Ionics

, Volume 13, Issue 3, pp 141–149

A-site deficient lanthanum-calcium chromite-titanates doped with 3d transition metals: synthesis, oxygen nonstoichiometry, electrical conductivity, and catalytic activity

  • V. Vashook
  • R. Müller
  • J. Zosel
  • K. Ahlborn
  • F. Gerlach
  • P. Tietz
  • G. Stöver
  • U. Guth
Original Paper

Abstract

Six \( {\text{La}}_{{0.4}} {\text{Ca}}_{{0.5}} {\text{Ti}}_{{0.5}} {\text{Cr}}_{{0.4}} {\text{M}}_{{0.1}} {\text{O}}_{{3 - \delta }} \) (M = Cr, Mn, Fe, Co, Ni, Cu) and two \( {\text{La}}_{{0.4}} {\text{Ca}}_{{0.4}} {\text{Ti}}_{{0.4}} {\text{Cr}}_{{0.4}} {\text{M}}_{{0.2}} {\text{O}}_{{3 - \delta }} \) (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 \( {\text{La}}_{{0.4}} {\text{Ca}}_{{0.5}} {\text{Ti}}_{{0.5}} {\text{Cr}}_{{0.5}} {\text{O}}_{{3 - \delta }} + 5\% {\text{NiO}} \) composite, shows the Cu-containing powders.

Keywords

3d-metal-doped chromites–titanates Oxygen stoichiometry Electrical conductivity Catalytic activity 

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • V. Vashook
    • 1
  • R. Müller
    • 2
  • J. Zosel
    • 2
  • K. Ahlborn
    • 2
  • F. Gerlach
    • 2
  • P. Tietz
    • 3
  • G. Stöver
    • 3
  • U. Guth
    • 1
    • 2
  1. 1.Institute of Physical Chemistry and ElectrochemistryDresden University of TechnologyDresdenGermany
  2. 2.Kurt-Schwabe-Institute for Measuring and Sensor Technology MeinsbergZiegra-KnobelsdorfGermany
  3. 3.Institute for Materials and Processes in Energy Systems (IWV-1)Research Centre JuelichJuelichGermany

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