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5631 articles

A0919 – Supported bis(maltolato)oxovanadium complexes as catalysts for cyclopentane and cyclooctane oxidations with dioxygen

Carbamated silica gel supported bis(maltolato)oxovanadium(IV or V) complexes, [VO(ma)2] (1), [VO(py)(ma)2] (2) (py = pyridine), cis- [VO(OCH3)(ma)2] (3) and cis-[VO(OC2H5)(ma)2] (4), were used as catalysts for the oxidation of cyclopentane and cyclooctane by molecular oxygen in a batch reactor, under moderate reaction conditions (typically p(O2) ca. 10-14 atm, at 150-160°C). The corresponding ketones, i.e. cyclopentanone and cyclooctanone are the main products (up to 10 and 25% yields, respectively) of the cycloalkane oxidations, but cyclopentanol and cyclooctanol are also formed in smaller amounts. The supported complex 1 shows the best activity and selectivity. The reaction is further promoted by the use of some heteroaromatic acids as co-catalysts, namely 2-pyrazine-carboxylic acid. Experiments with radical traps suggest the involvement of a free-radical mechanism.
G.S. Mishra, J.J.R. Frausto da Silva, A.J.L. Pombeiro, Journal of Molecular Catalysis A: Chemical 265 (2007) 59-69

A0918 – Low-temperature heat capacity and standard molar enthalpy of formation of crystalline 2-pyridinealdoxime (C6H6N2O)

The thermodynamic properties of 2-pyridinealdoxime were investigated through the thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). Low-temperature heat capacity Cp,m of 2-pyridinealdoxime (C6H6N2O; CAS 873-69-8) was measured in the temperature range from (80 to 373) K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The thermodynamic functions [HT - H298.15] and [ST - S298.15] were calculated in the range from (80 to 375) K. The constant-volume energy and standard molar enthalpy of combustion have been determined, ?cU (C6H6N2O, cr) = ?cHm° (C6H6N2O, cr) = - (3297.11 ± 1.53) kJ.mol-1 (based on ?n being zero in reaction of the combustion), by means of a precision oxygen- bomb combustion calorimeter at T = (298.15 ± 0.001) K. The standard molar enthalpy of formation has been derived, ?fHm° (C6H6N2O, cr) = (78.56 ± 2.43) kJ.mol-1, from the standard molar enthalpy of combustion in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.
Q. Shi, Z-C. Tan, B. Tong, Y-Y. Di, Z-H. Zhang, J-L. Zeng, L-X. Sun, Y-S. Li, J. Chem. Thermodynamics 39 (2007) 817-821

A0917 – Influence of the synthesis route on sol-gel SiO2-TiO2 (1:1) xerogels and powders

Five different sol-gel routes are used in order to synthesize mixed SiO2-TiO2 materials. Simple mixing of the Ti and Si precursors, prehydrolyzing of TEOS, modification of the Ti alkoxide with acetic acid, isoamyl alcohol and acetylacetone lead to translucent gels with different time of gelation. Different techniques such as TGA, DTA, XRD and IR spectroscopy are used to characterize each material. IR spectroscopy revealed the presence of Si-O-Ti and Si-O-Si bonds for all the xerogels letting suppose a composite microstructure of the gels. Pre-hydrolyzing of TEOS and modification of Ti alkoxide with isoamyl alcohol are the most appropriate routes to retain the anatase phase up to 1100°C.
S. Vives, C. Meunier, Ceramics International xxx (2007) xxx-xxx

A0920 – Synthesis and characterization of new addition compounds of bis(substituted-salicylaldehydo) cobalt(II) with 2,2′-bipyridine (bipy). Crystal and molecular structures of [Co(II)(3-methoxy-salicylaldehyde)2(bipy)].CH3OH (1) and [Co(II)(bipy)3]Br2 . 0.5(5-ch

The cobalt(II) addition compounds [Co(X-salo)2(bipy)], where X-salo is the anion of substituted salicylaldehydes (X = 3-OCH3 (1); 5-CH3 (2); 5-Cl (3); 5-NO2 (4)) and bipy the neutral 2,2'-bipyridine, were synthesized and characterized by physicochemical and spectral (IR, UV-Vis) data. Theoretical calculations (DFT, ZINDO) with GAUSSIAN-03 for the prediction of the electronic spectrum for the compound 1, gave good correlation with the experimental one in the solid state. The absorption spectra at different solvents showed that the compound is stable in CH3CN, but unstable in CH3OH and DMF solutions. The cyclic voltammetry study in CH3CN gave all the expected waves for the redox processes of the metal Co(II) and the ligands bipy and salicylaldehydes. The compound 1 is very stable at ambient temperature but unstable upon heating decomposing to CoO at 980°C in nitrogen, but at 500°C in oxygen atmosphere. The X-ray diffraction study of the compound 1 verified the proposed octahedral arrangement of the ligands around the cobalt(II) atom. Along with the main products (1-4), a side product (5) verified by X-ray diffraction study as [Co(II)(bipy)3]Br2 . 0.5(5-chlorosalicylaldehydeH) . 1.5CH3OH.
C.D. Papadopoulos, A.G. Hatzidimitriou, G.P. Voutsas, M. Lalia-Kantouri, Polyhedron 26 (2007) 1077-1086

A0921 – Preparation of molybdenum oxide thin films by MOCVD

In this study, molybdenum oxide films were prepared in a horizontal hot-wall MOCVD apparatus using molybdenum dioxide acetylacetonate as precursor. The molybdenum precursor was synthesized from acetylacetone and molybdenum oxide powder. Thermal gravimetric (TG) and differential thermal analyses (DTA) of the precursor suggested the formation of molybdenum oxides around 430°C (703 K). Thus, a range of deposition temperatures varying from 350 to 630°C (623-903 K) was explored to investigate the effects on the nature of the molybdenum oxide films. X-ray diffraction (XRD) results showed that the films consisted of alpha-MoO3 phase at deposition temperatures ranging from 400 to 560°C (673-833 K). Crystalline alpha-MoO3 films can be obtained from molybdenum dioxide acetylacetonate precursor, without need of a post-annealing treatment. The best crystalline quality was found in films having needle-like crystallites grown at deposition temperature of about 560°C (833 K), which exhibit a strong (0 1 0) preferred orientation and a transparent visual appearance.
R. Martinez Guerrero, J.R. Vargas Garcia, V. Santes, E. Gomez, Journal of Alloys and Compounds 434-435 (2007) 701-703

A0923 – Synthesis, structure and thermal behaviour of a barium-glutarate framework

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

A0922 – Characterization of the performance of an intumescent fire protective coating

The aim of this work is to study the efficiency of different intumescent formulations designed to protect steel in the case of hydrocarbon fire. The coating is based on a thermoset epoxy-amine resin system into which fire retardant agents, boric acid and ammonium polyphosphate derivative have been incorporated. The first part of the study evaluates, using large scale industrial furnace tests, the behavior of the thermoset resin containing alone or in combination with additives. It is revealed that in this epoxy resin, the combination between ammonium polyphosphate and boric acid leads to the best protective results. The second part of the study attempts to investigate more precisely the effect and the mode of action of the additives in terms of thermal stability, mechanical resistance and rheological properties using small scale lab tests, to explain why this combination works better than using the two fire retardants used separately. The experiments show that this combination leads to the smallest decrease of viscosity when the resin degrades, the highest mechanical resistance and the highest expansion.
M. Jimenez, S. Duquesne, S. Bourbigot, Surface & Coatings Technology 201 (2006) 979-987

A0924 – Cyclic oxidation of coated and uncoated single-crystal nickel-based superalloy MC2 analyzed by continuous thermogravimetry analysis

The previously developed cyclic thermogravimetry analysis (CTGA) [Monceau D, Poquillon D. Oxid Met 2004;61:143-163] method is applied to the cyclic oxidation at 1150°C of a NiCoCrAlYTa-coated and an uncoated single-crystal nickel-based superalloy MC2. A new procedure to correct the buoyancy effect is proposed in order to evaluate the amount of oxide formed during the heating periods, which can be important for alloys forming fast-growing transient oxides or during cycling with slow heating rates. It is shown that cyclic thermogravimetry is an useful technique for quantifying the oxidation resistance of an industrial alloy. Moreover, the behaviour of the alloy is better described with CTGA than with a classic cyclic gravimetric test, because both isothermal oxidation kinetics and spalling behaviour are assessed independently. In the present case, it is shown clearly that the NiCoCrAlYTa coating greatly improves the cyclic oxidation resistance without decreasing the isothermal oxidation kinetics. Finally, the use of CTGA for performance and time-of-life evaluations is demonstrated.
A. Raffaitin, D. Monceau, E. Andrieu, F. Crabos, Acta Materialia 54 (2006) 4473-4487

A0926 – Effect of Bronsted acidity in propane oxidation over Cs2.5H1.5PV1Mo(11-x)WxO40 polyoxometallate compounds

Cs2.5H1.5PV1Mo(11-x)WxO40 Keggin-type polyoxometallate (POM) compounds have been synthesised and studied for selective propane oxidation in the 300-400°C temperature range. Prior to reaction the samples were pre-treated at either 300°C or 400°C in order to change the concentration in Bronsted acid sites by decreasing the amount of constitutional water. Acid strength was enhanced by substituting increasing amounts of W6+ in the Keggin anion for Mo6+, between 0 and 6 per Keggin Unit (KU) as shown by NH3- TPD of the H+ form and IR of the lattice vibrational modes (M=O and M-O-M with M = Mo6+ or W6+). As a matter of fact vibrational mode frequencies and thus the corresponding bond energies were observed to increase with W6+ substitution. This results in more covalent M-O bonds and thus to freer protons. Chemical analysis, IR and DTA/TG data allowed us to determine the extent of W6+ substitution for Mo6+, the amount of constitutional water and any structural change in the samples. It was observed that under catalytic conditions, (C3/O2/He = 2/1/2, flow rate 15 cm3 min-1, 12 h on stream, reaction temperature in the 300-400°C range) the catalyst structure was maintained, with only a very small part of the substituted elements (V5+, W6+ and Mo6+ atoms) being extracted from the Keggin anion. Catalytic data have shown that introduction of W6+ to replace Mo6+ led to lower propane activation, which may be due to a decrease of lattice oxygen anion mobility, related to the stronger M-O bond (see supra and as shown by the higher reaction temperature necessary for the same conversion level). Compared to pre-treatment temperature at 300°C, pre-treatment at 400°C was observed to result in a higher extent of constitutional water removal i.e. a loss of Bronsted acid sites by a factor of 2-4.5 when W6+ amount varies from 0 to 6 per KU without destroying the primary Keggin structure, and to favour the formation of propene at the expense of acetic and acrylic acids and COx. This also shows that substituting W6+ for Mo6+, which enhances Bronsted acid strength is detrimental to propene formation and leads to higher selectivity to acetic acid and COx, i.e. the propane oxidation pathway via the isopropanol route and acetone rather at the expense of the usual main pathway forming acrylic acid via propylene.
N. Dimitratos, J.C. Védrine, Catalysis Communications 7 (2006) 811-818

A0925 – Estimation of adsorption energies using the physical characteristics of activated carbons and the molecular properties of volatile organic compounds

Adsorption of volatile organic compounds (VOCs) by granular activated carbons (GACs) is a highly exothermic process and leads to temperature rises, which may reduce the separation efficiency. This study points out the significant characteristics of VOCs and GACs on adsorption energies. Adsorption energies were measured for a wide variety of VOCs, representative of different chemical groups, using 8 different commercial GACs with different porous structures. Afterwards a statistical analysis was applied to the experimental database thus obtained, which enabled one to pinpoint the most significant variables, linked to either VOC molecular properties or the intrinsic characteristics of GACs. Two statistical models have been tested: multi linear regression (MLR) and neuronal networks, and their effi- ciencies were compared in terms of prediction skill. The best results have been obtained from the MLR approach, which discriminated five different properties of the system. These variables were the polarisability, the heat of vaporization, the ionization potential and the surface tension for adsorbates and the mean micropore radius for GACs. The MLR model enabled one to compute integral adsorption enthalpies with a precision of around 10% and to draw conclusions on the dominant adsorption mechanisms.
S. Giraudet, P. Pré, H. Tezel, P. Le Cloirec, Carbon 44 (2006) 2413-2421

A0927 – Study of rehabilitation mortars: Construction of a knowledge correlation matrix

In old building rehabilitation practices, the gathering of full knowledge on used mortars is the most difficult task due to their complexity and variability. At the same time, this necessity of knowledge is critical, since the rehabilitation work must guarantee physical, chemical and mechanical compatibility between former and restoration mortars, not relinquishing aesthetic details. However, the characterization of old mortars can be a very complex process, since it involves different techniques and potentially controversial outcomes. In this work, several mortars were prepared and characterized, in order to improve knowledge that will facilitate the further choice of a suitable material to replace any old mortar. Analytical techniques like XRD and DTA/TGA were used in the determinations of chemical compositions, and physical properties determinations (apparent density, open porosity, compression strength, flexural strength, elastic modulus) were important to understand the mechanical behaviour and durability and to relate it with the prepared formulations composition.
S.F. Marques, R.A. Ribeiro, L.M. Silva, V.M. Ferreira, J.A. Labrincha, Cement and Concrete Research 36 (2006) 1894-1902

A0929 – Improving the Na2SO4-induced corrosion resistance of Ti3AlC2 by pre-oxidation in air

Ti3AlC2 suffers severe Na2SO4-induced corrosion attacks at temperatures higher than 800°C in air. A convenient and efficient pre-oxidation method is proposed to enhance the corrosion resistance of Ti3AlC2. The corrosion weight-changes of the pre-oxidized samples were decreased by about four orders of magnitude compared with those of the untreated specimens. The mechanism on improvement of corrosion resistance was investigated by means of thermogravimetric analysis, X-ray diffraction and scanning electron microscopy/energy-dispersive spectroscopy. A continuous and adherent alpha-Al2O3 scale was prepared by high-temperature pre-oxidation treatment in air. The preformed dense Al2O3 scale has good compatibility with the Ti3AlC2 substrate, and consequently, can act as an efficient barrier against corrosion. Long-time corrosion tests demonstrate that the Al2O3 scale conserves after corrosion attack and is capable of long-term stability.
Z. Lin, Y. Zhou, M. Li, J. Wang, Corrosion Science 48 (2006) 3271-3280

A0928 – Indigo chemisorption in sepiolite. Application to Maya blue formation

Having first studied the loss of water in sepiolite via TGA, we then observed through FTIR the evolution of the indigo/sepiolite chemical bonds during the Maya blue formation process. Three stages, corresponding to three different temperature domains, were observed. They explain the peculiar properties of this pigment.
S. Ovarlez, A-M. Chaze, F. Giulieri, F. Delamare, C. R. Chimie 9 (2006) 1243-1248

