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5631 articles

A0814 – Hot corrosion and protection of Ti2AlC against Na2SO4 salt in air

The hot corrosion behavior of Na2SO4-coated Ti2AlC was investigated by means of thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy/energy dispersive spectroscopy. This carbide displays good hot corrosion resistance below the melting point of Na2SO4 while the corrosion attacks become virulent when the salt is molten. A protectively continuous Al2O3 layer forms and imparts good corrosion resistance, and consequently, the corrosion kinetics is generally parabolic at 850°C. However, porous oxide scales fail to protect the Ti2AlC substrate at 900 and 1000°C. The segregation of sulfur at the corrosion scale/substrate interface accelerates the corrosion of Ti2AlC. Furthermore, a convenient and efficient pre-oxidation method is proposed to improve the high-temperature hot corrosion resistance of Ti2AlC. An Al2O3 scale formed during pre-oxidation treatment can remarkably restrain the infiltration of the molten salt into the substrate and prevent the substrate from severe corrosion attacks.
Z. Lin, Y. Zhou, M. Li, J. Wang, Journal of the European Ceramic Society 26 (2006) 3871-3879

A0817 – Synthesis, FT-IR and X-ray diffraction investigations of gadolinium-substituted pyrochlore oxide Gd1.82Cs0.18Ti2O6.82 via a sol-gel process

Novel pyrochlore oxides Gd1.82Cs0.18Ti2O6.82 has been synthesized using the sol-gel process from the titanium alkoxide Ti(OR)4 and two ultra pure oxides Cs2CO3 and Gd2O3. Pure acetic acid was used as mutual solvent. This carboxylic acid does not act only as an acid catalyst, but also as ligand modifying the whole hydrolysis condensation process. The effect of heat treatment, to eliminate the organic material from xerogel was investigated by FT-IR spectroscopy. Based on thermal gravimetric (TG) and differential scanning calorimetric (DSC) analysis results, we suggest that thermal decomposition of the xerogel takes place in three major steps. X-ray powder diffraction (XRD) measurements were carried out to study the structure evolution of the sample and to determine the crystalline phases present after heat treatment. Crystal structure of oxygen deficient pyrochlore, Gd1.82Cs0.18Ti2O6.82 calcinated at 1000°C, was determined using the Rietveld method. It was found that the sample crystallise in the cubic symmetry with Fd3m space group and with a lattice parameter a = 10.1835 (4) Å. The oxygen vacancies in this compound are randomly distributed over the O sites. Conductivity in this material, which is an anionic conductor, results of migration of oxygen vacancies into the conduction pathways.
A. Garbout, S. Bouattour, M. Ellouze, A.W. Kolsi, Journal of Alloys and Compounds 425 (2006) 88-95

A0816 – High-temperature thermal characterization

G. Etherington, Ceramic Industry, feb 2007

A0818 – Structural and conductivity study of Y and Rb co-doped TiO2 synthesized by the sol-gel method

Nanoparticles of titanium dioxide co-doped with Y3+ and Rb+ were prepared using the sol-gel method and were characterized by thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Y3+ and Rb+ co-doped TiO2 powder calcined at 800°C shows a synergistic effect, which shifted the transformation anatase-rutile to higher temperature. X-ray diffraction and XPS analysis revealed that Y3+ and Rb+ did not enter into the crystal lattices of TiO2 and are uniformly dispersed onto TiO2 particles. In this study, the conductivity measurements were performed under ambient atmosphere on undoped and co-doped TiO2 in order to investigate the defect chemistry by identifying the predominant charge carriers. An increase in the conductivity r of nano-TiO2 is shown when the samples were co-doped with Y3+ and Rb+.
W. Kallel, S. Bouattour, A.W. Kolsi, Journal of Non-Crystalline Solids 352 (2006) 3970-3978

A0820 – Microwave-assisted synthesis of BaMoO4 nanocrystallites by a citrate complex method and their anisotropic aggregation

BaMoO4 powders, which have scheelite-type structure, were successfully synthesized at low temperatures by a modified citrate complex method assisted by microwave irradiation. The citrate complex precursors were heat-treated at temperatures from 300 to 500°C for 3 h. Crystallization of the BaMoO4 powders were detected at 350°C and completed at a temperature of 400°C. TEM image of the BaMoO4 product heat-treated at 400°C revealed spindle-rods-like and flake-like morphology at 500°C. The anisotropic aggregation habit of BaMoO4 lead to two-dimensionally aggregated powder morphology, which was attributed to the high chemical potentials of the intrinsic structure of BaMoO4.
J.H. Ryu, J-W. Yoon, K.B. Shim, Journal of Alloys and Compounds 413 (2006) 144-149

A0819 – Synthesis of nanocrystalline MMoO4 (M=Ni, Zn) phosphors via a citrate complex route assisted by microwave irradiation and their photoluminescence

Nanocrystalline MMoO4 (M=Ni, Zn) phosphors, which have wolframite-type structure, were successfully synthesized at low temperatures via a modified citrate complex route assisted by microwave irradiation. The citrate complex precursors were heat-treated from 300 to 600°C for 3 h. Crystallization of the MMoO4 (M=Ni, Zn) nanocrystallites were detected at 500°C, and entirely completed at a temperature of 600°C. The nanoparticles presented primarily dispersed and homogeneous morphology with particle size of 20-40 nm. The nanocrystalline MMoO4 (M=Ni, Zn) phosphors prepared at 600°C exhibited broad luminescence in green and blue wavelength region, respectively.
J.H. Ryu, S-M. Koo, J-W. Yoon, C.S. Lim, K.B. Shim, Materials Letters 60 (2006) 1702-1705

A0821 – Photoluminescence in nanocrystalline MMoO4 (M = Ca, Ba) synthesized by a polymerized complex method

NanocrystallineMMoO4 (M = Ca, Ba) were successfully synthesized at lowtemperatures via a polymerized complex route and room temperature photoluminescent properties were investigated in detail. Prepared nanocrystalline MMoO4 (M = Ca, Ba) showed primarily dispersed and homogeneous morphology with particle size of 20-40 nm. The photoluminescent spectra were decomposed to several individual Gaussian components in green and blue wavelength range. These photoluminescent features could be interpreted by Jahn-Teller splitting effect on [MoO4 2-] tetrahedron of the nanocrystalline MMoO4 (M = Ca, Ba).
J-W. Yoon, J.H. Ryu, K.B. Shim, Materials Science and Engineering B 127 (2006) 154-158

A0823 – Synthesis, characterization and thermal degradation mechanism of three poly(alkylene adipate)s: Comparative study

Three high molecular weight aliphatic polyesters derived from adipic acid and the appropriate diol e poly(ethylene adipate) (PEAd), poly(propylene adipate) (PPAd) and poly(butylene adipate) (PBAd) e were prepared by two-stage melt polycondensation method (esterification and polycondensation) in a glass batch reactor. Intrinsic viscosities, GPC, DSC, NMR and carboxylic end-group measurements were used for their characterization. Mechanical properties of the prepared polyesters showed that PPAd has similar tensile strength to low-density polyethylene while PEAd and PBAd are much higher. From TGA analysis it was found that PEAd and PPAd have lower thermal stability than poly(- butylene adipate) (PBAd). The decomposition kinetic parameters of all polyesters were calculated while the activation energies were estimated using the Ozawa, Flynn and Wall (OFW) and Friedman methods. Thermal degradation of PEAd was found to be satisfactorily described by one mechanism, with activation energy 153 kJ/mol, while that of PPAd and PBAd by two mechanisms having different activation energies: the first corresponding to a small mass loss with activation energies 121 and 185 kJ/mol for PPAd and PBAd, respectively, while the second is attributed to the main decomposition mechanism, where substantial mass loss takes place, with activation energies 157 and 217 kJ/mol, respectively.
T. Zorba, K. Chrissafis, K.M. Paraskevopoulos, D.N. Bikiaris, Polymer Degradation and Stability 92 (2007) 222-230

A0822 – Microwave-assisted synthesis of PbWO4 nano-powders via a citrate complex precursor and its photoluminescence

Nanocrystalline lead tungstate (PbWO4) powders, which have scheelite-type structure, were successfully synthesized at low temperatures using a modified citrate complex method assisted by microwave irradiation. The citrate complex precursors were heat-treated at temperatures from 300 to 600°C for 3 h. Crystallization of the PbWO4 precursor was detected at 400°C, and completed at 500°C. Nanocrystalline PbWO4 powders heat-treated between 400 and 600°C primarily showed spherical and disperse morphology. The average crystallite sizes of PbWO4 were between 17 and 28 nm at temperatures between 400 and 600°C, showing a tendency to increase with the temperature. The PbWO4 powders prepared at 600°C showed the strongest photoluminescent intensity, which was ascribed to the higher crystallinity and homogeneous particle morphology.
J.H. Ryu, S-M. Koo, D.S. Chang, J-W. Yoon, C.S. Lim, K.B. Shim, Ceramics International 32 (2006) 647-652

A0825 – Kinetic model identification and parameters estimation from TGA experiments

The presented work is a part of an ongoing research effort on the development of a general methodology for the determination of kinetic models of solid thermal decomposition under pyrolysis conditions with thermogravimetric analysis (TGA) devices. The goal is to determine a simple and robust kinetic model for a given solid with the minimum of TGA experiments. From the latter point of view, this work can be seen as the optimal design of TGA experiments for pyrolysis kinetic modelling. In this paper, a general procedure is presented and more precise results are given about the influence of the sensitivity matrix on the estimation of the kinetic parameters and about the important influence of the specific TGA runs used for parameter estimation on the precision of the fitted parameters. The first results are shown for simulated applications; in the final part, the presented results concern cellulose pyrolysis in a Setaram TGA device.
C. Reverte, J-L. Dirion, M. Cabassud, J. Anal. Appl. Pyrolysis 79 (2007) 297-305

A0824 – Effects of activated carbon properties on the adsorption of naphthalene from aqueous solutions

The aim of this work was to investigate the role of porous and chemical heterogeneities of activated carbons in the adsorption of naphthalene from aqueous media. A commercially available activated carbon was used as the adsorbent, and its surface heterogeneity was systematically altered by heat treatment at 450 and 850°C, obtaining a series of carbons with various oxygen contents and similar surface functionalities. The results confirmed that the adsorption of naphthalene depends strongly on the pore size distribution of the adsorbent, particularly narrow microporosity. Moreover, oxygen functionalities reduced the accessibility and affinity of naphthalene to the inner pore structure via formation of hydration clusters. Consequently, the hydrophobic/hydrophilic character of the adsorbent is important, since it dominates the competitive adsorption of water. Adsorbents with a high non-polar character (i.e., low oxygen content) have proven to be more efficient for naphthalene adsorption.
C.O. Ania, B. Cabal, C. Pevida, A. Arenillas, J.B. Parra, F. Rubiera, J.J. Pis, Applied Surface Science 253 (2007) 5741-5746

A0826 – Radiation-induced grafting of acrylamide onto guar gum in aqueous medium: Synthesis and characterization of grafted polymer guar-g-acrylamide

Mutual radiation grafting technique has been applied to carry out grafting of acrylamide (AAm) onto guar gum (GG) using highenergy Co60 gamma radiation to enhance its flocculating properties for industrial effluents. The grafted product was characterized using analytical probes like elemental analysis, thermal analysis, Fourier transformed infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The grafting extent was observed to decrease with the dose rate and increase with the concentration of AAm. Thermo gravimetric analysis (TGA) of grafted and ungrafted samples indicated better stability of grafted product. gamma and microwave radiation effect on grafted and virgin GG has also been reported.
J. Biswal, V. Kumar, Y.K. Bhardwaj , N.K. Goel, K.A. Dubey, C.V. Chaudhari, S. Sabharwal, Radiation Physics and Chemistry 76 (2007) 1624-1630

A0828 – Pyrolysis of wood impregnated with phosphoric acid for the production of activated carbon: Kinetics and porosity development studies

The pyrolysis of impregnated wood for the production of activated carbon is investigated. Laboratory experiments are performed in a TG for heating rates of 10°C/min and 20°C/min and a mathematical model for the kinetics of the pyrolysis process is developed and validated. The effect of the temperature and of the time duration of the pyrolysis process on the specific surface of the activated carbon is examined on the basis of experiments conducted in a crossed bed reactor. Results indicate that the temperature and the residence time in the pyrolysis reactor may be optimised. Indeed, it is found that the maximum specific surface of the end product is obtained for pyrolysis processes conducted at a temperature of 400°Cfor a time period of 1 h.
I. Ahmed Hared, J-L. Dirion, S. Salvador, M. Lacroix, S. Rio, J. Anal. Appl. Pyrolysis 79 (2007) 101-105

A0829 – Characterization of mesoporous silica and its pseudomorphically transformed derivative by gas and liquid adsorption

Pseudomorphism is a term introduced by mineralogist to describe phase transformation that does not change the shape of a material. Pseudomorphic process, assisted by surfactants, for mesoporous pre-shaped silica particles allows to narrow the mesopore size distribution, to increase the surface area and the pore volume without changing the initial shape of silica particles. The textural, chemical and mechanical comparisons between commercial silica LiChrospher 60 (Merck) and its pseudomorphic transformation at constant particle size and morphology opens a unique opportunity to understand the effects of such mesoporosity transformation and judge the performance of both types of materials. On a mechanical point of view, commercial silica and its pseudomorphic transformation are stable until 40 MPa, which is enough to resist to chromatographic column packing. Liquid chromatographic tests reveal that column efficiency and mass transfer properties are maintained during the pseudomorphic transformation. Adsorption from polar probes and thermogravimetric measurements show that the surface chemistry is strongly modified by the pseudomorphic transformation, which is not pseudochemical. The surfactants use to generate well defined mesoporosity induct in one hand a low silanol density and in the other hand a more homogeneous silanol distribution on the silica surface, which opens the route towards a better control of surface functionalization. Moreover, grafted-mesoporous silicas exhibit an extremely high mechanical stability (>280 MPa). Pseudomorphic-silicas are remarkable candidates for applications needing morphology and surface chemistry control.
J. Iapichella, J-M. Meneses, I. Beurroies, R. Denoyel, Z. Bayram-Hahn, K. Unger, A. Galarneau, Microporous and Mesoporous Materials 102 (2007) 111-121

