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Dense and thin electrolytes composed of yttrium-stabilized zirconia for anode-supported solid oxide fuel cells were produced by slip casting of different powder suspensions. These suspensions were obtained by mixing different proportions of nanocrystalline powder made by spray pyrolysis and commercial micro-sized powder in ethanol. Two parameters influence mostly the formation of gastight thin films: the powder morphology which controls the green density of the films and the powder sintering activity on which depends the formation of cracks during drying and sintering and adhesion. Here, optimized powder mixtures allowed the formation of a 5 μ m thick electrolyte with efficient gastightness besides industrial applications. It is shown in this study that the optimum suspension composition corresponds to the best compromise between powder morphology and powder sintering activity. [ABSTRACT FROM AUTHOR]

Powders of perovskite LaMnO3+δ with large over-stoichiometry coefficient δ up to δ=0.29 have been synthetized by two different soft chemistry routes using hydrothermal treatment at 150 °C and sol–gel process. Structural and morphological properties were examined by thermal analysis, X-ray diffraction and transmission electron microscopy. Rietveld refinement led to rhombohedral distorted perovskite for all the over-stoichiometric LaMnO3+δ with 0.10<δ<0.29. These studies confirm from structural parameters analysis the solubility limit of cationic vacancies previously evidenced by Maurin et al. by X-ray absorption spectroscopy. Special attention was devoted to the correlation between grain size, synthesis pathways, calcination temperature and the formal MnIV content. [Copyright &y& Elsevier]

Abstract: Al-doped ZnO powders were synthesised by a Pechini process in order to obtain visible non-absorbent and near-Infrared absorbent particles. Firstly, it has been shown that synthesis under argon combined with the lowest synthesis temperatures (700°C) allows getting the optimal properties for pure ZnO compounds due to creation of n-type defects segregated on oxide grain surface (Zn/O ratio superior to 1). Nevertheless, the near-Infrared absorption properties of the pure ZnO compounds remain low. The Al3+ doping of ZnO compounds was then investigated. The Al solubility limit inside ZnO doped compounds decreases drastically with the grain size, i.e. with the synthesis temperature. Then, the Al cations distribution varies inside ZnO grains, Al3+ segregation at the grain surfaces taking place for high synthesis temperatures. The optimal optical properties (high near-Infrared absorption) are reached combining Al-doping and adequate synthesis conditions: annealing under argon at low temperatures. In these conditions, the highest extrinsic (via Al doping) and intrinsic n-types defects rates are indeed reached. [Copyright &y& Elsevier]