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5631 articles

E0132 – Local and average atomic order of ion-conducting Bi0.775La0.225O1.5 studied by neutron scattering and reverse Monte Carlo simulations

Bi0.775La0.225O1.5 has been investigated by means of neutron scattering in combination with Rietveld refinement and reverse Monte Carlo (RMC) simulations to study the average and local atomic order of the material. At low temperature the crystallographic analysis shows a clear split of anionic positions similar to that reported for Sr doped bismuth oxides. Although this split appears to be absent in the average structure at high temperature, an even larger split of Bi-O local distances is found in the pair distribution function calculated from the RMC models. This latter feature can be indicative of a tendency to have similar oxygen environments for all Bi atoms at high temperature, as a precursor of the fluorite structure that is the stable phase at even higher temperatures.
A. Ahi, A. Mellergard, S-G. Eriksson, Solid State Ionics 177 (2006) 289-297

E0143 – Three-dimensional framework of uranium-centered polyhedra with non-intersecting channels in the uranyl oxy-vanadates A2(UO2)3(VO4)2O (A = Li, Na)

The uranyl vanadates A2(UO2)3(VO4)2O (A = Li, Na) have been synthesized by solid-state reaction and the structure of the Li compound was solved from single-crystal X-ray diffraction. The crystal structure is built from [UO5] 4- chains of edge-shared U(2)O7 pentagonal bipyramids alternatively parallel to a- and b-axis and further connected together to form a three-dimensional (3-D) arrangement. The perpendicular chains are hung on both sides of a sheet [(UO2)(VO4)2] 4- parallel to (001), formed by U(1)O6 square bipyramids connected by VO4 tetrahedra, and derived from the autunite-type sheet. The resulting 3-D framework creates nonintersecting channels running down the a- and b-axis formed by empty face-shared oxygen octahedra, the Li+ ions are displaced from the center of the channels and occupy the middle of one edge of the common face. The peculiar position of the Li+ ion together with the full occupancy explain the low conductivity of Li2(UO2)3(VO4)2O compared with that of Na(UO2)4(VO4)3 containing the same type of channels half occupied by Na+ ions in the octahedral sites. Crystallographic data for Li2(UO2)3(VO4)2O: tetragonal, space group I41/amd, a = 7,3303(5) Å, c = 24,653(3) Å, V = 1324,7(2) Å^3, Z = 4, Pmes = 5,32(2) g/cm3, Pcal = 5,36(3) g/cm3, full-matrix least-squares refinement basis on F² yielded, R1 = 0,032, wR2 = 0,085 for 37 refined parameters with 364 independent reflections with I>2s(I).
S. Obbade, L. Duvieubourg, C. Dion, F. Abraham, Journal of Solid State Chemistry 180 (2007) 866-872

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

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

E0142 – Fabrication and characterization of Pb-free transparent dielectric layer for plasma display panel

Glasses within the Bi2O3-B2O3-BaO-ZnO system were examined as potential replacements for PbO-based glass frits with low firing temperatures. These frits are used in the transparent dielectric layer of plasma display panels (PDP). The glass transition temperature (Tg) of the prepared glasses varied between 450 and 460°C. These glasses display dynamic dielectric properties, high transparency and thermal expansion as well as matching well with substrate glass. The thermal coefficient of expansion (TCE) was with the desired range of 81-86.10^(-7)/K. Moreover, when the screen printed film was heat-treated at 570°C for 30 min, optical transmittance (83%), root-mean square (rms) roughness (177.6 Å ), dielectric constant (10.25) and withstand voltage (4.15 kV) satisfied the requirements necessary for transparent dielectric layers to be used in PDP applications.
J-Y. Song, S-Y. Choi, Displays 27 (2006) 112-116

E0130 – Chemical inhomogeneity of intermetallic phases precipitates formed during solidification of Al-Si alloys

In this work, the results of an examination of the solidification process of the AlSi6 and AlSi12 alloys as influenced by the content of the transition metals, Fe, Mn and Cr, are presented. The concentration of these elements in alloys prepared from pure components has been changed in the following range: Fe 0.5-3 wt.%, Mn 0-2 wt.% and Cr 0.3 wt.%. The thermal effects during solidification of alloys at a cooling rate of 3.3 K/min (between liquidus and solidus) connected with forming of structural components of alloy were determined. The temperature of the phase transformations was evaluated and correlated with chemical composition of alloys. It was stated that, on an average, an increase in Fe and Mn content of about 1 wt.% increases the temperature of primary proeutectic iron-bearing phase precipitation by about 40 K (in the examined range of the alloys compositions). By means of microscopic observations of the alloy microstructure, the morphology of the primary phase precipitates frozen at a chosen temperature was estimated. On the basis of the results of X-ray microanalysis (EDS), the chemical composition of the primary iron-bearing phases was analysed, and a relation among the components (i.e., Al, Si, Fe, Mn and Cr) was established. The sequence of microstructural component formation during solidification of the alloys examined was presented.
M. Warmuzek, W. Ratuszek, G. Sek-Sas, Materials Characterization 54 (2005) 31-40

E0153 – Preparation of nanocrystalline Mn-Al-C magnets by melt spinning and subsequent heat treatments

Mn54Al44C2 ribbon samples have been prepared by melt spinning in a single-phase epsilon hexagonal disordered state and its exothermal transformation at around 500°C into a tetragonal L10 type magnetic structure (t-phase) was followed by DTA, DSC, X-ray diffraction and thermomagnetic measurements. The metastable t-phase stabilized by carbon addition could be transformed reversibly into the epsilon-phase at around 800°C, without decomposition into the stable Al8Mn5 and beta manganese phases. The almost constant Curie temperature obtained for partially transformed two-phase samples indicated a compositionally invariant transformation. By grinding the thin (25 µm) ribbon into sub-millimeter flakes, a bulk anisotropic magnet could be compacted by magnetic field oriented powder technology.
E. Fazakas, L.K. Varga, F. Mazaleyrat, Journal of Alloys and Compounds 434-435 (2007) 611-613

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

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

E0151 – Magnetically soft nanomaterials for high-temperature applications

The paper summarizes the current status of research in the field of magnetically soft nanocrystalline materials especially highlighting the influence of alloy composition on structure and magnetic properties as well as their stability at elevated temperature during very long time annealing (several thousand hours at temperature up to 550°C). Modification of the alloys allows to tailor their chemical composition and manufacturing process to particular application temperature requirements. FINEMET is the most suitable material for application at temperature up to 300°C, FINEMET modified by cobalt (Fe0.6Co0.4)73.5Cu1Nb3Si13.5B9 for 300°C
T. Kulik, J. Ferenc, A. Kolano-Burian, X.B. Liang, M. Kowalczyk, Journal of Alloys and Compounds 434-435 (2007) 623-627

E0149 – Barium borosilicate glass – a potential matrix for immobilization of sulfate bearing high-level radioactive liquid waste

Borosilicate glass formulations adopted worldwide for immobilization of high-level radioactive liquid waste (HLW) is not suitable for sulphate bearing HLW, because of its low solubility in such glass. A suitable glass matrix based on barium borosilicate has been developed for immobilization of sulphate bearing HLW. Various compositions based on different glass formulations were made to examine compatibility with waste oxide with around 10 wt% sulfate content. The vitrified waste product obtained from barium borosilicate glass matrix was extensively evaluated for its characteristic properties like homogeneity, chemical durability, glass transition temperature, thermal conductivity, impact strength, etc. using appropriate techniques. Process parameters like melt viscosity and pour temperature were also determined. It is found that SB-44 glass composition (SiO2: 30.5 wt%, B2O3: 20.0 wt%, Na2O: 9.5 wt% and BaO: 19.0 wt%) can be safely loaded with 21 wt% waste oxide without any phase separation. The other product qualities of SB-44 waste glass are also found to be on a par with internationally adopted waste glass matrices. This formulation has been successfully implemented in plant scale.
C.P. Kaushik, R.K. Mishra, P. Sengupta, Amar Kumar, D. Das, G.B. Kale, Kanwar Raj, Journal of Nuclear Materials 358 (2006) 129-138

E0148 – Effect of Pb addition on ageing behavior of AZ91 magnesium alloy

The ageing behavior of AZ91 alloy containing 2 wt.% lead is investigated. The results show that addition of Pb suppresses the discontinuous precipitation and thereby slows down the ageing kinetics. Even though the peak hardness obtained for both alloys is almost same, the peak hardness reaches after 2400 min for Pb added alloy against 900 min for the base alloy. The presence of Pb in solid solution might have inhibited the diffusion of Al and Mg atoms, which is essential for the formation, and growth of discontinuous precipitation in this alloy.
A. Srinivasan, U.T.S. Pillai, B.C. Pai, Materials Science and Engineering A 452-453 (2007) 87-92

E0147 – Influence of expandable graphite on fire resistance and water resistance of flame-retardant coatings

Expandable graphite (EG) coating and ammonium polyphosphate-pentaerythritol-melamine (APP-PER-MEL) coating were prepared. Thermal degradation and char formation of the coatings were investigated by differential thermal analysis (DTA), thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results have shown that the anti-oxidation and fire-resistant properties of expandable graphite coating containing EG with size of 74 lm are better than those of APP-PER-MEL coating. The static immersion test was applied to study water resistance of the coatings, and the fire protection test and mechanical test were used to analyse heat insulation and mechanical properties of coatings before and after water immersion. The fire-resistant and mechanical properties of APP-PER- MEL coating were severely damaged by water immersion, whereas EG coating containing 8.5% EG with size of 74 lm could retain the good fire resistance even after 500 h water immersion.
Z. Wang, E. Han, W. Ke, Corrosion Science 49 (2007) 2237-2253

E0146 – Proof of the ISS-concept for LTA and FAU membranes and their characterization by extended gas permeation studies

Molecular sieve membranes are expected to separate molecules by size and shape provided that the intercrystalline defect transport is negligible. However, in the case of a non-negligible mass transport through the grain boundaries in the polycrystalline zeolite layer, the separation properties of the membrane become influenced by both the regular and defective transport. Nevertheless, also in this case proper separation performance is found due to adsorptive and/or diffusive interactions of the mixture components with the membrane. In a previous report [M. Noack, P. Kölsch, A. Dittmar, M. Stöhr, G. Georgi, R. Eckelt, J. Caro, Micropor. Mesopor. Mater. 97 (2006) 88] the concept of crystal intergrowth supporting substances (ISS) was demonstrated. The charge neutralization of the negatively charged crystal surfaces of a growing MFI membrane by the positively charged ISS molecules improves the crystal intergrowth and results in a higher permeation selectivity. LTA and FAU membranes can separate water-organic mixtures in an excellent way but they fail in shapeselective gas separations. Therefore, many attempts were made to improve the separation properties of LTA and FAU membranes for gases. Zeta potential measurements on the Al-rich zeolite crystals LTA and FAU show a strong negative surface charge like it was found in [Noack et al., 2006] for MFI. In this work LTA and FAU multi-layer membranes were prepared by using an ISS. These membranes were characterized by SEM, XRD, permporosimetry, single gas permeation in combination with different probe molecules for the selective blocking of the micro and mesopore system. The results are discussed on the basis of pore condensation or pore narrowing according to the Kelvin and Halsey equations. Repeated strong de-watering of the hydrophilic LTA and FAU membranes have changed the membrane structure.
M. Noack, P. Kölsch, A. Dittmar, M. Stöhr, G. Georgi, M. Schneider, U. Dingerdissen, A. Feldhoff, J. Caro, Microporous and Mesoporous Materials 102 (2007) 1-20

E0145 – The effect of Al2O3 on sintering and crystallization of MgSiO3-based glass-powder compacts

