A-site deficient lanthanum-calcium chromite-titanates doped with 3d transition metals: synthesis,oxygen nonstoichiometry,electrical conductivity,and catalytic activity |
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Authors: | V Vashook R Müller J Zosel K Ahlborn F Gerlach P Tietz G Stöver U Guth |
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Institution: | (1) Institute of Physical Chemistry and Electrochemistry, Dresden University of Technology, Dresden, Germany;(2) Kurt-Schwabe-Institute for Measuring and Sensor Technology Meinsberg, Ziegra-Knobelsdorf, Germany;(3) Institute for Materials and Processes in Energy Systems (IWV-1), Research Centre Juelich, 52425 Juelich, Germany |
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Abstract: | Six (M = Cr, Mn, Fe, Co, Ni, Cu) and two (M = Ni, Cu) single-phase compositions were prepared by conventional solid-state reactions. Oxygen nonstoichiometry, electrical
conductivity, phase transformations under reduction-reoxidation at high temperatures and catalytic activity for hydrocarbons
oxidation of these compositions were investigated in a wide temperature and oxygen partial pressure range. The Cu-, Ni-, Co-,
and Fe-containing compositions are decomposed in reducing Ar/H2O/H2 atmosphere with pH2O / pH2 = 0.3 at 1,000 °C, while the Cr- and Mn-containing ceramics remain stable at the same conditions. The metallic particles
of the added 3d elements formed after decomposition were registered by X-ray diffraction method in case of Cu- and Ni-containing
compositions. These formed composites can be completely reoxidized with formation of initial compositions by treatment in
air at 1,000 °C. The electrical conductivity of the ceramics investigated in air and Ar/H2O/H2 gas flow increases with rising M content. The highest catalytic activity for oxidation of CH4 and C3H6, which was comparable with the activity of the composite, shows the Cu-containing powders.
Dedicated to Prof. Dr. Werner Weppner |
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Keywords: | 3d-metal-doped chromites– titanates Oxygen stoichiometry Electrical conductivity Catalytic activity |
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