A0931 – Cefdinir: A comparative study of anhydrous vs. monohydrate form Microstructure and tabletting behaviour

Anhydrous cefdinir (AC) vs. monohydrated cefdinir (MHC) was compared in order to be used as antimicrobial in therapeutics. Different techniques have been used to characterize physically AC and MHC, and also a complete microstructural analysis of raw materials was carried out. Cefdinir and Maltodextrin QDM® 500 (3:2) formulations were compressed in order to obtain tablets with typical dose of Cefdinir, i.e. 300 mg. Dissolution profiles were obtained for both AC and MHC tablets. Finally tablet X-ray diffraction was performed to ensure the stability of the monohydrated form after tabletting being clearly different in both AC and MHC crystals. AC crystal structure was agreed with the known pattern of anhydrous Cefdinir described in the literature. Microstructural analysis showed large differences in specific surface area (SSA), confirmed by mercury intrusion. Crystal structures of both AC and MHC were stable under mixing, compression and storing processes. Dissolution profiles were faster for hydrate form, probably related to microstructural properties of the crystal which remained after tabletting. In conclusion, it is possible to isolate Cefdinir in two forms anhydrous and monohydrate, well characterized and differentiated. The use of this later improves dissolution of tablet dosage form due to the lack of interconversion during tablet manufacture.
W. Cabri, P. Ghetti, M. Alpegiani, G. Pozzi, A. Justo-Erbez, J.I. Pérez-Martinez, R. Villalon-Rubio, M.C. Monedero-Perales, A. Munoz-Ruiz, European Journal of Pharmaceutics and Biopharmaceutics 64 (2006) 212-221

A0930 – Synthesis and electrochemical properties of a new vanadyl phosphate: Li4VO(PO4)2

The exchange of lithium for proton in VO(H2PO4)2 has been studied. Beside the continuous exchange from VO(H2PO4)2 to Li2H2- VO(PO4)2, a new cathode material Li4VO(PO4)2 has been synthesized, whose structure is closely related to that of VO(H2PO4)2. The electrochemical evaluation of Li4VO(PO4)2 vs. Li shows that it undergoes reversible lithium deintercalation/intercalation at high voltage, ~ 4.0 V with a reversible capacity of ~ 70 mAh/g.
M. Satya Kishore, V. Pralong, V. Caignaert, U.V. Varadaraju, B. Raveau, Electrochemistry Communications 8 (2006) 1558-1562

A0933 – Magnetic and transport properties of cobalt-doped perovskites SrTi(1-x)CoxO3 (x<0.5)

SrTi(1-x)CoxO(3-d) solid solutions (0.050.35 exhibit paramagnetic to antiferromagnetic transitions. The resistivity data show an unexpected dependence ln (p) ~ T^(-1/2) for all the measured temperature range.
C. Pascanut, N. Dragoe, P. Berthet, Journal of Magnetism and Magnetic Materials 305 (2006) 6-11

A0932 – Relation between composition, microstructure and oxidation in iron aluminides

The relation between chemical composition, microstructure and oxidation properties has been investigated on various FeAl based alloys, the aim being to induce changes in the microstructure of the compound by selective oxidation of aluminium. Oxidation kinetics that was evaluated on bulk specimens showed that, due to fast diffusion in the alloys, no composition gradient is formed during the aluminium selective oxidation. Accordingly, significant aluminium depletion in the compound could be observed in the thinnest part of oxidised wedge-shape specimens. Another way to obtain samples of variable aluminium content was to prepare diffusion couples with one aluminide and pure iron as end members. These latter specimens have been characterised using electron microscopy and first results of oxidation experiments are presented.
M. Martinez, B. Viguier, P. Maugis, J. Lacaze, Intermetallics 14 (2006) 1214-1220

A0934 – From thorium phosphate hydrogenphosphate hydrate to beta-thorium phosphate diphosphate: Structural evolution to a radwaste storage ceramic

beta-Thorium phosphate diphosphate (beta-TPD), considered as a very promising radwaste storage material, was obtained from thorium phosphate hydrogenphosphate hydrate (TPHPH) precursor through dehydration and hydrogen phosphate condensation. The structures of TPHPH, intermediate alpha-thorium phosphate diphosphate (alpha-TPD) and its hydrate (alpha-TPDH) have been resolved ab initio by Rietveld analysis of their synchrotron diffraction patterns. All were found orthorhombic (space group Cmcm) and similarly composed of [ThPO4]4 4+ slabs alternating with disordered layers hosting either [HPO4.H2O]2 4- (TPHPH), [P2O7.2H2O]4- (alpha-TPDH), or [P2O7]4- (alpha-TPD), unlike the 3D structure of beta-TPD. The diphosphate groups of alpha-TPD and alpha-TPDH are strongly bent. The irreversible transition to the final beta-TPD consists in a shearing of the slabs and a reduction of the interslabs cavities that explains the stability of this high-temperature form.
G. Wallez, N. Clavier, N. Dacheux, M. Quarton, W. van Beek, Journal of Solid State Chemistry 179 (2006) 3007-3016

A0937 – Difference in high-temperature oxidation resistance of amorphous Zr-Si-N and W-Si-N films with a high Si content

The high-temperature oxidation resistance of amorphous Zr-Si-N and W-Si-N films with a high Si content ( 20 at.%) deposited by reactive dc magnetron sputtering at different partial pressures of nitrogen was systematically investigated by means of a symmetrical high-resolution thermogravimetry in a flowing air up to an annealing temperature of 1300°C (a temperature limit for Si(1 0 0) substrate). Additional analyses including X-ray diffraction (XRD), light optical microscopy (LOM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and microhardness measurement were carried out as well. The obtained results showed (i) an excellent high-temperature oxidation resistance of the Zr- Si-N films up to 1300°C, (ii) a considerably lower oxidation resistance of the W-Si-N films. The W-Si-N films are completely oxidized at 800°C with a subsequent volatilization of unstableWOx oxides. On the other hand, the Zr-Si-N films are oxidized only very slightly on the surface, where a stable oxide barrier layer preventing further inward oxygen diffusion is formed. The thickness of the oxide layer is only about of 3% of the total film thickness. The phase composition, thermal stability of individual phases and amorphous structure were found to be key factors to achieve a high oxidation resistance.
P. Zeman, J. Musil, Applied Surface Science 252 (2006) 8319-8325

A0936 – Structural characterization and properties of [4-CH3C5H4NH][SbBr4]. The mechanism of phase transitions in 4-methylpyridinium bromoantimonates(III)

The crystal structure of [4-CH3C5H4NH][SbBr4] is determined at 297 K. The compound crystallizes in the monoclinic space group: P21/c. The structure consists of SbBr4- ions which form infinite chains through the crystal via halogen linkages. The anions are connected with the 4-methylpyridinium via weak N-H...X hydrogen bonds. The phase situation was studied on two methyl-substituted pyridinium analogous: [4-CH3C5H4NH][SbBr4] and [4-CH3C5H4NH]2[SbBr5] with the differential scanning calorimetry and dilatometric methods. The former derivative undergoes two structural phase transitions: at 351/349 K (heating-cooling) and at 385/381. [4-CH3C5H4NH]2[SbBr5] reveals one phase transition at 426/419 K. The dielectric relaxation studies on [4-CH3C5H4NH]2[SbBr5] in the frequency range between 800 Hz and 6 MHz indicate a presence of relaxation process below room temperature. The dielectric response is well explained in terms of an existence of two dielectric relaxators. The mechanism of the phase transitions in the studied crystals is discussed.
B. Kulicka, R. Jakubas, Z. Ciunik, Solid State Sciences 8 (2006) 1229-1236

A0935 – Polycationic disorder in [Bi6O4(OH)4](NO3)6: Structure determination using synchrotron radiation and microcrystal X-ray diffraction

The bismuth basic nitrate [Bi6O4(OH)4](NO3)6 crystallizes in a rhombohedral hexagonal unit cell with parameters a = 15.1332(6) Å, c = 15.7909(9) Å, V = 3131.8(3) Å3, Z = 6, space group R-3. The synthesis, formula determination, thermogravimetric analysis and nitrate assay, and finally, its crystal structure refinement determined at 150(2)K by synchrotron X-ray microcrystal diffraction are reported. Its structure is built from [Bi6O4(OH)4]6+ polycations, six per unit cell, disordered over two positions. Two oxygen atoms are common to the two antagonist polycations (full occupancy) while the remaining six are partially occupied. The [Bi6O4(OH)4]6+ hexanuclear clusters form columns along the c-axis. The cohesion between polycationic entities is effected by nitrate anions through either OH-ONO2 hydrogen bonds or Bi-ONO2 bonds. One of the two independent [NO3]- groups is also disordered over two positions. Only a local order in the columns is obtained by formation of pairs of ordered [Bi6O4(OH)4]6+ polycations.
N. Henry, O. Mentré, F. Abraham, E.J. MacLean, P. Roussel, Journal of Solid State Chemistry 179 (2006) 3087-3094

A0940 – Iodide-based electrolytes: A promising alternative for thermal batteries

Molten iodide-based salts due to their low melting points were envisaged to improve the performances of thermal batteries. Iodide-based salt drying and the determination of the basic properties (electrochemical window, conductivity, thermal heat capacity, ... ) of some electrolytes were carried out. The results obtained showed that some of iodide-based electrolytes are suitable for thermal batteries. In addition, the LiF-LiCl-LiI and LiF-LiBr-KBr electrolytes were tested in Li-Si/FeS2 single cells in the temperature of thermal battery operating conditions. The LiF-LiCl-LiI electrolyte could be considered as an interesting alternative for the improvements of thermal battery performances.
P. Masset, Journal of Power Sources 160 (2006) 688-697

A0939 – Effect of organic acids and nano-sized ceramic doping on PEO-based solid polymer electrolytes

Composite solid polymer electrolytes (CSPEs) consisting of polyethyleneoxide (PEO), LiClO4, organic acids (malonic, maleic, and carboxylic acids), and/or Al2O3 were prepared in acetonitrile. CSPEs were characterized by Brewster Angle Microscopy (BAM), thermal analysis, ac impedance, cyclic voltammetry, and tested for charge-discharge capacity with the Li or LiNi0.5Co0.5O2 electrodes coated on stainless steel (SS). The morphologies of the CSPE films were homogeneous and porous. The differential scanning calorimetric (DSC) results suggested that performance of the CSPE film was highly enhanced by the acid and inorganic additives. The composite membrane doped with organic acids and ceramic showed good conductivity and thermal stability. The ac impedance data, processed by non-linear least square (NLLS) fitting, showed good conducting properties of the composite films. The ionic conductivity of the film consisting of (PEO)8LiClO4:citric acid (99.95:0.05, w/w%) was 3.25x10^(-4) S cm-1 and 1.81x10^(-4) S cm-1 at 30°C. The conductivity has further improved to 3.81x10^(-4) S cm-1 at 20°C by adding 20 w/w% Al2O3 filler to the (PEO)8LiClO4 + 0.05% carboxylic acid composite. The experimental data for the full cell showed an upper limit voltage window of 4.7V versus Li/Li+ for CSPE at room temperature.
J.W. Park, E.D. Jeong, M-S. Won, Y-B. Shim, Journal of Power Sources 160 (2006) 674-680

A0938 – Low-temperature synthesis of nanocrystalline NiO-YSZ powders by succinic acid-assisted combustion

Nanocrystalline composite powders, NiO-YSZ were prepared by the succinic acid-containing gel-combustion method at a temperature as low as 310°C. FT-IR, XRD, DTA/TGA, SEM and TEM were employed to characterize the thermal decomposition of the precursor and the phase evolution and morphology of the calcined powders. The results of FT-IR and thermal analysis showed that the pyrolysis of the precursor began at 171°C followed by the decomposition of carbonate-containing residues at 245°C and finally the removal of all pyrolyzed species was completed at 302°C, accompanied by the crystallization of the metallic nickel, NiO and cubic YSZ phases. The examination of TEM also showed that the nanocrystallites were closely bonded and homogeneously distributed at the nanometric scale.
F-Y. Shih, K-Z. Fung, H-C. Lin, G-J. Chen, Journal of Power Sources 160 (2006) 148-154

A0941 – Steam activation of tyre pyrolytic carbon black: Kinetic study in a thermobalance

Kinetic parameters for the steam activation of tyre pyrolytic carbon black have been determined by thermogravimetric analysis (TGA). Pyrolytic carbon black is a mainly macro and mesoporous material whose surface area can be improved via gasification to obtain microporous activated carbons. The pyrolytic carbon black sample was produced in an experimental-scale assembly where shredded tyre was pyrolysed under controlled conditions in a fixed bed reactor. Then, the activation of the resulting solid was studied by TGA using steam as activating agent. Kinetic regime was ensured fixing experimental conditions and therefore, avoiding internal and external mass transfer and heat transmission phenomena. Temperature (850-950°C) and activating gas concentration (10-40 vol.%) were the influencing variables under study. This is the first time that the random pore model (RPM) has been used to fit experimental data of the activation of pyrolytic carbon black with steam. Excellent fittings have been obtained because of the special applicability of this model to predict the behaviour of solid-fluid reactive systems, in which the solid phase shows a porous structure. Reaction evolution has successfully been modelled, including the maximum reaction rate obtained in experimental results. Additionally, intrinsic kinetic parameters of the activation reaction-reaction order, activation energy and pre-exponential factor - were calculated.
A. Aranda, R. Murillo, T. Garcia, M.S. Callén, A.M. Mastral, Chemical Engineering Journal 126 (2007) 79-85

A0942 – Solderability of Sn-9Zn-0.5Ag-1In lead-free solder on Cu substrate Part 1. Thermal properties, microstructure, corrosion and oxidation resistance

The thermal properties, microstructure corrosion and oxidation resistance of the Sn-9Zn-0.5Ag-1In lead-free solder have been investigated by differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersive spectrometry, potentiostat and thermogravimetry. The Sn-9Zn-0.5Ag-1In solder alloy has a near-eutectic composition, it melts at 187.6°C and the heat of fusion is determined as 71.3 J/g. The Sn-9Zn-0.5Ag-1In solder alloy with a corrosion potential of -1.09VSCE and a current density of 9.90x10^(-2) A/cm2, shows a better corrosion resistance than that of the Sn-9Zn solder alloy. From the thermogravimetry analysis, the weight gain ratio of the Sn-9Zn solder alloy appears a parabolic relationship at 150°C. The initial oxidation behavior of the Sn-9Zn-0.5Ag and Sn-9Zn-0.5Ag-1In solder alloys also shows a parabolic relationship but the weight gain ratio of them appears a negative linear one after aging at 150°C for 2.5 and 5 h, respectively.
T-C. Chang, J-W. Wang, M-C. Wang, M-H. Hon, Journal of Alloys and Compounds 422 (2006) 239-243