The influence of Al2O3 (8 wt.%) on sintering and crystallization features of glass powders based on magnesium silicate (MgSiO3) was experimentally determined. The investigated compositions were Y0.125Mg0.875Si0.875B0.125O3 and Y0.125Mg0.725Ba0.15Si0.875B0.125O3. For the experiments, glasses in bulk and frit forms were produced by melting in Pt-crucible at 1600°C for 1.5 h. Glass-powder compacts were sintered at different temperatures between 900°C and 1100°C. The evolution of crystalline regime was determined by in situ recording of X-ray diffractograms of fine glass powders at elevated temperatures. The results and their discussion showed that addition of 8 wt.% Al2O3 in glass batches affected the thermal properties of the glasses and resulted in MgSiO3-based glass ceramics well sintered between 900°C and 1100°C. In the BaO-free MgSiO3 glass ceramics, clino- and orthoenstatite crystallize while the presence of BaO favours the formation of hexacelsian.
A. Goel, D.U. Tulyaganov, S. Agathopoulos, J.M.F. Ferreira, Ceramics International xxx (2007) xxx-xxx

E0155 – High temperature behavior of ball-milled Al-Ni-Ce-Co alloys

Microstructure of ball-milled Al85Ni8Ce5Co2 powder indicates the formation of fine nanoparticles with some amorphous fraction. Thermal analysis revealed that the release of internal stress and grain growth is followed by the redistribution and possible melting of high solute concentration interfaces. In addition, mechanical properties of compacted powder specimens were also investigated.
A. Révész, P. Henits, Zs. Kovacs, Journal of Alloys and Compounds 434-435 (2007) 424-427

E0154 – An investigation into fire protection and water resistance of intumescent nano-coatings

The objective of the paper is to develop nano-coatings that can provide good fire protection for the underlying substrate. The thermal degradation and fire resistance of nano-coatings have been investigated by differential thermal analysis (DTA), thermogravimetry (TG) and fire performance test. It is illustrated that nano-coatings can give an excellent fire resistance. The dispersion state and bonding of nano-SiO2 particles are characterized by the use of transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). Water immersion test, fire performance test and mechanical test reveal that sodium silicate coating is vulnerable to water and hence fire resistance is severely damaged by water immersion, whereas nano-coatings demonstrate good water resistance and fire resistance even after water immersion.
Z. Wang, E. Han, W. Ke, Surface & Coatings Technology 201 (2006) 1528-1535

E0163 – Effect of acrylic polymer and nanocomposite with nano-SiO2 on thermal degradation and fire resistance of APP-DPER-MEL coating

Acrylic nanocomposite and flame retardant coatings with different acrylic polymers were prepared. The effect of molecular structure and molecular weight of acrylic resins and nanocomposite with nano-SiO2 on the interaction and char formation of ammonium polyphosphate- dipentaerythritol-melamine (APP-DPER-MEL) coating was investigated using differential thermal analysis (DTA), thermogravimetry (TG), Limiting Oxygen Index (LOI), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and fire protection test. The interaction of APP, DPER, MEL and 3F-1 acrylic resin led to the formation of intumescent coherent char at 300-450°C. Owing to low molecular weight and lack of benzene rings, F-963 acrylic resin decomposed at lower temperature than APP, and hence their endothermic interaction was destroyed. The well-distributed nano-SiO2 particles in acrylic nanocomposite could modify char formation and anti-oxidation of char structure at high temperature. It is noted that the fire protection properties of nanocoating with acrylic nanocomposite were better than those of flame retardant coatings with conventional acrylic resins.
Z. Wang, E. Han, W. Ke, Polymer Degradation and Stability 91 (2006) 1937-1947

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

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

E0161 – Study of the magnesia additive on the characterization of zirconia-magnesia composite sphere

Zirconia composite with varying amounts of magnesia was prepared by sol-gel technique. A series of carefully designed experiments were conducted to obtain data needed to assist the comparison of the resultant composites in terms of surface area, pore diameter, pore volume, crystalline phase and their stability to temperature. The results show that the presence of magnesia can be helpful for stabilization of zirconia composite, and different amounts of magnesia doping result in ultimate composite materials with different properties. We can tailor the structural and surface characteristics through changing the reactant ratio of magnesium chloride to zirconyl chloride to cater for its various applications, such as catalysts, chromatographic packings and so on.
Z-G. Shi, L. Xu, S-L. Da, Y-Q. Feng, Microporous and Mesoporous Materials 94 (2006) 34-39

E0160 – The A(1-x)UNbO(6-x/2) compounds (x = 0, A = Li, Na, K, Cs and x = 0.5, A = Rb, Cs): from layered to tunneled structure

Attempts to prepare alkaline metal uranyl niobates of composition A(1-x)UNbO(6-x/2) by high-temperature solid-state reactions of A2CO3, U3O8 and Nb2O5 led to pure compounds for x = 0 and A = Li (1), Na (2), K (3), Cs (4) and for x = 0.5 and A = Rb (5), Cs (6). Single crystals were grown for 1, 3, 4, 5, 6 and for the mixed Na0.92Cs0.08UNbO6 (7) compound. Crystallographic data: 1, monoclinic, P2 1/c, a = 10.3091(11), b = 6.4414(10), c = 7.5602(5) Å , beta = 100.65(1), Z = 4, R1 = 0.054 (wR2 = 0.107); 3, 5 and 7 orthorhombic, Pnma, Z = 8, with a = 10.307(2), 10.272(4) and 10.432(3) Å , b = 7.588(1), 7.628(3) and 7.681(2) Å , c = 13.403(2), 13.451(5) and 13.853(4) Å , R1 = 0.023, 0.046 and 0.036 (wR2 = 0.058, 0.0106 and 0.088) for 3, 5 and 7, respectively; 6, orthorhombic, Cmcm, Z = 8, and a = 13.952(3), b = 10.607(2) Å , c = 7.748(2) Å , R1 = 0.044 (wR2 = 0.117). The crystal structure of 1 is characterized by [UNbO6]- layers of uranophane sheet anion topology parallel to the (100) plane. These layers are formed by the association by edge-sharing of [UO5]4- chains of edge-shared UO7 pentagonal bipyramids and [NbO4]3- chains of corner-shared NbO5 square pyramids alternating along the [010] direction. The Li+ ions are located between two consecutive layers and hold them together; the Li+ ions and two layers constitute a neutral "sandwich" {(UNbO6)- - (Li)2 2+ - (UNbO6)-}. In this unusual structure, the neutral sandwiches are stacked one above another with no formal chemical bonds between the neutral sandwiches. The homeotypic compounds 3, 5, 6, 7 have open-framework structures built from the association by edge-sharing in two directions of parallel [UO5]4- chains of edge-shared UO7 pentagonal bipyramids and [Nb2O8]6- ribbons of two edge-shared NbO6 octahedra further linked by corners. In 3, 5 and 7, the mono-dimensional large tunnels created in the [001] direction by this arrangement can be considered as the association by rectangular faces of two columns of triangular face-shared trigonal prisms of uranyl oxygens. In 3 and 7, all the trigonal prisms are occupied by the alkaline metal, in 5, they are half-occupied. In 6, the polyhedral arrangement is more symmetric and the tunnels created in the [010] direction are built of face-sharing cubes of uranyl oxygens totally occupied by the Cs atoms. This last compound well illustrates the structure-directing effect of the conterion.
S. Surblé, S. Obbade , S. Saad, S. Yagoubi, C. Dion, F. Abraham, Journal of Solid State Chemistry 179 (2006) 3238-3251

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

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

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

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

E0158 – Phase equilibria and phase transformations in the Ti-rich corner of the Fe-Ni-Ti system

While the main features of the Fe-Ni-Ti system are well known at low Ti content, literature review of the Ti-rich corner revealed inconsistencies between experimental reports. This investigation presents new experimental results, defined to remove the uncertainties concerning melting behavior and solid-state phase equilibria of the (Ni,Fe)Ti2 phase with the adjacent (Fe,Ni)Ti (B2, CsCl-type structure) and beta-Ti (A2, W-type) phases. Six samples have been prepared and examined by differential thermal analysis performed in yttria and alumina crucibles, and by scanning electron microscopy in the as-cast state as well as equilibrated at 900°C.
P. Riani, G. Cacciamani, Y. Thebaut, J. Lacaze, Intermetallics 14 (2006) 1226-1230

E0168 – Cytotoxicity of Zr-based bulk metallic glasses

Recently we developed a family of Ni-free Zr-based bulk metallic glasses in the Zr-Cu-Fe-Al system. X-ray diffraction and differential thermal analysis measurements demonstrate its good glass-forming ability, and amorphous rods of up to 13 mm in diameter can be produced for the alloy Zr58Cu22Fe8Al12. This new glassy system is potentially very interesting for biomedical applications. Thus we have investigated the effect of surface modification (treatment with nitric acid and oxygen plasma) on the alloy's cytotoxicity and compared it with the results for a Ni-bearing Zr-based bulk metallic glass. The surfaces were analyzed by X-ray photoelectron spectroscopy, and cytotoxicity was tested by measuring the viability and metabolic activity of mouse fibroblasts. Our results show that the surfaces of the as-cast glasses consist almost exclusively of zirconium oxide, which yields good biocompatibility. With nitric acid treatment this oxide layer can be stabilized further, to the extent that the cytotoxicity becomes as good as that of the non-toxic negative control (polystyrene).
S. Buzzi, K. Jin, P.J. Uggowitzer, S. Tosatti, I. Gerber, J.F. Löffler, Intermetallics 14 (2006) 729-734

E0157 – The nucleation and crystallization of fine grained leucite glass-ceramics for dental applications

Objectives. The aims of the study were to control the nucleation and crystal growth of selected aluminosilicate glass powders, to produce uniform leucite glass-ceramic microstructures consisting of fine (<1000 nm) grained leucite crystals. Methods. A starting glass composition of wt%; 64.2% SiO2, 16.1% Al2O3, 10.9% K2O, 4.3% Na2O, 1.7% CaO, 0.5% LiO2 and 0.4% TiO2 was heated in an electric furnace and later quenched to produce glasses. The glass powders were ball milled to two different particle sizes and heattreated using one and two-step crystallization heat treatments. Dta, Xrd, and Sem analyses was used to characterise and explore the crystallization kinetics of the glasses. Results. Selected heat treatments of the glass powders produced a uniform distribution of fine tetragonal leucite crystals (mean±S.D.) 0.1±0.2 µm2 in the glassy matrix, with minimal matrix microcraking in the glass-ceramics produced. The addition of a two-step heat treatment increased the leucite volume fraction in all instances. Significance. Selected crystallization heat treatments and powder particle sizes were used to control the leucite crystal size, distribution and volume fraction, in order to produce uniformly distributed ultra fine grained tetragonal leucite glass-ceramics for dental applications.
M.J. Cattell, T.C. Chadwick, J.C. Knowles, R.L. Clarke, D.Y.D. Samarawickrama, Dental Materials 22 ( 2006 ) 925-933

E0167 – Production and identification of rare-earth doped lithium triborate

Research in the field of non-linear optical (NLO) devices lead to an increasing interest in new borate compounds, capable of expanding the frequency range provided by common laser sources. Lithium triborate (LBO) is a newly developed ideal non-linear optical crystal used in laser weapon, welder, radar, tracker, surgery, communication, etc. In this study, synthesis and identification of rare-earth doped lithium triborate was carried out. Borates containing rare-earth elements are of great interest since they are found to be superior in non-linear optical applications. Lithium triborate was produced from the solid-state reaction. Lithium triborate was then doped with some rare-earth elements (Gd, La, Y, etc.) in several different concentrations. In this study, LBO samples doped with Gd are presented. Characterization of the new products was done by X-ray diffraction (XRD) and infrared (IR) analysis. Differential thermal analysis (DTA) was used for examination of the thermal properties of the compounds, morphology of new compounds was observed by scanning electron microscopy (SEM). The compounds are then subjected to thermoluminescence (TL) studies. From the XRD studies, no change related to addition of the rare-earth elements was observed. IR analysis showed that there is no change related to B-O link with the addition of rare-earth elements. DTA studies showed that the melting point of LBO decreases with the addition of rare-earth elements. In the SEM images, particles of rare-earth elements and lithium triborate were observed clearly.
B. Ardiçoglu, G. Özbayoglu, Z. Özdemir, A. Yilmaz, Journal of Alloys and Compounds 418 (2006) 77-79