A0832 – CrAlYN/CrN superlattice coatings deposited by the combined high power impulse magnetron sputtering/unbalanced magnetron sputtering technique

CrAlYN/CrN coatings represent a new generation Ti-free PVD coatings tailored to serve high temperature applications such as dry high speed machining and protection of special grades aerospace and automotive alloys against environmental attack. The novel High Power Impulse Magnetron Sputtering (HIPIMS) technique was used for substrate pre-treatment (etching) followed by coating deposition utilising Unbalanced Magnetron Sputtering (UBM). The employment of HIPIMS resulted in smooth (Ra=0.036 ?m) and well adherent films with typical scratch adhesion critical load values on M2 high speed steel of LC=65 N. Low-angle XRD analysis showed that the coating has a nanoscale multilayer (superlattice) structure with a typical bi-layer thickness of 4 nm. XTEM observations confirmed this result and further revealed the dense, growth defect free structure of the coating due to the HIPIMS etching. CrAlYN/CrN combines high hardness of HK0.025=3320 with a low coefficient of friction of 0.5 and an exceptionally low sliding wear coefficient of 3.7x10^(-17) m3 N-1 m-2, which is comparable to that of TiAlN/VN and Me- Carbon films. In dry high speed milling (Vcutting=385 m min-1) of hardened A2 tool steel (HRC=58), 8 mm cemented carbide ball nosed end mills coated with CrAlYN/CrN outperformed TiAlCrYN, which is one of the market leading coatings dedicated to this application. When the test is carried out at the higher end of the cutting speed range of 500 m min-1 this difference in performance becomes even more pronounced (factor of 8 longer life time), which demonstrates the excellent quality of CrAlYN/CrN.
P.Eh. Hovsepian, C. Reinhard, A.P. Ehiasarian, Surface & Coatings Technology 201 (2006) 4105-4110

A0831 – Effect of Pt and Al content on the long-term, high temperature oxidation behavior and interdiffusion of a Pt-modified aluminide coating deposited on Ni-base superalloys

The present work is devoted to the effect of Al and Pt content on the oxidation behavior and interdiffusion of the industrial NiPtAl coating RT22 deposited on SCB and IN792 Ni-base superalloys. Some specimens of RT22/SCB experienced a defective aluminization resulting in one side with a lower Al content, and some specimens of RT22/IN792 had less platinum than the specification. The effect of both Pt and Al on the initial microstructure of the coating is discussed. Isothermal oxidation tests for 100 h and long-term cyclic oxidation/interdiffusion tests at 1050°C were performed (up to 51 cycles of 300 h). It is shown that a 50 ?m coating with 30 at.% Al instead of a nominal 70 ?m coating with 52 at.% Al leads to the full transformation of the beta phase after 6x300 h at 1050°C and to the formation of large voids and spinel oxides after 35x300 h, but also to less surface undulations than the standard coating. A lower Pt concentration in the RT22 coating results in lower aluminization kinetics and increased spalling and Al consumption during long-term cyclic oxidation without decreasing the isothermal oxidation kinetics.
N. Vialas, D. Monceau, Surface & Coatings Technology 201 (2006) 3846-3851

A0830 – Sol-gel preparation and characterization of gadolinium aluminate

This paper reports on the results concerning the sol-gel preparation of nanocrystalline gadolinium aluminate (GdAlO3, GAP) using different starting materials. The gadolinium nitrate or gadolinium oxide as Gd raw compounds and aluminium nitrate as Al source were used in the sol-gel processing. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursor for the GAP. The phase transformations, composition and micro-structural features in the gels and polycrystalline samples were studied by thermal analysis (TGA/DTA), powder X-ray diffraction analysis (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The XRD patterns of the GAP ceramic sintered at 1000°C using gadolinium oxide as starting material were identical with the single-phase perovskite GdAlO3 composition.
S. Cizauskaite, V. Reichlova, G. Nenartaviciene, A. Beganskiene, J. Pinkas, A. Kareiva, Materials Chemistry and Physics 102 (2007) 105-110

A0833 – Oxidation resistance improvement of arc-evaporated TiN hard coatings by silicon addition

Ti-Si-N coatings were deposited on M2 steel by arc evaporation using a Ti-Si composite target in an industrial reactor. The films structure before and after heat treatment at 700°C was characterised by XRD. In addition, two types of quantitative experiments were performed in thermobalance: oxidation rate was deduced from isothermal thermogravimetric analyses at 800°C, while the temperature of oxidation beginning (Tc) was measured in dynamic mode. Tc was then calculated by a mathematical approximation based on the non-linear least square. The results were compared to those obtained using TiN and SiNx standards. Depending on the deposition conditions, ternary films have been deposited with an atomic ratio Si/Ti of 0.10 and 0.15. The hardness of the films was close to 40 GPa. Only the TiN phase was detected by XRD. The mean crystal size was estimated to be in the 6-8 nm range, which suggested the nanocomposite nature of the coatings. After air oxidation at 700°C, it was found that this crystal size was not affected by the thermal treatment, indicating a good thermal stability of the structure. Moreover, incorporation of silicon into TiN-based coatings led to a drastic decrease of their oxidation rate, together with a shift of 200°C of Tc. The high resistance of oxidation of Ti-Si-N films at elevated temperature is attributable to the network of refractory SiNx, which acted as a diffusion barrier for oxygen and insulated TiN nanograins from the aggressive atmosphere.
P. Steyer, D. Pilloud, J.F. Pierson, J-P. Millet, M. Charnay, B. Stauder, P. Jacquot, Surface & Coatings Technology 201 (2006) 4158-4162

A0835 – Encapsulation of direct blue dye into mesoporous silica-based materials

Mesoporous hexagonal silica CMI-1, MCM-41,SBA-15 and Al-incorporated silica AlCMI-1 with pore sizes of 2, 2.7, 3.8 and 3.6 nm, respectively, have been synthesized and used as host materials for the fabrication of optical materials by the encapsulation of direct blue 71 dye. The surface silanol groups of these mesoporous silicas were functionalized by silylation with 3-(aminopropyl)-triethoxysilane or methyltrimethoxylsilicate, which allow a successful doping of organic dye molecules. X-ray diffraction, N2 adsorption, thermogravimetric analysis, infrared, UV-vis diffuse reflectance and solid-state NMR spectroscopy were used to structurally characterize these composite products. It is found that the dye molecules of direct blue 71 have been encapsulated in the pores of MCM-41, SBA-15 and AlCMI-1, whereas attached on the external surface of CMI-1. The steric effect from the pore size of the host materials is significant. Moreover, Al-species in the AlCMI-1 were believed to take an important role in the dye encapsulation, resulting in a larger blue-shift of 21 nm than other mesoporous dye/silica composites.
T-Z. Ren, Z-Y. Yuan, B-L. Su, Colloids and Surfaces A: Physicochem. Eng. Aspects 300 (2007) 79-87

A0834 – Metallic interconnects for SOFC: Characterization of their corrosion resistance in hydrogen/water atmosphere and at the operating temperatures of differently coated metallic alloys

Chromia forming alloys are one of the best candidates for the interconnecting materials in solid oxide fuels cells (SOFC). Recent research has enabled to decrease the operating temperature of the SOFC from 1000°C to 800°C. However, low electronic conductivity and high volatility of the chromia scale need to be solved to improve performance of interconnects. In the field of high temperature oxidation of metals, it is well known that the addition of reactive elements into alloys or in thin film coatings, improve the oxidation resistance of alloys at high temperature. The elements of the beginning of the lanthanide group and yttrium are the most efficient. The goal of this study is to make rare-earth oxides coatings by MOCVD (Metal Organic Chemical Vapour Deposition) on Crofer 22 APU alloy in order to form perovskite oxides which possess good conductivity at high temperatures. The coatings were analysed after 100 h ageing at 800°C by SEM, TEM, EDX and XRD analyses. ASR (Area Specific Resistance) was measured in air for the same times and temperature, using a four point technique with Pt paste for electrical contacts between surfaces. In conclusion reactive elements have beneficial effects on the oxidation behaviour (decrease of the oxidation rate) as well as on the stability of the electrical conductivity as proved by the value of ASR parameter.
P. Piccardo, S. Chevalier, R. Molins, M. Viviani, G. Caboche, A. Barbucci, M. Sennour, R. Amendola, Surface & Coatings Technology 201 (2006) 4471-4475

A0836 – Highly ordered mesoporous carbon materials CMI-8 with variable morphologies synthesised by nanocasting

The synthesis of ordered mesoporous carbon materials, which have been named CMI-8, using the hexagonally ordered mesoporous silica CMI-1 as an exotemplate is reported. The morphology of these new mesoporous carbon materials is exactly the same as the CMI-1 template. The hexagonal pore structure replication was confirmed by XRD and TEM. From a textural point of view, the carbon replica shows a type IV isotherm and a narrow pore size distribution centred at 2.2 nm. A high surface area and total pore volume, of 1653 and 0.86 cm3/g, respectively, were obtained. The advantage of using mesoporous silica CMI-1 as a template is its variable but uniform morphologies, from sphere, gyroid, toroid to ropes.
A. Vantomme, L. Surahy, B.L. Su, Colloids and Surfaces A: Physicochem. Eng. Aspects 300 (2007) 65-69

A0837 – Layer-by-layer assembly of a magnetic nanoparticle shell on a thermoresponsive microgel core

We describe the surface modification of magnetic nanoparticles (MNPs), the coverage of poly(N-isopropylacrylamide) (PNiPAM) microgel with the MNPs and the inductive heating of these carriers. PNiPAM surface itself was modified using the layer-by-layer (LbL) assembly of polyelectrolytes to facilitate the deposition of surface-modified MNPs. One advantage of this concept is it allows the tuning of the magnetic and thermoresponsive properties of individual components (nanoparticles and microgels) separately before assembling them. Characterisations of the hybrid core-shell are discussed. In particular, it is shown that (i) each layer is successfully deposited and, more importantly, (ii) the coated microgel retains its thermoresponsive and magnetic behaviour.
J.E. Wong, A.K. Gaharwar, D. Müller-Schulte, D. Bahadur, W. Richtering, Journal of Magnetism and Magnetic Materials 311 (2007) 219-223

A0838 – Hollow TS-1 crystals formed via a dissolution-recrystallization process

Post-synthesis treatment of a calcined TS-1 zeolite with aqueous solutions of tetrapropylammonium hydroxide leads to hollow TS-1 crystals. By contrast to conventional dissolution experiments using NaOH as mineralizing agent, the creation of intra-particle voids also involves a partial recrystallization of the zeolite. Hollow crystals possess the same chemical composition and approximately the same size as those of the original crystals, but the distribution of Ti species certainly differs. The method reported here is particularly attractive in the case of zeolites contaminated with extraframework Ti oxide species: the formation of the hollow structure is accompanied by a reincorporation of Ti in the zeolite framework, which considerably increases the catalytic activity.
Y. Wang, M. Lin, A. Tuel, Microporous and Mesoporous Materials 102 (2007) 80-85

A0839 – Highly carbonized polyaniline micro- and nanotubes

We have obtained unique highly carbonized polyaniline micro- and nanotubes as a new, thermally stable nanomaterial for nanosensors and nanodevices with a wide range of possible applications, comparable to carbon nanotubes. Polyaniline nanostructures are easy to prepare and handle in wet conditions, including controlled growth. Temperature-induced transformations of polyaniline micro- and nanotubes into highly carbonized analogues have been observed at and above 800°C, while the temperature was elevated slowly from 20°C up to 1100°C. Carbonized products have the same morphology (micro- and nanotubes), but a lower spin density than the starting material (e.g. 10^14 g-1 for the sample heated at and above 800°C, and 10^19 g-1 before heating). Simultaneously, the electrical conductivity changes from 7.4 x 10^(-5) S/cm for the starting material to 4.8 x 10^(-9) S/cm, 1.3 x 10^(-11) S/cm and finally 2.4 x 10^(-6) S/cm for samples obtained at room temperature, 250°C, 500°C and 800°C, respectively. Chemical transformations and unique molecular structures formed are discussed. Applications in nanotechnology, including sensors and electronic nanodevices, are expected in the light of experiments already performed.
J.J. Langer, S. Golczak, Polymer Degradation and Stability 92 (2007) 330-334

A0841 – Direct blue dye-encapsulated mesostructured MCM-41 composites: Microwave-assisted preparation and characterization

The preparation of triazo dye direct blue 71 (DB71)-encapsulated mesostructured MCM-41 materials has successfully been performed by a microwave-assisted method or under conventional room temperature condition. The structures and properties were characterized by XRD, N2 adsorption analysis, electron microscopy, FT-IR, 13C NMR, UV-vis, and TGA-DSC. A blue-shift of UV-vis spectra was observed in the conventional room temperature-synthesized DB71/MCM-41 sample, and a red-shift in the microwave-synthesized DB71/MCM-41 samples, which may give a wide optical application.
T-Z. Ren, Z-Y. Yuan, B-L. Su, Colloids and Surfaces A: Physicochem. Eng. Aspects 300 (2007) 88-93

A0843 – Formation of the nanocrystalline mesoporous niobium-silicon oxynitride

A new method for the preparation of crystalline mesoporous niobium-silicon oxynitride (NbSiON) by the straightforward technique is described. The characterization has been performed by various techniques showing that the material has: (i) the specific surface area of 160 m2 g-1 and mesopores centered at 4.0 nm from N2 adsorption, (ii) the crystalline walls from wide-angle XRD pattern, (iii) the wormhole-like framework from low-angle XRD pattern and TEM images, (iv) the nanobelts and nanowires morphology from TEM images, and (v) Si-O-Nb and Si-N-Nb bonds from FTIR spectroscopy.
I. Nowak, M. Ziolek, Catalysis Today 118 (2006) 410-415

A0842 – The role of hydrogen peroxide in the deposition of cerium-based conversion coatings