A0946 – Oxygen permeability, electronic conductivity and stability of La0.3Sr0.7CoO3-based perovskites

The electrical properties of perovskite-type (La0.3Sr0.7)(1-y)CoO(3-d) (y = 0-0.03) and La0.3Sr0.7Co0.8M0.2O(3-d) (M = Al, Ga), promising parent materials of dense mixed-conducting membranes for oxygen separation, were studied in the oxygen partial pressure range from 10^(-14) to 0.5 atm. The steady-state oxygen permeation fluxes through cobaltite ceramics at 973-1223K are limited by both bulk ionic conductivity and surface exchange kinetics. The substitution of cobalt with Al3+ or Ga3+ increases cubic perovskite unit cell volume, oxygen deficiency and Seebeck coefficient, whereas the thermal expansion, p-type electronic conductivity and oxygen permeability decrease. The creation of A-site cation vacancies, compensated by Co4+ formation, leads to higher p-type electronic conductivity and thermal expansion at temperatures above 700 K, whilst the ionic transport in A-site deficient cobaltite is lower than that in La0.3Sr0.7CoO(3-d). Reducing oxygen pressure down to approximately 10^(-5) atm results in transition into brownmillerite-type phases having essentially p(O2)-independent electrical properties until decomposition, which occurs at p(O2) values 10^2 to 10^4 times higher compared to CoO/Co boundary. The average thermal expansion coefficients of cobaltite ceramics in air are (15.9-19.6)x10^(-6) K-1 at 300-750K and (27.9-29.7)x10^(-6) K-1 at 750-1240 K.
V.V. Kharton, E.V. Tsipis, A.A. Yaremchenko, I.P. Marozau, A.P. Viskup, J.R. Frade, E.N. Naumovich, Materials Science and Engineering B 134 (2006) 80-88

A0945 – Oxygen permeability, electronic conductivity and stability of La0.3Sr0.7CoO3-based perovskites

The electrical properties of perovskite-type (La0.3Sr0.7)(1-y)CoO(3-d) (y = 0-0.03) and La0.3Sr0.7Co0.8M0.2O(3-d) (M = Al, Ga), promising parent materials of dense mixed-conducting membranes for oxygen separation, were studied in the oxygen partial pressure range from 10^(-14) to 0.5 atm. The steady-state oxygen permeation fluxes through cobaltite ceramics at 973-1223K are limited by both bulk ionic conductivity and surface exchange kinetics. The substitution of cobalt with Al3+ or Ga3+ increases cubic perovskite unit cell volume, oxygen deficiency and Seebeck coefficient, whereas the thermal expansion, p-type electronic conductivity and oxygen permeability decrease. The creation of A-site cation vacancies, compensated by Co4+ formation, leads to higher p-type electronic conductivity and thermal expansion at temperatures above 700 K, whilst the ionic transport in A-site deficient cobaltite is lower than that in La0.3Sr0.7CoO(3-d). Reducing oxygen pressure down to approximately 10^(-5) atm results in transition into brownmillerite-type phases having essentially p(O2)-independent electrical properties until decomposition, which occurs at p(O2) values 10^2 to 10^4 times higher compared to CoO/Co boundary. The average thermal expansion coefficients of cobaltite ceramics in air are (15.9-19.6)x10^(-6) K-1 at 300-750K and (27.9-29.7)x10^(-6) K-1 at 750-1240 K.
V.V. Kharton, E.V. Tsipis, A.A. Yaremchenko, I.P. Marozau, A.P. Viskup, J.R. Frade, E.N. Naumovich, Materials Science and Engineering B 134 (2006) 80-88

A0944 – Effects of the sintering atmosphere on Nb-based dielectrics

The effects of a forming atmosphere on the stability, the sintering and the dielectric properties of Ba5Nb4O15, BaNb2O6, ZnNb2O6 and Zn3Nb2O8 ceramics were investigated, because of the primary importance of the sintering atmosphere in relation to copper sintering. These Nbbased materials were sintered in air and in Ar/H210%. Zn-containing samples are very sensitive to the reductive atmosphere. ZnO volatilises at 800-850°C and the resulting compound does not exhibit the expected properties. BaNb2O6 and Ba5Nb4O15 are more stable in term of relative weight loss. Nevertheless, the phase analysis reveals a modification of the BaNb2O6 phase, what induces the degradation of the dielectric property stability versus temperature. The properties of Ba5Nb4O15 are not modified by a sintering in reductive atmosphere. A relative permittivity of 38.8, a permittivity temperature coefficient of -150 ppm°C-1 and an insulating resistivity of 10^10.9 V cm were obtained for this latter.
S. d'Astorg, S. Marinel, Ceramics International xxx (2007) xxx-xxx

A0943 – Effects of iron oxide (Fe2O3, Fe3O4) on hydrogen storage properties of Mg-based composites

When magnesium powder containing small additions of certain multiple valence transition metal oxides (TMOs) is ball milled in hydrogen, the hydrogenated Mg-based product can show remarkable improvements in hydrogen absorption/desorption properties. Using a magnetically controlled Uni-Ball-Mill, small amounts of the iron oxides, Fe2O3 and Fe3O4, were ball milled with Mg powder in a hydrogen atmosphere (Mg to Fe atomic ratio; 20:1). Milling products as well as samples used in hydrogen absorption/desorption experiments were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. TG analysis combined with DSC revealed a higher hydrogen storage capacity for the Mg+ Fe2O3 +H2-milled product (6 wt% H) compared with 5 wt% H for Mg+ Fe3O4 +H2. XRD revealed that during heating, both iron oxides were reduced to pure Fe, a result not previously reported for similar materials milled using different milling devices. For both samples, there was little difference found in the decomposition temperature of the as-prepared MgH2 and rehydrogenated composites. However, storage capacity degradations were observed for the rehydrogenated composites (4 wt%Hstorage capacity for MgH2 +Fe2O3 and 4.4 wt%Hfor MgH2 +Fe3O4). The higher capacity degradation of rehydrogenated MgH2 +Fe2O3 composite is also believed to be a result of the reduction reaction, during which more magnesium was consumed than was consumed by the same amount of Fe3O4. The results also were related to the particular ball-milling equipment and low-energy shearing milling mode employed, which promoted the development of a nanostructural hydride product which subsequently changed structure significantly during the first desorption cycle.
Z.G. Huang, Z.P. Guo, A. Calka, D. Wexler, C. Lukey, H.K. Liu, Journal of Alloys and Compounds 422 (2006) 299-304

A0947 – Synthesis of MCM-41 from coal fly ash by a green approach: Influence of synthesis pH

The present study reports a green synthesis method for preparing pure (free of fly ash) and ordered MCM-41 materials from coal fly ash at room temperature (25°C) during 24 h of reaction. It was shown that the impurities in the coal fly ash were not detrimental to the formation of MCM-41 at the tested conditions. The influence of initial synthesis pH on material properties of calcined MCM-41 samples was investigated by various techniques such as XRF, XPS, XRD, FTIR, DR-UV-vis, solid state NMR, N2 physisorption, TG-DTA, SEM and TEM. The experimental results showed that the amount of trace elements such as Al, Na, Ti and Fe incorporated into the sample increased with synthesis pH value. More aluminum species were incorporated with tetrahedral coordination in the framework under a high pH value. The particle size of the sample decreased with the synthesis pH value. Samples synthesized at high pH values had a larger pore size and were more hydrothermally stable than those at low pH values. From thermal analysis, it was observed that the synthesized MCM-41 samples showed a high thermal stability. These properties made the synthesized MCM-41 suitable for further processing into more useful materials in a wide range of applications.
K.S. Hui, C.Y.H. Chao, Journal of Hazardous Materials B137 (2006) 1135-1148

A0949 – Influence of sulfate ions on the interaction between fatty acids and calcite surface

The effect of sulfate ions on adsorption/displacement of long chain fatty acids onto/from calcite surface is investigated. The fatty acids used in this work are stearic acid (SA), oleic acid (OA) and 18-cyclohexyl-octadecanoic acid (CHOA). The main methods are thermogravimetric analysis for determining the extent of surface modification and vapour adsorption isotherm to evaluate the wetting behaviour. An appreciable reduction of adsorbed amount of fatty acids is observed in presence of sulfate ions. This is interpreted by the high affinity of the sulfate ions for the active sites of the calcite. In addition, they modify the calcite surface to a negative charge, as indicated by zeta potential measurements, hence reducing the availability of the active sites for carboxylate ions. The ability of sulfate ions to displace the pre-adsorbed fatty acids from the calcite surface is also demonstrated. It is mostly related to the molecular structure of the fatty acids, where the percentage of displacement by 0.1M sulfate is found to be 7 and 10 for stearic acid and oleic acid, respectively. This work shows that the sulfate ions changed the wettability of calcite to more water-wet as indicated by water vapour adsorption isotherms.
K.A. Rezaei Gomari, A.A. Hamouda, R. Denoyel, Colloids and Surfaces A: Physicochem. Eng. Aspects 287 (2006) 29-35

A0948 – Effect of sodium addition on the preparation of hydroxyapatites and biphasic ceramics

HAP and biphasic ceramics of two different HAP and beta-TCP proportions with substituted sodium were prepared through an aqueous precipitation method. The prepared powders were characterized by XRD, thermal analysis, FT-IR and elemental analysis. Sodium was found to incorporate into the apatite structure without showing any significant change in the phase behaviour of the resultant apatites. The substitution of sodium in the calcium deficient apatites tends to form a biphasic mixture of HAP and beta-TCP, while the effect of calcination beyond 700°C and the resultant mixtures were dependent on the initial Ca/P ratios of the precursors. The calculated lattice parameter values for sodium substituted apatites have shown a marginal increase in c-axis values thereby leading to the enlargement of the hexagonal cell volume with respect to the pure HAP prepared under the same experimental conditions. Powders obtained from the present results were stable up to 1200°C.
S. Kannan, J.M.G. Ventura, A.F. Lemos, A. Barba, J.M.F. Ferreira, Ceramics International xxx (2007) xxx-xxx

A0950 – Calcium hydroxyapatite, Ca10(PO4)6(OH)2 ceramics prepared by aqueous sol-gel processing

Aqueous sol-gel chemistry routes based on ammonium-hydrogen phosphate as the phosphorus precursor and calcium acetate monohydrate as source of calcium ions have been developed to prepare calcium hydroxyapatite samples with different morphological properties. In the sol-gel processes, an aqueous solutions of ethylene diamine tetra-acetic acid (EDTA) or tartaric acid (TA) as complexing agents were added to the reaction mixture. The monophasic Ca10(PO4)6(OH)2 samples were obtained by calcination of precursor gels for 5 h at 1000°C. The phase transformations, composition and micro-structural features in the polycrystalline samples were studied by thermoanalytical methods (TGA/DTA), infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD) and scanning electron microscopy (SEM). It was shown that adjusting the nature of complexing agent in the aqueous sol-gel processing can be used to control the morphology of the ceramic samples.
I. Bogdanoviciene, A. Beganskiene, K. Tonsuaadu, J. Glaser, H-J. Meyer, A. Kareiva, Materials Research Bulletin 41 (2006) 1754-1762

A0952 – Optimizing synthesis of silicon/disordered carbon composites for use as anode materials in lithium-ion batteries

Pyrolysis conditions for the production of silicon/disordered carbon (Si-DC) nanocomposites using PVA as the carbon source were optimized in this work. It was found that the optimum sintering temperature for the Si-DC nanocomposites is 800°C. In order to achieve good cell performance, a high argon gas flow rate and a slow heating rate are preferred in sample preparation. The morphology of the carbon source (PVA) affects the electrochemical performance of the Si-DC nanocomposites as well. The key point to obtain Si-DC nanocomposites with good electrochemical performance is to reduce the chances of pyrolysis gases (especially CO2) to react with carbon, thereby preventing carbon burnoff during the sintering process.
Z.P. Guo, D.Z. Jia, L. Yuan, H.K. Liu, Journal of Power Sources 159 (2006) 332-335

A0951 – Synthesis and characterisation of a new stable organo-mineral hybrid nanomaterial: 4-Chlorobenzenesulfonate in the zinc-aluminium layered double hydroxide

4-Chlorobenzenesulfonate (4-CBS) was intercalated between layers of Zn-Al layered double hydroxides (LDHs). Two methods of incorporation were applied: (1) direct synthesis by coprecipitation of metal nitrates and sodium 4-CBS and (2) ion exchange of the LDH nitrate with the organic ion. The solids were characterized by X-ray diffraction and infrared spectroscopy. The direct method, effected at different pH values, led to a hybrid material with good degree of intercalation. In order to optimise the exchange conditions, particular attention was given to the effect of solution pH, 4-CBS/NO3 ratio and exchange temperature. The total exchange was successful and a new stable hybrid nanostructured material was obtained at pH 8 and with a 4-CBS concentration of 0.0028 M. This solid was further characterised by chemical and thermal analyses.
M. Lakraimi, A. Legrouri, A. Barroug, A. De Roy, J.P. Besse, Materials Research Bulletin 41 (2006) 1763-1774

A0953 – Synthesis of nanocrystalline 8 mol% yttria stabilized zirconia powder from sucrose derived organic precursors

An organic precursor synthesis of 8 mol% yttria stabilized zirconia (YSZ) powder from Zr-Y composite nitrate solution and sucrose has been studied. Oxidation of sucrose in Zr-Y composite nitrate solution containing excess nitric acid in situ generates hydroxy carboxylic acids that forms a white sol which showed peaks at 1640 cm-1 and 1363 cm-1 in IR spectrum corresponding to hydroxy carboxylic acid complexes of Zr and Y. Precursor mass obtained by drying the sol on calcinations at 600°C produced loosely agglomerated particles of cubic YSZ. Deagglomerated YSZ contain submicron particles with D50 value of 0.5 mm and the particles are aggregates of nanocrystallites of nearly 10 nm size. Compacts prepared by pressing the YSZ powder sintered to 96.7% TD at 1450°C. The sintered YSZ ceramic showed an average grain size of 2.2 mm.
K. Prabhakaran, Anand Melkeri, N.M. Gokhale, S.C. Sharma, Ceramics International xxx (2007) xxx-xxx

A0955 – Abatement of CO from relatively simple and complex mixtures III. Oxidation on Pd-CeO2/C and CeO2/C catalysts