E0156 – Magnetically soft nanomaterials for high-temperature applications

Nanomaterials for high-temperature applications must meet two basic requirements: (i) very soft magnetic behaviour at elevated temperature, and (ii) stable properties at elevated temperature for a long time (application time). The latter requirement is related to thermal stability of nanocrystalline structure of these materials. The paper presents the current status of research in the field of magnetically soft nanocrystalline materials, highlighting the influence of alloy composition on magnetic properties and their stability at elevated temperatures during very long time annealing (several thousands of hours at temperature up to 550°C). It was found that modification of the alloys allows to tailor their chemical composition and manufacturing process to particular application temperature requirements. FINEMETs are the most suitable materials for application at temperature, T, up to 300°C, FINEMET modified by cobalt (Fe0.6Co0.4)73.5Cu1Nb3Si13.5B9 (at.%) for T = 300-350°C, NANOPERM for T = 350-400°C and HITPERM (Fe0.6Co0.4)86Hf7B6Cu1 for T = 400-550°C.
T. Kulik, J. Ferenc, A. Kolano-Burian, X.B. Liang, M. Kowalczyk, Materials Science and Engineering A 449-451 (2007) 397-400

E0166 – A novel simple method to stably synthesize Ti3AlC2 powder with high purity

In this work, a novel simple method is presented to synthesize highly pure Ti3AlC2 powder by heating 2TiC/Ti/Al (molar ratio) powder system between 1300°C and 1400°C for 15-30 min in flowing argon atmosphere. 2TiC/Ti/Al is selected as the raw material because of its much lower exothermal quantity than elemental 3Ti/Al/2C powder system in reacting process. The purity of Ti3AlC2 is not sensitive to the final temperature, soaking time or raw material scale. Its content is maintained around 97 wt.%, even though the scale of mixed raw materials vary from 5 g to 1000 g. The synthesized samples can be easily ground into powders with a mean particle size of 4.9 µm. Synthesis mechanism shows that both Ti2AlC and Ti3AlC2 will generate from the reaction among TiC, Ti and Al below 1200°C. Above 1300°C, Ti2AlC will continue to react with TiC and generate Ti3AlC2. The formation of Al liquid phase above 660°C is considered as a promoting factor in the reacting process.
C. Peng, C-A. Wang, Y. Song, Y. Huang, Materials Science and Engineering A 428 (2006) 54-58

E0165 – High temperature phase transition in Sm0.95MnO2.925

Samarium deficient SmMnO3 crystallizes in orthorhombic phase and it transforms to another orthorhombic phase at ~743 K. The above phase transformation was experimentally investigated by a variety of techniques like differential thermal analysis, dilatometry, high temperature X-ray diffraction and electrical conductivity measurements.
R.V. Wandekar, B.N. Wani, S.R. Bharadwaj, Journal of Alloys and Compounds 437 (2007) 53-57

E0164 – Crystal structure and thermal evolution of inedite alpha-Zr2O(PO4)2 and alpha-Hf2O(PO4)2

The structures of isotypic alpha-Zr2O(PO4)2 (S.G. I 2/m, a = 10.2726(6), b = 6.5957(3), c = 10.0665(5) Å, beta = 95.433(3)°, V = 679.00(6) Å3, Z = 4) and alpha-Hf2O(PO4)2 (S.G. I 2/m, a = 10.2301(3), b = 6.5819(2), c = 10.0075(5) Å, beta = 95.371(1)°, V = 670.87(3) Å3, Z = 4) have been resolved ab initio by Rietveld analysis. At variance with the beta-form, they show both MO6 and MO7 polyhedra (M = Zr, Hf), forming ribbons with the PO4 tetrahedra. A lattice energy calculation explains why the alpha-form is less stable than the beta-form, thus making the alpha-beta transition irreversible. However, the substitution of smaller HfIV for ZrIV allows to keep the alpha-framework up to 1500°C by stabilizing the MO6 octahedra.
G. Wallez, J-P. Souron, M. Quarton, Solid State Sciences 8 (2006) 1061-1066

E0175 – Influence of the Ti/Zr ratio and the synthesis route on hydrogen absorbing properties of (Ti(1-x)Zrx)Mn1.5V0.5 alloys

The hydrogenation properties of two pseudo-binary Ti(1-x)ZrxMn1.5V0.5 alloys with x=0.15 and 0.5 obtained by arc melting and mechanical alloying have been studied. All alloys crystallize in the hexagonal C14 Laves phase. Arc-melted alloys are microcrystralline and exhibit local variations of Ti and Zr contents which are not overcome by annealing treatments. As for milled alloys, agglomerated nanocrystallites (~9 nm in diameter) are obtained after subsequent thermal annealing at 800°C. For high Zr-contents, a better chemical homogeneity is obtained by the milling route. Whatever the synthesis route is, the hydrogen equilibrium pressure decreases with increasing Zr content due to cell-volume increase of the intermetallic compound. As concerns kinetics, very fast hydrogenation rates of few seconds are obtained at room temperature, particularly for milled alloys.
B. Villeroy, F. Cuevas, J. Bettembourg, P. Olier, M. Latroche, Journal of Physics and Chemistry of Solids 67 (2006) 1281-1285

E0174 – Homogeneity range and order-disorder transitions in R(1-x)Ni2 Laves phase compounds

The homogeneity range of R(1-x)Ni2 Laves phases (R=Ce, Gd, Tb) has been studied by X-ray diffraction, microprobe analysis and density measurements. In these compounds, the number of R vacancies varies as a function of the atomic number of the rare earth metal and the nominal composition. For R=Tb the number of vacancies varies by 0
V. Paul-Boncour, A. Lindbaum, M. Latroche, S. Heathman, Intermetallics 14 (2006) 483-490

E0172 – Characteristics of chabazite modified by hexadecyltrimethylammonium bromide and of its affinity toward chromates

The FTIR, XRD, SEM and equilibrium data concerning the chabazite modified by hexadecyltrimethylammonium bromide (HDTMA) are presented. The zeolite plays the role of surfactant carrier. Its sodium form is converted to surfactant form through its equilibration with aqueous solutions of HDTMA. It is established that HDTMA cations are incorporated into the chabazite structure via ion-exchange and Van der Waals forces. Gauche and trans conformers are recognised in alkyl chains arrangement of surfactant cations. HDTMA-chabazite is evaluated as efficient adsorbent for chromates with quick kinetics (equilibrium completed in 120 min) and high adsorption maximum a=0.00005 mol/g.
M. Majdan, S. Pikus, Z. Rzaczynska, M. Iwan, O. Maryuk, R. Kwiatkowski, H. Skrzypek, Journal of Molecular Structure 791 (2006) 53-60

E0183 – Thermal characterization of Cu60ZrxTi(40-x) metallic glasses (x = 15; 20, 22, 25, 30)

The crystallization behavior, the thermal stability and the microhardness of Cu60ZrxTi(40-x) amorphous alloys (x = 15; 20, 22, 25, 30) prepared by melt-spinning have been studied by means of differential scanning calorimetry (DSC), differential thermal analysis (DTA), X-ray diffraction (XRD) and microhardness tests. DSC analysis have confirmed the existence of glass transition, followed by a supercooled liquid region in all the compositions. However, depending on the Zr content, different crystallization behavior has been observed. The apparent activation energies of the crystallization processes have been determined and the obtained values indicate high thermal stability for all the alloys. XRD-patterns of the as-quenched samples showed a broad symmetric halo typical of a fully amorphous structure. Independently of the composition, after the first crystallization stage the XRD patterns present a structure similar to that of an amorphous one. But the final developed microstructure depends on the composition of the alloys. The addition of Zr has not shown significant differences in microhardness of the amorphous alloys, although they have exhibited good mechanical properties.
A. Concustell, M. Zielinska, A. Révész, L.K. Varga, S. Surinach, M.D. Baro, Intermetallics 12 (2004) 1063-1067

E0171 – Pt29Zn49, a complex defective AlB2-type derivative structure

The crystal structure of the title compound has been determined by X-ray diffraction means. Pt29Zn49 forms a complex superstructure of a defective AlB2-type derivative of the order 58: a = 279.0(1) pm, b = 11895.2(4) pm, c = 698.0(1) pm, space group Amm2, Z = 2. Ordering of vacancies is accompanied by a particular distortion of defective graphite-like 63 nets consisting exclusively of Zn atoms. The ordering induces a modulation of the structure along ah of an AlB2-type structure with a periodicity of nearly 12 nm. A mechanistic model is proposed elucidating how Pt29Zn49 evolves from the eutectoid decomposition of the inter-mediate high temperature precursor Pt7Zn12.
S. Thimmaiah, B. Harbrecht, Journal of Alloys and Compounds 417 (2006) 45-49

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

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

E0170 – Er3+-doped PbF2: Comparison between nanocrystals in glass-ceramics and bulk single crystals

An appropriate annealing of a GeO2-PbO-PbF2:ErF3 glass leads to the formation of a glass-ceramic, composed of Pb(1-x)ErxF(2+x) nanosized crystallites dispersed throughout an amorphous oxide matrix. These nanocrystallites are compared to Er3+-doped PbF2 bulk single crystals. The influence of the annealing temperature on the glass-ceramics characteristics is thoroughly investigated. For several glass-ceramics resulting from different heat treatments, the quantity of crystallized PbF2, as well as the segregation of Er3+ ions into the crystallites, has been studied through two methods: first, the study of the crystallographic characteristics and second, the evolution of the optical properties. It was evidenced that, for a heat treatment over 365°C, the whole PbF2:Er has completely crystallized and that the segregation of Er3+ ions into the crystallites was total. Strong interactions between Er3+ ions occur in the Pb(1-x)ErxF(2+x) single and nanocrystals, promoting cross-relaxation processes, under 488-nm excitation, and favouring the 660- (red) and 810-nm emissions at the expense of the 550-nm (green) one.
G. Dantelle, M. Mortier, G. Patriarche, D. Vivien, Journal of Solid State Chemistry 179 (2006) 1995-2003

E0181 – Electrical impedance determination of phase transitions in glasses and melts

The electrical impedances of glasses in the system BaO*Al2O3*B2O3 were studied in the temperature range from 550 to 1150°C using different heating and cooling rates. The specific conductivities were illustrated by fitting Arrhenius functions to the data and the derivative (-d ln ?/ d(1/kT)). In this system, the activation energy of the electrical conductivity depends on temperature. Crystallization of the melt affects the derivative. Depending on the specific conductivities and the respective activation energies of the liquid and the crystalline phase, maxima or minima (or both) are observed in the derivative. The melting of the crystalline phase during heating results in a maximum of the derivative. The shape of the derivative can be explained taking into account the specific conductivities and the attributed activation energies of the liquid and crystalline phase.
R. Keding, D. Tauch, C. Rüssel, Journal of Non-Crystalline Solids 348 (2004) 123-130

E0180 – Floating zone growth and characterization of Pr5Si3 single crystals

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

E0179 – Mixed crystals in the system Cu2MnGexSn(1-x)S4: Phase analytical investigations and inspection of tetrahedra volumes

