cycles

Two complementary wearing off cycling methods based on an initial wet oxidation in a sodium hypochlorite solution or an initial dry oxidation under air, both followed by a thermal pyrolysis under nitrogen, have been applied to a same carbon molecular sieve to study its gradual pore structure modifications. The changes in microporous properties resulting from these cycles were studied by N2 physisorption at 77 K and analyzed by using the Dubinin-Radushkevich equation. The observed textural behaviour is different from those usually observed using conventional activation processes. The surface complexes created on the surface of carbon by each NaOCl oxidation were characterized by temperature-programmed desorption (TG-TPD-MS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Corresponding surface functional species have been identified and quantified. Each of the two methods leads to the formation of two distinct microporous domains developed on the obtained modified CMS series. The gradual mean pore size values of one of those domains are common to the two series while the others are much more enlarged by the oxygen than by the NaOCl treatments. Therefore, the two methods lead to complementary data allowing experimental differentiation of the different porosities encountered in activated carbons. Such series of materials of common origin and surface chemistry but different gradual textural properties are of great interest for activated carbons structural studies as well as for characterization technique improvements.
B. Cagnon, X. Py, A. Guillot, J.P. Joly, R. Berjoan, Microporous and Mesoporous Materials 80 (2005) 183-193

A0649 – Precipitation mechanisms of intermetallic compounds in W-Mo-Ni-Fe alloys

W-Mo-18at.%Ni-8at.%Fe alloys with different ratios ofWtoMo (Mo: 15-59 at.%) were liquid phase sintered, in order to investigate the effect of Mo on the microstructural evolution of W-Mo-Ni-Fe alloys, phase composition, and precipitation mechanism of the intermetallic compounds. Results indicated that the increased concentration of Mo in the matrix, as a result of increased Mo in the alloy, not only reduced the solidification temperature of the matrix phase from 1415°C to 1336°C, but also promoted the formation of a MoNi type intermetallic compound, (W1 aMoa)0.5 X(Ni1 bFeb)0.5+X, (X = 0-0.04). The molar ratio of Mo in this intermetallic compound was found to increase with increase in the Mo concentration in the alloy, but the precipitation temperature of this intermetallic compound was very consistent, ranging from 1349°C to 1355°C. Owing to the varying solidification temperature of the matrix phase with the variation of alloy composition, the phase transformation mechanism of the intermetallic compound was found to be determined by the molar ratio of Mo toWand Mo (MMo/MW+MMo) in the original alloy composition. It is a monoeutectic reaction when this ratio is higher than 0.66, or eutectic reaction when this ratio ranges between 0.5 and 0.66. When this ratio is lower than 0.5, the precipitation of the intermetallic compound takes place by either eutectoid or peritectoid reaction. However, no intermetallic compound was found for a ratio lower than 0.2, because of the low diffusion rates of atoms associated with a large temperature difference between the solidification temperature of the matrix phase and the precipitation temperature of the intermetallic compound.
C-S. Hsu, K-H. Lin, S-T. Lin, International Journal of Refractory Metals & Hard Materials 23 (2005) 175-182

A0650 – Influence of nano-LDHs on char formation and fire-resistant properties of flame-retardant coating

Flame-retardant nano-coatings were prepared by adding flame-retardant nano-concentrates to APP/PER/EN coating. Dispersion morphology and stability principle of nano-size magnesium aluminum-layered double hydroxides (nano-LDHs) have been studied by using transmission electron microscopy (TEM). Relation of added amount of nano-concentrates in flame-retardant coating to flame-retardant properties for APP/PER/EN system has been studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), differential thermal analysis (DTA), thermogravimetry (TG) and fire protection test. It was indicated that nano-LDHs could catalyze the esterification reaction between ammonium polyphosphate and pentaerythritol, and IPN network formed by nano-size thermal-decomposed products of LDH could efficiently enhance char formation and structure of char layer. Only specific content (1.5%) of nano-LDHs in flame-retardant coating could efficiently improve its char layer structure and fire-resistant properties. Nano-LDHs (1.5%) greatly improve mechanical properties (bonding strength, bending resistance and resistance to freeze-thaw cycle) of flame-retardant coating.
Z. Wang, E. Han, W. Ke, Progress in Organic Coatings 53 (2005) 29-37

A0651 – Novel monodentate phosphine modified Pd(acac)2/BF3OEt2 catalyst system for the synthesis of poly(5-alkyl-2-norbornene)s

Pd(acac)2 + 2PPh3 + 25BF3OEt2 catalyst system has been employed for the polymerization of 5-alkyl-2-norbornenes. The activity of the catalyst system is comparable to that of most active late transition metal catalysts described in the literature. The introduction of a phosphine to the system switched the carbocationic polymerization mechanism to the coordination Ziegler-Natta polymerization.
G. Myagmarsuren, K-S. Lee, O-Y. Jeong, S-K. Ihm, Catalysis Communications 6 (2005) 337-342

A0652 – A new model formulation of the SiO2-Al2O3-B2O3-MgO-CaO-Na2O-F glass-ceramics

Mono-phase glass-ceramics of akermanite were successfully produced from a Ca-mica and wollastonite via low-temperature sintering and crystallization. Doping with P2O5 considerably improves sintering behaviour since P2O5 increases the stability of glass against crystallization at the temperature of sintering onset. The resulting glass-ceramics feature good in vitro acceptance from osteoblasts, and moderate bioactivity due to the enrichment of the glassy phase with Ca and Si. The good quality of the white colour at the surface and throughout the bulk, the matching of microhardness with tooth enamel, and the possibility to coat other biomaterials such as ZrO2, Ti or hydroxyapatite make these materials promising for medical applications.
S. Agathopoulos, D.U. Tulyaganov, P. Valério, J. M.F. Ferreira, Biomaterials 26 (2005) 2255-2264

A0654 – The thermally induced transformation of pseudoboehmite gels-a comparison of the effects of corundum seeding and iron doping

The transformation of doped or seeded pseudoboehmite to corundum was studied by combining thermal analysis, X-ray diffraction, transmission electron microscopy, and electron paramagnetic resonance spectroscopy. The temperature of phase transformation to corundum was lowered by about 130°C when Fe3+ or corundum seeds were added to the sols. Action of Fe3+ ions depends on the actual degree of thermally induced transformation of pseudoboehmite via transition aluminas to corundum and the ability of these alumina phases to incorporate Fe3+ ions. These ions tend to aggregate with increasing iron concentration of the alumina phases and canwork as nucleation centers. Small (-20 nm) corundum particles act as active nucleation sites whereas larger grains (200-400 nm) also present in the samples are less effective. For the first time trapping and stabilization of NO2 molecules in transition aluminas formed by a sol-gel route was shown.
M. Nofz, R. Stösser, G. Scholz, I. Dörfel, D. Schultze, Journal of the European Ceramic Society 25 (2005) 1095-1107

A0653 – Preparation of silver thin films using liquid-phase precursors by metal organic chemical vapor deposition and their conversion to silver selenide films by selenium vapor deposition

A series of new Ag precursors containing h-diketonate and neutral phosphite ligands were synthesized and characterized by various spectroscopic methods. These volatile precursors in liquid phase were thermally stable and quite useful in the preparation of silver thin films through bubbler-type chemical vapor deposition (CVD). In a typical case of silver (I) 1,1,1-trifluoro-2,4-pentanedionate triethyl phosphite adduct ((tfac)AgP(OEt)3) precursor, very pure silver thin films were obtained under relatively mild conditions without any appreciable amount of F, O, and P impurities. These thin films were easily converted to h-orthorhombic silver selenide by simple selenium vapor deposition method. In scanning electron microscopic analyses, the average particle size of the latter was found to increase to about 1.26 Am after gas-phase selenization reaction.
H-K. Kim, H-C. Jeong, K.S. Kim, S.H. Yoon, S.S. Lee, K.W. Seo, I-W. Shim, Thin Solid Films 478 (2005) 72- 76