Oxidation of carbon monoxide on CeO2/C and Pd/CeO2/C catalysts was investigated at temperatures ranging from 50 to 700°C until the catalysts disintegrated. The CeO2/C catalyst, which was stored in air for an extended period of time, was found to be more active than the same catalyst which was annealed in inert atmosphere, which suggested that the catalyst could accumulate active surface oxygen over time. The effects of surface oxidation were further evident after preparing more active Pd catalysts on both oxidized and annealed forms of CeO2/C, with the latter catalyst showing a higher activity. Nitric oxide was found to inhibit CO oxidation on ceria and promote it on supported Pd catalysts. ESR spectra showed the presence of active oxygen, possibly in the forms of superoxide and peroxide on the surface of carbon and ceria. The reduced Pd clusters could generate superoxide radicals whereas they were stabilized by partially reduced Ce3+ and carbon. Adsorbed water most likely protected ceria sites from a complete oxidation into Ce4+. Long-term storage of a sealed container of Pd/CeO2/C at room temperature aged the catalyst, which possibly involved a Pd-assisted slow partial reduction of Ce4+ by carbon and an accumulation of Ce3+ ...O2 complexes.
A.J. Dyakonov, C.A. Little, Applied Catalysis B: Environmental 67 (2006) 52-59

A0954 – Hydrogen or synthesis gas production via the partial oxidation of methane over supported nickel-cobalt catalysts

Activity, selectivity, and coking-resistance of a series of NixCoy (where x, y are the respective metal loadings of 0, 1, 2 or 3 wt.%; x+y=3) bimetallic catalysts supported on CaAl2O4/Al2O3 have been studied for hydrogen/synthesis gas production via the catalytic partial oxidation (CPO) of methane. Catalysts were characterized by temperature programmed reduction (TPR), transmission electron microscopy (TEM) and X-ray fluorescence multi-element analysis (XRF). Their activity for the partial oxidation of methane to hydrogen and carbon monoxide (at 1 bar, gas hourly space velocity (GHSV) of 144, 000 cm3 g-1 h-1 and CH4/O2 molar ratio of 2) was investigated, and coke deposited on the spent catalysts was studied by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and thermogravimetric analysis (TGA). The activity was found to decrease in the order of Ni2Co>Ni3 >NiCo2 >> Co3, while CO and H2 selectivities were found to be in the order of Ni2Co>Ni3 ? NiCo2 >Co3. Ni2Co is also shown to be more resistant to coking as compared to Ni3, which is a current catalyst of choice. Results show that not only does Ni2Co have the highest activity and selectivity among all the catalysts tested, it is also relatively resistant to coking. This finding would be helpful for catalyst design to achieve high coking resistivity catalysts for hydrogen production from CPO of methane.
A.C.W. Koh, L. Chen, W.K. Leong, B.F.G. Johnson, T. Khimyak, J. Lin, International Journal of Hydrogen Energy 32 (2007) 725-730

A0957 – Synthesis of highly dispersed palladium alumina supported particles: Influence of the particle surface density on physico-chemical properties

Complexation with nitrite ions in aqueous medium was used to prepare highly dispersed Pd° particles supported on alumina. It has been possible to obtain catalysts with different Pd loading keeping the particle size lower than 1 nm as shown by HRTEM, chemisorption, or extended X-ray absorption fine structure (EXAFS) characterizations, and as a consequence with different particle surface density. We observed that electronic properties measured by IR(CO) or X-ray photoelectron spectroscopy (XPS) measurements are strongly influenced by this last parameter and that the origin of these variations can be related to the different strengths of the interactions of the palladium precursor with the alumina surface sites as shown by low temperature CO adsorption followed by FTIR spectroscopy. On increasing Pd loading, saturation of unsaturated Lewis surface sites follows their acid strength: the more acidic ones are the first to react as germination sites, followed by the medium and finally the weaker sites. These different interactions may explain the variation of electronic properties of such small reduced particles which appears to be very sensitive to the chemical nature of their initial germination site on the oxide support. On the other hand, no such effects were observed on changing the type of alumina (delta or gamma) support, in agreement with the principle of the synthesis method which tends to limit strong interaction with the support. Comparison with Pd° particles with the same particle size and particle surface density but prepared with the well known grafting of acetylacetonate precursor shows marked differences in terms of electronic properties followed by CO FTIR. This result illustrates the possibility to prepare highly dispersed Pd particles with different physico-chemical properties.
M. Benkhaled, S. Morin, Ch. Pichon, C. Thomazeau, C. Verdon, D. Uzio, Applied Catalysis A: General 312 (2006) 1-11

A0956 – Oxygen reduction reaction activity and surface properties of nanostructured nitrogen-containing carbon

Nitrogen-containing carbon nanostructures were prepared from the decomposition of acetonitrile at 900°C over silica and magnesia supports impregnated with Fe, Co, or Ni. For the carbon grown from supported Fe and Co particles, compartmentalized fibers with a stacked cup structure predominantly formed, while mostly broken multi-walled nanotubes formed from Ni particles. The fibers were purified from the support by removing silica with 1M KOH, or removing metal particles and magnesia with 1M HCl. Surface analysis was performed with XPS and hydrophobicity comparisons. Surface properties were related to nanostructure and edge plane exposure. Activity for the ORR was highest over CNx fibers grown from supported Fe and Co particles, which may also be related to edge plane exposure, and not necessarily to the presence of metal contamination. The most active materials were generally the most selective catalysts as well. Moreover, from Tafel plot slopes a trend was observed depending on the precursor metal used to prepare the CNx. The magnitude of the Tafel slope was smallest for the samples prepared from Fe or Co precursors. Compared to a state-of-the-art platinum catalyst, the most active alternative non-noble metal catalysts had less than 100mV potential drop difference, high selectivity for complete oxygen reduction, a similar Tafel slope, and good electrical conductivity.
P.H. Matter, E. Wang, M. Arias, E.J. Biddinger, U.S. Ozkan, Journal of Molecular Catalysis A: Chemical 264 (2006) 73-81

A0960 – Preparation, characterization and antimicrobial activity of chitosan/layered silicate nanocomposites

Chitosan/layered silicate nanocomposites with different ratios were successfully prepared via solution-mixing processing technique. Unmodified Ca2+-rectorite and organic rectorite modified by cetyltrimethyl ammonium bromide were used. Their structures were characterized by XRD, TEM and FT-IR techniques. The results showed that chitosan chains were inserted into silicate layers to form the intercalated nanocomposites. The interlayer distance of the layered silicates in the nanocomposites enlarged as its amount increased. When the weight ratio between chitosan and organic rectorite was 12:1, the largest interlayer distance of 8.24 nm was obtained. However, with further increase of its amount, the interlayer distance of the layered silicates in the nanocomposites reduced. In vitro antimicrobial assay showed that pristine rectorite could not inhibit the growth of bacteria, but chitosan/layered silicate nanocomposites had stronger antimicrobial activity than pure chitosan, particularly against Gram-positive bacteria. With the increase of the amount and the interlayer distance of the layered silicates in the nanocomposites, the nanocomposites showed a stronger antibacterial effect on Gram-positive bacteria, while the nanocomposites showed a weaker antibacterial effect on Gram-negative bacteria. The lowest minimum inhibition concentration (MIC) value of the nanocomposites against Staphylococcus aureus and Bacillus subtilis was 0.00313% (w/v), and the relative inhibition time (RIT) against B. subtilis with concentration of 0.00313% (w/v) was >120 h
X. Wang, Y. Du, J. Yang, X. Wang, X. Shi, Y. Hu, Polymer 47 (2006) 6738-6744

A0959 – Al-containing MCM-41 type materials prepared by different synthesis methods: Hydrothermal stability and catalytic properties

Al-containing MCM-41 type materials were prepared by three different synthesis methods (aluminum grafting on the calcined MCM- 41, pH adjustment during the crystallization period and crystallization in the presence of zeolite seeds). The samples were characterized by powder XRD, nitrogen adsorption, 27Al MAS NMR and FTIR with pyridine as probe molecule. All the samples exhibit a high hydrothermal stability at high temperature just with a minor structural degradation. N2 adsorption data obtained for the sample prepared from a gel containing zeolite seeds suggest a higher structural resistance to the hydrothermal treatment in comparison with the samples prepared by other methods. A different type of pyridine adsorbed, probably interacting simultaneously with a Brönsted and a Lewis acid site, is observed upon pyridine adsorption. This type of adsorption is stronger for the sample prepared in the presence of zeolite seeds and is not observed on Al-grafted MCM-41. The catalytic activity towards the isomerization of alpha-pinene depends mainly on the number of Brönsted acid sites. The data obtained in this study strongly indicate that for this type of materials, the Lewis acid sites do not influence the selectivity for the isomerization products.
J.P. Lourenço, A. Fernandes, C. Henriques, M.F. Ribeiro, Microporous and Mesoporous Materials 94 (2006) 56-65

A0958 – Baeyer-Villiger oxidation of cyclohexanone with hydrogen peroxide/benzonitrile over hydrotalcites as catalysts

Various Mg/Al, Mg/Al/Sn and Mg/Al/Zr hydrotalcite-like compounds (HTs) were prepared for use as catalysts in the Baeyer-Villiger (BV) oxidation of cyclohexanone with H2O2/benzonitrile as oxidant and benzonitrile itself as the solvent. The reaction gave water and benzamide as byproducts, the latter can be recycled in an appropiate process. Analysis of the solids revealed that tin and zirconium are in fact incorporated into the HT structure. The solids containing Mg/Al and Mg/Al/Sn and their calcination products (viz. Mg/Al and Mg/Al/Sn mixed oxides) were found to be effective catalysts for the BVoxidation of cyclohexanone. The Sn solids exhibited a higher activity than a more conventional catalyst obtained from an HT containing Mg and Al only (17% in the best case). Also, the catalyst containing tin was active when we used H2O2/acetonitrile system as oxidant. The solids containing Zr were found to promote the decomposition of the hydrogen peroxide and hence to adversely influence the oxidation reaction. A mechanism accounting for the experimental results is proposed. The reaction was conducted under very mild conditions (viz. atmospheric pressure and a temperature of 70°C), and conversions obtained were higher than 80% in some cases and 100% selectivity after 6 h. The most active catalyst, which was that containing the largest amount of tin, retained full activity after three reuses.
C. Jiménez-Sanchidrian, J.M. Hidalgo, R. Llamas, J.R. Ruiz, Applied Catalysis A: General 312 (2006) 86-94

A0961 – New granular material for hot gas filtration: Use of the “Lapilli”

A study was conducted on a new granular material (Lapilli) for hot gas filtration. We have characterized this material by means of set of instrumental methods involving: surface area (SBET), scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermogravimetry (TG), differential thermal analysis (DTA) and X-ray fluorescence (XRF). Also, we have used a fixed bed heat exchanger-filter (FHEF) for removing fine dust particles from gases. The influence of a number of variables was examined, including gas velocities, filter height and gas temperatures and the collection efficiency was found to decrease with increasing temperature. Also, a model was proposed to describe the granular filtration of the FHEF using Lapilli as a granular medium. A numerical solution of the filtration equations based on the finite element method was presented.
A. Macias-Machin, M. Socorro, J.M. Verona, M. Macias, Chemical Engineering and Processing 45 (2006) 719-727

A0963 – Heat treatment of chlorinated waste in a rotating kiln: Problems with intermediate reaction products and solutions applied

At the CEA, the incineration of radioactive wastes is carried out thanks to the IRIS process involving a oxidizing pyrolysis step performed with a rotary kiln. If the running of the process is very satisfactory for processing waste of a given composition, it appears that the behavior of the kiln may diverge when the composition of the waste change. Through the example of wastes containing a large amount of PVC and thanks to a very simple modelling of the heating of the kiln, it has been demonstrated that the deposits are involved in overheating of the pyrolysis kiln. Fundamental investigation carried out about the thermal degradation of PVC and cellulose have shown that the formation of intermediate PVC decomposition compounds together with the residues coming from the decomposition of the cellulose could be responsible of the large amount of deposits. In order to avoid the malfunctions it has been proposed to revise the furnace operating parameters by specifying a waste feed sequence that ensure a relaxation period to the furnace. By this way, the running of the facility shows a very good stability with a very thin temperature oscillation that can easily be explained by a thermal modelling of the kiln.
F. Lemort, Y. Soudais, L. Moga, Y. Blazeck, International Journal of Engineering Science 44 (2006) 1071-1081

A0962 – Frittage du phosphate tricalcique

Ce travail aborde l'étude du frittage du beta phosphate tricalcique obtenu par voie sèche, en vue d'élaborer des matériaux denses. L'évolution de la densité du matériau fritté en fonction du temps et de la température, a été suivie. Le phosphate tricalcique présente une bonne aptitude au frittage dans le domaine de température 1200-1350°C, ainsi des taux de densification de 92% ont pu être atteints à 1300°C. A des températures supérieures à 1350°C, la densification est entravée par le grossissement exagéré des grains et la formation de larges pores. La diffraction des rayons X montre en plus du beta phosphate tricalcique, la présence de traces de la phase alpha du phosphate tricalcique et du phosphate tétracalcique. L'analyse par résonance magnétique nucléaire du solide 31P illustre la présence de trois types de site tétraédrique. L'analyse thermique différentielle montre que les deux transformations allotropiques du phosphate tricalcique se produisent respectivement à 1285 et 1475°C.
F. Ben Ayed, K. Chaari, J. Bouaziz, K. Bouzouita, C. R. Physique 7 (2006) 825-835

A0966 – A detailed study of UO2 to U3O8 oxidation phases and the associated rate-limiting steps

The kinetic and crystalline evolutions of UO2 during its oxidation into U3O8 at 250°C in air were studied by isothermal thermogravimetry and calorimetry, coupled with an in situ synchrotron X-ray diffraction on the D2AM-CRG beamline at ESRF. This study was aimed at determining experimentally the validity of the kinetic assumptions made in existing literature to account for the oxidation of UO2 into U3O8 and also to determine precisely the structural evolution, in relation to the kinetic behaviour. Our results provide evidence of four distinct kinetic time domains, and the assumption of a single rate-limiting step is verified only for two of them. The crystalline phases associated with these domains are also identified. In fact, the first kinetic domain corresponds to the reaction of UO2 into U4O9; the second one is linked to the two simultaneous reactions, UO2 into U4O9 and U4O9 into U3O7. Finally, the transition from U3O7 into U3O8 corresponds to the third and fourth kinetic domains. These results show that the oxidation of UO2 into U3O8 cannot satisfactorily be described with modelling approaches used in the literature. A new general outline is proposed to study the oxidation of uranium oxides. This outline will improve both the understanding and predictions of oxidation processes at the relatively low temperatures that are expected during interim storage of spent nuclear fuel.
G. Rousseau, L. Desgranges, F. Charlot, N. Millot, J.C. Nièpce, M. Pijolat, F. Valdivieso, G. Baldinozzi, J.F. Bérar, Journal of Nuclear Materials 355 (2006) 10-20