Cerium-based conversion coatings are progressing as an effective alternative to hazardous chromate-based systems used in the treatment of metal surfaces. However, there is still considerable debate over the mechanism by which these coatings are formed. Here, titrations of cerium-based conversion coating solutions were carried out in order to model the reactions that occur at the metal-solution interface during coating, with a particular emphasis on investigating the role of hydrogen peroxide (H2O2). The titration curves obtained support the proposed formation of Ce(III) peroxo complexes such as Ce(H2O2)3+ as an initial step, followed by deprotonation, oxidation and precipitation to form peroxo-containing Ce(IV) species such as Ce(IV)(O2)(OH)2. The precipitates resulting from titrations were characterised by Raman spectroscopy, X-ray diffraction and thermogravimetric analysis, confirming the presence of peroxo bonds, and nano-sized CeO2 crystallites that decreased in size with increasing H2O2 concentration. Characterisation of cerium conversion coatings on aluminium alloy surfaces confirmed the presence of peroxo species in the coatings, thereby supporting the titration model.
F.H. Scholes, C. Soste, A.E. Hughes, S.G. Hardin, P.R. Curtis, Applied Surface Science 253 (2006) 1770-1780

A0844 – A new glance at ruthenium sorption mechanism on hydroxy, carbonate, and fluor apatites: Analytical and structural studies

The sorption mechanism of Ru3+ ions on hydroxy (HAp), carbonate (CO3HAp), and fluor apatites (FAp) has been studied in detail. Ru apatites were obtained by reaction of the apatites with RuCl3 in aqueous solution. The structure and composition of the ruthenium-modified apatites were studied by several techniques: elemental analysis, XRD, EXAFS, IR, NMR, SEM-EDS, TEM, and thermal analysis. The amount of Ru in the modified apatite varies from 7.8 to 10.5 wt% and is not related to the initial composition or the specific surface area of the apatite. The different characterization techniques show that in the Ru-modified apatites Ru is surrounded by six oxygen atoms and do not contain any chlorine. For Ru-HAp and Ru-CO3HAp the new phase is amorphous whereas it is crystalline for FAp. The catalytic oxidation ability is higher for Ru-HAp and Ru-CO3HAp compared to Ru-FAp apatite in the oxidation of benzylic alcohol.
K. Tõnsuaadu, M. Gruselle, F. Villain, R. Thouvenot, M. Peld, V. Mikli, R. Traksmaa, P. Gredin, X. Carrier, L. Salles, Journal of Colloid and Interface Science 304 (2006) 283-291

A0846 – Evaluation of meat and bone meal combustion residue as lead immobilizing material for in situ remediation of polluted aqueous solutions and soils: “Chemical and ecotoxicological studies”

As a result of bovine spongiform encephalopathy (BSE) crisis, meat and bone meal (MBM) production can no longer be used to feed cattle and must be safely disposed of or transformed. MBM specific incineration remains an alternative that could offer the opportunity to achieve both thermal valorization and solid waste recovery as ashes are calcium phosphate-rich material. The aim of this work is to evaluate ashes efficiency for in situ remediation of lead-contaminated aqueous solutions and soils, and to assess the bioavailability of lead using two biological models, amphibian Xenopus laevis larvae and Nicotiana tabaccum tobacco plant. With the amphibian model, no toxic or genotoxic effects of ashes are observed with concentrations from 0.1 to 5 g of ashes/L. If toxic and genotoxic effects of lead appear at concentration higher than 1mg Pb/L (1 ppm), addition of only 100 mg of ashes/L neutralizes lead toxicity even with lead concentration up to 10 ppm. Chemical investigations (kinetics and X-ray diffraction (XRD) analysis) reveals that lead is quickly immobilized as pyromorphite [Pb10(PO4)6(OH)2] and lead carbonate dihydrate [PbCO3.2H2O]. Tobacco experiments are realized on contaminated soils with 50, 100, 2000 and 10 000 ppm of lead with and without ashes amendment (35.3 g ashes/kg of soil). Tobacco measurements show that plant elongation is bigger in an ashes-amended soil contaminated with 10 000 ppm of lead than on the reference soil alone. Tobacco model points out that ashes present two beneficial actions as they do not only neutralize lead toxicity but also act as a fertilizer.
E. Deydier, R. Guilet, S. Cren, V. Pereas, F. Mouchet, L. Gauthier, Journal of Hazardous Materials 146 (2007) 227-236

A0845 – Application of a multi-dentate amphiphilic compound to transfer silver nanoparticles into an organic solvent

A multi-dentate amphiphilic compound, 3,3 -(dodecylazanediyl)-bis-[N-(2-aminoethyl)propanamide] (12C-2NH2) has been synthesized. The molecular structure was characterized by Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-vis) spectra, nuclear magnetic resonance (NMR) spectra, and fast atom bombardment mass (FAB-MS) spectra. 12C-2NH2 was employed to stabilize silver nanoparticles. Surface properties and stability of silver nanoparticles were controlled by adjusting the 12C-2NH2 to silver (0) molar ratio. 12C-2NH2 was also applied to transfer silver nanoparticles from an aqueous to an organic phase. The transfer efficiency depends on 12C-2NH2 concentration. When 12C-2NH2 to silver (0) molar ratio was 2:1, the highest efficiency of phase transfer to toluene was obtained. These 12C-2NH2 stabilized silver nanoparticles are very stable over a period of four days in toluene.
N. Gao, J. Dong, H. Zhang, X. Zhou, G. Zhang, J. Eastoe, Journal of Colloid and Interface Science 304 (2006) 388-393

A0849 – Selective mesoporous adsorbents for (Cr2O7)2- and Cu2+ separation

NH2-MCM-41 and COONa-MCM-41 were prepared by grafting aminopropyls and propionates on the pore wall of the mesoporous silica MCM-41 for the separation of (Cr2O7)2- and Cu2+. Single and binary component adsorptions show that (NH3+)-MCM-41 has a 100% selectivity for (Cr2O7)2- adsorption at low pH (<3.5 i.e., point of zero charge, p.z.c.), while COO Na+-MCM-41 adsorbs only Cu2+ over the entire pH range of the study (i.e., pH 1.5-5.5). Adsorption uptakes were rapid on both adsorbents reaching equilibrium in less than 3 h and in most cases less than 10 min. The adsorption capacity of (NH3+)-MCM-41 for (Cr2O7)2- is high, approaching the theoretical values of two aminopropyls for one (Cr2O7)2- , the Cu2+ adsorption on COO Na+-MCM-41 was less efficient requiring five propionates to adsorb one Cu2+. High purity hydrogen dichromate and copper chloride solutions were respectively recovered by a simple acid wash and the regenerated adsorbents were reused without a loss of performance.
K.F. Lam, K.L. Yeung, G. Mckay, Microporous and Mesoporous Materials 100 (2007) 191-201

A0848 – Preparations of nano-particles, nano-composites and fibers of ZnO from an amide precursor: Photocatalytic decomposition of (CH3)2S2 in a continuous flow reactor

High surface area hexagonal ZnO nano-particles were obtained at room temperature from hydrolysis of the amide derivative Zn[N(SiMe3)2]2. The same procedure applied on silica or cellulose substrates led to homogeneous crack-free hybrid materials for which micro- down to nano-meter replication into ZnO cloth was achieved by calcination at 700°C. These materials were characterized by FT-IR, UV-vis, photoluminescence, X-ray diffraction (XRD) and transmission electron microscopy (TEM). They demonstrated enhanced photocatalytic degradation of a tough pollutant such as CH3SSCH3 compared with commercial ZnO powder.
S. Daniele, M.N. Ghazzal, L.G. Hubert-Pfalzgraf, C. Duchamp, C. Guillard, G. Ledoux, Materials Research Bulletin 41 (2006) 2210-2218

A0851 – Comparative study of the effect of different nanoparticles on the mechanical properties and thermal degradation mechanism of in situ prepared poly(e-caprolactone) nanocomposites

Various poly(e-caprolactone) nanocomposites were prepared in situ by the ring-opening polymerization of e-caprolactone. Four different nanoparticles were used. Two layered silicates, such as montmorillonite (Cloisite Na+ and Cloisite 20A), one in the form of spherical nanoparticles (fumed silica SiO2) and multi-walled carbon nanotubes (MWNT). Thermal degradation under dynamic conditions as well as mechanical properties under tension of the prepared materials were comparatively examined. All nanoparticles, despite resulting in a small molecular weight (Mv) decrease, induced a substantial enhancement of Young's modulus and tensile strength compared to neat PCL. From TGA analysis it was concluded that modified montmorillonite and fumed silica accelerate the decomposition of PCL due to respective aminolysis and hydrolytic reactions that the reactive groups on the surface of these materials can induce. On the other hand, carbon nanotubes and unmodified montmorillonite can decelerate the thermal degradation of PCL due to a shielding effect. The activation energies of all the prepared samples were estimated using the Ozawa, Flynn and Wall (OFW) and Friedman methods. Thermal degradation of PCL and its nanocomposites was found to be satisfactorily represented by two mechanisms having different activation energies. The first corresponds to a small mass loss, while the second, attributed to the main decomposition mechanism, corresponds to the substantial mass loss that takes place. The nanoparticles do not affect the decomposition mechanism but only the activation energies.
K. Chrissafis, G. Antoniadis, K.M. Paraskevopoulos, A. Vassiliou, D.N. Bikiaris, Composites Science and Technology 67 (2007) 2165-2174

A0850 – Hydrothermal synthesis and characterization of a new organic templated metallophosphate [Zn(H2PO4)2(HPO4)][C7H17N2]

A new organic templated metallophosphate, [Zn(H2PO4)2(HPO4)][C7H17N2] (denoted in the following ZnP-AMEP), has been synthesized hydrothermally using 2-aminomethyl,1-ethylpyrrolidine (AMEP) as a structure-directing agent. The structure, determined by single crystal X-ray diffraction, exhibits a parallel arrangement (along the [1 1 0] direction) of infinite chains, built from (Zn2P2O12) four-membered rings sharing ZnO4 tetrahedra, interconnected together by strong hydrogen bonds to form a sheet-like architecture and with chains of (H2PO4)n n- extending along [100] at y = 1/2 to form a 3D anionic network. To the best of our knowledge, the compound ZnP-AMEP represents the first organic templated metallophosphate in which the four-membered rings interact with chains of dihydrogenophosphate. Intra-chain and inter-chain P-OH....O hydrogen bonds help to establish the crystal packing and form apertures, wherein the amine molecules are located. Similarities and differences with other organic templated metallophosphates are briefly discussed for the title compound. Ab initio calculations allow the attribution of phosphorus and carbon solid-state NMR signals to the independent crystallographic sites and to the various atoms of the organic groups. Additional characterizations of the compound have also been performed by IR spectroscopy and TG-DTA analyses.
R. Kefi, C. Ben Nasr, F. Lefebvre, M. Rzaigui, Polyhedron 26 (2007) 1603-1611

A0853 – Palladium(II) and platinum(II) 2-(methoxycarbonyl)ethylselenolates: Synthesis, spectroscopy, structures and their conversion into metal selenide

A diselenide, (MeOOCCH2CH2Se)2 (1) has been prepared by esterification of (HOOCCH2CH2Se)2 in methanol. The reductive cleavage of Se-Se bond in 1 by NaBH4 in methanol generates MeOOCCH2CH2SeNa. The latter in different stoichiometries reacts with [M2Cl2(l-Cl)2(PR3)2] to give a variety of products of compositions [M2Cl2(l-SeCH2CH2COOMe)2(PR3)2] (2); [M2Cl2(l-Cl)- (l-SeCH2CH2COOMe)(PR3)2] (3); [Pd2(SeCH2CH2COOMe)2(l-SeCH2CH2COOMe)2(PR3)2] (4); [Pd3Cl2(l-SeCH2CH2COOMe)4(PR3)2] (5). Treatment of complexes 2 with [M2Cl2(l-Cl)2(PR3)2] affords complexes 3 in nearly quantitative yield. The formation of various products in these reactions is sensitive to stoichiometric ratio of reactants employed. This enables interconversion of various complexes by manipulating mole ratios of appropriate starting materials. A homoleptic palladium complex, [Pd(SeCH2CH2COOMe)2]6 (6) was isolated from a reaction between Na2PdCl4 and MeOOCCH2CH2SeNa. All these complexes have been characterized by elemental analysis, IR, UV-Vis and NMR (1H, 13C, 31P, 77Se, 195Pt) spectroscopy. Structures of trans-[Pd2Cl2(l-SeCH2CH2COOMe)2(PPh3)2] (2d), [Pt2Cl2(l-Cl)(l-SeCH2CH2COOMe)(PnPr3)2] (3e), [Pd3Cl2(l-SeCH2CH2COOMe)4(PnPr3)2] (5) and [Pd(SeCH2CH2COOMe)2]6 (6) have been established unambiguously by X-ray crystallography. In these complexes, there are bridging selenolate ligands with their uncoordinated ester groups. Compound 6 has a centrosymmetric Pd6Se12 hexagon in which every two palladium atoms are bridged by selenolate ligands. Thermal behaviour of some complexes has been investigated. Pyrolysis of compound 2b in tributylphosphate at 195°C gave Pd17Se15 nanoparticles which were characterized by XRD and EDAX.
L.B. Kumbhare, V.K. Jain, P.P. Phadnis, M. Nethaji, Journal of Organometallic Chemistry 692 (2007) 1546-1556

A0852 – Hydrotalcites as catalysts for the Baeyer-Villiger oxidation of cyclic ketones with hydrogen peroxide/benzonitrile

Hydrotalcites (HTs) in variable Mg/Al ratios were used as catalysts for the Baeyer-Villiger (BV) oxidation of cyclic ketones with hydrogen peroxide. All HTs studied were found to be active in the BVoxidation of cyclohexanone, their activity increases with increasing Mg/ Al ratio. The reaction, which was conducted under very mild conditions (viz. atmospheric pressure and a temperature of 70°C), provided conversions above 70% with 100% selectivity only after 6 h. This outcome was found to require the presence of a nitrile in the reaction medium, so a mechanism involving adsorption of the nitrile and cyclohexanone onto the catalyst is proposed that is consistent with the experimental results. Based on the proposed mechanism, the presence of a surfactant should result in improved conversion and catalytic activity, as was indeed observed with sodium dodecylsulfate in the reaction medium. The best catalyst among those tested was used with other cyclic ketones and found to provide excellent conversion and selectivity results in most cases.
J.R. Ruiz, C. Jiménez-Sanchidrian and R. Llamas, Tetrahedron 62 (2006) 11697-11703