A0656 – Energy demand in sludge dewatering

This work investigates the energy required to dewater a suspension, i.e., activated sludge dewatered by centrifugation or consolidation.Total energy input to the suspension from the dewatering device, bond strength between adjacent water and solid surface, and intra-cake friction loss were evaluated for original and flocculated sludges.In centrifugal dewatering, most energy input during the initial stage was consumed by overcoming process irreversibility other than intra-cake friction, and, thereby, had a low energy efficiency.To increase centrifuge speed or to flocculate the sludge at optimal flocculant dosage would yield a high-energy input.In the consolidation test, most energy input at the initial stage was consumed in breaking down the bond strength until the moisture content reduced to less than the critical content.During subsequent dewatering stages, friction loss became the dominant source of energy loss.Dewatering sludge with high-energy efficiency is beneficial to optimally operate a dewatering process.
C.P. Chu, D.J. Lee, C.Y. Chang, Water Research 39 (2005) 1858-1868

A0655 – Synthesis, characterization and structure determination of a three-dimensional hydrated potassium zinc divanadate: K[Zn2.5V2O7(OH)2].H2O

K[Zn2.5V2O7(OH)2].H2O was obtained by hydrothermal synthesis at 170°C from a gel with the molar composition 1 V2O5; 1 ZnCl2; 4 KOH; 228 H2O. The solid crystallizes in the orthorhombic system, with the space group Pnnm (58) and with the unit-cell parameters a = 14.5493(12) Å, b = 10.1685(9) Å, c = 6.0668(5) Å. The structure was determined from the powder XRD pattern by an "ab initio" method using the EXPO software and refined with the GSAS Rietveld refinement software. The structure can be described as formed from an interrupted and lacunary oxohydroxo zinc layers bridged by divanadate into a three-dimensional framework. The potassium cations and the water molecules occupy the channels between the bridged layers. The thermal stability, studied with the use of TGA and XRD, shows that the compound remains crystalline during the dehydration which occurs between room temperature and 210°C.
D. Hoyos, J-L. Paillaud, A. Simon-Masseron, J-L. Guth, Solid State Sciences 7 (2005) 616-621

A0657 – A method for synthesis and functionalization of ultrasmall superparamagnetic covalent carriers based on maghemite and dextran

A new generation of susceptibility contrast agents for MRI and based on maghemite cores covalently bonded to dextran stabilizing macromolecules was investigated. The multistep preparation of these versatile ultrasmall superparamagnetic iron oxides (VUSPIO) consisted of colloidal maghemite synthesis, surface modification by aminopropylsilane groups, and coupling of partially oxidized dextran via Schiff's bases and secondary amine bonds. The dextran corona might be easily derivatized, e.g. by PEGylation.
S. Mornet, J. Portier, E. Duguet, Journal of Magnetism and Magnetic Materials 293 (2005) 127-134

A0658 – Characterization of iron counter-ion environment in bulk and supported phosphomolybdic acid based catalysts

Extended X-ray absorption fine structure (EXAFS) was used to characterize the environment of iron counter-cations in Keggin type phosphomolybdic compounds used as catalysts for oxidation reactions. Iron doped compounds corresponding to bulk acid and to acid supported on the cesium salt were prepared and studied. Iron formed hexa-hydrated complex of both Fe3C and Fe2C in the bulk acid, whereas it was present as Fe(OH)2 C hydroxy-cations in the acid supported on the cesium salt. Upon heating the hexa-hydrated complex lost one molecule of water to bind to the Keggin anion through a terminal oxygen. (Fe-O-Mo bond). The environment of the iron hydroxy-cation changed upon heating while its closer coordination append to remained unchanged.
Q. Huynh, J.M.M. Millet, Journal of Physics and Chemistry of Solids 66 (2005) 887-894

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°C. TEM image of the BaMoO4 product obtained above 400°C revealed spindle-rods-like or flake-like morphology. The anisotropic growth habit of BaMoO4 leads to the oriented aggregation, which is attributed to the high chemical potentials of the intrinsic structure of BaMoO4. The BaMoO4 powder prepared at 500°C showed the strongest photoluminescent intensity.
J.H. Ryu, J-W. Yoon, C.S. Lim, K.B. Shim, Materials Research Bulletin 40 (2005) 1468-1476

A0660 – Hydrothermal synthesis of nanosized BaTiO3 powders and dielectric properties of corresponding ceramics

BaTiO3 fine powders were synthesized by hydrothermal method at 150°C or 250°C for 7 h, starting from a mixture of TiCl3+BaCl2 or TiO2+BaCl2. The size of the crystallites is close to 20 nm whatever the starting mixture and the reaction temperature. These powders are well crystallized and constituted of a mixture of the metastable cubic and stable tetragonal phases. The ceramics obtained after uniaxial pressing and sintering at 1250°C for 10 h or 20 h present high densification (up to 99.8%). The Curie temperature (Tc) and the electrical permittivity (er) of the ceramics strongly depend on the type of titanium source that has been used for preparing the powder and on the sintering dwell time. Particularly, Tc is shifted towards lower temperature when TiCl3 is used. The permittivity value at Tc of BaTiO3 sintered at 1250°C for 10 h reaches 7000 and 11,000 with respectively TiCl3 and TiO2 used as titanium source
M. Boulos, S. Guillemet-Fritsch, F. Mathieu, B. Durand, T. Lebey, V. Bley, Solid State Ionics 176 (2005) 1301 - 1309

A0659 – Structure and properties of magnetron sputtered Zr-Si-N films with a high (z25 at.%) Si content

The Zr-Si-N films were deposited using an unbalanced dc reactive magnetron sputtering of the alloyed ZrSi2 target in a mixture of argon and nitrogen onto steel and silicon substrates. This article reports on a systematic investigation of dependences of the structure, elemental composition, mechanical properties and oxidation resistance of Zr-Si-N films with a high (z25 at.%) Si content on the partial pressure of nitrogen pN2, magnetron discharge current Id, total sputtering gas pressure pT, substrate temperature Ts and dc and pulsed substrate bias Us. It was demonstrated that (i) ZrSi2 films sputtered in (a) a pure argon ( pN2=0) and (b) Zr-Si-N films sputtered at very low values of pN2V0.03 Pa are crystalline, electrically conductive, optically opaque and exhibit a relatively high value of the microhardness Hc17-20 GPa; (ii) Zr- Si-N films sputtered at pN2z0.1 Pa are X-ray amorphous, electrically insulating, optically transparent and exhibit (a) a high microhardness H of about 30 GPa and (b) a low compressive macrostress r of about 1.2 GPa; (iii) an increase in the substrate temperature Ts from 300 to 750°C has no effect on the structure and H of as-deposited films; the structure of the Zr-Si-N film sputtered at Ts=750°C remains X-ray amorphous and its hardness H does not decrease with increasing Ts, i.e. it is approximately the same (c30 GPa) as that of the film sputtered at Ts=500°C; (iv) the Zr-Si-N films with high (z25 at.%) Si content and high Hc30 GPa can be produced in the metallic mode of sputtering, i.e. they can be produced approximately four times faster than the binary nitrides such as, for instance, the TiN films; and (v) the Zr-Si-N films with a high (z55 vol. %) content of the a-Si3N4 phase, composed of a mixture of a-Si3N4+ZrNxN1 phases, exhibit a high oxidation resistance in flowing air, greater than 1300°C.
J. Musil, R. Daniel, P. Zeman, O. Takai, Thin Solid Films 478 (2005) 238- 247

