Oxygen nonstoichiometry of the perovskite-type oxides BaCe0.9M0.1O3 - δ (M{double bond, short}Y, Yb, Sm, Tb, and Nd)

Masatsugu Oishi, Keiji Yashiro, Kazuhisa Sato, Junichiro Mizusaki, Naoto Kitamura, Koji Amezawa, Tatsuya Kawada, Yoshiharu Uchimoto

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39 Citations (Scopus)

Abstract

The oxygen nonstoichiometry, δ, of B-site doped BaCeO3 - δ under dry condition was determined as a function of oxygen partial pressures, PO2, between 1 bar and 10- 4 bar and temperatures between 773 K and 1373 K. The variation of δ in BaCe0.9Y0.1O3 - δ, BaCe0.9Yb0.1O3 - δ, BaCe0.9Sm0.1O3 - δ and BaCe0.9Tb0.1O3 - δ was very small through the experimental conditions. This indicates that charge imbalance due to the trivalent dopants is compensated essentially by the oxygen vacancy formation. A large variation was found for δ of BaCe0.9Nd0.1O3 - δ by PO2 and temperature. This result indicates that the valence of the metal elements change under the experimental conditions. The X-ray absorption spectroscopy (XAS) measurement was carried out to examine the valence of the B-site elements of BaCe0.9Nd0.1O3 - δ. The samples of different δ were prepared. From the XANES spectra of Ce and Nd, no spectra change for Ce L3-edge was observed, while spectra change was observed for Nd L3-edge and L2-edge. This indicates that the valence of Ce stay unchanged, while the valence of Nd may be changed by the different δ conditions. The measured δ of BaCe0.9Nd0.1O3 - δ was analyzed by considering the valence change of neodymium. By considering the defect equilibrium among Nd′Ce, Nd×Ce, VO••, and OO×, the change of δ against PO2 was well explained by assuming the defect equilibrium frac(1, 2) O2 + VO• • + 2NdCe' = OO× + 2NdCe×.

Original languageEnglish
Pages (from-to)529-535
Number of pages7
JournalSolid State Ionics
Volume179
Issue number15-16
DOIs
Publication statusPublished - 2008 Jun 30

Keywords

  • B-site doping
  • BaCeO
  • Oxygen nonstoichiometry
  • Proton conductive perovskite-type oxides
  • SOFC
  • XAS

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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