A0855 – Synthesis, characterization and hydrolysis of an aliphatic polycarbonate by terpolymerization of carbon dioxide, propylene oxide and maleic anhydride

Terpolymerization of propylene oxide (PO), carbon dioxide (CO2) and maleic anhydride (MA) was carried out by using a polymer-supported bimetallic complex (PBM) as a catalyst. A degradable aliphatic poly(propylene carbonate maleate) (PPCM) was synthesized, and determined by FT-IR, 1H NMR, 13C NMR, DSC, TGA and WAXD measurements. The influences of various reaction conditions such as molar ratio of the monomers, reaction time and reaction temperature on the terpolymerization progress were investigated. The results showed that MAwas inserted into the backbone of CO2-PO successfully. The viscosity, glass transition temperature and decomposition temperature of the terpolymers were much higher than those of poly(propylene carbonate) (PPC). Because of the existence of the MA ester unit, PPCM had stronger degradability than PPC in a pH 7.4 phosphate-buffered solution. MA offered an ester structural unit that gave the terpolymers remarkable degradability. And the degradation rate of the backbone increased with the insertion of MA into the terpolymers.
Y. Liu, K. Huang, D. Peng, H. Wu, Polymer 47 (2006) 8453-8461

A0854 – Phase equilibria in the partial system CePO4-K4P2O7-KPO3

The CePO4-K4P2O7-KPO3 portion of the oxide Ce2O3-K2O-P2O5 system has been investigated using thermoanalytical methods, powder X-ray diffraction, XPS and IR spectroscopy. The phase diagram with liquidus isotherms and isothermal section at room temperature of the system CePO4-K4P2O7-KPO3 has been determined. One section, CePO4-K5P3O10, which is quasi-binary only in the subsolidus region (below 560°C), have been found. The system contains one double phosphate K4Ce2P4O15, which exists only in solid state, below 880°C.
I. Szczygiel, Solid State Sciences 8 (2006) 178-184

A0856 – Polymerization of norbornene using novel palladium carboxylate/boron trifluoride etherate catalyst system

The vinyl polymerization of norbornene with Pd(carboxylate)2/BF3OEt2 catalyst system has been investigated by varying the molar cocatalyst/ metal ratio, the norbornene/metal ratio, the metal concentration and the reaction temperature. The effects on the catalyst activity were explained on the basis of complexation equilibrium for the active homogeneous complex. A "particular" activity of 154 100 kg NB per mole Pd for an hour has been achieved at B/Pd = 25 and 25°C. The molecular weights Mw from 77 700 to 293 800 g/mol and glass transition temperatures Tg from 240 to 262°C were observed for the representative samples of polynorbornene. The molar mass distribution indicates a single-site, highly homogeneous character of the active catalyst species. Catalytic activity and polymer molecular weight can be controlled by varying the reaction parameters over a wide range. NMR and IR spectroscopic studies of the polymer showed 2,3-enchained repeating units of polymer backbone with low diisotacticity. The simplicity of catalyst system composition might be of industrial importance.
G. Myagmarsuren, J-I. Park, S-K. Ihm, Polymer 47 (2006) 8474-8479

A0858 – Selective catalytic reduction of NO by ammonia on V2O5-(SO4)2- /TiO2 catalysts prepared by the sol-gel method

This paper examines the effect of sulfation of vanadia-titania binary solid prepared by sol-gel process on its activity for the selective catalytic reduction (SCR) of NO with NH3. Sulfated and unsulfated vanadia titania have been characterized by means of N2 adsorption-desorption at 77 K, XRD, TGA, propan-2-ol conversion as acid test, H2-TPR measurements, EPR, XPS and Raman spectroscopies. The main results of this study highlight the interaction of sulfate ions with vanadia species. The ternary catalyst VTiS exhibits a high activity compared to binary TiS or VTi samples. It is concluded that sulfate species improve the superficial acidity of solid and interact with vanadia leading to a better reducibility of VTiS oxide.
L. Baraket, A. Ghorbel, P. Grange, Applied Catalysis B: Environmental 72 (2007) 37-43

A0857 – Cr(VI) adsorption on functionalized amorphous and mesoporous silica from aqueous and non-aqueous media

A mesoporous silica (SBA-15) and amorphous silica (SG) have been chemically modified with 2-mercaptopyridine using the homogeneous route. This synthetic route involved the reaction of 2-mercaptopyridine with 3-chloropropyltriethoxysilane prior to immobilization on the support. The resulting material has been characterized by powder X-ray diffraction, nitrogen gas sorption, FT-IR and MAS NMR spectroscopy, thermogravimetry and elemental analysis. The solid was employed as a Cr(VI) adsorbent from aqueous and non-aqueous solutions at room temperature. The effect of several variables (stirring time, pH, metal concentration and solvent polarity) has been studied using the batch technique. The results indicate that under the optimum conditions, the maximum adsorption value for Cr(VI) was 1.83 ± 0.03 mmol/g for MP-SBA-15, whereas the adsorption capacity of the MP-SG was 0.86 ± 0.02 mmol/g. On the basis of these results, it can be concluded that it is possible to modify chemically SBA-15 and SG with 2-mercaptopyridine and to use the resulting modified silicas as effective adsorbents for Cr(VI).
D. Pérez-Quintanilla, I. del Hierro, M. Fajardo, I. Sierra, Materials Research Bulletin 42 (2007) 1518-1530

A0860 – Thermal stability of magnetron sputtered Zr-Si-N films

The article reports on thermal stability of the structure and mechanical properties of Zr-Si-N filmswith a high (>25 at.%) Si content deposited froma ceramic ZrSi2 target by reactive magnetron sputtering. The annealed films were characterized using X-ray diffraction, microhardness and macrostress measurements, and differential scanning calorimetry. Special attention was devoted to the influence of the annealing temperature (up to 1600°C), annealing environment and presence of the substrate. It was found that the phase composition of the films strongly influences its thermal stability. Furthermore, (i) microhardness of the Zr-Si-N films sputtered under conditions used in our experiments is determined by their structure and not by the macrostress, (ii) crystallization of the X-ray amorphous films strongly depends on its phase composition, the ambient atmosphere and the incorporation of the substrate elements into the filmdue to interdiffusion during annealing, and (iii) X-ray amorphous Zr-Si-N films containing a high (>50 vol.%) content of the Si3N4 phase exhibit the highest thermal stability considerably exceeding 1000°C.
R. Daniel, J. Musil, P. Zeman, C. Mitterer, Surface & Coatings Technology 201 (2006) 3368-3376

A0859 – Oxidation resistance of Cr(1-x)AlxN (0.18

Cr(1-x)AlxN coatings (0.18
M. Zhu, M. Li, Y. Zhou, Surface & Coatings Technology 201 (2006) 2878-2886

A0862 – Evolution of intermediate phases in the synthesis of zinc ferrite nanopowders prepared by the tartrate precursor method

The advanced electronic applications of zinc ferrite (ZnFe2O4) material are considered to require improvement in the powder processing, particularly, meticulous particle control in the nanometer range, stoichiometry and phase purity. This article presents the process of zinc ferrite formation from tartrate precursors, emphasizing the intermediate phase evolution during the thermal treatment. The variation of the intermediate phases, crystallite size and chemical composition of the products at different calcination temperatures have been investigated by X-ray diffraction (XRD), Fe2+ content analysis, transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS) techniques. Results show that the stoichiometry and phase purity of the resultant zinc ferrite nanopowders has been noted to be highly influenced by their intermediate phases. Finally, the formation mechanism of zinc ferrite is discussed. A single phase, approaching the desirable stoichiometric zinc ferrite nanoparticles, is noted to be possibly prepared produced by an annealing treatment of the precursor gel powders at 350°C for 4 h.
J.M. Yang, F.S. Yen, Journal of Alloys and Compounds xxx (2007) xxx-xxx

A0861 – In situ reaction synthesis and characterization of Ti3Si(Al)C2/SiC composites

The reaction route, microstructure, and properties of Ti3Si(Al)C2/SiC composites with 5-30 vol.% SiC content prepared by in situ hot pressing/solid-liquid reaction synthesis process are investigated. In contrast to monolithic Ti3Si(Al)C2, the SiC particle-reinforced composites exhibit higher elastic modulus, Vickers hardness, fracture toughness, improved wear, and oxidation resistance, but have a slight loss in flexural strength. The improvement in the properties is mainly ascribed to the contribution of SiC particles, and the strength degradation is due to the residual tensile stresses in the matrix.
D.T. Wan, Y.C. Zhou, Y.W. Bao, C.K. Yan, Ceramics International 32 (2006) 883-890

A0863 – Diffuse reflectance infrared Fourier transform spectroscopy as a tool to characterise water in adsorption/confinement situations

We present experimental data acquired by diffuse reflectance infrared spectroscopy in the mid-IR (4000-400 cm-1), on micrometric-sized mineral grain powders. The spectral evolution of the OH-stretching band is followed when the adsorbed water film is thinned under dry conditions, from high to low hydration states. The IR bands are found to be characteristic of the degree of adsorption/confinement of the liquid water. The OH-stretching band is shifted toward shorter wavenumbers than in bulk water, showing that a significant portion of adsorbed water has a higher intermolecular bonding energy. Complementary treatment of the kinetics of water desorption, varying with the surface forces in the water film, confirms the relationships of these bands with the constrained water state. We distinguish different water types obeying liquid-liquid interactions (free and capillary water) or dominated by solid-water interactions (confined and adsorbed water). Part of this study is devoted to mesoporous silica MCM-41, of interest due to the restricted geometries of its mesopores (4.7 nm) favouring the confined water state. The methodology allows us to distinguish bulk and adsorbed/confined water, using spectral analysis coupled with an understanding of the dynamic behaviour of the desorption process.
T. Richard, L. Mercury, F. Poulet, L. d'Hendecourt, Journal of Colloid and Interface Science 304 (2006) 125-136

A0865 – Sol-gel preparation of boron-containing cordierite Mg2(Al4-xBx)Si5O18 and its crystallization

Five cordierite-based powders were investigated regarding their thermal and crystallization behaviors. The powders were obtained from amorphous gels having nominal compositions of 2Mg: xAl : (4-x)B : 5Si where x=4 down to 0. Thermal gravimetry analysis of the dry gels showed some absorbed water and decomposition of organic ligands in addition to network condensation. Gradual substitution of B for Al in the dried gel powders showed a new band in their infrared spectra corresponding to triangular BO3, whereas the bands corresponding to Al vanished. This also showed a noticeable effect on the crystallization trends, type and stability of cordierite. Cordierite crystallized in samples of B/Al ratio up to 1 while protoenstatite predominated in samples of higher B/Al ratios. In addition, some silica minerals, with little amorphous phase, were formed. Incorporation of boron and increase in temperature enhanced the transformation of gamma cordierite to its alpha form.
E.M.A. Hamzawy, A.F. Ali, Materials Characterization 57 (2006) 414-418

A0864 – Synthesis and characterization of two new photochromic organic-inorganic hybrid materials based on isopolyoxomolybdate: (HDBU)3(NH4)[beta-Mo8O26].H2O and (HDBU)4[delta-Mo8O26]

Two new organic-inorganic hybrid compounds of molybdenum(VI) (HDBU)3(NH4)[beta-Mo8O26].H2O 1 and (HDBU)4[delta-Mo8O26] 2 have been synthesized and characterized by elemental analyses, FT-IR and UV-vis spectroscopies, and single-crystal X-ray diffraction (at 293 and 100 K, respectively). Compound 1 is obtained at room temperature by adding 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on aqueous molybdate solution at pH = 5.7. Compound 2 is obtained hydrothermally from 1 (110°C, 24 h, autogenous pressure). Compound 1 crystallizes in the triclinic crystal system, space group P1, with a = 11.2492(9), b = 14.1907(10), c = 16.7498(10) Å , alpha = 80.993(4), beta = 72.272(6), gamma = 71.696(7)°, V = 2412.5(3) Å3 at T = 20°C and Z = 2. The refinement of the structure leads to a residual factor R = 0.0697 for 10234 independent observed reflections [I/s(I)>2] and 623 parameters. Compound 2 crystallizes in the triclinic crystal system, space group P1, with a = 11.3158(9), b = 11.3773(8), c = 13.2884(17) Å , alpha = 92.110(8), beta = 112.127(9), gamma = 117.581(7)°, V = 1357.4(3) Å3 at T = 173°C and Z = 2. The refinement of the structure leads to a residual factor R = 0.0226 for 11812 independent observed reflections [I/s(I)>2] and 354 parameters. The structure of 1 consists of beta-[Mo8O26]4- anions with HDBU+ and (NH4)+ cations connected to the mineral parts by hydrogen bonds and the structure of 2 contains delta-[Mo8O26]4- anions with HDBU+ counter-cations. Both the thermal and chemical isomerizations of the two [Mo8O26]4- isomers are highlighted and discussed. Photochromic behaviors of compounds 1 and 2 are also reported.
V. Coué, R. Dessapt, M. Bujoli-Doeuff, M. Evain, S. Jobic, Journal of Solid State Chemistry 179 (2006) 3615-3627

A0867 – Interactions between chlorinated paraffins and melamine in intumescent paint – investing a way to suppress chlorinated paraffins from the formulations

It is known that acid source, carbon source and blowing agent are the main ingredients of an intumescent paint. Melamine and halogenated additives, such as polychlorinated alkanes (PCAs) are used as blowing agents, however, the legislation tends to prohibit the use of halogenated coumpounds for environmental reasons. The aim of our study is to investigate the mode of action of melamine and PCAs in an intumescent formulation. Their interactions are also studied. It is found that the combination of PCAs and melamine leads to more efficient systems. Spectroscopic analyses (FTIR and solid state 13C NMR) led us to conclude that when the intumescent paint was heated melamine condensed to create melem via Diels-Alder-type reaction. Melem could then react with PCAs leading to the stabilisation of the PCA-melamine mixture. The proposed mechanism of action led us to propose a method for the substitution of PCAs.
P. Ducrocq, S. Duquesne, S. Magnet, S. Bourbigot, R. Delobel, Progress in Organic Coatings 57 (2006) 430-438