A0965 – Thermogravimetric study on perovskite-like oxygen permeation ceramic membranes

The oxygen permeation properties of mixed-conducting ceramics SrFeCo0.5O(3-d) (SFCO), Ba0.5Sr0.5Co0.8Fe0.2O(3-d) (BSCFO), La0.2Sr0.8Co0.8Fe0.2O(3-d) (LSCFO) and Ba0.95Ca0.05Co0.8Fe0.2O(3-d) (BCCFO) were studied by thermogravimetric method in the temperature range 600-900°C. The results show that the oxygen adsorption rate constants ka of all material are larger than oxygen desorption rate constants kd and both ka and kd are not strongly dependent on temperature in the studied temperature range. The oxygen vacancy contents d(N2) and d(O2) in nitrogen and oxygen and their difference d = d(N2)-d(O2) play an important role in determining the temperature behavior of oxygen permeation flux JO2 .
J. Hu, H. Hao, C. Chen, D. Yang, X. Hu, Journal of Membrane Science 280 (2006) 809-814

A0964 – Reduction roasting of limonite ores: effect of dehydroxylation

The effect of pre-calcination in the reducibility of tropical limonite ore, obtained from New Caledonia, was investigated in this study. A series of reduction tests were carried out with pre-calcined and raw limonite ores. The extent of metallisation was determined from nickel and iron which dissolved in ammoniacal solution. Mineralogical transformations that occurred during reduction were analysed using thermal gravimetric, differential thermal analysis (TGA/DTA) and in situ high temperature synchrotron based X-ray diffraction. Bulk mineral analysis of the raw ore was also obtained using neutron diffraction. This study suggests that there is benefit in the pre-calcination of limonite ores. Pre-calcination of the ores which opens the main gangue mineral structure, goethite, allows a rapid interaction between the reductant gases and the nickel species during reduction. The greater nickel metallisation achieved in reduction of pre-calcined ores resulted in higher dissolved nickel whilst reduced raw limonite showed poorer nickel recovery. Reduction of metal minerals was also accompanied by diffusion of nickel into the reduced iron matrix that resulted in the formation of ferro-nickel alloy (Ni3Fe). The formation of this solid solution was monitored by in situ synchrotron based X-ray diffraction and was also reflected by the lower nickel leachability in ammoniacal solution. It was found that incorporation of nickel into the reduced iron oxide resulting from pre-calcination is significantly less in comparison to the diffusion occurring in reduced raw or uncalcined limonite ores. This effect is prevalent in prolonged reduction periods (greater than 20 min), at higher temperatures (>500°C) and highly reducing conditions (H2/CO2=1:1). This study showed that optimal nickel recovery can be achieved by controlling the incorporation of nickel into the reduced iron structure by pre-calcination of the limonite ore.
F. O'Connor, W.H. Cheung, M. Valix, Int. J. Miner. Process. 80 (2006) 88- 99

A0967 – A detailed study of UO2 to U3O8 oxidation phases and the associated rate-limiting steps

The kinetic and crystalline evolutions of UO2 during its oxidation into U3O8 at 250°C in air were studied by isothermal thermogravimetry and calorimetry, coupled with an in situ synchrotron X-ray diffraction on the D2AM-CRG beamline at ESRF. This study was aimed at determining experimentally the validity of the kinetic assumptions made in existing literature to account for the oxidation of UO2 into U3O8 and also to determine precisely the structural evolution, in relation to the kinetic behaviour. Our results provide evidence of four distinct kinetic time domains, and the assumption of a single rate-limiting step is verified only for two of them. The crystalline phases associated with these domains are also identified. In fact, the first kinetic domain corresponds to the reaction of UO2 into U4O9; the second one is linked to the two simultaneous reactions, UO2 into U4O9 and U4O9 into U3O7. Finally, the transition from U3O7 into U3O8 corresponds to the third and fourth kinetic domains. These results show that the oxidation of UO2 into U3O8 cannot satisfactorily be described with modelling approaches used in the literature. A new general outline is proposed to study the oxidation of uranium oxides. This outline will improve both the understanding and predictions of oxidation processes at the relatively low temperatures that are expected during interim storage of spent nuclear fuel.
G. Rousseau, L. Desgranges, F. Charlot, N. Millot, J.C. Nièpce, M. Pijolat, F. Valdivieso, G. Baldinozzi, J.F. Bérar, Journal of Nuclear Materials 355 (2006) 10-20

A0969 – Synthesis and crystal structure of a new adduct of dihydrogenphosphate phosphoric acid monohydrate with 8-aminoquinolinium (8-NH2-C9H6NH)2(H2PO4)2H3PO4.H2O

The synthesis and structure of a new adduct with formula: (8-NH2-C9H6NH)2(H2PO4)2H3PO4.H2O is reported. It crystallizes with triclinic unit cell. The following unit cell parameters were found: a = 9.371(2), b = 11.442(2), c = 13.340(2) Å, alpha = 96.78(6)°, beta = 97.34(5)°, gamma = 113.90(3)°, V = 1273.7(6) Å3 and ?cal. = 1.565 gcm-3. Crystal structure was solved with a final R = 0.041 for 3982 independent reflections. The space group is P-1 and Z = 2. The atomic arrangement can be described as wide pseudo-hexagonal channels including the organic entities. Solid-state 13C and 31P MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of the phosphorous signals to the three independent crystallographic sites.
J. Oueslati, A. Oueslati, C. Ben Nasr, F. Lefebvre, Solid State Sciences 8 (2006) 1067-1073

A0968 – A study on the phase transformation of the nanosized hydroxyapatite synthesized by hydrolysis using in situ high temperature X-ray diffraction

The biodegradable hydroxyapatite (HA) was synthesized by hydrolysis and characterized using high temperature X-ray diffraction (HT-XRD), differential thermal analysis and thermogravimetry (DTA/TG), and scanning electron microscopy (SEM). The in situ phase transformation of the HA synthesized from CaHPO4I2H2O (DCPD) and CaCO3 with a Ca /P=1.5 in 2.5 M NaOH(aq) at 75°C for 1 h was investigated by HT-XRD between 25 and 1500°C. The HA was crystallized at 600°C and maintained as the major phase until 1400°C. The HA steadily transformed to the alpha-tricalcium phosphate (alpha-TCP) which became the major phosphate phase at 1500°C. At 700°C, the minor CaO phase appeared and vanished at 1300°C. The Na+ impurity from the hydrolysis process was responsible for the formation of the NaCaPO4 phase, which appeared above 800°C and disappeared at 1200°C.
W-J. Shih, J-W. Wang, M-C. Wang, M-H. Hon, Materials Science and Engineering C 26 (2006) 1434-1438

A0971 – Preparation and photocatalytic activity of mesoporous anatase TiO2 nanofibers by a hydrothermal method

Mesoporous anatase TiO2 nanofibers were prepared by a simple hydrothermal post-treatment of titanate nanotubes. The as-prepared samples were characterized with transmission electron microscopy (TEM), thermogravimetry (TG), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and N2 adsorption-desorption measurement. The photocatalytic activity of the mesoporous TiO2 nanofibers was evaluated by photocatalytic oxidation of acetone in air. The effects of hydrothermal post-treatment time on the structures and photocatalytic activity of the mesoporous TiO2 nanofibers were discussed. The results showed that the photocatalytic activity of the TiO2 nanofibers prepared by this method exceeded that of Degussa P25 when the hydrothermal post-treatment time was kept at 200°C for 3-24 h. This could be attributed to the fact that the former had smaller crystallite size, larger specific surface area, and higher pore volume.
J. Yu, H. Yu, B. Cheng, X. Zhao, Q. Zhang, Journal of Photochemistry and Photobiology A: Chemistry 182 (2006) 121-127

A0970 – Thermochemistry of NaRb[B4O5(OH)4].4H2O

The enthalpies of solution of NaRb[B4O5(OH)4].4H2O in approximately 1 mol dm-3 aqueous hydrochloric acid and of RbCl in aqueous (hydrochloric acid + boric acid + sodium chloride) were determined. From these results and the enthalpy of solution of H3BO3 in approximately 1 mol dm-3 HCl(aq) and of sodium chloride in aqueous (hydrochloric acid + boric acid), the standard molar enthalpy of formation of -(5128.02±1.94) kJ mol-1 for NaRb[B4O5(OH)4].4H2O was obtained from the standard molar enthalpies of formation of NaCl(s), RbCl(s), H3BO3(s) and H2O(l). The standard molar entropy of formation of NaRb[B4O5(OH)4].4H2O was calculated from the Gibbs free energy of formation of NaRb[B4O5(OH)4].4H2O computed from a group contribution method.
J. Zhou, F. Zhao, Q. Yang, Y. Lu, S. Xia, S. Gao, Thermochimica Acta 448 (2006) 52-55

A0973 – Oxidized activated carbon as support for titanium dioxide in UV-assisted degradation of 3-chlorophenol

Strong adsorption of pollutants on activated carbon may inhibit their diffusion to the catalyst on the surface of the adsorbent and hence reduce the whole photocatalytic process. Oxidation of the carbon surface will change the adsorption properties of the carbon; and increase the capability of carbon surface to carry more titanium dioxide. In this work, activated carbon was oxidized with different oxidizing agents (nitric acid, ammonium persulfate, and hydrogen peroxide) to produce carbons with different surface chemistries. Titanium dioxide was deposited on oxidized and nonoxidized carbons, in which titanium dioxide loading was higher in the oxidized carbons. The produced materials were tested in UV-assisted mineralization of 3-chlorophenol in aqueous medium. Results showed that 1 g of the product made by deposition of titanium dioxide on hydrogen peroxide-oxidized carbon (23.5% titanium dioxide) caused photo-mineralization of 40% of the 3-chlorophenol within 5 h; while half gram of titanium dioxide (pure anatase) caused photo-mineralization of 58% of 3-chlorophenol within the same period. It seems that 3-chlorophenol decomposed entirely with titanium dioxide deposited on other oxidized and non-oxidized carbons, but complete mineralization into chloride, CO2 and H2O was not achieved. A mixture of titanium dioxide (anatase) and non-oxidized carbon showed that mineralization is taking place even when all 3-chlorophenol was adsorbed on carbon surface. This suggests that adsorbed 3-chlorophenol is involved in the mineralization process.
A.H. El-Sheikh, Y.S. Al-Degs, A.P. Newman, D.E. Lynch, Separation and Purification Technology 54 (2007) 117-123

A0972 – Synthesis and characterization of a new monophosphate (5-Cl-2,4-(OCH3)2C6H2NH3)H2PO4

Chemical preparation, crystal structure and NMR spectroscopy of a new organic cation 5-chloro(2,4-dimethoxy)anilinium monophosphate H2PO4 are given. This new compound crystallizes in the monoclinic system, with the space group P21/c and the following parameters: a = 5.524(2) Å , b = 9.303(2) Å , c = 23.388(2) Å , beta = 90.66(4), V = 1201.8(2) Å3, Z = 4 and Dx = 1.573 g cm-3. Crystal structure has been determined and refined to R = 0.031 and Rw = 0.080 using 1702 independent reflections. Structure can be described as an infinite (H2PO4)n n- corrugated chains in the a-direction. The organic groups (5-Cl-2,4- (OCH3)2C6H2NH3)+ are anchored between adjacent polyanions through multiple hydrogen bonds. This compound is also investigated by IR, thermal, and solid-state, 13C, 31P MAS NMR spectroscopies.
R. Kefi, S. Abid, C. Ben Nasr, M. Rzaigui, Materials Research Bulletin 42 (2007) 404-412

A0975 – Order-disorder phase transitions and high-temperature oxide ion conductivity of Er(2+x)Ti(2-x)O(7-d) (x = 0, 0.096)

The Er(2+x)Ti(2-x)O(7-d) (x = 0.096; 35.5 mol% Er2O3) solid solution and the stoichiometric pyrochlore-structured compound Er2Ti2O7 (x = 0; 33.3 mol% Er2O3) are characterized by X-ray diffraction (phase analysis and Rietveld method), thermal analysis and optical spectroscopy. Both oxides were synthesized by thermal sintering of co-precipitated powders. The synthesis study was performed in the temperature range 650-1690°C. The amorphous phase exists below 700°C. The crystallization of the ordered pyrochlore phase (P) in the range 800-1000°C is accompanied by oxygen release. The ordered pyrochlore phase (P) exists in the range 1000-1200°C. Heat-treatment at T > 1600°C leads to the formation of an oxide ion-conducting phase with a distorted pyrochlore structure (P2) and an ionic conductivity of about 10^(-3) S/cm at 740°C. Complex impedance spectra are used to separately assess the bulk and grain-boundary conductivity of the samples. At 700°C and oxygen pressures above 10^(-10) Pa, the Er(2+x)Ti(2-x)O(7-d) (x = 0, 0.096) samples are purely ionic conductors.
A.V. Shlyakhtina, A.V. Levchenko, J.C.C. Abrantes, V.Yu. Bychkov, V.N. Korchak, V.A. Rassulov, L.L. Larina, O.K. Karyagina, L.G. Shcherbakova, Materials Research Bulletin 42 (2007) 742-752

A0974 – Electrochemical properties of LiCrxNi(0.5-x)Mn0.5O2 prepared by co-precipitation method for lithium secondary batteries

The purpose of this research is to study a new synthesis of LiCrxNi(0.5-x)Mn0.5O2 (x = 0, 0.05 and 0.1) using a co-precipitation method for lithium secondary batteries. Investigations are made of the morphology, cyclic voltammetry and charge-discharge cycling of LiCrxNi(0.5-x)Mn0.5O2/Li cells. The particle size of LiNi0.5Mn0.5O2 has a narrow distribution range from 200 to 300 nm. The peak current of LiCr0.05Ni0.45Mn0.5O2 and LiCr0.1Ni0.4Mn0.5O2 in the 2.7 and 2.9V regions increases with increasing addition of Cr in LiCrxNi(0.5-x)Mn0.5O2. The discharge capacity of the LiNi0.5Mn0.5O2 electrode is 185 and 150 mAh g-1 at 1 and 15 cycles, respectively. The fading in capacity of Cr-doped LiNi0.5Mn0.5O2 is less than that of LiNi0.5Mn0.5O2 during cycling. LiCrxNi(0.5-x)Mn0.5O2 cathodes with 1M LiPF6 in an ethyl carbonate-dimethyl carbonate (EC-DMC) electrolyte exhibit good cycling performance.
G-T. Kim, J-U. Kim, Y-J. Sim, K-W. Kim, Journal of Power Sources 158 (2006) 1414-1418

A0977 – Formation of high surface area Li/MgO – Efficient catalyst for the oxidative dehydrogenation/cracking of propane