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

A0666 – Intumescent fire protective coating: Toward a better understanding of their mechanism of action

The aim of this work is to better understand the role and the mechanism of action of boric acid and of coated ammonium polyphosphate (pure ammonium polyphosphate coated with THEIC) used as flame retardants in a commercial intumescent epoxy-based formulation using analytical techniques including thermogravimetric analyses (TGA) and solid-state NMR. In a previous paper, we detected that some reactions took place during the intumescence phenomenon between boric acid and ammonium polyphosphate upon heating. The paper focuses on the analysis of the degradation of those sole components and on the study of their interaction. It is first shown that the THEIC increases the thermal degradation rate of ammonium polyphosphate. This enables the degradation products of boric acid and coated ammonium polyphosphate to react together, resulting in the formation of borophosphate. It is suggested that the formation of this product provides the superior mechanical resistance of the char and promotes the adhesion of char on the steel plate.
M. Jimenez, S. Duquesne, S. Bourbigot, Thermochimica Acta 449 (2006) 16-26

A0665 – Thermodynamic stability of Sr2CeO4

Thermochemistry of the reaction between SrCO3 and SrCeO3, represented as SrCO3(s) + SrCeO3(s) = Sr2CeO4(s) + CO2(g), was studied over the temperature range 1035-1135 K. The equilibrium pressure of CO2(g) over the ternary phase mixture of SrCO3(s), SrCeO3(s) and Sr2CeO4(s) was measured at various temperatures by a tensimetric apparatus. The temperature dependence of the measured equilibrium CO2(g) pressure could be represented as ln pCO2 (Pa)(±0.04) = -24742(±550) T + 28.43(±0.55) (1035 < T (K) < 1115) Simultaneous thermogravimetric (TG)/differential thermal analysis (DTA) experiments were carried out for reaction between SrCO3(s) and CeO2(s) in CO2 atmosphere. The results were used to derive the thermodynamic properties of Sr2CeO4(s).
A.N. Shirsat, K.N.G. Kaimal, S.R. Bharadwaj, D. Das, Thermochimica Acta 447 (2006) 101-105

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

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

A0669 – Inducing bioactivity in dental porcelain through bioglass®

Dental materials restore morphology and function of lost or destroyed teeth, but cannot completely rebuild the structural relationship with soft periodontal tissues. The induction of bioactivity on classic dental porcelain can be achieved through the addition of bioactive glass. The aim of this study was to investigate the effect of Bioglass® on the thermal properties of dental porcelain in order to correlate the proportions of mixtures with the changes in thermal properties. Differential thermal analysis was performed in order to determine the characteristic temperatures of the mixtures. The increase of bioactive glass concentration in mixtures induces a shift to lower temperatures of the melting point temperature. This observation is attributed to the substitution of silicon ions by aluminium ions and to the formation of Al-O bond, which is weaker than Si-O bond. Mixtures heated at 950°C were examined also by the transmission electron microscopy (TEM) in order to be studied the microstructure of these samples at this critical temperature. The observed microstructural changes, confirm the process of substitution of Si 4+ ions by Al 3+ ions.
X. Chatzistavrou, K. Chrissafis, E. Polychroniadis, E. Kontonasaki, P. Koidis and K.M. Paraskevopoulos, Journal of Thermal Analysis and Calorimetry 86 (2006) 255-259

A0668 – Defect concentration in Ti-substituted YIG from TG curves

The article discusses theory and experiment about the measurement of defect concentration in Ti-substituted yttrium iron garnet by means of thermogravimetry techniques. The two possible cases arising from oxygen interchange with atmosphere, oxygen vacancies and interstitial cations, may be analyzed quantitatively from the derived expressions. The possibility of another type of defects being present in the samples, not associated to oxygen evolution, is not excluded. Measurements were carried out in air and CO2 for different Ti contents. The substitution tends to increase slightly the defect parameter ? in YIG, while a CO2 reducing atmosphere is much more effective than the Ti substitution for increasing ?. Calculations for a given single-phased sample sintered in air show two possibilities: a deficit of one oxygen atom for every 2.5 unit cells of 96 atoms, or one excess cation for every 3.5 cells. Other samples show very similar results. The accuracy involved in the measurements is about 2-3%.
A. Gonzalez Arias, C. Torres, C. de Francisco, J.M. Muñoz, P. Hernandez Gomez, O. Alejos, O. Montero and J.I. Iñiguez, Journal of Thermal Analysis and Calorimetry 86 (2006) 195-198

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

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

A0673 – Kinetics of the pyrolysis and combustion of göynük oil shale

The pyrolysis and combustion kinetics of Göynük oil shale were investigated by thermogravimetric analysis in the present study. All experiments were conducted at non-isothermal conditions with a heating rate of 10-60 K min-1 in the 298-1173 K temperature interval under argon and air atmospheres for pyrolysis and combustion, respectively. Differential thermogravimetric data were analyzed by a reaction rate model assuming first order kinetics.
S. Yagmur and T. Durusoy, Journal of Thermal Analysis and Calorimetry 86 (2006) 479-482

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

A0675 – Synthesis and characterization of Mg2B2O5

Magnesium borate of the form Mg2B2O5 has been prepared and its structural and thermal properties were studied using X-ray diffraction and differential thermal analysis. An investigation of the electrical and optical properties of Mg2B2O5 system has been carried out. The electrical resistivity of the sample was measured in the temperature range of 170-400 K. The data analysis revealed an extrinsic nature of the conductivity with two impurity levels located at 0.13 and 0.71 eV in the temperature ranges of 170-230 K and 240-400 K, respectively. The optical transmission and reflection was recorded at 300 K in the incident photon energy range of 3.0-6.0 eV. The absorption coefficient data analysis revealed an indirect optical energy band gap of 4.73 eV. In addition, two impurity levels located at 3.43, and 4.49 eV were observed in the absorption spectra.
A.F. Qasrawi, T.S. Kayed, A. Mergen, M. Gürü, Materials Research Bulletin 40 (2005) 583-589

A0677 – Production and characterization of MgB2 coatings on various substrates by electrophoretic deposition

The electrophoretic deposition technique was applied for the production of MgB2 coatings on various substrates, such as Ni, Ag, stainless steel plates and Si wafers coated with Pt, by using a suspension of MgB2 powder in an organic solvent. The initial concentration of the suspension, the voltage applied, the kind of the organic solvent and the distance between the electrodes were investigated as these are the main parameters that affect the deposition rate of the processing and the quality of the coating produced. The appropriate subsequent sintering procedure was determined by means of thermal analysis techniques (TG, DTG, DTA). The produced coatings were characterized by several analytical techniques, such as XRD, SEM, RAMAN, DTA. The superconducting properties were measured by magnetic susceptibility measurements (SQUID). It resulted that by the optimized fast electrophoretic deposition technique and subsequent sintering procedure, uniform, dense and well-adhesive coatings on Ni, Ag and stainless steel substrates were obtained.
M. Ochsenkühn-Petropoulou, L. Mendrinos, A. Altzoumailis, R. Argyropoulou, Journal of Materials Processing Technology 161 (2005) 16-21

A0676 – Nitroaldol-reaction of aldehydes in the presence of non-activated Mg:Al 2:1 hydrotalcite; a possible new mechanism for the formation of 2-aryl-1,3-dinitropropanes

Commercially available, non-activated 2:1 Mg:Al hydrotalcite catalyzes the nitroaldol reaction between a variety of aromatic and aliphatic aldehydes and simple nitroalkanes such as nitromethane and nitroethane. A new mechanism is proposed for the formation of the 1,3-dinitropropanes. The threo/erythro diastereoselectivity of the nitroethane-adducts was determined by 1H NMR spectroscopy and was found to range from 50:50 to 70:30. The substituents of the aromatic aldehydes influenced the isomer ratio.
A. Cwik, A. Fuchs, Z. Hell and Jean-Marc Clacens, Tetrahedron 61 (2005) 4015-4021