A0866 – Study of hydromagnesite and magnesium hydroxide based fire retardant systems for ethylene-vinyl acetate containing organo-modified montmorillonite

A new flame retardant (FR) system for ethylene-vinyl acetate, mainly based on the combination of hydromagnesite (HM, obtained from an industrial by-product) and organo-modified montmorillonite (oMMT) has been compared with a magnesium hydroxide (MDH) and oMMT flame retardant system. The presence of oMMT in association with both hydrated minerals gave a strong decrease of heat release rate in cone calorimeter tests. Moreover, the HM/oMMT combination leads to a better improvement of resistance to ignition and self-extinguishability in comparison with the MDH/oMMT one. The study of residues formed during thermal decomposition revealed the formation of forsterite (Mg2SiO4) when either MDH or HM was used in combination with oMMT. SEM observations of residues showed sintering of the mineral particles at high temperature particularly in the case of HM/oMMT composition.
F. Laoutid, P. Gaudon, J-M. Taulemesse, J.M. Lopez Cuesta, J.I. Velasco, A. Piechaczyk, Polymer Degradation and Stability 91 (2006) 3074-3082

A0870 – Tungsten bronze-based nuclear waste form ceramics. Part 1. Conversion of microporous tungstates to leach resistant ceramics

The effective immobilization of Cs+ and/or Sr2+ sorbed on hexagonal tungsten oxide bronze (HTB) adsorbent materials has been achieved by heating in air at temperatures in the range 500-1000°C. Crystalline powdered HTB materials formed by heating at 800°C displayed leach characteristics comparable to Cs-containing hot-pressed hollandites in the pH range from 0 to 12. If the Cs-loaded HTB sorbents were pressed into pellets prior to calcination, ceramic monoliths could be prepared with negligible Cs volatilization losses. Heating to temperatures in excess of 1250°C under dynamic air flow resulted in the melting of the sorbent to form phase assemblages consisting of millimetre-sized crystals of bronzoid phases. Up to 5 wt% mass loss was observed for small scale samples of melted materials under dynamic air flow. Both the calcined and melted bronzoid waste forms are multiphase ceramics in which Cs+ remains bound within, and appears to stabilize, the hexagonal bronze phase, even after complete melting at 1300°C. The leachability of Sr from the phases prepared by heating appears to be somewhat worse than that of Cs. Saturation of the HTB adsorbents with lanthanide elements (Nd, La, Ce) gave rise to cubic bronze phases in which we propose that the lanthanides substitute at the tungsten or molybdenum sites rather than the tunnel positions. The lanthanides were rather easily leached from the calcined phases in 0.1 M HNO3 at 150°C.
V. Luca, C.S. Griffith, E. Drabarek, H. Chronis, Journal of Nuclear Materials 358 (2006) 139-150

A0869 – Kinetics of thermal decomposition of sodium methoxide and ethoxide

Sodium methoxide and sodium ethoxide were synthesized. Their thermal decomposition and reaction kinetics were investigated under non-isothermal and isothermal conditions. Non-isothermal experiments were carried out at different linear heating rates. Kinetics of decomposition in each run was evaluated from the dynamic TGA and MS data obtained from thermogravimetric analyzer (TGA) coupled with mass spectrometer based evolved gas analyzer (EGA-MS). The activation energies derived from isothermal experiments by Arrhenius plot were 187.81 ± 11.22 and 150.84 ± 5.32 kJ mol-1 for sodium methoxide and sodium ethoxide, respectively, which agree well with the values from non-isothermal method. The evolved gases were found to be a mixture of saturated and unsaturated hydrocarbons. XRD, IR, AES, CHNS analyzer and volumetric estimation were employed to characterize the decomposition residue and identified as a mixture of sodium carbonate, sodium hydroxide and amorphous carbon. The probable mechanism and kinetics of decomposition of sodium alkoxides described in this paper are reported for the first time.
K. Chandran, M. Kamruddin, P.K. Ajikumar, A. Gopalan, V. Ganesan, Journal of Nuclear Materials 358 (2006) 111-128

A0868 – Heat capacity and standard molar enthalpy of formation of crystalline 2,6-dicarboxypyridine (C7H5NO4)

Low-temperature heat capacity Cp,m of 2,6-dicarboxypyridine (C7H5NO4; CAS 499-83-2) was precisely measured in the temperature range from (80 to 378) 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 378) K. The standard molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined, ?cHm°(C7H5NO4, cr) = - (2741.41 ± 0.49) kJ.mol-1 and ?fHm°(C7H5NO4, cr) = - (727.74 ± 1.50) kJ.mol-1, by means of a precision oxygen-bomb combustion calorimeter at T = 298.15 K. The thermodynamic properties of the compound were further investigated through differential scanning calorimeter (DSC) and the thermogravimetric (TG) analysis.
Q. Shi, Z-C. Tan, Y-Y. Di, X-C. Lv, B. Tong, Z-H. Zhang, L-X. Sun, T. Zhang, J. Chem. Thermodynamics 38 (2006) 1701-1705

A0871 – Tungsten bronze-based nuclear waste form ceramics. Part 3: The system Cs0.3MxW(1-x)O3 for the immobilization of radio cesium

Previous studies in this series have indicated that Cs- and Sr-loaded Mo-doped hexagonal tungsten bronze (MoW-HTB) oxides, either in the form of fine grained powders, or as composite granules, can be converted to leach resistant ceramics at modest temperatures in the range 600-1200°C. In the present study it has been shown that such waste form ceramics can also be readily prepared through very simple conventional routes involving the blending of cesium nitrate with tungstic acid and other oxide components followed by heating in air. The phase chemistry resulting from the blending of these oxides has been explored. In the Cs0.3MxW(1-x)O3 compositional system where x = Ti, Zr, Nb and Ta the solid solution limit has been found to be where x = 0.2. For all values of x between 0 and 0.2 mixed phase materials of HTB andWO3 were obtained and Cs was found associated with HTB phases that are both rich and depleted in M element. At temperatures above about 1000°C, phase pure HTB compounds in the space group P63/mcm were obtained. Even when x greatly exceeds 0.2, the additional oxide content did not interfere with the formation of the HTB phase. Durability of the Cs0.3MxW(1-x)O3 compositions as gauged by the fractional Cs loss in de-mineralized water was lowest when M = Ti and Nb, and greatest when M = Zr. From these results the durability appears intimately linked with the unit cell a-dimension which in turn varies with M cation radius.
V. Luca, E. Drabarek, H. Chronis, T. McLeod, Journal of Nuclear Materials 358 (2006) 164-175

A0872 – Defect equilibria and partial molar properties of (La,Sr)(Co,Fe)O(3-d)

The oxygen nonstoichiometry d of La(1-x)SrxCo(1-y)FeyO(3-d) (x=0.6 and y=0.2, 0.4) was investigated by thermogravimetry in the range 703
E. Bucher, W. Sitte, G.B. Caraman, V.A. Cherepanov, T.V. Aksenova, M.V. Ananyev, Solid State Ionics 177 (2006) 3109-3115

A0875 – Morphologically controlled synthesis of mesoporous alumina

The morphologically controlled synthesis of mesoporous alumina using Al(NO3)3/NH3/urea/surfactant reaction system is demonstrated. Both the mesostructures and morphologies of the resulting alumina can be effectively controlled via adjusting the synthesis parameters, including reactant compositions, surfactant kinds and hydrothermal conditions. With the aid of surfactants, mesoporous alumina with spheres, rods, fibers and three-dimensional dumbbell, flower-like hierarchical superstructures on the microscopic scale has been obtained. Through characterization by N2 physisorption, X-ray diffraction, electron microscopy and thermogravimetry analysis, the effects of synthesis conditions on structures and shapes of products are explained and the possible formation mechanism of the controlled morphologies is also proposed.
Q. Liu, A. Wang, X. Wang, T. Zhang, Microporous and Mesoporous Materials 100 (2007) 35-44

A0874 – Design, synthesis and characterization of mixed matrix material for CO2 capture

S. Bertelle, C. Vallières, D. Roizard, E. Favre, Desalination 200 (2006) 456-458

A0873 – Fluorine-substituted hydroxyapatite scaffolds hydrothermally grown from aragonitic cuttlefish bones

Porous hydroxyapatite scaffolds with different levels of fluorine substitution (46% and 85%) on the OH sites were produced via hydrothermal transformation of aragonitic cuttlefish bones at 200°C and calcination at temperatures up to 1200°C. The increasing level of F substitution reduces the kinetics and probably the yield of the reaction. The incorporation of F in the lattice of hydroxypatite caused a lowering of the unit cell volume due to reduction of the length of the a-axis. The crystallites formed were close in size to bone-like apatite and were orientated along the a-axis rather than the c-axis. There was evidence of AB-type carbonated apatite.
S. Kannan, J.H.G. Rocha, S. Agathopoulos, J.M.F. Ferreira, Acta Biomaterialia 3 (2007) 243-249

A0877 – Adsorption thermodynamic and kinetic studies of trihalomethanes on multiwalled carbon nanotubes

Multiwalled carbon nanotubes (MWCNTs) were purified by mixed HNO3/H2SO4 solution and were employed as adsorbents to study adsorption kinetics and thermodynamics of trihalomethanes (THMs) from chlorinated drinking water. The amount of THMs adsorbed onto CNTs decreased with a rise in temperature and high adsorption capacities were found at 5 and 15°C. Under the same conditions, the purified CNTs possess two to three times more adsorption capacities of CHCl3, which accounts for a major portion of THMs in the chlorinated drinking water, than the commercially available PAC suggesting that CNTs are efficient adsorbents. The thermodynamic analysis revealed that the adsorption of THMs onto CNTs is exothermic and spontaneous.
C. Lu, Y-L. Chung, K-F. Chang, Journal of Hazardous Materials B138 (2006) 304-310

A0876 – Synthesis and consolidation of titanium diboride

Titanium diboride (TiB2) is one of the candidate materials for high temperature structural applications and also for control rod elements in high temperature nuclear reactors. This paper presents the experimental data on the synthesis, consolidation to dense pellets and property evaluation of TiB2 carried out in laboratory scale. TiB2 powder was prepared by the reduction of titanium oxide with boron carbide and carbon, purified by high temperature - high vacuum treatment and milled to obtain micron sized particles. The powders were characterized by XRD, chemical analysis and laser particle size analyzer. The reduction process was optimized for the production of titanium boride of ~1µm size median dia with oxygen, carbon and nitrogen contents close to 0.5% each. Studies on densification of TiB2 powders by hot pressing were conducted. Pellets with a high density of 97.56% pth were prepared by hot pressing at 1800°C. Hardness of this sample was measured as 26 GPa, fracture toughness as 5.3 MPa m1/2 and thermal conductivity as 59.44 W/m/K at 500°C.
C. Subramanian, T.S.R.Ch. Murthy, A.K. Suri, International Journal of Refractory Metals & Hard Materials 25 (2007) 345-350

A0881 – Nickel modified ultrananosized diamonds and their application as catalysts in methanol decomposition

Different ultrananosized diamonds obtained by shock-wave procedure and their nickel modifications were prepared and characterized by nitrogen physisorption, X-ray diffraction, Temperature-programmed reduction and IR spectroscopy. The catalytic behaviour of the modified composites in methanol decomposition to hydrogen, carbon monoxide and methane was also studied. The state of supported nickel particles as well as their reductive and catalytic properties strongly depends on the pretreatment conditions and the composition of the support.
T. Tsoncheva, V. Mavrodinova, L. Ivanova, M. Dimitrov, S. Stavrev, C. Minchev, Journal of Molecular Catalysis A: Chemical 259 (2006) 223-230

A0880 – Surface acidity of niobium phosphate and steam reforming of dimethoxymethane over CuZnO/Al2O3-NbP complex catalysts

Dimethoxymethane (DMM) is nontoxic and of high hydrogen content and may be used as a H2 storage material for small H2 sources. Steam reforming of DMM requires a bifunctional catalyst composed of an acidic component and a traditional copper catalyst, on which DMM is hydrolyzed on the acidic sites to methanol and formaldehyde, which are then further reformed to H2 and CO2 on metallic copper sites. In this work, samples of niobium phosphate with high surface areas were synthesized, characterized, and tested for the hydrolysis of DMM and used as acidic components for the reforming of DMM to produce H2. The structure and surface areas of these samples were characterized, and the activity for the hydrolysis of DMM was correlated with the surface acidities. It was found that all of the niobium phosphate samples exhibited high activity for the hydrolysis of DMM. The one with a high surface area (394 m2/g) was highly acidic with mainly Bronsted acid sites and thus was the most active for the hydrolysis of DMM among the niobium samples studied in this work. Mixing the niobium phosphate with CuZnO/Al2O3 did not affect the activity of CuZnO/Al2O3 for the reforming of methanol. The activity and selectivity to H2 were low for the steam reforming of DMM over traditional CuZnO/Al2O3 alone. Mechanically mixing niobium phosphate with CuZnO/Al2O3 greatly enhanced the conversion of DMM (e.g., 100% at 493 K) with high selectivity to H2. This indicates that niobium phosphate is an effective acidic component for the hydrolysis of DMM and can be used with CuZnO/Al2O3 for reforming DMM to produce H2.
Q. Sun, A. Auroux, J. Shen, Journal of Catalysis 244 (2006) 1-9