Cu2MnGeS4 crystallizes orthorhombic in a wurtzite superstructure type while Cu2MnSnS4 crystallizes in a tetragonal sphalerite superstructure type. Lattice constants and thermal analyses of the solid solution series Cu2MnGexSn(1-x)S4 are presented. A two-phase region is found from Cu2MnGe0.3Sn0.7S4 to Cu2MnGe0.5Sn0.5S4. The cell volume of the mixed crystals increases with increasing Sn content. The melting points increase smoothly with increasing Ge content to x = 0:5 and then steeply for higher Ge contents. The single crystal X-ray structure analysis of Cu2MnGe0.55Sn0.45S4 is presented. The refinement converges to R = 0:0270 and wR2 = 0:0586, Z is 2. The volumes of the tetrahedra [MS4] (M = Cu, Mn, Ge, Sn) are calculated. From these volumes the differences in size of the tetrahedra are derived and compared with the corresponding differences in the end members of the solid solution series. It turns out that the resulting structure type in these materials depends on the volume differences of the constituting tetrahedra [MS4].
T. Bernert, M. Zabel, A. Pfitzner, Journal of Solid State Chemistry 179 (2006) 849-854

E0178 – Thermodynamic and structural analyses and mechanisms of the crystallisation of multi-alkane model mixtures similar to petroleum cuts

Thermodynamic and structural analyses were carried out by X-ray diffraction and differential thermal analyses as functions of the temperature on multi-alkane samples whose distribution of mole fractions shows a shape of the 'exponential decreasing' type, as observed in petroleum cuts. Nine samples, whose number of normal-alkanes, Cns, varied from 15 up to 23, were studied with continuous distributions of mole fractions going from the C22-C36 series to the C14-C36 series: C22 and C14 corresponding respectively to the first Cns of the two terminal series and C36 is always the last Cn of each series: each mixture differed from the previous sample by the addition of a lighter C'n-1). At the solid state and according to literature, the multi-alkane samples of C22-C36, C21-C36 and C20-C36 series are in a two-phase solid thermodynamic state, C19-C36 to C15-C36, three-phase, the broader distribution C14-C36, four-phase and the mixtures with numbers of Cns<11, single-phase. Thus, the Cns crystallise in the solid phase, where the thickness of molecule layers is compatible with their own chain length. The results allow for extracting the recurring structural and thermodynamic properties for these types of mixtures during crystallisation, and to clarify the molecular mechanisms involved in the number of observed solid phases, in the order of their appearance and in their thermodynamic and structural behaviour during the course of cooling from the liquid state.
A-J. Briard, M. Bouroukba, D. Petitjean, N. Hubert, J-C. Moise, M. Dirand, Fuel 85 (2006) 764-777

E0177 – Dielectric properties of sodium fluoride added kaolinite at different firing temperatures

The dielectric properties of NaF doped and undoped kaolinite were measured as a function of frequency in the range 40 kHz to 50 MHz. The epsilon', tan d and ?ac values are given as a function of firing temperature and NaF concentration. The addition of NaF increased the dielectric constant of pure kaolinite. However, the dielectric constant and ac conductivity of mullite obtained by the addition of NaF to kaolinite decreased from the value for pure kaolinite. Furthermore, the addition of NaF reduced the formation temperature of mullite from 1200 to 1000°C.
H. Zipkin, L. Israel, S. Güler, C. Güler, Ceramics International 33 (2007) 663-667

E0176 – Influence of Ce3+ doping on the structure and luminescence of Er3+-doped transparent glass-ceramics

Transparent glass-ceramics possess high thermal and mechanical properties, easy shaping allowing fibers elaboration and easy synthesis. However, previously studied Yb:Er-doped glass-ceramics do not appear efficient enough for optical amplification at 1.5 µm in the telecommunication window. So, the addition of Ce3+ doping ions was performed. Oxyfluoride glasses (GeO2-PbO-PbF2) doped with ErF3, YbF3 and CeF3 were prepared and heated above glass transition temperature to obtain transparent glass-ceramics. Such treatment brings about the precipitation of fluorite-type nanocrystallites embedded into an amorphous oxide phase. Differential Thermal Analysis shows evidence that CeF3 acts as nucleating agent for the heterogeneous crystallization of the beta-PbF2 phase. Through Transmission Electron Microscopy the morphology of these glass-ceramics was studied. Energy dispersive X-ray microanalysis and unit cell parameter study show a segregation of the three rare-earth ions inside the fluorite crystallites, forming a solid solution Pb(1-x-y-z)Er(x)Yb(y)Ce(z)F(2+x+y+z). The luminescence characteristics of the glass-ceramics doped with ErF3, YbF3 and CeF3 were compared to those of Yb:Er-doped glass-ceramics. CeF3 enables to dramatically decrease the up-conversion fluorescence of Er3+. The study of temporal dynamic of the 4 I 13/2 level of Er3+ reveals a cross-relaxation process between Er3+ and Ce3+. Hence, the presence of Ce3+ enables to decrease the Er3+ up-conversion fluorescence at the benefit of the fluorescence of interest at 1.5 µm, which is strongly enhanced.
G. Dantelle, M. Mortier, D. Vivien, G. Patriarche, Optical Materials 28 (2006) 638-642

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

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

E0196 – Study on some thermo-physical properties in Li2O-ZnO-SiO2 glass-ceramics

Lithium zinc silicate (LZS) glasses containing Li2O-ZnO-SiO2-Na2O-B2O3-P2O5 were prepared by conventional melt and quench technique and subsequently converted to glass-ceramics by controlled nucleation and crystallization. Both these parameters were determined by differential thermal analysis (DTA) studies. The effect of ZnO/(ZnO+SiO2) ratio on various thermo-physical properties was investigated by changing the ratio from 0.1 to 0.31. A number of crystalline phases have been identified by X-ray diffraction studies on the glass-ceramics including cristobalite (SiO2), lithium zinc silicate (Li3Zn0.5SiO4) and lithium silicate (Li2SiO3). Density (?) was found to increase from 2.62 to 2.82 g cm-3 while microhardness (Vicker's hardness number, VHN) decreased from 6.56 to 5.79 GPa with increase in ZnO/(ZnO+SiO2) ratio in the glass-ceramics. Average thermal expansion coefficient (TEC) in the temperature range 30-450°C increased from 125 x 10^(-7) to 185 x 10^(-7)/°C. The increase in expansion coefficient and decrease in microhardness are thought to be due to the formation of different phases which in turn influence the rigidity/bonding in the glass-ceramics. The material has been used for the fabrication of hermetic seal with copper. A study on the microstructure close to the interface of the glass-ceramics to metal is also carried out. The seal withstands a vacuum off ~10^(-6) Torr at helium leak rate of 3 x 10^(-10) Torr l/s.
B. Indrajit Sharma, Madhumita Goswami, P. Sengupta, V.K. Shrikhande, G.B. Kale, G.P. Kothiyal, Materials Letters 58 (2004) 2423-2428

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

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

E0195 – Processing route to an oxide dispersed iron/carbide composite

A new combination of techniques which should make it possible to produce oxide dispersed alloys by internal oxidation is suggested. The new technique has been used to produce a prototype alloy with a ferritic matrix containing fine (10-20 nm) oxides as well as a large volume fraction of carbides (about 40%). The microstructure indicates that it would be possible to produce an ironbase hard material with improved hot hardness. The technique is based upon an intermetallic starting material and utilises powder metallurgy and attrition ball milling.
H. Larsson, R. Erni, L-O. Nordberg, J. Agren, International Journal of Refractory Metals & Hard Materials 22 (2004) 159-167

E0184 – Preparation and crystallization of glasses in the system tetrasilicic mica-fluorapatite-diopside

The production of glasses whose composition ranged between tetrasilicic mica and fluorapatite-diopsite 50/50 (in wt.%) was investigated. Glass-ceramics were obtained by both bulk crystallization and sintering of glass powder compacts. The experimental results showed that increasing amount of apatite and diopsite components in the ternary system until 50% mica content generally caused decrease of melting temperature and increasing stability of glass against spontaneous crystallization during cooling after casting. Liquid immiscibility, whose features depend on the particular glass composition, characterized all the investigated glasses but it was more pronounced in the glasses with higher amount of apatite and diopsite components. The investigated glasses are preferably crystallized in bulk form between 700 and 900°C, resulting in formation of different combinations between mica, fluorapatite and diopsite, depending on the particular composition. The obtained glass-ceramics exhibited attractive aesthetics, structural integrity and dense structure.
D.U. Tulyaganov, S. Agathopoulos, H.R. Fernandes, J.M. Ventura, J.M.F. Ferreira, Journal of the European Ceramic Society 24 (2004) 3521-3528

E0194 – Crystallization behavior of Fe62Nb(8-x)ZrxB30 bulk amorphous alloy

The effect of Zr addition on the glass-forming ability has been investigated in the Fe62Nb(8-x)ZrxB30 bulk amorphous alloy system by thermal (differential scanning calorimeter (DSC) and differential thermal analysis (DTA)) and structural (X-ray diffractometry (XRD) and high-resolution transmission electron microscope (HRTEM)) analysis. Zr addition reduces the bulk glass-forming ability (BGFA) and changes the microstructure obtained after crystallization. The Kissinger method was used to estimate the activation energy (Ea) of crystallization. A strong correlation between Ea and BGFA parameters was observed. Among the crystallization products the metastable Fe23B6 phase appeared, which is probably a consequence of the Nb content in the alloy.
M. Shapaan, J. Labar, J. Lendvai, L.K. Varga, Materials Science and Engineering A 375-377 (2004) 789-793

E0193 – Crystallization behavior of (Fe(100-x)Cox)62Nb8B30 bulk amorphous alloy

The effect of Co addition on the glass-forming ability (GFA) has been investigated in the (Fe(100-x)Cox)62 Nb8B30 (x = 0, 33, and 50) bulk amorphous alloy system by differential scanning calorimeter (DSC). The thermal stability measured by the apparent activation energies decreased from about 5.5 to 4.5 eV upon Co addition. The glass-forming ability measured by the temperature interval Tx - Tg was decreased substantially compared to Fe62Nb8B30 alloy, but it is still large enough for practical applications. The DSC and DTA parameters, Tg, Tx, Tm and Tl were combined in different parameters, Tg/Tm, Tx/Tl and Tx/(Tg + Tl) and Tx/(Tl - Tg) to express the glass-forming ability. The cystallization products were studied by XRD. The metastable Fe23B6 crystallization product was found in all the alloys.
M. Shapaan, J. Gubicza, J. Lendvai, L.K. Varga, Materials Science and Engineering A 375-377 (2004) 785-788

E0192 – Influence of the wheel speed on the thermal behaviour of Cu60Zr20Ti20 alloys

The effect of the wheel velocity's strong influence on the glass forming ability (GFA), the thermal stability and the crystallization kinetics of ductile Cu60Zr20Ti20 ribbons has been studied. The samples were characterised by differential scanning calorimetry (DSC) using continuous heating and isothermal annealings, X-ray diffraction and microhardness. The DSC measurements revealed that the higher wheel speed results in a higher glass transition (Tg) and higher crystallization temperature (Ton). Independent of wheel speed, the crystallization takes place in a two-stage process. From the isothermal treatment, the crystallization kinetics was analysed using the Avrami model. The microhardness exhibits a linear relationship as a function of the crystallized volume fraction. A perfect solute mixture model of defect free nanoparticles embedded in an amorphous matrix was used to account for this strengthening mechanism.
A. Révész, A. Concustell, L.K. Varga, S. Surinach, M.D. Baro, Materials Science and Engineering A 375-377 (2004) 776-780

E0191 – Thermal properties of Hf-based metallic glasses

Recently new Hf-based multicomponent amorphous alloys have been developed based on empirical rules for large glass forming ability. These ribbons were obtained by melt-spinning a master alloy, composed of Group IVB elements (Ti, Zr, Hf) of the Periodic Table with additions of late transition metals such as Cu or Ni. One of the best knownbulk glass-forming alloy systems is based on (Zr/Ti)-(Cu/Ni)-Al, the addition of Al of the IIIA group with sp electrons and strong interactions with Zr is a key factor in reducing the critical cooling rate for glass formation. Hf is chemically similar to Zr but has a much higher melting temperature. Characterization of the as-quenched (Hf/Zr/Ti)-(Cu/Ni)-(Al/Ga)-(Si/Ge) ribbonswas carried out by X-ray diffraction and the thermal stabilitywas followed by differential scanning calorimetry and differential thermal analysis.
A. Révész, J-L. Uriarte, D. Louzguine, A. Inoue, S. Surinach, M.D. Baro, A.R. Yavari, Materials Science and Engineering A 375-377 (2004) 381-384