A0679 – Zirconia-supported 12-tungstophosphoric acid as a solid catalyst for the synthesis of linear alkyl benzenes

The liquid-phase alkylation of benzene with 1-octene and 1-dodecene was investigated with zirconia-supported 12-tungstophosphoric acid (TPA) as catalysts. We prepared the catalysts, with different TPA loading (5-20 wt% calcined at 750°C) and calcination temperatures (15 wt% calcined from 650 to 850°C), by suspending hydrous zirconia in a methanol solution of TPA, followed by drying and calcination. These catalysts were characterized by X-ray diffraction, DTG-DTA, FTIR pyridine adsorption, NH3-TPD, and 31P MAS NMR spectroscopy measurements. The catalyst with optimum TPA loading (15%) and calcination temperature (750°C) was prepared in different solvents and characterized by 31P MAS NMR spectroscopy. The XRD results indicate that TPA stabilizes the tetragonal phase of zirconia. The catalysts show both Bronsted and Lewis acidity, and 15% TPA on zirconia calcined at 750°C shows the highest acidity. 31P MAS NMR spectra show two types of phosphorous species: one is the Keggin unit and the other is the decomposition product of TPA. The relative amount of each depends on TPA loading, calcination temperature, and the solvent used for the catalyst preparation. Under reaction conditions of 84°C and a benzene/1-olefin molar ratio of 10 (time 1 h), the most active catalyst, 15% TPA, calcined at 750°C, gave more than 98% olefin conversion with selectivity for 2-phenyl octane (53.5%) and 2-phenyl dodecane (47%).
B.M. Devassy, F. Lefebvre, S.B. Halligudi, Journal of Catalysis 231 (2005) 1-10

A0678 – Combustion synthesis of gadolinia doped ceria powder

Gadolinia doped ceria (GDC) powders with different gadolinia content in the range 0-15 mol% were prepared by solution combustion route using a solution of cerium nitrate, gadolinium nitrate and citric acid. In the experiments citric acid to metal nitrate molar ratio was taken as 5:6. The solution on heating formed gel before combustion. Thermal analysis of the gel precursors containing different mol% gadolinia showed single step combustion reaction and the initiation temperature of the combustion reaction increased with gadolinia content. Surface area of the combustion synthesized powder was found to increase with increase in gadolinia content. In correlation with surface area results finer crystallite size was obtained in higher gadolinia content compositions. Particle agglomeration in high gadolinia content powders, when calcined at 600°C, was observed and this was attributed to high reactivity of nano-crystalline powders. The combustion synthesized powders when sintered at 1250°C resulted in pellets with density in the range 94-97% of theoretical density.
T. Mahata, G. Das, R.K. Mishra, B.P. Sharma, Journal of Alloys and Compounds 391 (2005) 129-135

A0682 – Preparing nanometer scaled Tb-doped Y2O3 luminescent powders by the polyol method

Sub-micrometer Tb-doped Y2O3 luminescent powders were prepared from nitrate precursors using the polyol method. Just after precipitation, the powders consist of agglomerates with a spherical shape and a size ranging between 400 and 500 nm. Each agglomerate is composed of ultra-small crystallites (from 3 to 6 nm) of a bcc oxide phase whose luminescence presents original features in comparison with bulk materials. Powders were further calcinated at different temperatures and for annealing below 900°C, highly crystalline samples with the classical green 5D4-7F5 luminescent transitions of Tb3+ ions are obtained. For optimized annealing temperatures, sintering between the agglomerates is avoided and a sub-micrometric powder with a narrow size distribution and a high luminescence is obtained.
M.A. Flores-Gonzalez, G. Ledoux, S. Roux, K. Lebbou, P. Perriat, O. Tillement, Journal of Solid State Chemistry 178 (2005) 989-997

A0681 – Calorimetric study and thermal analysis of crystalline 2,4-dinitrobenzaldehyde (C7H4N2O5)

Calorimetric study and thermal analysis for 2,4-dinitrobenzaldehyde were performed. The low-temperature heat capacity of this compound was measured with a precise automated adiabatic calorimeter over the temperature range from (78 to 368) K. The melting point, molar enthalpy, and molar entropy of fusion of this substance were determined to be (344.91 ± 0.15) K, (21,177 ± 14) J . mol-1, and (61.40 ± 0.07) J . K-1 . mol-1, respectively. The melting temperatures for the sample and the absolutely pure compound have been obtained from fractional melting experiments to be (344.910 and 345.146) K, respectively, and the chemical purity of the sample was calculated to be 0.9950 mol fraction according to the Van t Hoff equation. The thermal stability of the compound was further investigated by differential scanning calorimetry and thermogravimetric analysis.
S-X. Wang, Z-C. Tan, Q. Shi, Y-Y. Di, H-T. Zhang, F. Xu, L-X. Sun, T. Zhang, J. Chem. Thermodynamics 37 (2005) 349-355

A0680 – Selective p-xylene formation upon toluene disproportionation over MCM-22 and ZSM-5 zeolites modified with indium

A simple modification procedure of MCM-22 and ZSM-5 zeolites consisting in controllable alteration of the nature and concentration of the acid sites has been applied with the help of the method of reductive solid-state ion exchange with In2O3 in order to achieve selective p-xylene formation upon toluene disproportionation. The partial replacement of the zeolite protons with InO+ counter ions results in enhanced activity and p-xylene selectivity accompanied by fast deactivation in case of MCM-22. The modification procedure of ZSM-5 is more favorable in respect to the catalytic stability and also leads to increased p-xylene formation, however, in lower extent compared to MCM-22. The contribution of the InO+ Lewis-connected acid sites in regulation of the disproportionation rate, catalysts aging and p-xylene selectivation in dependence on the pore structure characteristics of the zeolites is discussed.
V. Mavrodinova, M. Popova, Catalysis Communications 6 (2005) 247-252

A0683 – Dissociative adsorption of water in CaNaA zeolites studied by TG, DRIFTS and 1Hand 27Al MAS NMR spectroscopy

Three CaNaA zeolites, in which, respectively, 49%, 65% and 83% of the Na+ cations were exchanged with Ca2+ ions, along with a NaA sample were studied by thermogravimetry, temperature-programmed DRIFT spectroscopy and MAS NMR. Thermogravimetric desorption profiles of the Ca2+ exchanged zeolites show a low-temperature peak between 423 and 508K as well as two high-temperatures peaks at 853 and 973K, which are missing in case of the NaA sample. Three main bands at 3603-3611, 3495- 3510 and 3552-3565cm 1, of which the first two are due to bridging Si-OH-Al groups located in 8- and 6-rings, respectively, whereas the third corresponds to Ca(OH)+ groups dominate the DRIFT spectra of zeolite samples exchanged with Ca2+ ions. The intensity of the band at 3603-3611cm 1 decreases significantly until it vanishes almost completely at 823K. A simultaneous decreases of the intensity of the band of Ca(OH)+ groups is indicative of a low-temperature dehydroxylation process between these two species. The intensity of the other Si-OH-Al group bands at 3495-3510cm 1 shows almost no change up to 823K, thus suggesting that these groups participate in a high-temperature dehydroxylation process. A weak band in the region 3670-3680cm 1 is attributed to Al-OHgroups of extra-framework aluminum species formed during dehydration of the CaNaA zeolites. Peaks at 4.3 and 5.2ppm in the 1HMAS NMR spectra are assigned to Si-OH-Al groups in 8- and 6-rings, respectively. 27Al MAS NMR spectra show two main peaks at 57.3 and 78.7ppm, which are due to tetrahedrally coordinated aluminum and calcium alumosilicate groups. A weak signal between 12 and 13ppm ascribed to octahedrally coordinated aluminum disappears at higher temperatures.
I.A. Beta, B. Hunger, W. Böhlmann, H. Jobic, Microporous and Mesoporous Materials 79 (2005) 69-78