A0879 – The dynamic process in the formation of Tyr/LDH nanohybrids

The dynamic intercalation process of tyrosine (Tyr) into layered double hydroxide (LDHs) by co-precipitation method was investigated by powder X-ray diffractometry, Fourier transform infrared spectroscopy, specific surface area measurements, pore size distributions as well as thermal analysis. The nanohybrids were found to have an expanded layered structure indicating that amino acid anions were intercalated into the gallery space. Two kinds of arrangements such as mono- or bilayers of the tyrosinate anions could be deduced from the XRD patterns. The arrangement changed from monolayer to bilayer, then again to monolayer with increasing aging time of the synthesis solution. The diffraction intensity increased then decreased with aging time, because of the variation in the orientation and ordering of the particles. TG analysis and the varying M2+/M3+ results revealed that the amount of tyrosinate anions in the gallery first decreased then increased with the increase of aging time. In addition, the morphology results showed that the degree of ordering also increased then decreased with aging time. On all accounts, the intercalation of the tyrosinate anions was a typical dynamic process. At the beginning numerous biomolecules entered the gallery space, giving rise to increased basal spacings and BET surface areas. Later the increase of aging time led to the escape of amino acid anions from the gallery space, hence to the decrease of basal spacing and surface areas.
Shu-Ping Li, Colloids and Surfaces A: Physicochem. Eng. Aspects 290 (2006) 56-61

A0878 – Effect of surface roughness on the development of protective Al2O3 on Fe-10Al (at.%) alloys containing 0-10 at.% Cr

The effect of alloy surface roughness, achieved by different degrees of surface polishing, on the development of protective alumina layer on Fe- 10 at.% Al alloys containing 0, 5, and 10 at.% Cr was investigated during oxidation at 1000°C in 0.1 MPa oxygen. For alloys that are not strong Al2O3 formers (Fe-10Al and Fe-5Cr-10Al), the rougher surfaces increased Fe incorporation into the overall surface layer. On the Fe-10Al, more iron oxides were formed in a uniform layer of mixed aluminum- and iron-oxides since the layer was thicker. On the Fe-5Cr-10Al, more iron-rich nodules developed on an otherwise thin Al2O3 surface layer. These nodules nucleated preferentially along surface scratch marks but not on alloy grain boundaries. For the strong Al2O3-forming Fe-10Cr-10Al alloy, protective alumina surface layers were observed regardless of the surface roughness. These results indicate that the formation of a protective Al2O3 layer on Fe-Cr-Al surfaces is not dictated by Al diffusion to the surface. More cold-worked surfaces caused an enhanced Fe diffusion, hence produced more Fe-rich oxides during the early stage of oxidation.
Z.G. Zhang, P.Y. Hou, F. Gesmundo, Y. Niu, Applied Surface Science 253 (2006) 881-888

A0883 – Structure and magnetism in rare earth strontium-doped cobaltates

Substantial interest has recently been generated by rare earth cobaltate compounds as cathode materials for solid oxide fuel cells. We have synthesised a wide range of single-phase perovskite-based rare earth cobaltates (Ln(1-x)SrxCoO(3-d)) (Ln = La3+-Yb3+). A combination of electron and X-ray diffraction of these phases reveals a complex family of tetragonal and orthorhombic superstructures. The nature of structural and magnetic ordering relies on both cation and oxygen vacancy distribution. Phase boundaries exists between compounds containing large, medium and small rare earths (between Nd3+ and Sm3+, and also between Gd3+ and Dy3+) and also at different Sr-doping levels. Powder neutron diffraction has been used in conjunction with the other techniques to reveal cation and oxygen vacancy ordering within these materials. These phases show mixed valence (3+/4+) cobalt oxidation states that increases with Sr content. A range of magnetic behaviours has been observed, including ordered antiferromagnetism at elevated temperatures (>300 K) in Ho0.2Sr0.8CoO2.75.
M. James, L. Morales, K. Wallwork, M. Avdeev, R. Withers, D. Goossens, Physica B 385-386 (2006) 199-201

A0882 – Immobilization of inert TRISO-coated fuel in glass for geological disposal

Vitrification of TRISO-coated gas reactor fuel particles was achieved via two methods: glass melting and sintering. Inert TRISO-coated fuel particles and a borosilicate glass were used. With glass melting at 1200-1300°C floatation and decomposition of carbon and silicon carbide occurred. Thermal pre-treatment of the particles for oxidation of pyrocarbon did not improve the coating properties of the glass. During cooling most of the particles floated and sorbed on the crucible or mold walls. The sintered glass at 700°C showed better coating properties of the TRISO-coated fuel particles despite higher porosity compared to glass made by melting. Aqueous leaching properties of glass with particles are similar regardless the mode of fabrication, indicating the good chemical durability of the sintered glass. Sintered glasses may constitute a good technique for TRISO-coated fuel particles immobilization for an eventual deep geological disposal.
A. Abdelouas, S. Noirault, B. Grambow, Journal of Nuclear Materials 358 (2006) 1-9

A0885 – Preparation and characterization of activated carbon derived from the thermo-chemical conversion of chicken manure

Physico-chemical properties of a bioorganic char were modified by pyrolysis in the presence of NaOH, and with subsequent physical activation of carbonaceous species with CO2 a value-added activated carbon was fabricated. Bioorganic char is produced as a co-product during the production of bio-fuel from the pyrolysis of chicken litter. Untreated char contains ~37 wt% of C and ~43-45wt% of inorganic minerals containing K, Ca, Fe, P, Cu, Mg, and Si. Carbonization and chemical activation of the char at 600°C in the presence of NaOH in forming gas (4% H2 balanced with Ar) produced mainly demineralized activated carbon having BET (Brunauer, Emmett, and Teller) surface area of 486m2/g and average pore size of 2.8 nm. Further physical activation with CO2 at 800°C for 30min resulted in activated carbon with BET surface area of 788m2/g and average pore size of 2.2 nm. The mineral content was 10 wt%. X-ray photoelectron spectroscopy (XPS) indicated that the latter activation process reduced the pyrrolic- and/or pyridonic-N, increased pyridinic-N and formed quaternary-N at the expense of pyrrolic- and/or pyridonic-N found in the untreated char.
S. Koutcheiko, C.M. Monreal, H. Kodama, T. McCracken, L. Kotlyar, Bioresource Technology 98 (2007) 2459-2464

A0884 – Ionic conductivity of brownmillerite-type calcium ferrite under oxidizing conditions

The thermogravimetric and Mossbauer spectroscopy studies showed that, at atmospheric oxygen pressure, the oxygen content in Ca2Fe2O5 brownmillerite is very close to stoichiometric at 300-1270 K. The orthorhombic lattice of calcium ferrite undergoes a transition from primitive (space group Pnma) to body-centered (I2mb) at 950-1000 K, which is accompanied with decreasing thermal expansion coefficient (TEC) and increasing activation energy for the total conductivity, predominantly p-type electronic. The steady-state oxygen permeation through dense Ca2Fe2O5 ceramics is limited by the bulk ionic conduction. The ion transference numbers in air vary in the range 0.002-0.007 at 1123-1273 K, increasing with temperature. Analysis of stereological factors, which may affect oxygen diffusivity, suggests a dominant role of the ion jumps along octahedral and, possibly, tetrahedral layers of the brownmillerite structure. The ionic conductivity of calcium ferrite is higher than that of Ca2FeAlO5+d, but lower compared to the oxygen-deficient perovskite phases based on SrFeO3-d where the diffusion pathways form a threedimensional network. The average TECs of Ca2Fe2O5 ceramics, calculated from dilatometric data in air, are 13.1x10^(-6) K-1 at 370-950 K and 11.3x10^(-6) K-1 at 970-1270 K.
A.L. Shaula, Y.V. Pivak, J.C. Waerenborgh, P. Gaczyñski, A.A. Yaremchenko, V.V. Kharton, Solid State Ionics 177 (2006) 2923-2930

A0887 – Crystal structure, thermal analysis and IR spectrometric investigation of L-tyrosine hydrazide diphosphate monohydrate

The monoclinic crystal structure of (C9H15N3O2)2P2O7.H2O denoted DLTHDP [a = 14.626(1), b = 6.1990(2), c = 14.562(1) Å, beta = 97.289(3)°, Z = 2, monoclinic P21, Dcal = 1.508, Dmes = 1.49 g cm-3] has been solved using direct methods and refined to a reliability factor R = 4.37% for 2079 independent reflections. The DLTHDP structure can be described by infinite polyanions [P2O7 H2O]n 4n- organized in chains parallel to the b-direction and located at z = 1/2, alternating with organic cations associated in ribbons spreading along the a-direction. Multiple hydrogen bonds originating from amine, hydroxyl groups and water molecules donors [N-H....O(N) and O(W)-H....O] connect the different components of the lattice. The IR data of DLTHDP is reported and discussed according to the theoretical group analysis and by comparison with IR results of similar compounds. The coupled thermogravimetric analysis (TGA)-differential thermal analysis (DTA) thermal study shows the departure of one water molecule, confirming the hydrated character of this compound.
A. Gharbi, T. Guerfel, A. Jouini, Materials Research Bulletin 41 (2006) 2024-2034

A0886 – Analytical and experimental study of premixed methane-air flame propagation in narrow channels

This study investigates analytically and experimentally the influence of preheat temperature on flame propagation and extinction of premixed methane-air flame in single quartz tubes with inner tube diameters of 3.9, 3, 2 and 1 mm respectively. The effects of preheat temperature, tube diameter, equivalence ratio and mixture flow rate on the flame speed and extinction conditions are determined. The analytical results show that high preheat temperature of the mixture can effectively suppress flame quenching, and the occurrence of stable solution in the slow flame branch extends the flammability limit leading to possible flame propagation in mini channels. Experimental results confirm that the flame speed increases and the flammability limit shifts toward the fuel lean direction either through increasing the preheat temperature or decreasing the mixture flow rate, or both. Decrease of propagating flame speed is observed before the stoichiometric equivalence ratio at high preheat temperatures. The analytical model provides insights into how propagating flame in mini channels can be sustained; however, the model is only good at predicting flame speed near the fuel lean branch. Influence of Cu2+ ions exchanged zeolite 13X catalyst on flame speed is also addressed. It is noted that the zeolite based catalyst can lower the preheat temperature requirement in order to sustain the flame propagation in narrow channels.
C.Y.H. Chao, K.S. Hui, W. Kong, P. Cheng, J.H. Wang, International Journal of Heat and Mass Transfer 50 (2007) 1302-1313

A0889 – Vanadium loaded carbon-based catalysts for the reduction of nitric oxide

Carbon-based SCR catalysts for the reduction of NO with NH3 at low temperatures have been prepared using activated carbons obtained from a local Spanish coal, doped with several vanadium compounds. Among them, the ashes of a petroleum coke (PCA) were also employed. Both the catalysts and the carbon supports have been characterized by means of N2 and CO2 physisorption, NH3 and O2 chemisorption and temperature programmed desorption (TPD). The activity of the catalysts has been tested in a laboratory-scale unit, measuring significant conversions of NO (above 50%) with almost 100% selectivity toward N2 at 150°C. The feasibility of using the petroleum coke ashes as the active phase was confirmed comparing the activity of the catalysts doped with these residues, with the one measured for the catalysts prepared using model vanadium compounds. The physical-chemical features of the carbon support resulted of key importance for achieving a considerable catalytic activity. The values of apparent energy of activation calculated for the catalysts presented in this paper were very similar to other carbon-based catalysts and smaller than the ones corresponding to TiO2-supported systems. The gas residence time on the catalytic bed influences the catalytic activity to a great extent, thus being a determinant parameter for designing the SCR de-NOx unit. To avoid ammonia slip, inlet concentrations of NH3 has to be little under the stoichometric NH3/NO ratio ( 0.7). The catalysts stability was tested in terms of carbon support gasification followed by termogravimetric analysis and gas chromatography. The activity of the catalysts was maintained at least over 24 h of reaction.
M.J. Lazaro, M.E. Galvez, C. Ruiz, R. Juan, R. Moliner, Applied Catalysis B: Environmental 68 (2006) 130-138

A0888 – Preparation of freestanding and crack-free titania-silica aerogels and their performance for gas phase, photocatalytic oxidation of VOCs

Freestanding and crack-free titania-silica aerogels with high titanium content (i.e., Ti/Si = 1) were successfully prepared by adjusting the hydrolysis of the two alkoxide precursors to a comparable rate during the sol-gel processing. Two titania-silica aerogels were prepared by ethanol and CO2 supercritical drying methods. Well-dispersed, nanometer-sized anatase crystal domains (ca. 10 nm) were crystallized by high temperature, ethanol supercritical drying. The crystalline domains were solidly anchored to the aerogel network by Ti-O-Si bonds. Titania- silica aerogels prepared by CO2 supercritical drying method were devoid of TiO2 crystals. A molecular-level mixing was achieved and anatase TiO2 was only crystallized with difficulty by high temperature calcination (1073 K). Both aerogels were mesoporous and displayed similar open pore structure that is readily accessible to reactant molecules. However, only the titania-silica aerogel with anatase TiO2 prepared by ethanol supercritical drying was active for the gas phase, photocatalytic oxidation of volatile organic compounds (i.e., isopropanol and trichloroethylene). Catalysts prepared from Degussa P25 TiO2 displayed lower activity under similar reaction conditions.
S. Cao, K.L. Yeung, P-L. Yue, Applied Catalysis B: Environmental 68 (2006) 99-108

A0890 – Low temperature synthesis of nanocrystalline lanthanum monoaluminate powders by chemical coprecipitation

Nanocrystalline lanthanum monoaluminate (LaAlO3) powders were prepared by chemical coprecipitation using 25 vol.% of NH4OH, 0.05M La(NO3)3.6H2O and 0.05M Al(NO3)3.9H2O aqueous solutions as the starting materials. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analyses (TGA/DTA), X-ray diffraction (XRD), Raman spectrometry, specific surface area (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) were utilized to characterize the LaAlO3 powders prepared by chemical coprecipitation. The crystallization temperature of the LaAlO3 precursor gels precipitated at pH 9 is estimated as 810°C by TG/DTA. The XRD pattern of the LaAlO3 precursor gels precipitated at pH 8-12 and calcined at 700°C for 6 h shows a broad arciform continuum exist between 24° and 32° and sharp peaks of LaAlO3 except the precursor gels precipitated at pH 9. For the LaAlO3 precursor gels precipitated at pH 9 and calcined at 700°C for 6 h, the formation of the perovskite LaAlO3 phase occurs and the presence of crystalline impurities is not found. The crystallite size of LaAlO3 slightly increases from 37.8 to 41.5 nm with calcination temperature increasing from 700 to 900°C for 6 h. The LaAlO3 powders prepared by chemical coprecipitation have a considerably large specific surface of 30m2/g. The relative density greater than 97% is obtained when these nanocrystalline LaAlO3 powders are sintered at 1550°C for 2 h.
C-L. Kuo, C-L. Wang, T-Y. Chen, G-J. Chen, I-M. Hung, C-J. Shih, K-Z. Fung, Journal of Alloys and Compounds 440 (2007) 367-374