E0190 – Revised phase diagram for the Pt-Ti system from 30 to 60 at.% platinum

Alloys of the Ti-Pt system between 30 and 61 at.% Pt were studied using metallography with optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential thermal analysis (DTA). A phase of nominal composition Ti4Pt3, in the range 41.7-43.4 at.% Ptwas found in samples containing between 30 and 47 at.% Pt, andwas apparently formed by a peritectoid reaction between beta-TiPt and Ti3Pt at 1205 ± 10°C. The eutectic reaction betweenTi3Pt and -TiPtwas found to be at ~35 at.% Pt and 1424 ± 10°C, and theTi3Pt phase melted at circa 1500°C. The other phase boundaries agreed with the published literature, except that a slightly wider range was found at 1200°C for beta-TiPt.
T. Biggs, L.A. Cornish, M.J. Witcomb, M.B. Cortie, Journal of Alloys and Compounds 375 (2004) 120-127

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

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

E0188 – Calcium phosphates and glass composite coatings on zirconia for enhanced biocompatibility

Calcium phosphates (CaP) and phosphate-based glass (P-glass, xCaO-(0.55 x)Na2O-0.45P2O5 composition) composite coatings were obtained on a strong ZrO2 to improve biocompatibility, the mechanical strength and biological activity. Hydroxyapatite (HA) and P-glass mixed powder slurries were coated on the ZrO2 substrate, and subsequently heat-treated to obtain CaP- and P-glass composite coatings. The effects of glass composition (x=0.3, 0.4, 0.5 mol), mixing ratio of glass to HA (30%, 40%, 50% wt/wt), and heat treatment temperature (800°C, 900°C, 1000°C) on the coating properties were investigated. After heat treatment, additional calcium phosphates, i.e., dicalcium phosphate (DCP) and tricalcium phosphate (TCP), were crystallized, resulting in the formation of triphasic calcium phosphates (HA-TCP-DCP) surrounded by a glass phase. The relative amounts of the crystalline phases varied with coating variables. The higher heat treatment temperature and glass amount, and the lower CaO content in the glass composition rendered the composite coatings to retain the higher amounts of TCP and DCP while the initial HA decreased. These appearance of additional crystalline phases and reduction of HA amount were attributed to the combined effects, i.e., the meltingcrystallization of P-glass and the reaction between glass liquid phase and HA powder during thermal treatment. As a result of the glass phase in the composite coatings, their microstructures became much denser when compared to the pure HA coating. In particular, a completely dense structure was obtained at coating conditions with large amount of glass addition (50 wt%) at the glass composition of lower CaO content (0.3 mol CaO), and the following heat treatment above 800°C for 2 h. As a result, the adhesion strengths of the composite coating layers were significantly improved when compared to the pure HA coating. The highest strength of the composite coating was ~40 MPa, an improvement of ~80% with respect to the pure HA coating. The composite coatings showed much higher dissolution rates than the pure HA coating due to the newly formed crystallines (TCP and DCP) and the remaining glass phase. The osteoblast-like cells grew and spread actively on the composite coating samples. The proliferation numbers and alkaline phosphate (ALP) activities of the cells on the composite coatings were improved by ~30-40% when compared to Thermanox control and ZrO2 substrate, and were comparable to the pure HA coating. These findings suggested that the CaP and P-glass composites are potentially useful for hard tissue coating system, due to their morphological and mechanical integrity, enhanced bioactivity, and favorable responses to the osteoblast-like cells.
H-W. Kim, G. Georgiou, J.C. Knowles, Y-H. Koh, H-E. Kim, Biomaterials 25 (2004) 4203-4213

E0187 – Effect of Ce-Zr mixed oxides on the thermal stability of transition aluminas at elevated temperature

Ce-Zr mixed oxides is a kind of promoted oxygen storage capability material widely used in three-way catalysts. Various contents (10, 20, 30 and 40%) of Ce-Zr were physically mixed into the pure gamma-alumina for surface modification. The thermal stability of a series of Ce-Zr/Al2O3 supports was examined. Differential thermal analysis shows Ce-Zr mixed oxides increase the theta-alumina transformation temperature up to 1222°C. The powder X-ray diffraction studies show that minor theta-alumina phase still exists in the samples with > 20% Ce-Zr doping content after aging at 1050°C for 50 h. The best stabilizing effect is observed in the case of 20% Ce-Zr/Al2O3. Even after the accelerated aging test, it maintains an acceptable specific surface area (24m2 g-1) in relation with the delayed transformation of theta into alpha-alumina.
X. Wu, B. Yang, D. Weng, Journal of Alloys and Compounds 376 (2004) 241-245

E0207 – Synthesis and properties of biodegradable plastic films obtained by microwave-assisted cellulose acylation in homogeneous phase

Microwave-induced esterification of cellulose in homogeneous phase has been investigated. Cellulose was first solubilized in the solvent system LiCl/N,N-dimethylacetamide and then esterified by lauroyl chloride in the presence of N,N-dimethyl-4- aminopyridine. Microwave activation resulted in a drastic reduction of reaction time (1 min) compared to conventional heating. The mechanical and thermal properties of the plastic films obtained were established and a preliminary study of their biodegradability has been performed.
C. Satgé, R. Granet, B. Verneuil, P. Branland, P. Krausz, C. R. Chimie 7 (2004) 135-142

E0206 – Phosphate glasses for tissue engineering: Part 2. Processing and characterisation of a ternary-based P2O5-CaO-Na2O glass fibre system

This paper presents the results of a study of the thermal properties, solubility and dimensions of a range of phosphate-based glass fibres (PB-GFs). The glass compositions were limited by fixing the P2O5 content to 45, 50 and 55 mol%, and varying the CaO mol% at 30, 35 and 40. PB-GFs were obtained from the 50 and 55 mol% P2O5 compositions; however, we were unable to obtain fibres from the 45 mol% compositions. This was linked to the cross-linked density, network connectivity and average chain length of the compositions studied. With regards to thermal parameters investigated, initial data showed an increase of the Tg and crystallisation temperatures with increasing CaO mol% at each fixed phosphate content. A decrease in Tg temperatures was also observed with increasing P2O5 content to 55 mol%. The crystallisation temperatures obtained for compositions with fixed phosphate at 55 mol%, showed a reverse pattern, with a decrease in values as compared to the fixed 50 mol% phosphate compositions. The diameters of the fibres all decreased with increasing RPMs as expected, and the solubility also increased with increasing RPMs. This was related to the increased surface area of the higher RPM fibres. There was also a decrease seen in solubility with increasing CaO mol%.
I. Ahmed, M. Lewis, I. Olsen, J.C. Knowles, Biomaterials 25 (2004) 501-507

E0205 – Phosphate glasses for tissue engineering: Part 1. Processing and characterisation of a ternary-based P2O5-CaO-Na2O glass system

This paper presents the results of a study of the thermal properties, X-ray powder diffraction (XRPD), NMR and solubility of a range of phosphate-based glasses. Ion release and pH measurements were also obtained. The compositions were limited by fixing the P2O5 mol% content at 45, 50 and 55 mol%, and varying the CaO mol% at 30, 35 and 40 mol%. Initial data collected from thermal analysis showed an increase in the Tg values, with increasing CaO mol%, as expected. An increase in crystallisation temperatures with increasing CaO mol% was also observed, with sharp peaks indicating the presence of single and/or double phases. Initial XRPD data revealed that the 45mol% P2O5 precipitated a calcium bridged trimetaphosphate (Na4Ca[PO3]6) at the sodium oxide contents of 25 and 20 mol%, but at the 15mol% level two phases formed, NaCa[PO3]3 and Ca2P2O7. The 50 mol% P2O5 compositions showed two sodium phosphate-rich phases [NaCa(PO3)3 and NaPO3] for the lower calcium containing compositions, and a calcium phosphate phase [CaP2O6] for compositions with higher CaO mol%. The 55 mol% P2O5 compositions, exhibited similar phases for the lower calcium containing compositions, and a single calcium phosphate phase (CaP2O6) was identified for the higher calcium containing composition. NMR analysis revealed the presence of Q1 and Q2 species in the 45mol% P2O5 compositions, and Q2 species present in the 50 and 55mol% P2O5 compositions. The non-linear data obtained from the thermal and solubility analyses conducted were attributed to the packing density of the 45mol% P2O5 compositions. The solubility was seen to decrease with increasing CaO mol%, for all the glasses investigated, and all the compositions showed a gradual decrease in pH with time, and this was accounted for by the release of Na+ and Ca2+ ions into solution.
I. Ahmed, M. Lewis, I. Olsen, J.C. Knowles, Biomaterials 25 (2004) 491-499

E0204 – Thermal stability and glass forming ability of cast iron-phosphorus amorphous alloys

The effect of P addition on the thermal stability and on the glass forming ability (GFA) of bulk amorphous sheets and melt-spun ribbons of cast iron Ci(100-x)Px (x = 1.56, 3.1, 4.63, 6.14, 7.63, 9.1 at.%) was studied by calorimetric measurements. Bulk amorphous sheets of 1mm x 4mm transverse cross-section were prepared by centrifugal copper mold casting. For the as-quenched ribbons, it was found that only for x = 7.63 and 9.1 glass transition temperatures Tg were detected. The reduced glass transition temperatures Tg/Tl (where Tl is the liquidus temperature) are 0.542 and 0.551, respectively. The as-quenched melt-spun ribbons and the bulk amorphous sheets have nearly the same thermal transition and glass forming ability characteristics.
M. Shapaan, A. Bardos, L.K. Varga, J. Lendvai, Materials Science and Engineering A366 (2004) 6-9

E0203 – The crystal structure of zeta1-Al3Cu4

The crystal structure of the zeta1-phase Al3Cu4 was determined by means of X-ray powder diffraction: a = 812.67(3) pm, b = 1419.85(5) pm, c = 999.28(3) pm, space group Fmm2, Pearson symbol oF88-4.7, RI = 0.0633. The structure represents a distinctive 2a x 2?3a x 2c superstructure of a metal-deficient Ni2In-related structure. The ordering of the minor component and the vacancies in the atomic layers of hexagonal topology fulfill the principle of maximal self-avoidance.
L.D. Gulay, B. Harbrecht, Journal of Alloys and Compounds 367 (2004) 103-108

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

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

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

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

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

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

E0199 – Observation of nucleation effect on crystallization in lithium aluminosilicate glass by viscosity measurement

The crystal nucleation effect in lithium aluminosilicate glasses was investigated by the viscosity measurement with aid of the fiber elongation method. The abrupt increase of viscosity due to the crystallization of glass was observed in viscosity-temperature curve but the minimum viscosity temperature (Tn) related with crystallization showed a strong dependence on the nucleation state such as nucleation temperature, nucleation time and heating rate. The results by viscosity agreed well with those of DTA. The nucleation effect on the microstructure of glass-ceramics was also discussed. Finally, the nucleation effect on the crystallization kinetics was approached quantitatively by calculating the crystal volume from viscosity value.
K-D. Kim, S-H. Lee, H-K. Ahn, Journal of Non-Crystalline Solids 336 (2004) 195-201

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

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

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

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

E0218 – Phase transformation temperatures of pure iron and low alloyed steels in the low temperature region using DTA