A0684 – Polypropylene as a reductive agent for dehalogenation of brominated organic compounds

A new method for debromination of organics by a reductive medium like polypropylene is investigated. The reaction is carried out in inert atmosphere to avoid rapid oxidation of the polymer. Through this detoxification procedure, hydrogen bromide and small brominated alkanes are formed. Experiments in closed ampoules are carried out with tetrabromobisphenol A, dibromophenol, pentabromodiphenyl ether, dichlorophenol and an oil formed by pyrolysis of printed circuit boards in the Haloclean process. The reaction is examined under isothermal conditions in a temperature range between 300 and 400 (C and a residence time between 10 and 30 min. Optimal conditions were found at 350 (C and at a residence time of 20 min. As chlorinated phenols are not destroyed under these conditions, the process may be a valuable procedure to gain hydrogen bromide out of mixtures of halogenated feed materials. Also, under atmospheric pressure, a reaction between polypropylene and brominated compounds takes place as could be proved by thermogravimetric analysis. Bromobenzene has an accelerating effect on the rate of weight loss of the polymer, but at higher concentrations, it can also be slowed down.
A. Hornung, S. Donner, A. Balabanovich, H. Seifert, Journal of Cleaner Production 13 (2005) 525-530

A0687 – Kinetic analysis of pyrolysis of cross-linked polymers

Decomposition of crossed-linked polymers in an inert atmosphere occurs in such a way that they tend to conserve the structure of their matrix. Bond breaking inside the polymer matrix requires a large amount of energy. That is why decomposition of crossedlinked polymers preferentially takes place via a chemical conversion of side chains. Probably, to a first approximation, the side chains can be considered as being almost independent during the decomposition. In other words, the overall decomposition can be described as a set of parallel processes. In such a case, the final residue of the polymer after decomposition can be described as a substance with certain properties independent of the way of obtaining this residue. The accuracy of approximation of kinetic information by using such assumptions is exemplified in four-stage decomposition of cross-linked (rigid) polyurethane in nitrogen. As shown, the set of four activation energies, obtained as a result of the approximation, can be used for sufficiently accurate prediction of the decomposition under arbitrary thermal conditions.
J. Lefebvre, V. Mamleev, M. Le Bras, S. Bourbigot, Polymer Degradation and Stability 88 (2005) 85-91

A0686 – Intumescent polypropylene/flax blends: a preliminary study

This study deals with the effect resulting from the association of pentaerythritol with flax fibres in an intumescent PP/Fibre/ ammonium polyphosphate/pentaerythritol/melamine system. This consists only in a preliminary to prove the efficiency of intumescent additives systems in polyolefin/flax composites considering the fire behaviour and the thermal stability of the material. The study confirms the Fire Retardance performances of a PP/flax/ammonium polyphosphate composite considering cone calorimeter data. Moreover, it shows that charring of the flax fibers in this composite does not give an interesting material in term of dynamic property. Using an intumescent model additive, we show that association of charring of the cellulosic material and of the intumescent system allows to obtain an optimized FR formulation.
M. Le Bras, S. Duquesne, M. Fois, M. Grisel, F. Poutch, Polymer Degradation and Stability 88 (2005) 80-84

A0685 – Thermoplastic resins for thin film intumescent coatings – towards a better understanding of their effect on intumescence efficiency

This study investigates the role of the binder in the efficiency of intumescent coatings. It is generally known that an acid source, a carbon source and a blowing agent are the main ingredients of such paints. However, since the binder may react with these ingredients, it may significantly affect the intumescence process. To begin with, the effect of the nature of the monomers, which compose the binder, on the chemical reactivity between the binder and the intumescent additives is investigated using thermogravimetric analysis. It is found that the thermal stability is enhanced when the copolymer is prepared with substituted styrene. Subsequently, the effect of the binder is investigated from a physical aspect. Special attention is devoted to the expansion rate and the dynamic viscosity. Finally, the efficiency of protective behaviour of the intumescent coatings prepared with the copolymers is evaluated. It is found that the thermal insulation is greatly improved when using a mixture of linear and crosslinked copolymers as the binder in intumescent coatings particularly when these copolymers are prepared from monomers showing good reactivity with ammonium polyphosphate.
S. Duquesne, S. Magnet, C. Jama, R. Delobel, Polymer Degradation and Stability 88 (2005) 63-69

A0688 – Synthesis and characterization of uranium (IV) phosphate-hydrogenphosphate hydrate and cerium (IV) phosphate-hydrogenphosphate hydrate

A new uranium (IV) phosphate of proposed formula U2(PO4)2HPO4 H2O, i.e. uranium phosphate-hydrogenphosphate hydrate (UPHPH), was synthesized in autoclave and/or in polytetrafluoroethylene closed containers at 150°C by three ways: from uranium (IV) hydrochloric solution and phosphoric acid, from uranium dioxide and phosphoric acid and by transformation of the uranium hydrogenphosphate hydrate U(HPO4)2 nH2O. The new product appears similar to the previously published thorium phosphatehydrogenphosphate hydrate Th2(PO4)2HPO4 H2O (TPHPH). From preliminary studies, it was found that UPHPH crystallizes in monoclinic system (a = 2,1148(7)nm; b = 0,6611(2)nm; c = 0,6990(3)nm; b = 91,67(3)° and V = 0,9768(10)nm3). Heated under inert atmosphere, this compound is decomposed above 400°C into uranium phosphate-triphosphate U2(PO4)P3O10, uranium diphosphate alpha-UP2O7 and diuranium oxide phosphate U2O(PO4)2. Crystallized cerium (IV) phosphate-hydrogenphosphate hydrate Ce2(PO4)2HPO4 H2O (CePHPH) was also synthesized from (NH4)2Ce(NO3)6 and phosphoric acid solutions by the same method (monoclinic system: a = 2,1045(5)nm; b = 0,6561(2)nm; c = 0,6949(2)nm; b = 91,98(1)° and V = 0,9588(9)nm3). When heating above 600°C, cerium (IV) is reduced into Ce (III) and forms a mixture of CePO4 (monazite structure) and CeP3O9.
V. Brandel, N. Clavier, N. Dacheux, Journal of Solid State Chemistry 178 (2005) 1054-1063

A0689 – Submicrometric NASICON ceramics with improved electrical conductivity obtained from mechanically activated precursors

Na3Si2Zr1.88Y0.12PO11.94 was for the first time synthesised using mechanically activated mixtures of (ZrO2)0.97(Y2O3)0.03, Na3PO4.12H2O and SiO2 aiming to lower the sintering temperature thus improving chemical homogeneity. The best result was obtained with powder mixtures activated in Teflon containers with partial amorphisation of the reactants attained after milling for 70 h at a maximum of 300 rpm, without significant contamination. The microstructure consists of 300-500 nm agglomerates of smaller grains with size in the range 50-100 nm. Dense, single phase ceramics with submicrometric grain size were obtained from the activated mixture after sintering at 1050°C for 10 h. The ionic conductivity of these ceramics is 2.5 x 10^(-3) S cm-1 at room temperature, and 0.24 S cm-1 at 300°C. These values are higher than those obtained with non-activated solid state reaction samples and amongst the highest reported in the literature.
R.O. Fuentes, F.M. Figueiredo, M.R. Soares, F.M.B. Marques, Journal of the European Ceramic Society 25 (2005) 455-462