A0892 – Effects of milling on the thermal stability of synthetic hydromagnesite

Hydromagnesite is a basic magnesium carbonate that undergoes an endothermic decomposition with water and carbon dioxide release in the temperature range of 200-550°C. Due to this thermal behaviour it has been studied as flame retardant filler for polymers in cable applications. For this purpose the particle size distribution should be optimized, as it is in most cases responsible for decrease in final composite mechanical properties. This work describes the variations found in the thermal behaviour of hydromagnesite associated with the process of particle size reduction. Air jet micronization was compared with mechanical milling. Thermogravimetry and differential scanning calorimetry were used to study thermal decomposition. FTIR spectroscopy and XRD analysis of the solid residue after heating were used to follow structural changes. Decomposition behaviour of synthetic hydromagnesite was shown to be dependent of the applied particle size reduction process. A remarkable increase in the decomposition rate was observed for the milled sample, which was attributed to the introduction of defects in the crystalline structure during the mechanical milling. Therefore, it was concluded that the mechanical milling process may affect the thermal decomposition of hydromagnesite and therefore its characteristics as flame retardant.
L. Haurie, A.I. Fernandez, J.I. Velasco, J.M. Chimenos, J.M. Lopez-Cuesta, F. Espiell, Materials Research Bulletin 42 (2007) 1010-1018

A0891 – Ca-Na-N-H system for reversible hydrogen storage

Ca-Na-N-H system was introduced and evaluated in this paper for reversible hydrogen storage. Similar to other amide-hydride systems already reported, interaction between Ca(NH2)2-NaH (1/1) was observed in the temperature range of 120-270°C with 1.1 wt% of hydrogen desorption, from which 0.96 wt% of hydrogen can be recharged. XRD and FTIR identified NaNH2 and Ca-N-H solid solution as dehydrogenation products. Concurrent with hydrogen absorption/desorption transformation between -NH and -NH2 units within solid solution was observed.
Z. Xiong, G. Wu, J. Hu, P. Chen, Journal of Alloys and Compounds 441 (2007) 152-156

A0894 – Enhanced oxidation of the 9%Cr steel P91 in water vapour containing environments

The short term ( ~100 h) oxidation behaviour of the 9%Cr steel P91 was studied at 650°C in N2- O2-H2O gas mixtures containing a relatively low oxygen level of 1%. The oxidation kinetics were measured thermogravimetrically and the oxide scale growth mechanisms were studied using H2 18O-tracer with subsequent analyses of oxide scale composition and tracer distribution by MCs+-SIMS depth profiling. The corrosion products were additionally characterised by light optical microscopy, SEM-EDX and XRD. It was found that the transition from protective, Cr-rich oxide formation into non-protective mixed oxide scales is governed by the ratio H2O(g)/O2 ratio rather than the absolute level of H2O(g). The results of the tracer studies in combination with the data obtained from experiments involving in situ gas changes clearly illustrated that under the prevailing conditions the penetration of water vapour molecules triggers the enhanced oxidation and sustains the high growth rates of the poorly protective Fe-rich oxide scale formed in atmospheres with high H2O(g)/O2 ratios. The experimental observations can be explained if one assumes the scale growth to be governed by a competitive adsorption of oxygen and water vapour molecules on external and internal surfaces of the oxide scales in combination with the formation of a volatile Fe-hydroxide during transient oxidation. The formation of the non-protective Fe-rich oxide scales is suppressed in atmospheres with low H2O(g)/O2 -ratios, and the healing of any such scale is promoted.
J. Ehlers, D.J. Young, E.J. Smaardijk, A.K. Tyagi, H.J. Penkalla, L. Singheiser, W.J. Quadakkers, Corrosion Science 48 (2006) 3428-3454

A0893 – Kinetic modelling of the thermal decomposition of ettringite into metaettringite

Despite recent insights into thermal stability of ettringite and structural changes during decomposition, a lack of knowledge on nucleation and growth mechanisms of metaettringite remained. Therefore, a better understanding of the kinetic modelling of this heterogeneous reaction was proposed. Thanks to an experimental approach allowing to check the validity of kinetic assumptions (rate-determining step, expression of the rate as dalpha/dt=k f (alpha)...), a good agreement was found between the calculated and experimental alpha vs. t and dalpha/dt vs. t kinetic curves. The reaction area of the region in which the rate-limiting step occurs was also elucidated. Finally, we demonstrated that the rate-limiting step of the growth process follows an Arrhenius law in non-isothermal conditions.
J. Pourchez, F. Valdivieso, P. Grosseau, R. Guyonnet, B. Guilhot, Cement and Concrete Research 36 (2006) 2054-2060

A0896 – EPR and TGA study of two Zn3Fe4V6O(24-x) samples prepared by different thermal treatments

Two samples of multicomponent vanadate, Zn3Fe4V6O(24-x), compound have been prepared following two different thermal annealing processes. XRD measurements have shown the same values of lattice parameters for both samples. The TGA results indicate the possibility of oxygen deficiency. The EPR g-factor is the same for both samples, but large differences in the EPR amplitude and line width have been recorded. The integrated intensities of EPR lines differ slightly, what indicates a difference in the number of paramagnetic centers in the samples. The oxygen deficiency processes can introduce disorder and thus influence magnetic interactions in a multicomponent vanadate system. As a result, a slight change of technological conditions during sample preparation can cause drastic changes in physical properties and thus influence the application possibilities of this group of compounds.
G. Zolnierkiewicz, N. Guskos, J. Typek, A. Blonska-Tabero, Journal of Non-Crystalline Solids 352 (2006) 4362-4365

A0895 – Technological and chemical assessment of various thermochemical cycles: From the UT3 cycle up to the two steps iron oxide cycle

The studies carried out on the UT-3 cycle lead to propose an operating mode that was tested with the Mascot Mockup. Additional investigations, partially presented in the present paper point out that the physicochemical properties of the solid and gaseous reactants will make the running of an industrial process very difficult. For instance, the sintering of the solid, the possible reactivity of the embedding matrix, ... induce additional operation and then lower very sensibly the efficiency of the cycle. Furthermore, if the toxicity of the reactants is taken into consideration, the attractivity of this cycle decreases. If other considerations than the efficiency of the cycle are taken into consideration, it is possible to investigate other cycles. The present paper shows the first results of the studies carried out on alternative cycles having either low efficiency but involving inoffensive reactants or high efficiency but without using bromine. In the first case illustrated by the iron oxide cycle, it seems that the low efficiency can be partially offset by using abundant and inexpensive energy source. In the second one illustrated by the cerium chloride cycle, the significant industrial experience regarding the chemical engineering of the chloride could make the industrial development easier.
F. Lemort, P. Charvin, C. Lafon, M. Romnicianu, International Journal of Hydrogen Energy 31 (2006) 2063 - 2075

A0898 – One-step synthesis of dispersed bimetallic carbides and nitrides from transition metals hexamethylenetetramine complexes

Bimetallic nitrides and carbides Co(Ni)-Mo were obtained from the decomposition of transition metals complexes with hexamethylenetetramine (HMTA) under inert atmosphere. The precursor complexes were prepared by means of aqueous precipitation of ammonium molybdate with cobalt nitrate or nickel nitrate and HMTA. During the decomposition, HMTA acts at once as a reducing agent and as a source of carbon and nitrogen. The precursor's composition and the decomposition conditions are the key parameters to influence the nature of the obtained phases. The method developed provides a simple one-step way to highly divided bimetallic nitrides and carbides.
S. Chouzier, P. Afanasiev, M. Vrinat, T. Cseri, M. Roy-Auberger, Journal of Solid State Chemistry 179 (2006) 3314-3323

A0897 – Probing the interaction between di- and tri-functionalized carboxy-phosphonic acid and LDH layer structure

A series of carboxyphosphonate-derivatives of (Zn, Al) layered double hydroxide (LDH) was prepared and characterized by a combination of techniques including powder X-ray diffraction, FTIR spectroscopy and solid-state 13C CP-MAS and 31P MAS NMR spectroscopies. The number of carbon atoms, n = 1 or 2 in HO2C(CH2)nPO3H2, was found to have an influence on the accommodation of the interleaved molecule, the carboxylate function lying perpendicular or parallel to the inorganic sheets of the LDH host material. These observations are in agreement with NMR results which evidence an interaction of the interlayered molecules through either the carbonyl or the phosphonate group or both in the case of the larger molecule, N-(phosphonomethyl)iminodiacetic acid. The variation of the basal spacing of the hybrid materials as a function of the temperature indicates a rearrangement of the molecule within the host material gap.
E.M. Sabbar, M.E. de Roy, F. Leroux, Journal of Physics and Chemistry of Solids 67 (2006) 2419-2429

A0900 – Defect formation and transport in La0.95Ni0.5Ti0.5O(3-d)

Deficiency in the A sublattice of orthorhombic perovskite-type La(1-x)Ni0.5Ti0.5O(3-d), with maximum at x = 0.07-0.08, is compensated by the formation of trivalent nickel and oxygen vacancies. The atomistic computer simulations showed that these defects are trapped near the A-site cation vacancies, resulting in the stabilization of Ni3+ cations and low electronic and oxygen-ionic transport. The average thermal expansion coefficient of La0.95Ni0.5Ti0.5O(3-d) ceramics, calculated from dilatometric data in air, increases from 8.6 x 10^(-6) K-1 at 300-800 K to 12.0 x 10^(-6) K-1 at 1300-1500 K. The data on Seebeck coefficient and total conductivity, predominantly p-type electronic, suggest a broadband mechanism of hole transport. The activation energies for the hole and ionic conductivities are 89 and 430 kJ/mol, respectively. The oxygen ion transference numbers determined by the faradaic efficiency measurements in air, vary in the range 9.5 x 10^(-5) - 8.1 x 10^(-4) at 1173-1248 K, increasing with temperature. Reducing oxygen partial pressure leads to a moderate decrease of the conductivity, followed by phase decomposition in the p(O2) range 9x10^(-11) to 8 x 10^(-9) atm at 1073-1223 K. The low-p(O2) stability limit of La0.95Ni0.5Ti0.5O(3-d) perovskite was found between that of La3Ni2O7 and Ni/NiO boundary.
S.O. Yakovlev, V.V. Kharton, E.N. Naumovich, J. Zekonyte, V. Zaporojtchenko, A.V. Kovalevsky, A.A. Yaremchenko, J.R. Frade, Solid State Sciences 8 (2006) 1302-1311

A0899 – Oxygen permeability, thermal expansion and mixed conductivity of GdxCe(0.8-x)Pr0.2O(2-d), x = 0, 0.15, 0.2

The non-linear thermal expansion behaviour observed in Ce(1-y)PryO(2-d) materials can be substantially controlled by Gd substitution. Coulometric titration shows that the charge compensation mechanism changes with increasing x, in the system GdxCe(0.8-x)Pr0.2O(2-d). For x = 0,15, charge compensation is by vacancy formation and destabilises the presence of Pr4+. At x = 0,2, further Gd substitution is charge compensated by additionally raising the oxidation state of Pr rather than solely the creation of further oxygen ion vacancies. Oxygen concentration cell e.m.f. measurements in an oxygen/air potential gradient show that increasing Gd content decreases ionic and electronic conductivities. Ion transference numbers measured under these conditions show a positive temperature dependence, with typical values to = 0.90, 0.98 and 0.80 for x = 0, 0.15 and 0.2, respectively, at 950°C. These observations are discussed in terms of defect association. Oxygen permeation fluxes are limited by both bulk ambipolar conductivity and surface exchange. However, the composition dependent trends in permeability are shown to be dominated by ambipolar conductivities, and limited by the level of electronic conductivity. At the highest temperatures, oxygen permeability of composition x = 0.2 approaches that of composition x = 0, Ce0.8Pr0.2O(2-d), with specific oxygen permeability values approximately 2 x 10^(-9) mol s-1 cm-1 at 950°C, but offering much better thermal expansion properties.
D.P. Fagg , I.P. Marozau, A.L. Shaula, V.V. Kharton, J.R. Frade, Journal of Solid State Chemistry 179 (2006) 3347-3356

A0903 – Thermal stability of carbon-encapsulated Fe-Nd-B nanoparticles

Thermal stability of various magnetic nanomaterials is very essential, due to their prospective future applications. In this paper, thermal behaviour of the carbon-encapsulated Fe-Nd-B nanoparticles is studied. These nanostructures were produced by direct current arcing of carbon anodes filled with Nd2Fe14B material. The thermogravimetry and differential thermal analysis curves were recorded in an oxygen atmosphere. The thermal processes were monitored by X-ray diffraction to follow the changes in the phase composition. The investigated samples have been thermally stable up to 600 K.
M. Bystrzejewski, S. Cudzilo, A. Huczko, H. Lange, Journal of Alloys and Compounds 423 (2006) 74-76

A0902 – Conversion of crystal structure of the chitin to facilitate preparation of a 6-carboxychitin with moisture absorption-retention abilities

Chitin has been subjected to regiospecific oxidation at C-6 with NaOCl in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and NaBr at room temperature in aqueous solution to yield fully soluble 6-carboxychitin. Several physical and chemical pretreatments of the original chitin changed its crystal structure from alpha to beta. After this pretreatment of the chitin the oxidation was easier to effect and the yield was greatly increased from 36% to 97% and the molecular weight was about 4 x 10^4 which was ca. 8 times that from the unpretreated chitin. Infrared spectroscopy (IR), X-ray diffraction, 13C NMR and solid-state NMR measurements, and thermal analysis techniques were used to characterize their molecular structures. The moisture absorption and retention abilities of these types of compounds were compared with those of sodium hyaluronan and carboxymethyl chitosan (CMCS) and were found to be superior. They therefore have the potential to substitute for hyaluronan for use in cosmetics and clinical medicine fields.
L. Sun, Y. Du, J. Yang, X. Shi, J. Li, X. Wang, J.F. Kennedy, Carbohydrate Polymers 66 (2006) 168-175

