An X-ray absorption spectroscopic study on mixed conductive La 0.6Sr0.4Co0.8Fe0.2O 3-δ cathodes. I. Electrical conductivity and electronic structure

Yuki Orikasa, Toshiaki Ina, Takayuki Nakao, Atsushi Mineshige, Koji Amezawa, Masatsugu Oishi, Hajime Arai, Zempachi Ogumi, Yoshiharu Uchimoto

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)


    The electrical conduction mechanism of mixed conductive perovskite oxides, La0.6Sr0.4Co0.8Fe0.2O 3-δ, for cathode materials of solid oxide fuel cells has been investigated from electronic structural changes during oxygen vacancy formation. La0.6Sr0.4Co0.8Fe0.2O 3-δ was annealed under various oxygen partial pressures p(O2)s at 1073 K and quenched. Iodometric titration indicated that the oxygen nonstoichiometry of La0.6Sr0.4Co 0.8Fe0.2O3-δ depended on the annealing p(O2), with more oxygen vacancies introduced at lower than at higher p(O2)s. X-Ray absorption spectroscopic measurements were performed at the O K-, Co L-, Fe L-, Co K-, and Fe K-edges. The valence states of the Co and Fe ions were investigated by the X-ray absorption near edge structure (XANES) at the Co and Fe LIII-edges. While the Fe average valence was almost constant, the valence of the Co ions decreased with oxygen vacancy introduction. The O K-edge XANES spectra indicated that electrons were injected into the Co 3d/O 2p hybridization state with oxygen vacancy introduction. Both absorption edges at the Co and Fe K-edge XANES shifted towards lower energies with oxygen vacancy introduction. The shift at the Co K-edge resulted from the decrease in the Co average valence and that at the Fe K-edge appeared to be caused by changes in the coordination environment around the Fe ions. The total conductivity of La0.6Sr0.4Co0.8Fe 0.2O3-δ decreased with decreasing p(O2), due to a decreasing hole concentration.

    Original languageEnglish
    Pages (from-to)16637-16643
    Number of pages7
    JournalPhysical Chemistry Chemical Physics
    Issue number37
    Publication statusPublished - 2011 Oct 7

    ASJC Scopus subject areas

    • Physics and Astronomy(all)
    • Physical and Theoretical Chemistry

    Fingerprint Dive into the research topics of 'An X-ray absorption spectroscopic study on mixed conductive La <sub>0.6</sub>Sr<sub>0.4</sub>Co<sub>0.8</sub>Fe<sub>0.2</sub>O <sub>3-δ</sub> cathodes. I. Electrical conductivity and electronic structure'. Together they form a unique fingerprint.

    Cite this