A0691 – Synthesis and structure of [Ce2(H2O)3](C2O4)2.5(H3C2O3) and Ce2(C2O4)(H3C2O3)4: The latter structure presents an interesting new framework, with 2-fold interpenetration

Single crystals of two cerium complexes, with mixed-ligands oxalate and glycolate, have been prepared in a closed system, at 200°C for one month: [Ce2(H2O)3](C2O4)2.5(H3C2O3) 1 and Ce2(C2O4)(H3C2O3)4 2. 1 crystallizes in the orthorhombic system, space group Pbca, with a = 13,0090(13) Å ; b = 10,3870(8) Å ; and a = 22,102(3) Å while 2 crystallizes in the tetragonal system, space group P42/nbc, with a = 11,7030(4) Å ; c = 13,2570(2) Å. For both complexes, the three-dimensional framework structure is built up by the linkages of the cerium and all the oxygen atoms of oxalate and glycolate ligands. For 2, its structure presents a nice case of two 3D identical sub-lattices, with 2-fold interpenetration. The only link between these two sub-lattices is assumed by strong hydrogen bonds between the hydroxyl function of the glycolate and the oxygen atoms of the oxalate. The schematized framework of 2, including only the cerium atoms, can be compared to that of cooperite (PtS). For 1, the two independent cerium have 9- or 10-fold coordination, forming a distorted monocapped or bicapped square antiprism polyhedron while for 2, the two independent cerium present 8-fold coordination, forming an almost regular dodecahedron. A quite relevant feature of 2 is the complete absence of water. 2 has been extended to other lanthanides (Ln = Ce . . . Lu; yttrium included) leading to a family, which has been characterized by infra-red and thermal analysis.
J.C. Trombe, J. Jaud, J. Galy, Journal of Solid State Chemistry 178 (2005) 1094-1103

A0690 – Thermal and fire behaviour of ammonium polyphosphate/acrylic coated cotton/PESFR fabric

The influence of an intumescent back coating, applied to a cotton/PESFR (Trevira CS ) fabric, on thermal and fire behaviour system is investigated. The intumescent system is made of an acrylic binder resin and ammonium polyphosphate (APP). Thermal and fire behaviours are analysed. The pure acrylic binder resin coated on fabric leads to a decrease in the thermal and fire properties of the virgin materials. When APP is added to the binder resin, the decrease in the properties due to the handling treatment is limited.
C. Drevelle, J. Lefebvre, S. Duquesne, M. Le Bras, F. Poutch, M. Vouters, C. Magniez, Polymer Degradation and Stability 88 (2005) 130-137

A0692 – Flame retardancy of biodegradable polymers and biocomposites

The efficiency of ammonium polyphosphate in different biocomposites was compared. For the comparison flame retarded lignocellulosic filler reinforced biocomposites were prepared using polypropylene (PP), polyurethane (PUR) and fully biodegradable starch matrices. The compatibility of wood flake with PP was improved by application of an alkoxy silane based reactive surfactant. The silylation improved not only the compatibility but also the thermal stability of the wood flake according to TG measurements. Raman spectroscopic analysis of the silylated product showed that the improved thermal stability is the result of reduced ratio of the amorphous phase of cellulose. The phosphorus additives in flame retarded PUR biocomposites, comprising waste bio fillers and recycled polyol, proved to be very effective because both the matrix and the filler components participate in mechanism of flame retardancy. Plasticised thermoplastic starch could be flame retarded efficiently by as little as 10% ammonium polyphosphate. After their service life the biocomposites can be utilised as chemical fertilizer.
Sz. Matko, A. Toldy, S. Keszei, P. Anna, Gy. Bertalan, Gy. Marosi, Polymer Degradation and Stability 88 (2005) 138-145

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

A0693 – Reduction kinetics of Goro nickel oxide using hydrogen

Nickel oxide (NiO) granules formed by vapour deposition from a chloride solution, were reduced in hydrogen using thermal gravimetry. In the temperature range from 400 to 600°C, the rate of reduction increased with increasing temperature and increasing hydrogen pressure. Microscopic analysis showed that in this temperature range the reaction followed the shrinking core model. The activation energy for reduction was found to be 90 kJ/mol in this temperature range. When the temperature was increased above 600°C, the reduction rate decreased noticeably before suddenly becoming extremely fast above 950°C. Microscopy showed inner bands of metallization inside the outer metallic rim, indicating partial blockage of the interface between the reacted and un-reacted NiO core. At these temperatures, particle agglomeration and sintering were also found to take place. Surface segregation of sulphur may account for the slow-down in reduction rate above 600°C.
T.A. Utigard, M. Wu, G. Plascencia, T. Marin, Chemical Engineering Science 60 (2005) 2061 - 2068

A0695 – Colloidal synthesis of indium nanoparticles by sodium reduction method

Nanocrystalline indium particles are prepared by direct reaction of sodium metal with anhydrous indium trichloride in N,NVdimethylformamide (In-1) or n-trioctylphosphine (In-2 and In-3) as a solvent at a temperature between 120 and 360°Cunder the atmosphere of argon. The product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible spectroscopy and thermogravimetric analysis (TGA). XRD patterns of In-1 exhibit broad peaks with particle diameter of about 15 nm while In-2 and In-3 particles have bigger particle size of about 50 nm reflecting the effect of solvents and reaction temperatures. Absorption spectroscopy measurements reveal the solvent dependence of surface plasmon resonance with the sharp absorption peaks at about 290 nm for In-1 in toluene and 260 nm for In-3 in dichloromethane.
P.K. Khanna, K-W. Jun, K.B. Hong, J-O. Baeg, R.C. Chikate, B.K. Das, Materials Letters 59 (2005) 1032-1036

A0697 – New iron containing mesoporous catalysts

Ferroceneacetic acid (FAA) was immobilised on protonated MCM-41, AlMCM-41, NbMCM-41 and amorphous silica. The organometallic complex is anchored to the surface by the interaction with hydroxyl groups and/or niobium species in case of NbMCM-41 support. Thermal stability of ferrocene species immobilised on the solid surface is not significantly influenced by the nature and composition of the matrix contrary to leaching behaviour, which is higher in case of NbMCM-41 and silica supports. The feature of these solids as catalysts has been estimated in the hydroxylation/polymerisation of phenol and decomposition of isopropanol. In the latter reaction the redox properties are slightly pointed out. All FAA modified solids exhibit very high activity in the polymerisation of phenol, which dominates over the hydroxylation activity. The nature of polymers formed is strongly dependent on the type and composition of the matrix applied for FAA immobilisation.
M. Trejda, M. Ziolek, Catalysis Today 101 (2005) 109-116

A0696 – A new chemical polymerization process for substituted anilines. Application to the synthesis of poly(N-alkylanilines) and poly(o-alkylanilines) and comparison of their respective properties

A new chemical polymerization process has been developed for the synthesis of polyaniline derivatives. Various poly(N-alkylanilines) and poly(o-alkylanilines) bearing different alkyl chain lengths (3-18 carbons) can be prepared by oxidation with ammonium persulfate in a mixture comprising methanesulfonic acid, water, hexane and a cosolvent (THF). Using this general process and further purification procedures, we found that numerous polymers can be produced in their dedoped forms with very high purity and reproducibility. The physical, spectral and thermal properties of poly(N-alkylanilines) and poly(o-alkylanilines) were studied and compared. As expected, the solubility of these substituted polyanilines in their dedoped form increased with alkyl chain length, and doped polymers containing long alkyl chains were also totally soluble in the usual organic solvents.
A. Falcou, A. Duchêne, P. Hourquebie, D. Marsacq, A. Balland-Longeau, Synthetic Metals 149 (2005) 115-122