A0901 – Protonic conductivity and lithium intercalation in a new iron hydroxyphosphate hydrate: (H3O)[Fe(H2O)]3[H8(PO4)6].3H2O

A new hydroxonium iron phosphate, (H3O)[Fe(H2O)]3[H8(PO4)6].3H2O, was synthesized through a precipitation route by means of acidic media. The crystal structure was solved by X-ray powder diffraction. Electrochemical characterizations, performed on this compound, show reversible intercalation of lithium and substantial lithium diffusion. Protonic conductivity is observed in agreement with the simultaneous presence of H2O, hydrated protons and OH groups in the large intersecting tunnels of this intersecting tunnel structure.
V. Pralong, V. Caignaert, B. Raveau, Solid State Ionics 177 (2006) 2453-2456

A0906 – Proton conduction in ceria-doped Ba2In2O5 nanocrystalline ceramic at low temperature

Sintered pellets of Ce-doped Ba2In2O5 (BIC) were prepared from nanopowders. The electrical conductivities were measured using ac impedance spectroscopy under different atmospheres and temperatures. The electrical conductivity of sintered BIC was found sensitive to environmental humidity when the temperature was below 300°C. However, in the presence of hydrogen, the electrical conductivities were independent of water content in the range of 0-30 vol%. The electrical conductivities of BIC were significantly affected by the presence of hydrogen in a temperature range of 100-300°C. The estimated protonic transference number and the measured open circuit voltage suggested the existence of electronic conduction. The coefficient of thermal expansion of BIC is 11.2x10^(-6) K-1 from 25 to 1250°C.
R. Hui, R. Maric, C. Decès-Petit, E. Styles, W. Qu, X. Zhang, J. Roller, S. Yick, D. Ghosh, K. Sakata, M. Kenji, Journal of Power Sources 161 (2006) 40-46

A0905 – Electrorheological properties of suspensions of silica nanoparticles modified by urea and N,N-dimethylformamide

In this study, electrorheological (ER) behaviour of suspensions of silica nanoparticles treated with urea and N,N-dimethylformamide in DC electric field has been investigated. While the ER effect of the neat silica was very low, its modification improved compatibility of the solid and liquid phase and considerably increased ER activity of the system. The dependence of the dynamic yield stress t0 on the electric field strength E obeyed the power law t0 = qE^alpha, where the exponent alpha depended on the intensity of solidification of the suspension in the electric field. The 25 wt.% fluid showed a high absolute value of dynamic yield stress, but its relative increase due to high field-off value was much lower than for 20 wt.% suspension, so the latter is more suitable for practical applications.
T. Belza, V. Pavlinek, P. Saha, O. Quadrat, Colloids and Surfaces A: Physicochem. Eng. Aspects 297 (2007) 142-146

A0904 – Preparation of nanostructured nitrogen-containing carbon catalysts for the oxygen reduction reaction from SiO2- and MgO-supported metal particles

Nitrogen-containing carbon was prepared from the vapor deposition of acetonitrile at 900°C over silica- or magnesia-supported Fe, Co, and Ni particles. The byproducts of pyrolysis were monitored by mass spectrometry. The carbon formed from silica precursors was washed with KOH to remove the silica and HCl to remove metal particles, whereas the carbon formed from magnesia samples was washed with HCl to remove the support and the metal. The solid carbon product was characterized with N2 physisorption to measure surface area and pore volume distribution, X-ray diffraction to determine the crystalline phases present, and temperature- programmed oxidation to determine ash and nitrogen content. Magnesia was more readily removed from the carbon compared with silica. A significant amount of metal, encased in carbon, remained in the samples after washing. The Co particles led to a higher content of bulk nitrogen in the carbon, as high as 2.9% based on oxidation measurements. Electron microscopy imaging confirmed that all of the metal particles catalyzed the formation of various types of carbon nanofibers, with the diameter and structure of the fibers varying with different metal-support precursor combinations. A possible application for these fibers is oxygen reduction reaction catalysts for proton-exchange membrane fuel cell cathodes.
P.H. Matter, E. Wang, U.S. Ozkan, Journal of Catalysis 243 (2006) 395-403

A0908 – Heterogeneous Suzuki cross-coupling reactions over palladium/hydrotalcite catalysts

The efficiency of various heterogeneous solids consisting of palladium supported on hydrotalcite as catalysts in the Suzuki cross-coupling reaction between bromobenzene and phenylboronic acid was studied. Based on the catalytic activity results, the reaction develops to an acceptable extent with 100% selectivity at moderate temperatures in the presence of some of the catalysts. The best results were provided by a catalyst consisting of an acetate.pyridine complex of Pd supported on hydrotalcite that gave high conversion values even after three reuses. The reactions conditions were very mild (a temperature of 55°C and atmospheric pressure). In fact, the catalyst provided conversion and selectivity results surpassing those of existing heterogeneous phase catalysts and most homogeneous phase catalysts for the same purpose.
M. Mora, C. Jiménez-Sanchidrian, J.R. Ruiz, Journal of Colloid and Interface Science 302 (2006) 568-575

A0907 – Iron-oxide-modified nanosized diamond: Preparation, characterization, and catalytic properties in methanol decomposition

Nanosized diamond (UDD), obtained by a detonation procedure, was modified with iron from the corresponding acetylacetonate precursor under various pretreatment conditions. Nitrogen physisorption, X-ray diffraction, temperature-programmed reduction, and FTIR and Mössbauer spectroscopy were used for their characterization. The samples' catalytic behavior in methanol decomposition was also studied. The physicochemical and catalytic properties of the obtained materials (Fe/UDD) were compared with those of other iron-oxide-modified mesoporous supports with different nature and functionality (MCM-48 silica and CMK-1 carbon). The highest catalytic activity and stability was achieved with air-pretreated Fe/UDD.
T. Tsoncheva, L. Ivanova, D. Paneva, M. Dimitrov, I. Mitov, S. Stavrev, C. Minchev, Journal of Colloid and Interface Science 302 (2006) 492-500

A0911 – Structure and oxygen stoichiometry of SrCo0.8Fe0.2O(3-d) and Ba0.5Sr0.5Co0.8Fe0.2O(3-d)

High temperature X-ray diffraction (HT-XRD), temperature programmed desorption (TPD), thermogravimetric analysis-differential thermal analysis (TGA/DTA) and neutron diffraction were combined to determine the structure and oxygen stoichiometry of SrCo0.8Fe0.2O(3-d) (SCF) and Ba0.5Sr0.5Co0.8Fe0.2O(3-d) (BSCF) up to 1273 K in the pO2 range of 1 to 10^(-5) atm. Formation of the vacancy-ordered brownmillerite phase, SrCo0.8Fe0.2O2.5, was observed as a region of zero oxygen release in the TPD measurements and confirmed by HT-XRD and TGA/DTA. No ordering was observed in the BSCF system by any of the techniques utilized in this work. The oxygen vacancy concentration of BSCF was found to be considerably higher than that of SCF and always higher than that of the ordered brownmillerite phase of SCF, d=0.5. The combination of a high vacancy concentration and absence of ordering leads to higher oxygen permeation fluxes through BSCF membranes in comparison to SCF.
S. McIntosh, J.F. Vente, W.G. Haije, D.H.A. Blank, H.J.M. Bouwmeester, Solid State Ionics 177 (2006) 1737-1742

A0910 – In-situ Mössbauer spectroscopy and thermogravimetry of La0.2Sr0.8FeO3-? and La0.4Sr0.6FeO3-?

Single phase perovskite-type oxides La0.2Sr0.8FeO3-? (LSF28) and La0.4Sr0.6FeO3-? (LSF46) were prepared by the glycine nitrate process. The oxygen nonstoichiometry of LSF46 was studied by precision thermogravimetry at 700 and 900°C as a function of oxygen partial pressure. Mössbauer spectra were measured at room temperature, as well as at 500 and 700°C (LSF28) and at 700 and 900°C (LSF46) under varying oxygen partial pressures. Good agreement is observed for the pO2-dependent nonstoichiometry of LSF46 at 700 and 900°C as derived from thermogravimetry and in-situ Mössbauer spectroscopy. At low pO2, the Mössbauer isomer shifts and quadrupole splittings indicate a phase transition in LSF46 at 700°Cand in LSF28 at the two temperatures studied from a disordered perovskite phase to a brownmillerite-like structure with larger quadrupole splitting.
O. Bartels, K.D. Becker, E. Bucher, W. Sitte, Solid State Ionics 177 (2006) 1677-1680

A0909 – Preparation, characterization and thermodynamic stability of Rh3Te2O10

A new ternary compound Rh3Te2O10 was synthesized by reacting Rh2O3 and TeO2 under 1 bar oxygen at 950 K. The compound was characterized by TG-DTA, XRD, EDX and magnetic susceptability analyses. From the TG experiment, the formation reaction could be expressed as 6Rh2O3(s) + 8TeO2(s) + 3O2(g) = 4Rh3Te2O10(s). Rh3Te2O10 crystallizes with a rutile type structure, a = 456.6(2), c = 385.9(1) pm, space group P4 2/mnm (No. 136). The thermodynamic stability of the compound was determined by measuring the vapor pressure of TeO2(g). The vapor pressure over the two-phase mixture of Rh2O3 and Rh3Te2O10 is given by the relation lnp(TeO2)/Pa (±0.07) = - 36138.9 T-1 + 35.3, 915 < T/K < 985. The Gibbs energy of formation of the compound derived using the above vapor pressure data can be expressed as ?fG°(Rh3Te2O10, s) (±7.0 kJ mol-1) = -1510.3 + 0.897 T, 915 < T/K < 985.
R. Mishra, S.R. Bharadwaj, D. Das, Martin Valldor, Rainer Pöttgen, Journal of Nuclear Materials 357 (2006) 183-190

A0913 – Soft chemistry synthesis and characterizations of fully oxidized and reduced NdBaCo2O(5+d) phases d=0, 1

The double ordered perovskites NdBaCo2O5 and NdBaCo2O6 were prepared by soft chemistry. The samples were characterized from a structural and chemical point of view, concomitantly with their physical properties. Upon reduction, NdBaCo2O5 is formed with a tetragonal unit cell (a=b=3.94 Å, c=7.57 Å) and presents an antiferromagnetic behavior. Upon oxidation, a complete stoichiometric ordered phase NdBaCo2O6 with a tetragonal unit cell (a=b=3.88 Å, c=7.63 Å) could be obtained with a ferromagnetic and a metallic behavior. Finally it is shown that these phases are able to reversibly catch and release oxygen, suggesting a high anionic conductivity.
V. Pralong, V. Caignaert, S. Hebert, A. Maignan, B. Raveau, Solid State Ionics 177 (2006) 1879-1881

A0912 – Synthesis and characterization of La4Ni(3-x)CoxO(10±d) (0.0

The cobalt-doped lanthanum-nickel oxide system, La4Ni(3-x)CoxO(10±d) (0.02.0. AC impedance measurements of the x=0.4 composition in symmetrical cells with LSGM as an electrolyte show improved electrode performance over the parent nickelate La4Ni3O9.78. Long-term thermal stability studies show the x=0.4 composition to be more stable than the x=3.0 phase after annealing at 1173K in air for 1 week making this material a viable candidate for cathodes in solid oxide fuel cells.
G. Amow, J. Au, I. Davidson, Solid State Ionics 177 (2006) 1837-1841

A0916 – Crystal structure of a new organic dihydrogenomonophosphate (C6H8N3O)2(H2PO4)2

Chemical preparation, X-ray single-crystal, thermal behavior, and IR spectroscopy investigations are given for a new organic cation dihydrogenomonophosphate (C6H8N3O)2(H2PO4)2 (denoted IAHP) in the solid state. This compound crystallizes in the orthorhombic space group P212121. The unit cell dimensions are: a = 7.422(3) Å , b = 12.568(5) Å , c = 20.059(8) Å with V = 1871.1(13) Å3 and Z = 4. The structure has been solved using direct method and refined to a reliability R factor of 0.029. The atomic arrangement can be described as inorganic layers of (H2PO4)- anions between which are located the organic groups (C6H8N3O)+ through multiple hydrogen bonds.
L. BenHamada, A. Jouini, Materials Research Bulletin 41 (2006) 1917-1924

A0915 – Hydrogen photoproduction over new catalyst CuLaO2

Excellent quality CuLaO2 has been synthesized through solid reaction in evacuated silica tubes and the delafossite structure was refined in the space group R3m. The oxide is thermally stable up to ~200°C, above ~610°C it converts irreversibly to CuLa2O4. The conduction band (-1.99Vsce) lies below H2O/H2 level leading to a thermodynamically favorable H2-photoevolution with concomitant oxidation of X2- (=S2- or (SO3)2-). The surface platinization improved the activity by increasing the rate constants of X2- oxidation. The redox kinetic is relatively fast with (SO3)2- whereas the electrochemical system S2-/Pt behaves irreversibly and where the polarization is mainly of activation. The charge carriers move in a narrow conduction band made up primarily of Cu 3d orbitals. The rate determining step is the supply of electrons at the interface because of their low electron mobility. The system is optimized with respect to some physical parameters and the best photoactivity (47 ml g-1 h-1) was obtained with (SO3)2- at pH ~8. In a closed reactor, the oxidized species namely (S2O6)2- and (Sn)2- tend to stop the H2 formation because of their competitive reductions with H2O. Moreover, the formation of (Sn)2- leads to a less transparent electrolyte that permits fewer photons to reach the crystallites.
S. Saadi, A. Bouguelia, A. Derbal, M. Trari, Journal of Photochemistry and Photobiology A: Chemistry 187 (2007) 97-104

A0914 – Three-dimensional ionic frameworks built up from La (III) and Ce (III) succinates

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