The paper reports a study of temperatures of phase transitions of nine samples of real grades of low-alloyed steels, including one sample of pure iron, using differential thermal analysis. Temperatures of phase transitions were measured in the low-temperature interval (20–10008C). Investigated systems were analysed at selected rates of heating/cooling and then temperatures of phase transitions for zero heating/cooling rate were determined. The results obtained are compared with temperatures of the equilibrium metastable diagram Fe–C, with results from the software IDS and with temperatures of phase transitions calculated according to relations published in available literature. It follows from the results that differences, sometimes considerable ones, still exist between experimental and theoretical data, which implies the necessity for further systematic research in this area.
Bedrich Smetana, Simona Zlá, Jana Dobrovská, Petr Kozelsky, Int. J. Mat. Res. (formerly Z. Metallkd.) 101 (2010) 3

E0217 – Contribution à l’étude de la précipitation des phases intermétalliques dans l’alliage 718

Many structural alloys are strengthened by the presence of precipitates in the grains or at grain boundaries. Nickel based superalloys often present an austenitic matrix in which ordered intermetallic phases precipitate. In the alloy Inconel 718, one can find ?' L12 cubic ordered precipitates together with the compound Ni3Nb in its metastable form ?" (D022 - tetragonal) or the stable phase ? (D0a - orthorhombic). The incidence of those precipitates on macroscopic properties of the alloy 718 is well known and widely used in industrial applications. However the mechanisms responsible for the precipitation and transformation of these phases are not fully understood, which motivated the present study. The alloy microstructure has been observed by optical microscopy (OM) and electron microscopy (scanning and transmission, SEM and TEM) in the as received state as well as after heat treatment (isothermal and anisothermal). Differential thermal analysis (DTA) was used to determine the precipitation and dissolution temperatures of the phases ?', ?" and ?. Various precipitation microstructures were obtained by heat treatments based on available TTT diagrams. Some of the structural defects present in ?" and ? precipitates have been characterised by lattice imaging TEM observations. It is shown that stacking faults in phase can act as a seed for the germination of ?. The structure of the interface and the orientation defects in lamellae suggest that the growth of phase occurs directly from the matrix (and not by transformation of the ?’’ phase).
Aliou NIANG, Thèse Université de Toulouse, 2010

E0216 – Thermophysical and structural study of IN 792-5A Nickel based superalloy

The presented paper deals with study of phase transformations temperatures of nickel based superalloy IN 792-5A with application of DTA – method and use of experimental laboratory system for simultaneous thermal analysis SETARAM Setsys 18TM. Samples taken from as-received state of superalloy were heated with controlled ramp rates (1, 5, 10 and 20 °C·min-1) and immediately after melting they were cooled with the same controlled ramp rate. The samples before and after DTA-analysis were also subjected to the phase analysis with use of scanning electron microscopy on the microprobe (JCXA 733) equipped with energy dispersive analyser EDAX (EDAM 3).
S. Zla, J. Dobrovska, B. Smetana, M. Žaludova, V. Vodarek, K. Konecna, METABK 2010

E0215 – Application of high temperature DTA to micro-alloyed steels

Paper deals with investigation of phase transitions temperatures for selected real grades of micro-alloyed steels. Temperatures of characteristic phase transitions were obtained using Setaram SETSYS 18TM. The DTA technique was selected for the study of micro-alloyed steels. Temperatures of phase transitions (liquidus, solidus etc.) were obtained. Influence of admixed and alloyed elements on shift of temperatures was investigated. Resulting data were compared with temperatures of phase transitions of Fe-C, Fe-Mn systems and with temperatures calculated according to relations published in available literature. Thermodynamic-kinetic solidification model IDS was used to calculate characteristic equilibrium temperatures of investigated systems.
B. Smetana, S. Zla, M. Žaludova, J. Dobrovska, P. Kozelsky, METABK 2010

E0214 – Direct measurements of fusion and phase transition enthalpies in lanthanum oxide

Enthalpies of high-temperature phase transitions and fusion in lanthanum oxide (La2O3) were directly measured for the first time. Three samples were prepared by laser melting, sealed in tungsten crucibles, and heated in a differential thermal analyzer calibrated by melting Al2O3. Transformation enthalpy of La2O3 from A to H phase is 23 ± 5 kJ/mol at 2046 ± 5 °C and from H to X phase is 17± 5 kJ/mol at 2114 ± 5 °C. Lanthanum oxide melts at 2301 ± 10 °C, with enthalpy of fusion of 78 ± 10 kJ/mol.
Sergey V. Ushakova, Alexandra Navrotsky, J. Mater. Res., Vol. 26, No. 7, Apr 14, 2011

E0213 – Crystallization study of Na–Gd phosphate glass using non-isothermal DTA

Na–Gd phosphate glasses doped with Ce3+ are intensively studied due to their high intensity radioluminescence. Crystallization kinetics of glass with nominal composition of NaGd(PO3)4 was investigated using non-isothermal DTA at heating rates between 10 and 115 K min–1 and evaluated by the Kissinger and Ozawa peak methods. The activation energy for crystallization was determined for heating rates lower than 72 Kmin–1 as 789.91 and 802.77 kJmol–1 by using the Kissinger and Ozawamethods, respectively. Formation of nuclei, their dimensions and movement of the crystallization front were observed using isothermal optical thermomicroscopy
K. Nitsch, M. Rodová, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 1, 137–140

E0212 – Effect of Na2O/K2O substitution on thermophysical properties of PbO based phosphate glasses

PbO based phosphate glasses having composition 40P2O5 12Al2O3 6B2O3 9PbO xNa2O (33–x)K2O (x=0–33) [F=Na/(Na+K)] have been prepared using conventional melt quench technique. Density, morphology, thermal expansion coefficient ( ) and glass transition temperature (Tg) were studied as a function of Na/(Na+K) ratio. Formation of transparent, bubble free and clear glass was observed up to x=18 mol%. Density was found to vary from 2.70 to 3.69 g cm–3. The significant changes were noticed in external morphologies at temperatures corresponding to softening, half ball and melting points under high temperature microscope for three compositions (x=0, 10 and 15 mol%). These glasses recorded the softening and half ball temperatures in the range 454–470°C and 523–576°C respectively and melting temperatures agree well with DTA studies within the experimental limits. Glass transition temperature showed a broad maxima while thermal expansion coefficient (TEC) a broad minima around Na/(Na+K)=0.54. This behaviour is explained on the basis of bond formation/phase separation.
K. V. Shah, M. Goswami, D. K. Aswal, V. K. Shrikhande, S. K. Gupta, G. P. Kothiyal, Journal of Thermal Analysis and Calorimetry, Vol. 89 (2007) 1, 153–157

E0211 – Phase transition in LAMOX type compounds

La2Mo2O9 (LMO) was synthesized at lower temperature 973 K (LT-phase) by ceramic route. Differential thermal analysis (DTA) scan of LT-phase of LMO showed ??? transition at 843 K during heating and ??? conversion via a metastable g-phase during cooling. This was also confirmed by thermo-dilatometry and impedance spectroscopy. La2Mo1.95V0.05O9–d (LMVO), La1.96Sr0.04Mo2O9–d (LSMO) and La1.96Sr0.04Mo1.95V0.05O9–d (LSMVO) were prepared in a similar way. These compounds exhibited ??? transition on heating with shift in transition temperature, but the existence of ?-phase during cooling disappeared. Substitution increased the ionic conductivity of ?-phase and reduced that of ?-phase.
M. Ali (Basu), B. N. Wani, S. R. Bharadwaj, Journal of Thermal Analysis and Calorimetry, Vol. 96 (2009) 2, 463–468

E0221 – Effect of TiO2 addition on the crystallization and tribological properties of MgO–CaO–SiO2–P2O5–F glasses

The kinetic parameters including the activation energy for crystallization (E), the Avrami parameter (n) and frequency factor (?) of a glass in the MgO–CaO–SiO2–P2O5–F system were studied using non-isothermal differential thermal analysis (DTA) with regard to small amount of TiO2 additions. It has been shown that the role of TiO2 changes from a glass network former to a glass network modifier with increasing TiO2 content in this system. The kinetic parameters of the crystallizing phases, apatite and wollastonite, indicated changes accompanied with TiO2 additions, implying that the TiO2 is an effective nucleating agent for promoting the crystallization of apatite and wollastonite. The most effective addition is of about 4 wt% TiO2 in this system. The wear rate and friction coefficient decreased from 1.8 ± 0.1 to 0.9 ± 0.2 and 0.87 to 0.77, respectively, when 4 wt% TiO2 was incorporated to the base glass
Jongee Park, Abdullah Ozturk, Thermochimica Acta ,470 (2008) 60–66

E0210 – Application of high temperature DTA technique to Fe based systems

The paper deals with the study of phase transformation temperatures of Fe (Fe-C) based metallic alloys. Influence of heating/cooling rate and composition on shift of phase transformation temperatures is investigated in this paper. Six samples with graded carbon content were investigated. Plasma and vacuum melting was performed to prepare alloys. Liquidus-solidus and ??? region was studied. Temperatures of phase transformations were obtained using DTA and Setaram Setsys 18TM laboratory system. DTA experiments of prepared alloys were conducted under inert atmosphere (Ar, >6N). Controlled rate of heating/cooling of alloys was conducted: 2, 4, 7, 10, 15, 20 K min-1. Aproximation to the equilibrium conditions was achieved. The extrapolation of obtained phase transformation temperatures to a zero heating/cooling rate was performed. Comparison of obtained experimental data with data presented in the literature and IDS results was carried out. It follows from copmarison of obtained results with accessible data in the literature the lack of these data and differencies between them. The knowledge of simple binary system Fe-C behaviour is important for the description of more complex systems; ternary, quaternary,… and multicomponent (steels) also. This study is the base of wide research activity at our department in the future.
Bed!ich Smetana, Monika Žaludova, Simona Zla, Jana Dobrovska, Michal Cagala, Ivo Szurman, Daniel Petlak, Metal 2010, Roznov pod Radhostem,Czech Republic

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

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

E0209 – Investigation of relevant phase diagrams for high temperature solder materials: The binary systems Cu-Sn and Cu-Sb

Although solders in the electronic industry have only a relative small contribution to the worldwide consumption of lead, the recycling of the electronic waste is complicated and thus it pollutes the environment. Therefore the electronic industry has tried to substitute the poisonous lead in the solders for less harmful materials during the last decade. Interested alloys are those ones which could include the components of the lead free solder and the substrate materials. This work concentrates on the experimental research of the binary systems Cu-Sn and Cu-Sb. Experimental techniques are the powder X-ray diffraction at normal and higher temperatures (PXRD / HTPXRD), thermal analysis (DTA) and metallographic methods (EPMA / ESEM).
Siegfried Fürtauer, Thesis, University of Vienna, 2010

E0219 – Investigation of Selected Thermo-physical Properties of Ternary Sn-Zn-Al Alloys Using DTA

The paper deals with the investigation of temperatures and latent heats of phase transformations of two binary alloys Sn-Zn and five ternary Sn-Zn-Al alloys using the DTA method. The investigated alloys belong to the area of the so called eutectic „valley“ of the Sn-Zn-Al system. DTA of investigated samples was performed at the rate of heating/cooling of 4°C/min. In this way there were obtained temperatures of phase transformations of the ternary system Sn-Zn-Al, temperature of ternary eutectics TE1 197.6°C, temperature of liquidus, and other transformations. Latent heats of melting and solidification were calculated. Latent heat of melting of alloys varies within the interval 71-91 J?.g-1, solidification within the range 73-99 J?g-1. Theoretical isoplethic phase diagrams were created with use of the software MTData and Pandat. Experimental data were compared with the calculated temperatures. It follows from bibliographic searches that description of behaviour of ternary system Sn-Zn-Al is still not quite known. The Sn-Zn-Al alloys could become a suitable alternative substitute of lead based solders for temperatures up to 350°C.
Bed?ich Smetana, Simona Zlá, Jaromír Drápala, Aleš Kroupa, Kristina Pe?inová, Rostislav Burkovi?, Neželezné kovy a slitiny, Hutnické listy ?.1/2010, ro?. LXIII

E0208 – The Structure and Stability of High Temperature Intermetallic Phases for Application within Coating Systems