In this study nanoscale clusters of Li/MgO oxide with varying lithium contents are prepared via the sol-gel method. The preparation routine consists of co-gelation of LiNO3 and Mg(OCH3)2 in methanol/water solution followed by drying at 50°C under vacuum and calcination at 500°C in air. The structural and textural transformations that take place during oxide formation are studied with TGA-DSC-MS and FTIR spectroscopy. The obtained materials are characterized by TEM, N2 physisorption and XRD. Presence of increasing amounts of lithium precursor causes extensive hydrolysis of the alkoxide sol. Appreciable amounts of lithium ions can be incorporated in the magnesia gel even under the mild conditions during sol-gel transformation. Non-incorporated lithium ions form a separate carbonate phase, which has a detrimental effect on the surface area due to enhanced sintering. The Li/MgO oxide materials thus prepared possess high surface area (50-190 m2/g) depending on Li content. Small amounts of lithium ions, when present as a dispersed phase, do not seem to influence the structural and textural characteristics of the magnesia gel and, in these cases, nanoscale Li/MgO oxide clusters with high surface areas similar to pure MgO can be prepared. Sol-gel derived Li/MgO provides significantly higher olefin yields in ODH of propane in comparison with conventional Li/MgO catalysts, especially at lower temperatures.
C. Trionfetti, I.V. Babich, K. Seshan, L. Lefferts, Applied Catalysis A: General 310 (2006) 105-113

A0976 – Synthesis, characterization and catalytic properties of vanadium aluminophosphate molecular sieves VAPO-31 and VAPSO-Amr from non-aqueous media

Vanadium samples containing aluminophosphate molecular sieve (VAPO-31) and amorphous vanadium silicoaluminophosphate (VAPSOAmr) have been synthesized using hexamethyleneimine template from non-aqueous media for the first time. XRD and SEM analyses confirm the phase purity of the synthesized samples. FT-IR analysis suggests the incorporation of V4+ in the aluminophosphate framework. ESR, UV-vis spectroscopic, and XPS techniques and cyclicvoltametric studies confirm the incorporation of vanadium and reveal its presence in tetrahedral and square pyramidal environments in the as-synthesized samples. Cyclic voltammetry reveals the presence of two redox couples in VAPO-31. This catalyst is found to be a good oxidation catalyst. Although most of the properties of VAPO-31NA and VAPSO-Amr are similar, the latter can access more vanadium and V4+ ions. Compared to aqueous media samples, it can incorporate more vanadium especially V5+ ions and has been found to be better oxidation catalyst. The physicochemical properties also change with media.
N. Venkatathri, Applied Catalysis A: General 310 (2006) 31-39

A0979 – Crystal structure and physicochemical properties of a new organic condensed phosphate (C7H10NO)3P3O9.4H2O

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

A0978 – A one-step hydrothermal way for the synthesis of vanadium oxide nanotubes containing the phenylpropylamine as template obtained via non-alkoxide route

Vanadium oxide nanotubes (VOx-NTs) with high crystallinity were synthesized by using the crystalline V2O5 as precursor for the first time with 3- phenylpropylamine as structure-directing template via one-step hydrothermal way. Structure and morphology of the nanotubes were investigated by Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray powder diffraction, Thermal analysis and Infrared. The inner and the outer of the obtained nanotubes vary respectively between 15 to 25 nm and 70 to 100 nm with a length up to 4 ?m.
F. Sediri, F. Touati, N. Gharbi, Materials Letters 61 (2007) 1946-1950

A0981 – Effects of ozone pretreatment on the performance of Au/TiO2 catalyst for CO oxidation reaction

O3-pretreated O3-Au/TiO2 catalyst exhibited better catalyst dispersion and stability compared with O2-pretreated O2-Au/TiO2. Ozone effectively removed the carbonaceous byproducts of catalyst preparation that oxygen was unable to completely decompose. This resulted in the poor catalyst dispersion and a bimodal gold particle size distribution of O2-Au/TiO2. The catalyst performance was tested for the CO oxidation reaction and compared with the gold reference catalyst (GRC). The reaction was carried out in an in situ DRIFTS apparatus that provides real-time monitoring of surface reaction and simultaneous collection of reaction conversion data. Both Au/TiO2 catalysts displayed higher conversion rates for CO oxidation reaction compared with GRC. Gold sintering was evident for the O2-Au/TiO2 and GRC after the CO oxidation reaction at 473 K, and both catalysts suffered a loss in activity. The formation of oxidic gold observed in O3-Au/TiO2 is expected to afford a stronger metal-support interaction and may be the reason for the excellent stability of this catalyst against sintering.
K.Y. Ho, K.L. Yeung, Journal of Catalysis 242 (2006) 131-141

A0980 – Water-gas shift reaction over sulfided molybdenum catalysts supported on TiO2-ZrO2 mixed oxides Support characterization and catalytic activity

Supported sulfided molybdenum and nickel-molybdenum catalysts were applied in the water-gas shift (WGS) reaction with sulfided feed. TiO2, ZrO2 and binary systems of TiO2-ZrO2, in which composition was changed in 10 wt.% intervals, were used as the supports for sulfided Mo and Ni-Mo catalysts. The concentration of Mo (8 wt.%) and Ni (3 wt.%) was the same in all studied catalysts. Supports and selected catalysts were characterized with XRD, BET, TPR (H2), TPD of ammonia, FTIR and NO adsorption measurements. The comparison of pure TiO2 or ZrO2 with TiO2-ZrO2 systems shows that introduction of the second component always resulted in almost duplication of the surface area of the supports. No simple relationship between surface area and catalytic activity was found. The choice of the support with appropriate ratio of surface acid-base sites, high dispersion of supported Ni-Mo-S surface species as well as much easier reductivity of Mo6+ ions in the presence of nickel ions can lead towards high activity in the WGS reaction with sulfided feed. The highest activity was obtained for Ni-Mo-S catalysts supported on TiO2 (40)- ZrO2 (60).
M. Laniecki, M. Ignacik, Catalysis Today 116 (2006) 400-407

A0983 – The phase diagram and crystal chemistry of strontium-doped rare earth cobaltates: Ln(2-x)SrxCoO(4+d) (Ln = La-Dy)

Single-phase tetragonal K2NiF4-type phases Ln(2-x)SrxCoO(4+d) (Ln=La3+-Dy3+) have been prepared for (x = 0.75-1.50). For the first time, the phase field for these compounds has been defined using a combination of electron microscopy and powder X-ray diffraction. An extensive solid solution was observed for the largest rare earth ions, while only a limited range was found for Ln = Sm3+, Gd3+, and Dy3+. The K2NiF4 structure could not be formed for Y3+ and smaller rare earths ions under atmospheric conditions. Thermogravimetric analysis indicates a range of average cobalt oxidation states increases with Sr-doping and varies from 2.96 to 3.72. Rietveld refinement using X-ray powder diffraction data confirm that Ln3+ and Sr2+ ions are disordered over the same lattice sites.
M. James, A. Tedesco, D. Cassidy, M. Colella, P.J. Smythe, Journal of Alloys and Compounds 419 (2006) 201-207

A0982 – Isoconversional kinetic analysis of stoichiometric and off-stoichiometric epoxy-amine cures

The curing reaction of stoichiometric and off-stoichiometric diglycidyl ether of bisphenol A (DGEBA) and 1,3-phenylene diamine (m-PDA) mixtures was studied by differential scanning calorimetry, thermogravimetric analysis and rheological measurements. In order to highlight the side reactions such as etherification and homopolymerization, the neat DGEBA and DGEBA/DMBA (N,N-dimethylbenzylamine) mixture were examined. The classical model-fitting and the advanced isoconversional methods were used to determine the activation energy of the different reactions. The advanced isoconversional method leads to a good agreement between isothermal, nonisothermal and rheological results. The effective activation energies of primary amine epoxy reaction, etherification and homopolymerization were estimated to about 55-60, 104 and 170 kJ mol-1, respectively.
N. Sbirrazzuoli, A. Mititelu-Mija, L. Vincent, C. Alzina, Thermochimica Acta 447 (2006) 167-177

A0984 – Studies on a new carrier of trimethylsilyl-modified mesoporous material for controlled drug delivery

To better control drug delivery rate, a simple and effective approach has been developed for controlled drug delivery carrier system through one-step surface modification of the ibuprofen-impregnated silica MCM-41 with 1, 1, 1, 3, 3, 3-hexamethyldisilazane (HMDS). The 29Si MAS NMR characterization demonstrated that different contents of trimethylsilyl (TMS) groups were successfully grafted onto the samples modified with different silylation times. The results obtained from in vitro tests exhibited that the introduction of TMS groups greatly retarded the ibuprofen release rate. Even after in vitro test for 48 h, only 75% of the impregnated ibuprofen could be released from the modified sample with TMS groups content of 14.5% (related to the total silicon atoms). However, the release of ibuprofen could be completed just after about 1 h from the pure silica MCM-41 under the same release conditions. Furthermore, the release rate of ibuprofen could be well modulated by changing the grafted content of TMS groups, and was found to decrease with increasing grafted amount of TMS groups.
Q. Tang, Y. Xu, D. Wu, Y. Sun, J. Wang, J. Xu, F. Deng, Journal of Controlled Release 114 (2006) 41-46

A0985 – Estimation of adsorption energies using physical characteristics of activated carbons and VOCs’ molecular properties

Adsorption of volatile organic compounds (VOCs) by granular activated carbons (GACs) is a highly exothermic process and leads to temperature rises, which can be hazardous for high pollutant contents. This study points out the significant characteristics of VOCs and GACs on adsorption energies. For that purpose, adsorption energies were measured for a wide variety of VOCs, representative of different chemical groups, using eight different commercial GACs with different porous structures. Afterwards a statistical analysis was applied to the experimental database thus obtained, which enabled to enlighten the most significant variables, linked to either VOCs' molecular properties or intrinsic characteristics of GACs. Two statistical models have been tested: multi-linear regression (MLR) and neuron networks (NN), and their efficiencies were compared in terms of prediction skill. The best results have been obtained from the MLR approach, which discriminated five different properties of the system. These explicative variables were the polarizability, the heat of vaporization, the ionization potential and the surface tension for adsorbates and the average micropore radius for GACs. The MLR model enabled to compute integral adsorption enthalpies with a precision around 10%. Thanks to the properties discriminated, we came to some conclusions on the dominant mechanisms of adsorption.
S. Giraudet, P. Pré, H. Tezel, P. Le Cloirec, Carbon 44 (2006) 1873-1883

A0987 – Photocatalytic hydrogen production over newoxide CuLaO2.62

The new oxide CuLaO2.62, synthesized through solid reaction under O2 atmosphere from CuLaO2 at 380°C, crystallizes in a pseudodelafossite structure. The formulation comes from thermal analysis and iodometric titrations. It exhibits a p-type semiconductivity; the resistivity p300 K (2485 ?cm) and the thermopower S300 K (93 µV K-1) suggest a mechanism conduction by small polarons hopping between Cu2+/3+. The material is thermally stable up to ~ 500°C beyond which it converts irreversibly to CuLa2O4. Its photocatalytic ability, in contact with S2- and (SO3)2- aqueous solutions for H2 production, has been evaluated in connection with some physical parameters. The title oxide is chemically stable in KOH media, its conduction band (-1.46Vsce), determined from photoelectrochemical measurements, lies below the H2O/H2 level (-0.82Vsce) leading to a spontaneous H2-evolution under visible light. The most H2, with a generation rate of 0.465 ml h-1 mg-1, was obtained in an aqueous sulfite solution (0.1M (SO3)2- , pH 8.04) and increases parallel to (S2O6)2- and/or (SO4)2- formation. The thermal enhancement of the photoactivity is attributed to an increase in carrier doping moving in narrow bands of Cu-3d parentage. The whole photoelectrochemical process is limited by the supply of electrons at the interface. The photoactivity slows down with time because of competitive reductions of end products (S2O6)2- and (Sn)2- with H2O.
N. Koriche, A. Bouguelia, M. Trari, International Journal of Hydrogen Energy 31 (2006) 1196-1203

A0986 – New efficient Fe2O3 and FeMo supported OMCVD catalysts for single wall carbon nanotubes growth

Organometallic chemical vapor deposition (OMCVD) has been used for the preparation of Fe2O3/Al2O3 and FeMo/Al2O3 catalysts from zero-valent carbonyl precursors. These systems have been successfully applied in the methane decomposition reaction to produce selectively single wall carbon nanotubes. The performances of these catalysts are compared to that obtained with monometallic Fe/Al2O3 and Mo/Al2O3 systems also prepared by OMCVD. From the results present therein, it appears that the selective production of SWNT is associated with the formation of small iron clusters during the reduction step of an oxide phase.
E. Lamouroux, P. Serp, Y. Kihn, P. Kalck, Catalysis Communications 7 (2006) 604-609

A0988 – Iron oxide modified diamond blends containing ultradispersed diamond

Iron oxide modified diamond blends containing different amounts of ultradispersed diamond were prepared and characterized by nitrogen physisorption, X-ray diffraction, temperature programmed reduction, Mössbauer and IR spectroscopy. The catalytic behavior of these composite materials inmethanol decomposition to hydrogen, carbon monoxide, and methane has been also studied. The initial state and phase transformations of the supported highly dispersed iron oxide particles in various pretreatment media, as well as their reductive and catalytic properties, strongly depend on the ultradispersed diamond content in the diamond blends.
T. Tsoncheva, M. Dimitrov, L. Ivanova, D. Paneva, D. Mitev, B. Tsintsarski, I. Mitov, S. Stavrev, C. Minchev, Journal of Colloid and Interface Science 300 (2006) 183-189

A0992 – Oxidation behaviour of unirradiated sintered UO2 pellets and powder at different oxygen partial pressures, above 350°C

The oxidation of sintered UO2 pellets and powder into U3O8 has been studied by thermogravimetry at 370°C, under controlled oxygen partial pressures (PO2 ranging from 2 to 40 kPa). Sigmoidal curves of oxidation weight gain were measured for both pellet and powder test samples. The rate of oxidation increased as the oxygen partial pressure increased. It has been shown, by simultaneous TG-DSC, that the reaction proceeds in a pseudo steady state. An experimental methodology based on temperature or PO2 jumps has shown that the assumption of a rate-limiting step is validated, and a mean value of activation energy for the formation of U3O8 of 103 kJ mol-1 was estimated.
F. Valdivieso, V. Francon, F. Byasson, M. Pijolat, A. Feugier, V. Peres, Journal of Nuclear Materials 354 (2006) 85-93

A0991 – Oxidation behaviour of unirradiated sintered UO2 pellets and powder at different oxygen partial pressures, above 350°C

