A family of mesoporous, self-aggregated zinc oxide materials with spherical morphologies of high crystalline quality, is obtained through a facile, additive-free polyol procedure.
In the present work the LaCoO3 formation from gel precursors obtained by water-based sol-gel method with citric acid was studied. As precursors La and Co nitrates were used. The obtained gels were analyzed by TG/ DTA and TG/EGA. The decomposition of the gels takes place in two main steps with the evolution of the same volatile compounds (H2O, CO2 and NO2) leading to the conclusion that two types of bonding of the components in the gels occurred. The decomposition of the gels takes place up to 400?C. The gels thermally treated at 600?C lead to single pure perovskite rhombohedral phase of lanthanum cobalt oxide (LaCoO3). Some electrical properties of LaCoO3 measured in 'operando' conditions, i.e. in gas flow, at atmospheric pressure (by using the differential step technique DST) are presented and discussed.
Tin and cerium based oxide ceramics, due to their peculiar properties, are good candidates for using as sensors, solid electrolytes in fuel cells, and catalysts. In the present work, Sn-Ce-O powders with the composition of interest for catalysis applications were obtained by solid state reactions and by thermal decomposition of the different tin and cerium precursors. The structural characterization of the resulted samples was performed by X-ray diffraction. Morphological characteristics were evaluated from X-ray microstructural parameters and BET surface areas measurements. Surface evolution of the studied powders was investigated by electrical measurements in various atmospheres in the 25-400°C temperature range. The samples studied behave as a n-type semiconductor. The catalytic activity for CO oxidation was measured in gas flow between 25 and 400°C. The conversion degree depends on the preparation method of the samples. Magnetic susceptibility measurements at room temperature of the samples before and after catalytic test indicated a paramagnetic behavior. Higher values of magnetic susceptibility of the samples after catalytic test compared to initial ones could indicate the influence of CeO 2 on the catalytic activity.
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