Oxygen nonstoichiometry and thermo-chemical stability of La 0.6Sr 0.4CoO 3-δ

M. Kuhn, S. Hashimoto, K. Sato, K. Yashiro, J. Mizusaki

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

The oxygen nonstoichiometry of La 0.6Sr 0.4CoO 3-δ has been the topic of various reports in the literature, but has been exclusively measured at high oxygen partial pressures, pO 2, and/or elevated temperatures. For applications of La 0.6Sr 0.4CoO 3-δ, such as solid oxide fuel cell cathodes or oxygen permeation membranes, knowledge of the oxygen nonstoichiometry and thermo-chemical stability over a wide range of pO 2 is crucial, as localized low pO 2 could trigger failure of the material and device. By employing coulometric titration combined with thermogravimetry, the oxygen nonstoichiometry of La 0.6Sr 0.4CoO 3-δ was measured at high and intermediate pO 2 until the material decomposed (at log(pO 2/bar)≈-4.5 at 1073 K). For a gradually reduced sample, an offset in oxygen content suggests that La 0.6Sr 0.4CoO 3-δ forms a super-reduced solid solution before decomposing. When the sample underwent alternate reduction-oxidation, a hysteresis-like pO 2 dependence of the oxygen content in the decomposition pO 2 range was attributed to the reversible formation of ABO 3 and A 2BO 4 phases. Reduction enthalpy and entropy were determined for the single-phase region and confirmed interpolated values from the literature.

Original languageEnglish
Pages (from-to)38-45
Number of pages8
JournalJournal of Solid State Chemistry
Volume197
DOIs
Publication statusPublished - 2013 Jan

Keywords

  • Coulometric titration
  • Defect
  • La Sr CoO
  • Oxygen nonstoichiometry
  • SOFC
  • Thermo-chemical stability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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