The oxidation of sintered UO2 pellets and powder into U3O8 has been studied by thermogravimetry at 370°C, under controlled oxygen partial pressures (PO2 ranging from 2 to 40 kPa). Sigmoidal curves of oxidation weight gain were measured for both pellet and powder test samples. The rate of oxidation increased as the oxygen partial pressure increased. It has been shown, by simultaneous TG-DSC, that the reaction proceeds in a pseudo steady state. An experimental methodology based on temperature or PO2 jumps has shown that the assumption of a rate-limiting step is validated, and a mean value of activation energy for the formation of U3O8 of 103 kJ mol-1 was estimated.
F. Valdivieso, V. Francon, F. Byasson, M. Pijolat, A. Feugier, V. Peres, Journal of Nuclear Materials 354 (2006) 85-93

A0990 – Synthesis and characterization of thorium-bearing britholites

In the field of the immobilization of tri- and tetravalent minor actinides, apatites and especially britholites were already proposed as good candidates. In order to simulate tetravalent minor actinides, the incorporation of thorium, through dry chemical routes, was studied in britholite samples of general formula Ca9Nd(1-x)Thx(PO4)(5-x)(SiO4)(1+x)F2. The study showed that the incorporation of thorium was effective whatever the thorium reagent used or the grinding conditions considered. Nevertheless, it appeared necessary to use mechanical grinding (30 Hz, 15 min) before heating treatment (T = 1400°C, 6 h) to improve the reactivity of powders and the sample homogeneity. In these conditions, the incorporation of thorium in the britholite structure occurred above 1100°C. The heating treatment at 1400°C led to single phase and homogeneous compounds. This work also underlined the necessity to prefer the coupled substitution (Nd3+, (PO4)3-) <=> (Th4+, (SiO4)4-) instead of (Nd3+, F- ) <=> (Th4+, O2- ) in order to prepare pure and single phase samples in all the range of composition examined.
O. Terra, F. Audubert, N. Dacheux, C. Guy, R. Podor, Journal of Nuclear Materials 354 (2006) 49-65

A0989 – Study of Ga modified Cs2.5H1.5PV1Mo11O40 heteropolyoxometallates for propane selective oxidation

The selective oxidation of propane by oxygen has been investigated on a series of gallium modified Cs2.5H1.5PV1Mo11O40 samples, with Ga content varying from 0 to 0.32 per Keggin unit (KU). The physicochemical properties of the samples have been studied by using a variety of techniques, namely ICP, FTIR, XRD, 31P-NMR, BET and TG-DTG-DSC. The effect of several parameters, such as pre-treatment temperature, reaction temperature, residence time (W/F) on the conversion and product distribution has been examined. The presence of gallium has been observed to increase surface area by a factor of more than two and to improve the selectivity to oxygenates (acrylic and acetic acids, acrolein). It has been found that there is an optimum value of Ga content of 0.16 per KU in the Keggin structure and of pre heating temperature of 300°C for maximizing propane conversion and acrylic acid selectivity. The latter aspect is related to the presence of both Bronsted acid and redox sites.
N. Dimitratos, J.C. Védrine, Journal of Molecular Catalysis A: Chemical 255 (2006) 184-192

A0994 – Nickel and cobalt precipitation from sulphate leach liquor using MgO pulp as neutralizing agent

The research work presented in this paper determined the conditions at which nickel and cobalt can be recovered, as easily filterable precipitates, from leach liquors, which are produced by sulphuric acid leaching of nickel oxide ores, at atmospheric pressure. More specifically, nickel and cobalt were precipitated as hydroxides at pH = 9, using MgO pulp as a neutralizing agent, by 99.9% and 99.0%, respectively. At this pH value, manganese, which was contained in the leach liquor, was precipitated having a concentration of about 3% in the final mixed precipitate. Statistical design and analysis of experiments were used in order to determine the main effects and interactions of the precipitation factors, which were the pH at equilibrium and the addition of seed material. The characterization of the produced mixed precipitate was carried out by X-ray diffraction, TG-DTA, scanning electron and optical microscopy and particle size distribution analyzer. The main mineralogical phases in the precipitate were theophrastite (Ni(OH)2) and brucite (Mg(OH)2). The microscopic observation revealed that the presence of brucite was, mainly, due to the un-reacted MgO pulp, during the precipitation process. This brucite content acted as seed material for nickel precipitation.
P. Oustadakis, S. Agatzini-Leonardou, P.E. Tsakiridis, Minerals Engineering 19 (2006) 1204-1211

A0993 – Defect formation and transport in mixed-conducting La0.90Sr0.10Al(0.85-x)FexMg0.15O(3-d)

The redox behavior of perovskite-type La0.90Sr0.10Al(0.85-x)FexMg0.15O(3-d) (x = 0.20-0.40) mixed conductors was analyzed by the Mössbauer spectroscopy and measurements of the total conductivity and Seebeck coefficient in the oxygen partial pressure range from 10^(-20) to 0.5 atm at 1023-1223 K. The results combined with oxygen-ion transference numbers determined by the faradaic efficiency technique in air, were used to calculate defect concentrations, mobilities, and partial ionic and p- and n-type electronic conductivities as a function of oxygen pressure. The redox and transport processes can be adequately described in terms of oxygen intercalation and iron disproportionation reactions, with the thermodynamic functions independent of defect concentrations. No essential delocalization of the electronic charge carriers was found. The oxygen non-stoichiometry values estimated from the conductivity vs. p(O2) dependencies, coincide with those evaluated from the Mössbauer spectra.
E.V. Tsipis, J.C. Waerenborgh, V.V. Kharton, E.N. Naumovich, J.R. Frade, Journal of Physics and Chemistry of Solids 67 (2006) 1882-1887

A0995 – Laser-induced fluorescence and thermoluminescence response of a Na-Ca rich silicate

Pectolite (NaCa2Si3O8(OH)) is an inosilicate of hydrothermal origin hosted in Cretaceous basalt with calcite and iron oxides and is almost always associated with zeolites. The emission of this silicate was studied by laser-induced fluorescence (LIF) and thermal stimulated luminescence (TL). The fluorescence spectra of different areas of the sample induced by exposition to 266 nm UV laser light (5 nm of spectral resolution, FWHM) give rise to two peaks at 550 and 830 nm that can be, respectively, linked to the presence of Mn2+ and Cr3+ emission centres. The stability tests at different temperatures show clearly that the TL glow curves at 400 nm in natural pectolite samples, track the typical pattern of a system produced by a continuous trap distribution, well defined in other silicates. This process could be mainly associated to dehydroxylation effect, as observed by differential thermal analysis (DTA), and probably is also linked to chromophore oxidation.
V. Correcher, J. Garcia-Guinea, M. Castillejo, M. Oujja, E. Rebollar, P. Lopez-Arce, Radiation Measurements 41 (2006) 971-975

A0996 – Synthesis, structure refinement and thermal behavior of HEuP2O7.4H2O

The synthesis, the structure refinement and the thermal behavior are reported for a new diphosphate HEuP2O7.4H2O. This salt crystallizes in a monoclinic cell, a space group P21/n with: a = 6.6320(2); b = 11.5273(5); c = 11.7574(5) Å; beta = 92.024(2)°; Z = 4. The crystal structure was refined to R = 0.0402 using 1572 reflections. The corresponding atomic arrangement consists of corrugated layers of [(HP2O7)3-] groups alternating with layers of the Eu3+ cations perpendicular to the [101] direction. Three of the crystallization water molecules are intercalated between these layers and participate to the coordination of the europium atom, the fourth one is located inside the anionic layer. The thermal decomposition of HEuP2O7.4H2O, which was followed by thermogravimetry and differential thermal analysis, shows that the dehydration of this salt took place between 361 and 1223 K. It gave, after dehydration, a mixture of europium diphosphate Eu4(P2O7)3 and europium tripolyphosphate Eu(PO3)3.
Z. Anna-Rabah, F. Chehimi-Moumen, D. Ben Hassen-Chehimi, M. Trabelsi-Ayadi, Solid State Sciences 8 (2006) 932-939

A0997 – Resistance of polyimide/silica hybrid films to atomic oxygen attack

Polyimide/silica (PI/SiO2) hybrid films were prepared by the sol-gel process to improve the erosion resistance of polyimide materials in atomic oxygen (AO) environments. The p-aminophenyltrimethoxysilane (APTMOS) was used as a coupling agent to enhance the compatibility between the PI and SiO2. The effects of the APTMOS addition on the morphology and property of the PI/SiO2 hybrids were investigated using UV-Vis spectrophotometer, FTIR spectroscopy and SEM. The thermal properties and AO resistance of the PI/SiO2 hybrids were investigated by TGA and in the AO simulator, respectively. The results showed that the addition of APTMOS remarkably reduced the size of the silica particles, the PI/SiO2 hybrid films became transparent, and the compatibility between the PI and SiO2 and the thermal stability of the hybrids were significantly improved. During AO exposure, a passive inorganic SiO2 layer was formed on the PI/SiO2 hybrid films, causing the hybrid films to possess excellent AO resistance. The optical properties of the PI/SiO2 hybrid films were not altered after AO exposure.
S. Duo, M. Li, M. Zhu, Y. Zhou, Surface & Coatings Technology 200 (2006) 6671-6677

A0999 – Yb3+-doped NaBi(WO4)2 fibre single crystals grown by the micro-pulling down technique and emission spectroscopic characterization

NaBi(1-x)Ybx(WO4)2 fibres single crystals were successfully grown by micro-pulling down technology (MPD). The Yb3+-doped NaBi(WO4)2 fibres single crystals have been pulled using MPD technique with controlled diameter and stationary stable growth conditions corresponding to flat crystallization interface with meniscus length equal to the fibre radii and pulling rate range [6- 48 mm h-1]. We have determined the monophased field of NaBi(1-x)Ybx(WO4)2 for x < 0.3. The lattices parameters decrease as a function of Yb3+ substitution in Bi3+ sites. The melt behaviour has been study by DTA/TG analysis. We have found that the stoichiometric compounds NaBi(WO4)2 melt congruently at 935°C. The fibre diameters varied from 0.5 to 1 mm depending on the capillary die diameter, pulling rate and the molten zone temperature. Complementary Yb3+ spectroscopic characterization in the NaBi(WO4)2 lattice has been done by IR emission measurements under laser pumping at room temperature.
A. Karek, K. Lebbou, M. Diaf, A. Brenier, G. Boulon, Materials Research Bulletin 42 (2007) 532-543

A0998 – Structure of zinc hydroxy-terephthalate: Zn3(OH)4(C8H4O4)

The new lamellar hydroxide teraphthalate Zn3(OH)4(C8H4O4) was synthesised by the hydrothermal method and was characterized by single crystal X-ray diffraction, IR and UV spectroscopy and thermogravimetric analysis. The compound crystallises in the monoclinic space group C2/c with: a = 28.1000(5) Å, b = 6.3101(1) Å, c = 14.8359(3) Å, beta = 121.564(1)°, V = 2241.43 Å3, Dx = 2.538 g/cm3 and Z = 4. The zinc(II) atoms present four, five and six fold O-coordination. Due to the peculiar coordination of the zinc atoms, the inorganic layers form stairways running along [001]. These stairways-like layers are bridged by terephthalate (tp) groups leading to a 3D framework.
A. Carton, S. Abdelouhab, G. Renaudin, P. Rabu, M. François, Solid State Sciences 8 (2006) 958-963

A1000 – Synthesis of all-silica BEA-type material in basic media

Previous investigations have shown that an all-silica BEA-type (Si-BEA) material is difficult to be nucleated in basic media and that the fluorosilicic precursors formed in near neutral media play an important role in its formation. The present study reports on the synthesis of this microporous material under basic conditions by using TEA2SiF6 as an additional silica source that provides preformed fluorosilicate species. The effect of the amount of TEA2SiF6 on the purity of the final product, crystallization kinetics and morphological features of Si-BEA were systematically studied. The investigation showed that above a certain concentration corresponding to TEA2- SiF6/SiO2 = 0.07 pure Si-BEA was obtained and further increase in the concentration improved substantially the crystallization kinetics. The increase in TEA2SiF6 content led also to a gradual increase of the size of the pyramidal (h0l) face coupled with the decrease of pinacoidal (001) one. Thus, the morphology of the zeolite crystals can be varied from well developed truncated bipyramids to plate-like crystals with dominating pinacoidal faces. A consequence of this morphological changes is the number the pore openings of the channel systems running along the a- and c-axes per total external surface. The framework defectness and water content in the synthesized materials were studied by 29Si NMR spectroscopy and TG analysis, respectively. This combined study revealed that materials with a high level of hydrophobicity, due to the specific effect of fluorine anions, have been synthesized under basic conditions.
O. Larlus, V. Valtchev, Microporous and Mesoporous Materials 93 (2006) 55-61

A1002 – The rock salt oxide Li2MgTiO4: Type I dielectric and ionic conductor

The exploration of the Li-Ti-Mg-O system, using both sol-gel technique and solid state reaction method, allowed a new phase, Li2MgTiO4, with disordered rock salt structure (a = 4.159 Å ) to be synthesized. The latter is shown to be a good type I dielectric material, with a relative constant of 15 at high frequency and low dielectric loss (tand < 10^(-3)) over the temperature range - 60 to 160°C. It is also observed that the sintering temperature of this phase is strongly lowered by adopting the sol-gel technique compared to solid state reaction (1150°C instead of 1300°C). Finally we show that this phase exhibits cationic conductivity above 400°C (s600°C = 9 x 10^(-5) S cm-1).
M.V.V.M. Satya Kishore, S. Marinel, V. Pralong, V. Caignaert, S. D'Astorg, B. Raveau, Materials Research Bulletin 41 (2006) 1378-1384

A1001 – Photoluminescence and microstructure of Mn-doped ZnS phosphor powder co-fired with ZnS nanocrystallites

In this study, we correlated the photoluminescence (PL) with the microstructure of ZnS:Mn phosphor powders prepared by firing ZnS with MnO (1 mol%), NaCl (1 mol%) and ZnS nanocrystallites (NCs) in the range of 0-100 wt% at 600-1000°C for 2 h in the atmosphere of 3%H2/Ar. ZnS NCs of 10-30 nm in size were produced by co-precipitation of zinc nitrate and sodium sulfide solutions at room temperature. Thermal analysis (DTA/TG) and X-ray diffraction (XRD) results indicated that the cubic-hexagonal transformation temperature of ZnS NCs was lowered to approximately 600°C, which was much lower than that of bulk ZnS (1020°C). PL measurements revealed that ZnS:Mn fired with 1 wt% ZnS NCs showed the optimal luminescence intensity when compared to those without or with higher ZnS NCs (>1 wt%). An appropriate amount of ZnS NCs (1 wt%) acting as the flux in the firing process was inferred to avoid the inhomogeneous distribution of Mn2+ as well as the migration of excitation energy to quenching sites and therefore to result in the enhanced PL intensity.
Y-T. Nien, H-S. Hsu, I-G. Chen, C-S. Hwang, S-Y. Chu, Journal of Non-Crystalline Solids 352 (2006) 2539-2542