The reduction of noise and emissions is becoming increasingly important in civil aircraft jet engines as well as requirements for reduced fuel consumption and improved efficiency. This has resulted in the drive towards increasing turbine entry temperatures and the development of thermal barrier coatings (TBCs). Due to the effectiveness of the platinum-modified nickel aluminides currently used as bond coat layers for Ni-based superalloy TBCs, higher temperature ruthenium-containing bond coat layers are being examined as a possible low cost alternative to platinum.The aim of this research was to examine the stability of various phases within platinum and ruthenium-containing multilayer systems formed during the above reaction process and to determine the most stable intermetallics for inclusion in future coating systems. Foil samples were manufactured using multilayer sputter coating methods and the exothermic formation of these phases was examined using differential scanning calorimetry. The identification of the phases formed was carried out using X-ray diffraction.
Tracey Roberts, Thesis, Cranfield University November 2009

E0239 – Study of DTA method experimental conditions and of their influence on obtained data of metallic systems

Differential thermal analysis (DTA) is one of the methods that are suitable for obtaining of thermo-physical and thermo-dynamical data. This method enables determination of temperatures and latent heats of phase transformations of metallic systems. This paper deals with the influence of the experimental conditions settings of the used DTA method on the obtained data. The paper is focused on the study of heating rate and sample mass influence on shift of phase transformations’ temperatures of Fe sample. Research was aimed at high temperature region. Melting region was studied. DTA measurements were realised using Setaram Setsys 18TM laboratory system. Controlled heating of Fe samples (with different mass) was conducted at the following rates: 1, 2, 5, 10, 20 K/min. On the basis of adjusted experimental conditions (different heating rates and different sample masses), the experimental data set was obtained and corresponding dependencies were derived. Using corresponding dependencies the corrections can be applied to reduce the influence of experimental conditions on studied data of investigated alloys (samples). Application of derived dependencies can substantially lead to reduction (minimization) of the influence of experimental conditions, and extrapolation to the so called “zero” mass and “zero” heating rate is possible.
Monika Žaludova, Bed?ich Smetana, Simona Zla, Jana Dobrovska, Karel Gryc, Karel Michalek, Rostislav Dudek, Metal 2012 conference, 23-25. 5. 2012, Brno, Czech Republic

E0228 – Electrical properties of some Y2O3 and/or Fe2O3-containing lithium silicate glasses and glass-ceramics

The ac electrical properties of some lithium silicate glasses and glass-ceramics containing varying proportions of Y2O3 and/or Fe2O3 were measured to investigate their electronic hopping mechanism. There is a clear variation of these properties with composition. The obtained results were related to the concentration and role of Y2O3 and/or Fe2O3 in the lithium silicate glass structure. In crystalline solids the electrical properties data obtained were correlated to the type and content of the mineral phases formed as indicated by X-ray diffraction analysis (XRD). The conductivity, dielectric constant and dielectric loss of the studied glasses were studied using the frequency response in the interval 30 Hz–100 KHz and the effect of compositional changes on the measured properties was investigated. The measurements revealed that the electrical responses of the samples were different and complex. The addition of Y2O3 generally, decreased the ac conductivity, dielectric constant and dielectric losses of the lithium silicate glasses. The addition of Fe2O3 in Y2O3-containing glasses increases the conductivity, while, the dielectric constant and dielectric losses were found to be decreased. However, the addition of Fe2O3 instead of Y2O3 led to decrease the ac conductivity and increased their dielectric constant and dielectric losses. The obtained data were argued to the internal structure of the lithium silicate glass and the nature or role-played by weakness or rigidity of the structure of the sample. Lithium disilicate-Li2Si2O5, lithium metasilicate-Li2-SiO3, two forms of yttrium silicate Y2Si2O7 & Y2SiO5, iron yttrium oxide-YFeO3, lithium iron silicate-LiFeSi2O6 and a-quartz phases were mostly developed in the crystallized glasses. The conductivity of the crystalline materials was found to be relatively lower than those of the glass. At low frequency, as the Y2O3 content increased the ac conductivity, dielectric constant and dielectric loss data of the glass-ceramics decreased. However, the addition of Fe2O3 to the Y2O3 containing glass-ceramic led to increase the conductivity. The addition of high content of Fe2O3 instead of Y2O3 in the glass ceramic led to increase the ac conductivity.
Mohamed M. Gomaa, Hussein Darwish, Saad M. Salman, J Mater Sci: Mater Electron (2008) 19, 5–15

E0238 – Crystallization and dielectric and optical properties of borate glasses (1 ? x)Na2B4O7 + xNb2O5

The crystallization and dielectric and optical properties of glasses (1 ? x)Na2B4O7 + xNb2O5, where x = 0.15–0.35, have been studied. The formation of structural entities based on NbO6 octahedra in the glass has been detected by Raman spectroscopy. In the thermally poled glass, a layer with nonlinear optical properties is formed under the anode surface. The nonlinear optical properties of the poled sample have been studied by the second harmonic generation method using laser radiation. The nonlinear optical coefficient d 33 for the poled glass with the maximal content of niobia is 0.1 pm/V.
A. P. Malakho, S. Yu. Stefanovich, V. A. Morozov, B. I. Lazoryak, E. Fargin, V. Rodriguez, Russian Journal of Inorganic Chemistry, 2007, Vol. 52, No. 3, pp. 301–307

E0227 – In vivo behavior of bioactive phosphate glass-ceramics from the system P2O5–Na2O–CaO containing TiO2

Soda lime phosphate bioglass-ceramics with incorporation of small additions of TiO2 were prepared in the metaphosphate and pyrophosphate region, using an appropriate two-step heat treatment of controlled crystallization defined by differential thermal analysis results. Identification and quantification of crystalline phases precipitated from the soda lime phosphate glasses were performed using X-ray diffraction analysis. Calcium pyrophosphate (b-Ca2P2O7), sodium metaphosphate (NaPO3), calcium metaphosphate (b-Ca(PO3)2), sodium pyrophosphate (Na4P2O7), sodium calcium phosphate (Na4Ca(PO3)6) and sodium titanium phosphate (Na5Ti(PO4)3) phases were detected in the prepared glass-ceramics. The degradation of the prepared glass-ceramics were carried out for different periods of time in simulated body fluid at 37 °C using granules in the range of (0.300–0.600 mm). The released ions were estimated by atomic absorption spectroscopy and the surface textures were measured by scanning electron microscopy. Evaluation of in vivo bioactivity of the prepared glass-ceramics was carried through implanting the samples in the rabbit femurs. The results showed that the addition of 0.5 TiO2 mol% enhanced the bioactivity while further increase of the TiO2 content decreased the bioactivity. The effect of titanium dioxide on the bioactivity was interpreted on the basis of its action on the crystallization process of the glass-ceramics.
Ahmed Soltan Monem, Hatem A. ElBatal, Elsayed M. A. Khalil, Moenis A. Azooz, Yousry M. Hamdy, J Mater Sci: Mater Med (2008) 19, 1097–1108

E0237 – Cu9Ni6Sn: Determination of Phase Transformation at High Temperature

The copper rich corner of the CuNiSn system is frequently studied for the high tensile strength and good electrical conductivity of the alloys. In this study, we focus on the phase transfor- mations at high temperature. The incipient melting is studied in some detail just below 1000 °C since the presence of an unexpected peak at 985 °C on the DTA’s thermograms is detected.
A. Deraisme, C. Servant, D. Pachoutinsky, Y. Bienvenu, J.-D. Bartout, L.-T. Mingault, P. Bertrand, R. Bailly, Journal of Phase Equilibria and Diffusion Vol. 31 No. 2 2010

E0226 – Development and bioactivity evaluation of bioglasses with low Na2O content based on the system Na2O–CaO–MgO–P2O5–SiO2

Osteoconductive bioglasses, free of K2O and Al2O3 and with content of Na2O lower than 10 mol%, were designed based on the ratio (SiO2 + MgO)/(P2O5 + CaO + Na2O) in the system Na2O–CaO–MgO–P2O5–SiO2. The developed glasses have shown a strong potential for the formation of hydroxycarbonated apatite (HCA) in vitro. The particles of HCA aggregates tend to be of finer size with increasing the ratio of (SiO2 + MgO)/(CaO + P2O5 + Na2O) in the glass chemical composition indicating significant bioactivity. Critical size bone defects created in the femurs of albino adult female rats, and grafted with the glass particles for 12 weeks post implantation, were completely healed by filling with mineralized bone matrix without infection showing a strong potential for new bone formation in vivo. Osteoblasts and osteocytes were observed close to the surface of the granular implants with active areas of bone deposition, resorption and remodelling. The bioglass with lowest (SiO2 + MgO)/(CaO + P2O5 + Na2O) ratio has shown the highest bioactivity while the bioglass with the highest (SiO2 + MgO)/(CaO + P2O5 + Na2O) has shown the lowest bioactivity. The newly formed bone in vivo has shown a similar structure to that of the original bone as indicated by the histology and microstructural results. In addition, Ca/P molar ratio of the newly formed bone was found to be (~1.67), which is similar to that of the original bone.
Emad El-Meliegy, Esmat M. A. Hamzawy, Abeer M. El-Kady, Aida Salama, Ahalam El-Rashedi, J Mater Sci: Mater Med (2012) 23, 2069–2080

E0236 – Influence of the nature and porosity of different supports on the acidic and catalytic properties of H3PW12O40

In order to obtain highly dispersed heteropolyacid (HPA) species, H3PW12O40 was supported on various supports exhibiting different porosities and surface chemical properties. Amorphous and monoclinic amphoteric zirconias, activated montmorillonite (AC) and hexagonal silica (HMS) were chosen as supports. It was observed that the zirconia support partly decomposed HPA at low coverage, giving the lacunary anion PW11O7?39 , due to the reaction with basic hydroxyl groups, whereas montmorillonite and HMS did not. Catalytic properties for n-butane to isobutane isomerisation at 473 K and propan-2-ol decomposition at 353 K were compared for all samples as a function of HPA loadings and compared to data already published on bulk H3PW12O40 and Cs1.9H1.1PW12O40 samples. It was found for HPA/AC samples that, although their activity for propan-2-ol decomposition varied linearly with HPA loading, their activity for n-butane isomerisation was very weak, which indicates a weaker acid strength by supporting the HPA. This is probably due to the exchange of protons from the HPA by the exchangeable cations of the montmorillonite, the new protons associated with the clay being much less acidic. It also appeared, when comparing with catalytic data already published on for HPA/HMS, that HMS was the best support for HPA without modifying appreciably its catalytic and thus their acid properties, the HPA being certainly bonded to the HMS walls by hydrogen bonding. Assuming a diameter of 1.2 nm for each Keggin anion, the turnover frequency (TOF) values for n-butane isomerisation at 473 K were calculated per surface Keggin species for HPA/HMS, bulk H3PW12O40 and Cs1.9H1.1PW12O40, and were found to be equal to 155, 113 and 100 × 10?5 s?1, respectively, and thus to be very close, showing that the acid strength of the three samples was comparable. It was found to equal only 3.4×10?5 s?1 for the HPA/AC sample, in agreement with a weaker acid strength. At last, mesoporosity of the support was found to favour n-butane isomerisation reaction.
Cédric Trolliet, Gisèle Coudurier, Jacques C. Védrine, Topics in Catalysis Vol. 15, No. 1, 2001