A0698 – Kinetic studies of graphon and coal-char reaction with NO and O2: direct non-linear regression from TG curves

The reactions of carbonaceous materials (graphon and coal-char) with NO, O2 and NO+O2 were investigated by a thermogravimetric analysis (TGA). A method of direct non-linear regression of the kinetic equation was applied for a simultaneous calculation of the apparent activation energy, frequency factor and reaction order from a single TG curve of carbon gasification in various atmospheres. It was proven that the proposed calculation method is applicable for the calculation of kinetic parameters from overlapping processes. Calculations from TG curves of the above reactions demonstrate that NO-carbon and (NO+O2)-carbon reactions contain two processes, while O2-carbon is a single process. The reaction order of O2-carbon is approximate 0.5, while the reaction orders of NOcarbon or (NO+O2)-carbon reaction are dependent on the process and type of carbon. Graphon shows higher apparent activation energy than coal-char due to the pore structure and uncatalysed effects.
S. Wang, V. Slovak, B.S. Haynes, Fuel Processing Technology 86 (2005) 651- 660

A0699 – Highly active and selective AlSBA-15 catalysts for the vapor phase tert-butylation of phenol

Hexagonally ordered mesoporous AlSBA-15 catalysts having nSi/nAl ratios from 7 to 215 have been synthesized hydrothermally using a cheap non-ionic block copolymer as the structure-directing agent. The obtained materials were analyzed by XRD and nitrogen adsorption to determine the structural order and the textural properties. It has been observed by 27Al MAS NMR spectroscopy that aluminum atoms are exclusively in tetrahedral coordination for all samples except AlSBA-15(7), where octahedral aluminum has been detected to some extent. Temperature-programmed desorption of pyridine showed that AlSBA-15(45) has a higher number of strong acid sites as compared to other mesoporous materials such as FeMCM-41, AlMCM-41 and FeAlMCM-41. The catalyst AlSBA-15(45) showed superior performance in the acid-catalyzed tertiary butylation of phenol employing tert-butanol as the alkylation agent. A high phenol conversion of 86.3% is observed for this catalyst at a reaction temperature of 150°C. Over AlSBA-15(45), the 4-TBP yield amounts to 40.5% and the 2,4-DTBP yield corresponds to 37.9%.
A. Vinu, B.M. Devassy, S.B. Halligudi, W. Böhlmann, M. Hartmann, Applied Catalysis A: General 281 (2005) 207-213

A0702 – Pyrolysis study of sol-gel derived TiO2 powders. Part III. TiO2-anatase prepared by reacting titanium(IV) isopropoxide with acetic acid

A homogeneous TiO2 gel was obtained by hydrolysing titanium(IV) isopropoxide that was previously modified by reaction with acetic acid. The so stabilized precursor was hydrolysed under strong acidic medium (pH=0 by HCl). Dried TiO2 powders were characterized by FT-IR, XRD, N2 adsorption analyses, coupled thermogravimetric (TG) gas chromatographic (GC) and mass spectrometric (MS) analyses. A semiquantitative analysis of the main evolved chemical species allowed to depict both the chemical rearrangements occurring in the TiO2 matrix during pyrolysis and the chemical composition of the initial gel.
R. Campostrini, M. Ischia and L. Palmisano, Journal of Thermal Analysis and Calorimetry 75 (2004) 13-24

A0701 – Pyrolysis study of sol-gel derived TiO2 powders. Part II. TiO2-anatase prepared by reacting titanium(IV) isopropoxide with oxalic acid

Homogeneous TiO2 powders were obtained, via sol-gel method, hydrolysing titanium(IV) isopropoxide, previously reacted with oxalic acid in order to better control the gelling process. The characterization of the amorphous TiO2 powders was carried out by using different techniques such as FT-IR, XRD and N2 adsorption analysis. Coupled thermogravimetric (TG) gas chromatographic (GC) and mass spectrometric (MS) analyses were performed to quantify the organic content present in the titania gel and its release during pyrolysis. A detailed semiquantitative analysis of the evolved chemical species from TG-MS data allowed to describe the chemical composition of the TiO2 gel and the chemical rearrangements occurring in matrix during pyrolysis up to its crystallization to anatase form at 530°C.
R. Campostrini, M. Ischia and L. Palmisano, Journal of Thermal Analysis and Calorimetry 71 (2003) 1011-1021

A0700 – Pyrolysis study of sol-gel derived TiO2 powders. Part I. TiO2-anatase prepared by reacting titanium(IV) isopropoxide with formic acid

A homogeneous TiO2 gel sample was prepared, via sol-gel method, hydrolysing titanium(IV) isopropoxide, previously modified by reaction with formic acid. The amorphous TiO2 gel was characterized using various techniques such as FT-IR, XRD and N2 adsorption analysis. Thermoanalyses (TG, DTA) coupled with gas chromatographic (GC) and mass spec trometric measurements (MS), by means of a home-assembled instrumental interfaces, were performed in order to quantify the organic component still present in the titania gel and its release during pyrolysis. Several chemical species were evolved and detected in gas phase for temperatures up to 350°C, before crystallization of TiO2-anatase.
R. Campostrini, M. Ischia and L. Palmisano, Journal of Thermal Analysis and Calorimetry 71 (2003) 997-1009

A0703 – Pyrolysis study of sol-gel derived TiO2 powders. Part IV. TiO2-anatase prepared by hydrolysing titanium(IV) isopropoxide without chelating agents

An amorphous TiO2 gel was obtained by hydrolysing titanium(IV) isopropoxide with a stoichiometric amount of water using SnCl2 as catalyst. In these operative conditions, a TiO2 gel matrix containing a lower fraction of organic residual was obtained with respect to samples prepared by previously modifying the titanium alkoxide precursor with chelating ligands. Dried gel powders were characterized by N2 adsorption analyses, FT-IR and XRD measurements. Thermogravimetric (TG) and differential thermal analysis (DTA) coupled with mass spectrometric (MS) and gas chromatographic (GC) measurements were performed in order to identify the organic products released from TiO2 gel pyrolysis. The TG-MS semiquantitative analysis of the main evolved species allowed to describe both the chemical composition of the initial TiO2 gel and the chemical rearrangements occurring in the matrix during heating up to its crystallisation to anatase form at 420°C.
R. Campostrini, M. Ischia and L. Palmisano, Journal of Thermal Analysis and Calorimetry 75 (2004) 25-34

A0706 – LSFM perovskites as cathodes for the electrochemical reduction of NO

Six La0.6Sr0.4Fe1 xMnxO3 d (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) perovskite compounds have been synthesised by the citric-acid route. The perovskites have been characterised by powder XRD and are shown to belong to the hexagonal crystal system. The perovskites are also evaluated by TG-measurements in 50% oxygen in nitrogen and in nitrogen. From this the redox capacity is calculated and shown to be highest for the iron rich compounds. Cyclic voltammetry has been recorded on cone shaped electrodes of the LSFM compounds in atmospheres containing either NO or O2 at temperatures of 300, 400 and 500°C on a ceria based electrolyte. Only La0.6Sr0.4Fe0.8Mn0.2O3 d (LSFM020) and La0.6Sr0.4FeO3 d (LSFM000) show significant activity for the reduction of NO. This can probably be related to the high redox capacity of these compounds. The activity of the perovskites for the reduction of oxygen increases systematically with increasing iron content. The selectivity of the perovskites towards the reduction of NO with regard to the reduction of O2 is highest at the lowest temperatures.
K. Kammer, E.M. Skou, Solid State Ionics 176 (2005) 915-920

A0705 – Thermal analysis of the cyclic reduction and oxidation behaviour of SOFC anodes