A1004 – Adsorption of pesticides Carbetamide and Metamitron on organohydrotalcite

This paper reports on the adsorption of low polarity pesticides Carbetamide and Metamitron on hydrotalcite [Mg3Al(OH)8]2 CO3.nH2O and organohydrotalcites [Mg3Al(OH)8]2DDS.nH2O with different degree of dodecyl sulphate (DDS) saturation. The adsorbents and the adsorption products were characterized by X-ray diffraction method and FT-IR spectroscopy. Both pesticides were better adsorbed on organohydrotalcite with higher DDS saturation, while their adsorption on inorganic hydrotalcite was very low. The results indicate that the adsorption capacity of different materials depends on their nature as well as structure and polarity of the pesticides and suggest the possibility of use of organohydrotalcite to uptake the Carbetamide and Metamitron from contaminated waters. The results also showed that the recyclability of organohydrotalcite and their reutilization as adsorbent is possible.
F. Bruna, I. Pavlovic, C. Barriga, J. Cornejo, M.A. Ulibarri, Applied Clay Science 33 (2006) 116-124

A1003 – Study on the potential use of Tunisian clays as pozzolanic material

Samples of Tunisian clays from different locations are calcined at 600, 700 and 800°C. Geotechnical, chemical and physical properties of both untreated and calcined samples are studied. The pozzolanic activity of the calcinated clays is evaluated by compressive strength performed on calcinated clay-calcium hydroxide mini-cylinders. The geotechnical study associated with the chemical analysis was found to be useful to predict the pozzolanic activity of the clays. Clays rich in kaolinite were shown to have the highest strength and therefore the best pozzolanic activity. The presence of some mineral clays such as illite, montmorillonite and muscovite does not improve the pozzolanic activity despite their relatively high level of silica, alumina and iron.
A. Chakchouk, B. Samet, T. Mnif, Applied Clay Science 33 (2006) 79-88

A1005 – Study of catalytic behaviour and deactivation of vanadyl-aluminum binary phosphates in selective oxidation of o-xylene

This study involved the catalytic behaviour and the deactivation of aluminum-vanadium-phosphorus (Al-V-P-O) systems obtained by the sol-gel method with several P/Al/V molar ratios and calcined at 450°C in the selective oxidation of o-xylene. Activity values as well as the reducibility of Al-V-P-O systems were influenced by the Al/V ratio, increasing with Al content, while selectivity to phthalic anhydride and phthalide values only changed slightly. All catalysts always showed a high degree of resistance to deactivation in function of time on-stream. Furthermore, water in the feed or coke generation treatment negatively affected catalytic activity, although the initial conversion values were recovered. This fact along with the unchanged textural properties and XRD patterns of the catalysts after such treatments suggest that reversible deactivation could be attributed to partial poisoning of active sites.
F.M. Bautista, J.M. Campelo, D. Luna, J. Luque, J.M. Marinas, M.T. Siles, Chemical Engineering Journal 120 (2006) 3-9

A1006 – Low temperature synthesis of YAG:Eu spheroidal monocrystalline submicron-sized particles

Yttrium aluminum garnet, Y3Al5O12, (YAG), doped with Eu (0-4%) was synthesized reacting appropriate metal nitrates in NaNO2-KNO2 eutectic mixture. Pure cubic garnet phase was formed upon heating for a few hours at temperature as low as 470°C. The particle sizes of the powders were mostly in the range of 200-300 nm, but a small fraction of material crystallized in particles of about 20-40 nm. Selected area electron diffraction patterns proved that the larger particles are monocrystalline. Excitation and emission spectra of the Eu-doped powders are characteristic for Eu3+ in an oxide host. The most intense luminescence lines are located around 590 nm.
E. Zych, A. Walasek, L.Kepinski, J. Legendziewicz, Journal of Luminescence 119-120 (2006) 576-580

A1008 – Sr4PbPt4O11, the first platinum oxide containing (Pt2)6+ ions

We report the synthesis and crystal structure of the new compound Sr4PbPt4O11, containing platinum in highly unusual square pyramidal coordination. The crystals were obtained in molten lead oxide. The structure was solved by X-ray single crystal diffraction techniques on a twinned sample, the final R factors are R = 0.0260 and wR = 0.0262. The symmetry is triclinic, space group P1, with a = 5.6705(6) Å, b = 9.9852(5) Å, c = 10.0889(5) Å, alpha = 90.421(3)°, beta = 89.773(8)°, gamma = 90.140(9)° and Z = 2. The structure is built from dumbell-shaped Pt2O9 entities formed by a dinuclear metal-metal bonded (Pt2)6+ ion with asymmetric environments of the two Pt atoms, classical PtO4 square plane and unusual PtO5 square pyramid. Successive Pt2O9 entities deduced from 90° rotations are connected through the oxygens of the PtO4 basal squares to form [(Pt4O10)8-] columns further connected through Pb2+ and Sr2+ ions. Raman spectroscopy confirmed the peculiar platinum coordination environment.
C. Renard, P. Roussel, A. Rubbens, S. Daviero-Minaud, F. Abraham, Journal of Solid State Chemistry 179 (2006) 2101-2110

A1007 – From amorphous phase separations to nanostructured materials in sol-gel derived ZrO2:Eu3+/SiO2 and ZnO/SiO2 composites

ZrO2:Eu3+-SiO2 and ZnO-SiO2 composites have been synthesized by a sol-gel method by using a specific gelation and drying procedure. In the two cases we were able to produce large and transparent monolithic samples. Microstructural properties of these materials were investigated by thermo-differential and thermo-gravimetric analysis, X-ray diffraction, transmission electron microscopy and small angle X-ray scattering. The existence of a miscibility gap in both systems results in the formation of nanocomposites where crystallized zirconia or amorphous zinc oxide nanoparticles are dispersed in a silica glass matrix. These two kinds of nanocomposites are potential high efficiency luminescent materials because the nanoparticles size is easily controlled by the annealing conditions.
A. Gaudon, F. Lallet, A. Boulle, A. Lecomte, B. Soulestin, R. Guinebretière, A. Dauger, Journal of Non-Crystalline Solids 352 (2006) 2152-2158

A1009 – Synthesis and structural characterization of perovskite type proton conducting BaZr(1-x)InxO(3-d) (0.0

Solid state sintering has been used to prepare the cubic perovskite structured compounds BaZr(1-x)InxO(3-d) (0.0600°C.
I. Ahmed, S-G. Eriksson, E. Ahlberg, C.S. Knee, P. Berastegui, L-G. Johansson, H. Rundlöf, M. Karlsson, A. Matic, L. Börjesson, D. Engberg, Solid State Ionics 177 (2006) 1395-1403

A1011 – Determination of the fractal dimension of activated carbons: Two alternative methods

The fractal dimension of three samples of activated carbon has been determined according to two different experimental methods. The first method is based on the vaporization of gas species from the sample into a CO2 flow up to a constant temperature of 573 K, and the adsorption of CO2 from the CO2 flow onto the surface of the sample under cooling. The second method is based on the application of the equation proposed by Frankel, Halsey and Hill. The degree of concordance between both methods is excellent.
E.M. Cuerda-Correa, M.A. Diaz-Diez, A. Macias-Garcia, J. Ganan-Gomez, Applied Surface Science 252 (2006) 6102-6105

A1010 – Zirconia coatings deposited by electrostatic spray deposition – A chemical approach

The present study is focused on the preparation of zirconia-based coatings obtained by Electrostatic Spray Deposition (ESD). Microstructural properties of ESD coatings were optimised versus the composition of the precursor solution and the substrate nature. This chemical approach includes the influence of zirconia precursors, yttrium chloride, solvent mixtures, zirconia precursor concentration, additives and substrate nature in order to optimally tune the microstructure of the coating. A smooth, dense and homogeneous thin layer was successfully deposited.
R. Neagu, D. Perednis, A. Princivalle, E. Djurado, Solid State Ionics 177 (2006) 1451-1460

A1013 – Improvement of the preparation of sintered pellets of thorium phosphate-diphosphate and associated solid solutions from crystallized precursors

Several compositions of thorium-uranium (IV) phosphate-hydrogenphosphate hydrate (U(x/2)Th(2-x/2)(PO4)2- (HPO4).H2O, TUPHPH) were prepared starting from actinides chloride solutions and concentrated phosphoric acid. The experimental synthesis parameters were optimized in order to get the quantitative precipitation of the cations and a good crystallization state. The extensive characterization of the solids demonstrated the existence of a complete solid solution between Th and U end-members and evidenced the good homogeneity of the powders. Their behaviors during heating treatment were then checked and confirm the formation of anhydrous thorium-uranium (IV) phosphate-hydrogenphosphate (TUPHP) and alpha-UxTh(4-x)(PO4)4(P2O7) (alpha-TUPD) acting as intermediates. Finally, the low-temperature crystallized precursors were used in original sintering processes in order to improve the efficiency of the former cold-pressing sintering procedure.
N. Clavier, N. Dacheux, G. Wallez, M. Quarton, Journal of Nuclear Materials 352 (2006) 209-216

A1012 – 2-Mercaptothiazoline modified mesoporous silica for mercury removal from aqueous media

Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl- SBA-15 or Cl-MCM-41. In a second step a multifunctionalized N, S donor compound (2-mercaptothiazoline, MTZ) was incorporated to obtain the functionalized silicas denoted as MTZ-SBA-15-Het or MTZ-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MTZ-SBA-15-Hom or MTZ-MCM-41-Hom. The functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions contaminated with Hg (II) at room temperature. SBA-15 and MCM-41 functionalized with MTZ by the homogeneous method present good mercury adsorption values (1.10 and 0.7 mmol Hg (II)/g of silica, respectively). This fact suggests a better applicability of such mesoporous silica supports to extract Hg (II) from aqueous solutions. In addition, it was observed the existence of a correlation between mercury adsorption with pore size and volume since, SBA-15 with lower areas and higher pore sizes functionalized with sterically demanding ligands, show better adsorption capacities than functionalized MCM-41.
D. Pérez-Quintanilla, I. del Hierro, M. Fajardo, I. Sierra, Journal of Hazardous Materials B134 (2006) 245-256

A1016 – Yttrium, cobalt and yttrium/cobalt oxide coatings on ferritic stainless steels for SOFC interconnects

Ferritic stainless steels are being considered as potential interconnect materials for SOFCs, in part because of their low cost relative to alternatives. These materials are, however, susceptible to degradation over time. A primary source of degradation is an increase in the area specific resistance (ASR), which is due to the formation of poorly conducting oxides (Mn-Cr spinel and Cr2O3) on the surface. In this work, the influence of Y, Co and Y/Co oxide coatings on the oxidation behaviour of a ferritic stainless steel (16-18 wt% Cr) has been investigated. Samples were oxidized in air for up to 500 h at temperatures ranging from 700 to 800°C. Coated and uncoated samples were characterized, before and after heat treatment, using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TG) analysis and four-point probe resistance measurements. Surface morphology investigations of coated and uncoated stainless steels showed differences for Y and Co in terms of oxide formation. In all cases, Cr-Mn spinel and Cr2O3 were the two main surface oxides; however, the morphology of the spinel phase was dependent on the type of coating. The lowest resistances were obtained for the Y/Co-coated samples, which had ASR values up to seven times lower than corresponding uncoated ferritic stainless steels.
W. Qu, L. Jian, D.G. Ivey, J.M. Hill, Journal of Power Sources 157 (2006) 335-350

A1015 – Mesoporous gamma-alumina synthesized by hydro-carboxylic acid as structure-directing agent

A facile and non-surfactant-templating route is described for preparing mesoporous gamma-aluminas with improved textural properties. In this synthesis, hydro-carboxylic acid (HCA) was used as the structure-directing agent and boehmite sol as the precursor. By drying the mixture of HCA and boehmite sol at a suitable temperature and then calcining at 773 K, the mesoporous gamma-alumina with controllable pore structures could be obtained. The drying temperature of the initial boehmite-HCA mixture had an important effect on the pore structure of the final product. As the drying temperature increased successively from 303 K to 373 K and 423 K, the products changed correspondingly from a bimodal mesoporous structure to a uniform mesostructure and a micro-mesoporous structure. By means of various characterization techniques, including N2 physical adsorption, TEM, SEM, XRD, 27Al NMR, FTIR and TG-DTA, it was demonstrated that the coordination between HCA and aluminum became stronger with the increase of the drying temperature, so that the strong coordination interaction between the HCA and the boehmite colloid particulates could induce a kind of arrangement of rigid boehmite "building blocks", thus giving rise to different pore structures.
Q. Liu, A. Wang, X. Wang, T. Zhang, Microporous and Mesoporous Materials 92 (2006) 10-21

A1014 – Immobilization of tetravalent actinides in phosphate ceramics

Three phosphate-based ceramics were studied for the immobilization of tri- and tetravalent actinides: britholite Ca9Nd(1-x)AnIV(x)(PO4)(5-x)(SiO4)(1+x)F2, monazite/brabantite LnIII(1-2x)CaxAnIV(x)PO4 and thorium phosphate diphosphate beta - Th(4-x)AnIV(x)(PO4)4P2O7 (beta-TPD). For each material, the incorporation of thorium and uranium (IV) was examined through dry chemistry routes, using mechanical grinding of the initial mixtures then heating at high temperature (1373- 1673 K). The quantitative incorporation of thorium in the britholite structure was obtained up to 20 wt% through the coupled substitution (Nd3+; (PO4)3- <=>(Th4+; (SiO4)4-). On the contrary, the incorporation of uranium was limited to 5-8 wt% and always led to a two-phase system composed by U-britholite and CaU2O(5+y). The incorporation of Th and U(IV) was also examined in both matrices, beta-TPD and monazite/brabantite solid solutions. Homogeneous and single phase samples of beta-TUPD and (Th,U)-monazite/brabantite solid solutions were obtained using successive cycles of mechanical grinding/calcination. The three matrices were prepared in the pellet form then leached in 10^(-1) M or 10^(-4) M HNO3 at 363 K. The very low normalized dissolution rates confirmed the good resistance of the materials to aqueous alteration. Moreover, in over-saturation conditions, the formation of neoformed phases onto the surface of the pellets was evidenced for several sintered samples.
O. Terra, N. Dacheux, F. Audubert, R. Podor, Journal of Nuclear Materials 352 (2006) 224-232