E0225 – Titanium—hydroxyapatite porous structures for endosseous applications

Materials for uncemented endosseous implants have to assure an as short as possible osseointegration time. Thus, a material with both surface bioactivity and a porous outer structure can become a preferred choice for this type of applications. This paper presents a class of titanium-base PM composites, reinforced with particulate hydroxyapatite. Raw materials were titanium powder, obtained through hydriding—milling—dehydriding, with the grain size of 63–100?m, and sol-gel hydroxyapatite (HA) powder, produced by the reaction between Ca(NO3)2·4H2O and (NH4)2HPO4. Blends with 5 to 50% HA were prepared and pressed in a rigid die, producing single composition or gradual composition samples. The applied pressure was of 400, 500 or 600 MPa. Sintering was performed in vacuum, at 1160 ?C. All samples, although well sintered, displayed swelling during sintering, due to diffusion into the matrix. The increase in volume is more severe for higher amounts of HA in the green compacts and for higher applied compaction pressure. Compacts with a gradual increase of the HA content are recommended from the functional and mechanical point of view, but the increase should be slow, not to produce interlayer cracks. The outer surface shows interconnected pores, suitable for the ingrowth of vital new bone.
C. Popa, V. Simon, I . Vida-Simiti, G. Batin, V. Candea, S. Simon, Journal of Materials Science: Materials in Medicine 16 (2005) 1165-1171

E0235 – Development and characterization of glass-ceramic sealants in the (CaO-Al2O3-SiO2-B2O3) system for Solid Oxide Electrolyzer Cells

The efficiency of glass-ceramic sealants plays a crucial role in Solid Oxide Electrolyzer Cell performance and durability. In order to develop suitable sealants, operating around 800 °C, two parent glass compositions, CAS1B and CAS2B, from the CaO-Al2O3-SiO2-B2O3 system were prepared and explored. The thermal and physicochemical properties of the glass ceramics and their crystallization behavior were investigated by HSM, DTA and XRD analyses. The microstructure and chemical compositions of the crystalline phases were investigated by microprobe analysis. Bonding characteristic as well as chemical interactions of the parent glass with yttria-stabilized zirconia (YSZ) electrolyte and ferritic steel-based interconnect (Crofer!) were also investigated. The preliminary results revealed the superiority of CAS2B glass for sealing application in SOECs. The effect of minor additions of V2O5, K2O and TiO2 on the thermal properties was also studied and again demonstrated the advantages of the CAS2B glass composition. Examining the influence of heat treatment on the seal behavior showed that the choice of the heating rate is a compromise between delaying the crystallization process and delaying the viscosity drop. The thermal Expansion Coefficients (TEC) obtained for the selected glass ceramic are within the desired range after the heat treatment of crystallization. The crystallization kinetic parameters of the selected glass composition were also determined under non-isothermal conditions by means of differential thermal analysis (DTA) and using the formal theory of transformations for heterogeneous nucleation.
Hichem Khedim, Hélène Nonnet, François O. Méar, Journal of Power Sources 216 (2012) 227-236

E0224 – Thermodynamic Evaluation of the C-Co-W-Hf-Zr System for Cemented Carbides Applications

Cemented carbides consist of hard carbide particles of hexagonal WC and often also of cubic carbides cemented together in a binder consisting of mainly cobalt (Co). A thermodynamic evaluation of the cubic carbide formers hafnium (Hf) and zirconium (Zr) in cemented carbides has been done. Both thermodynamic evaluations of lower-order systems and experimental investigations have been performed. The new experimental information was necessary for a satisfactory thermodynamic description because there is a lack of earlier experiments of this alloy system. The assessment work with the C-Co-W-Hf-Zr system has resulted in a satisfactory description of the thermodynamic properties compared with the experimental values. This work has been done by combining a new assessment of the CoHf and CoZr systems with already assessed investigations of the Hf-C and Zr-C systems. New experimental information in higher-order systems has been used to improve the thermodynamic descriptions and to verify the reliability of the assessments. The main results of the experimental work are measurements of the composition of the cubic carbide in selected equilibria; measurements of the temperatures of the L + fcc + WC + graphite and L + fcc + WC + M6C equilibria in the C-Co-Hf, C-Co-Zr, and C-Co-W-X (X=Hf and Zr) systems; and measurements of the solubility of Hf and Zr in liquid cobalt. Detailed comparisons between calculated and experimental data are presented.
Johan Bratberg, Bo Jansson, Journal of Phase Equilibria and Diffusion Vol. 27 No. 3 (2006) 213-219

E0234 – Etude des évolutions microstructurales et comportement mécanique des alliages base nickel 617 et 230 à haute température

Afin de répondre aux contraintes sévères subies par les parties chaudes du circuit de refroidissement du VHTR (Very High Temperature Reactor) contenant de l’hélium en sortie des Réacteurs à Haute Température, l’alliage base nickel en solution solide Inconel 617 a été sélectionné dans les années 1980 pour le projet allemand grâce à ses propriétés mécaniques, sa stabilité thermique et sa résistance à la corrosion. L'ATD est utilisée pour caractériser les évolutions de microstructure des matériaux
Chomette Sébastien, Thèse Université de Toulouse, Novembre 2009

E0223 – Use of spent pot linings from primary aluminium production as raw materials for the production of opal glasses

The use of the carbonaceous fraction of spent pot linings (SPL) from primary aluminium electrolytic cells as a raw material for the production of opal glasses is evaluated. The SPL was heat treated and mixed with limestone to eliminate carbon and to minimise fluorine volatilisation. This material was then mixed with other glass formers, melted, and quenched to produce a glass. The cyanide which forms part of the SPL was thermally decomposed and some of the fluorine is incorporated into the glass matrix. The final material contains small crystals of fluorspar, which are responsible for light scattering and the opacity of the material, dispersed in an amorphous phase. The crystalline phase was identified by x-ray diffraction and its morphology was observed by scanning electron microscopy
U.S. do Prado, J.R. Martinelli, J.C. Bressiani, Glass Technology - European Journal of Glass Science and Technology Part A, Volume 51, Number 5, October 2010 , pp. 205-208(4)

E0233 – Structure and Magnetic Properties of Nickel–Zinc Ferrite Nanoparticles Prepared by Glass Crystallization Method

The magnetic and microstructure properties of Fe2O3–0.4NiO–0.6ZnO–B2O3 glass system, which was subjected to heat treatment in order to induce a magnetic crystalline phase (Ni0.4Zn0.6-Fe2O4 crystals) within the glass matrix, were investigated. DSC measurement was performed to reveal the crystallization temperature of the prepared glass sample. The obtained samples, produced by heat treatment at 765 C for various times (1, 1.5, 2, and 3 h), were characterized by X-ray diffraction, IR spectra, transmission electron microscopy, and vibrating sample magnetometer. The results indicated the formation of spinel Ni–Zn ferrite in the glass matrix. Particles of the ferrite with sizes ranging from 28 to 120nm depending on the sintering time were observed. The coercivity values for different heat-treatment samples were found to be in the range from 15.2 to 100 Oe. The combination of zinc content and sintering times leads to samples with saturation magnetization ranging from 12.25 to 17.82emu=g.
Ahmed M. El-Sayed, Esmat M. A. Hamzawy, Monatshefte f€ur Chemie 137, 1119–1125 (2006)

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

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

E0232 – Effects of Liquid Quenching and Subsequent Heating on the Structure of Co–Al Alloys

The phase composition and structure of Co–Al alloys after liquid-quenching (LQ) and subsequent heating were determined by x-ray diffraction, differential thermal analysis, and differential scanning calorimetry. The phase composition of the LQ alloy and the lattice parameters of the intermetallic phase CoAl and solid solution corresponded to a solidification temperature of 1100 °C, rather than to the eutectic temperature (1400°C). Heating to 1000°C brought the alloy to the equilibrium state. In the range 25–28 at % Al, the LQ alloys were single-phase and consisted of Co-enriched CoAl (B2). Decomposition of this intermetallic phase during heating in the calorimeter gave rise to an exothermic peak at 680°C and led to precipitation of hcp Co. The activation energy of the decomposition process, evaluated by the Kissinger method, was Ea = 125 ± 10 kJ/mol.
V. K. Portnoi, K. V. Tretyakov, S. E. Filipova, J. Latuch, Inorganic Materials, Vol. 41, No. 4, 2005, pp. 350–355

E0231 – Thermodynamic properties of pentalead tris(vanadate) chloride

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

E0230 – Cascade of Peritectic Reactions in the B-Fe-U System

The solidification paths for UFeB4, UFe3B2 and UFe4B, ternary compounds, situated along the U:(Fe,B) = 1:5 line in the B-Fe-U phase diagram, are proposed based on x-ray powder diffraction measurements, differential thermal analysis, heating curves and scanning electron microscopy observations complemented with energy and wavelength dispersive x-ray spectroscopies. The compounds melt incongruently and are formed by peritectic reactions. The present work demonstrates the existence of a cascade of peritectic reactions along the U:(Fe,B) = 1:5 composition line, establishes peritectic temperatures and proposes an isopleth diagram along this line.
M. Dias, P.A. Carvalho, A.P. Dias, M. Bohn, N. Franco, O. Tougait, H. Noël, A.P. Gonçalves, Journal of Phase Equilibria and Diffusion Vol. 31 No. 2 2010

E0240 – Martensitic Transformations, Microstructure, and Mechanical Workability of TiPt

The TiPt phase with the B2 structure has been reported to undergo a reversible displacive transformation to B19 martensite at about 1000°C. This system could, therefore, serve in principle as the basis of a high-temperature shape-memory alloy (SMA). However, very few additional details of the B2 and B19 forms of TiPt have been published. In the present work, the B19®B2 transformation temperatures previously reported are confirmed, but the B2 ? B19 temperatures are found to be about 40°C lower than previously accepted. The hardness of B19 martensite shows a minimum at a stoichiometry of ~ 50 at. pct Pt. Between 45 and ~ 50 at. pct Pt, the B2 ? B19 transformations appear to take place in a complex sequence, with up to two intermediate phases being stable over a range of about 50°C. No evidence for this intermediate phase was found for Pt contents from 50 to 56 at. pct Pt. It is clear that a Pt content of about 50 at. pct marks a significant change in the nature of the TiPt phase and its martensite or martensites. It was also found that TiPt has a slightly wider stability range than is shown in the current phase diagram, extending from 45 to 56 at. pct Pt at 1300°C.
T. Biggs, M.B. Cortie, M.J. Witcomb, L.A. Cornish, Metallurgical and Materials Transactions A, Volume 32A, August 2001—1881

E0229 – The effect of TiO2 and P2O5 on densification behavior and properties of Anortite-Diopside glass-ceramic substrates

In this work the synthesis of anorthite-diopside glass-ceramics (GCs) was carried out via sintering and crystallization of glass powder compacts in the temperature interval 800°C and 950°C. Glass powder compacts with mean particle size of 2 ?m were prepared. The effects of adding TiO2 and P2O5 on the sintering behavior of glass powder compacts and on the properties of resultant glass-ceramics were studied. Mechanical, thermal, chemical and dielectric properties of sintered GCs were investigated with the aim to evaluate the potential of the GCs as substrate materials for microelectronics applications.
Vitor M. F. Marques, Dilshat U. Tulyaganov, Govind P. Kothiyal, José M. F. Ferreira, J Electroceram (2010) 25, 38–44

E0250 – Characterization of nanostructured magnetite thin films produced by sol–gel processing

Nanocrystalline films of magnetite have been prepared by a novel sol–gel route in which, a solution of iron (III) nitrate dissolved in ethylene glycol was applied on glass substrates by spin coating. Coating solution showed Newtonian behaviour and viscosity was found as 0.0215 Pa.s. Annealing temperature was selected between 291 and 350 °C by DTA analysis in order to obtain magnetite films. In-plane grazing angle XRD and TEM studies showed that magnetite phase was present upon annealing the films at 300 °C. The films had crack free surfaces and their thicknesses varied between *10 and 200 nm. UV–Vis spectrum results showed that transmittance of the films increases with decreasing annealing temperature and increasing spinning rate. Up to 96% transmittance was observed between the wavelengths of 900–1,100 nm. Vibrating sample magnetometer measurements indicated that magnetite thin films showed ferromagnetic behavior and the saturation magnetization value was found as ~35 emu/cm3.
Ali Erdem Eken, Macit Ozenbas, J Sol-Gel Sci Technol (2009) 50, 321–327