The reduction and oxidation (redox) kinetics of a Ni/YSZ cermet were studied at temperatures between 400 and 850°C by thermogravimetric analysis (TGA) and reduction and oxidation activation energies were determined. In addition, the volume change after redox cycling was examined by thermomechanical analysis (TMA). Samples with fine microstructure similar to a typical SOFC anode functional layer (AFL) and samples with coarse microstructure similar to a typical anode substrate were characterized. Coarse structured samples experienced no volume change or cracking upon redox cycling. Fine structured anode samples did not change in volume after reduction, but expanded between 0.9% and 2.5% after oxidation. The samples were significantly cracked after oxidation. The amount of expansion and cracking was reduced by lowering the Ni content of the anode and by reducing the oxidation temperature. The reduction of the NiO/YSZ samples followed linear kinetics with an activation energy of 78 kJ/mol. Ni/YSZ oxidation followed parabolic kinetics at temperatures lower than 700°C. A divergence from parabolic kinetics was seen at higher temperatures (700-850°C). This divergence has been seen in many other kinetic studies and is usually attributed to short-circuit diffusion mechanisms. An activation energy of 87 kJ/mol was calculated for oxidation.
D. Waldbillig, A. Wood, D. G. Ivey, Solid State Ionics 176 (2005) 847-859

A0704 – Hydrogenative regeneration of a Pt/La-Y zeolite catalyst deactivated in the isobutane/n-butene alkylation

The formation of carbonaceous deposits during the alkylation of isobutane with 1-butene was investigated on a La-Y zeolite catalyst loaded with 0.4 wt.% of platinum in a continuous-flow stirred tank reactor at 75°C in the liquid phase. By combined elemental analysis and UV-vis spectroscopy, the amount and the nature of the coke deposits were found to change significantly with time-on-stream. Olefins formed by cracking of isododecyl- or higher carbocations are supposed to be important precursors of the carbonaceous deposits, as they form unsaturated carbocations blocking the acid sites. The hydrogenative regeneration of coked alkylation catalysts was studied in the gas phase. Under suitable regeneration conditions, e.g. at a hydrogen pressure of 15 bar and a temperature of 300°C, the alkylation activity can be fully restored.
R. Klingmann, R. Josl, Y. Traa, R. Gläser, J. Weitkamp, Applied Catalysis A: General 281 (2005) 215-223

A0708 – Low-temperature synthesis and characterization of yttrium-gallium garnet Y3Ga5O12 (YGG)

To obtain yttrium-gallium garnet (Y3Ga5O12, YGG) a simple "chimie douce'' method has been developed. This sol-gel method yielded excellent starting gel precursor for the fabrication of YGG phase, which could be used as host material for optical applications. The pattern of X-ray diffraction analysis of the ceramic sample sintered for 10 h at 1000°Cshowed the formation of monophasic Y3Ga5O12 phase. The phase transformations, composition and micro-structural features in the gels and polycrystalline sample were studied by thermoanalytical methods (TGA/DTA), powder X-ray diffraction analysis (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The quality of the resulting products (homogeneity, crystallisation temperature, grain size, grain size distribution, etc.) is discussed.
S. Mathur, H. Shen, A. Leleckaite, A. Beganskiene, A. Kareiva, Materials Research Bulletin 40 (2005) 439-446

A0707 – Synthesis of acidic Al-MCM-48: influence of the Si/Al ratio, degree of the surfactant hydroxyl exchange, and post-treatment in NH4F solution

Al-MCM-48 mesostructures with different Al contents (Si/Al = 40, 30, and 20) have been prepared with hydroxyl-exchanged cetyltrimethylammonium bromide as the template and a post-synthesis treatment in NH4F solution. The solid structures were analyzed by XRD, N2 adsorption, DRIFT, SEM, HREM, and 27Al and 29Si MAS NMR. Moreover, surface acidity was determined with the use of pyridine (Py) and 2,6-dimethylpyridine (DMPy) as probe molecules. The catalytic activity of Al-MCM-48 materials in isopropylbenzene dealkylation was compared with those of the microporous H-Y and ZSM-5 zeolites and that of a commercial silica-alumina catalyst (Harshaw, Si235, 13 wt% alumina). For these solids, the catalytic activity was related to the tetrahedral or octahedral (probably AlO5F species) aluminum for nonfluorinated and fluorinated catalysts, respectively.
J.M. Campelo, D. Luna, R. Luque, J.M. Marinas, A.A. Romero, J.J. Calvino, M.P. Rodríguez-Luque, Journal of Catalysis 230 (2005) 327-338

A0710 – Catalyst based on BaZrO3 with different elements incorporated in the structure .II. BaZr(1 x)RhxO3 systems for the production of syngas by partial oxidation of methane

New catalytic systems, synthesised by a variant of the citrate route, are proposed for the partial oxidation of methane. They consist of solid solutions - barium, zirconium, rhodium and oxygen - with a perovskite structure of formula BaZr(1 x)RhxO3. Detailed analysis of the XRD diffractograms and the TGA cycles show that Rh is randomly distributed as RhIV among the B sites of the perovskite, together with Zr. The activities of the catalysts have been tested for the catalytic partial oxidation of methane at short contact times to evaluate the potential of materials giving promising results in terms of syngas yield at low Rh loading.
P. Viparelli, P. Villa, F. Basile, F. Trifiro, A. Vaccari, P. Nanni, M. Viviani, Applied Catalysis A: General 280 (2005) 225-232

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

A0711 – Reforming of methane with carbon dioxide over supported bimetallic catalysts containing Ni and noble metal .I. Characterization and activity of SiO2 supported Ni-Rh catalysts

The activity and stability of silica supported monometallic Ni, Rh and bimetallic Ni-Rh catalysts have been studied towards the carbon dioxide reforming of methane. The catalysts were prepared by incipient wetness impregnation with different contents of Rh and Ni and they were characterized by H2 chemisorption, TPRH2 , XRD and FT-IR methods. SiO2 supported monometallic Ni, Rh and bimetallic Ni-Rh catalysts are comparably good catalysts for carbon dioxide reforming of methane and Rh-rich catalysts are resistant to deactivation and carbon formation. Temperature-programmed hydrogen assisted decomposition of bimetallic Ni-Rh/SiO2 catalyst precursors leads to formation of Ni-Rh alloys. Segregation of metals leads to the formation of Ni-rich surface alloy. TG-DTA-MS, TPSRH2, TPO, TPSRCO2 , TOC and SEM methods were used in order to characterize the carbonaceous deposits. At least two types of carbon deposit with different reactivity have been detected on the surface of bimetallic catalysts. The results suggest a significant metal-metal interaction in the bimetallic systems.
W.K. Jozwiak, M. Nowosielska, J. Rynkowski, Applied Catalysis A: General 280 (2005) 233-244

A0713 – Kinetic studies on the pyrolysis of chitin and chitosan

The thermal degradation of chitin and chitosan have been studied by using simultaneous TG and DSC in nitrogen atmosphere. The model-free iso-conversional method has been employed to evaluate the activation energies as a function of the extent of degradation. The obtained dependencies are interpreted in terms of degradation mechanisms. Under nitrogen, the thermal degradation of chitin and chitosan follows a random scission pathway, which is initiated at weak links. The activation energies of thermal degradation of chitin are constant and this process follows 1.23 order reaction. As for chitosan, the activation energies of thermal decomposition are obviously dependent on the extent of conversion. The pyrolysis reaction of chitosan is analysed by using a distributed activation energy model (DAEM) because the residual N-acetylated side-chains are randomly distributed on the chitosan main chains. Also, the parameters of the DAEM are evaluated.
T. Wanjun, W. Cunxin, C. Donghua, Polymer Degradation and Stability 87 (2005) 389-394