X-ray absorption spectroscopic study on La0.6Sr 0.4CoO3-δ cathode materials related with oxygen vacancy formation

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

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    45 Citations (Scopus)

    Abstract

    The electronic structural changes of La0.6Sr 0.4CoO3-δ cathodes with oxygen vacancy formation by reducing oxygen partial pressures, p(O2)'s were investigated in detail using X-ray absorption spectroscopy to understand metallic-like electronic conduction mechanism. The oxygen nonstoichiometry of La 0.6Sr0.4CoO3-δ was controlled by annealing the samples under various p(O2)'s and quenched to room temperature. Co K-edge X-ray absorption near edge structure (XANES) spectra revealed that the Co average valence decreased with decreasing p(O2), which was also confirmed by iodometric titration. The Co L-edge XANES spectra were hardly changed with changing p(O2)-s. Meanwhile, the peak area of the O K-edge XANES spectra strongly depended on p(O2). This result revealed the strong hybridization between the O 2p and Co 3d states. It was concluded the introduction of oxygen vacancies narrowed the hybridized orbital of O 2p and Co 3d states, resulted in a decrease in the mobility as well as the concentration of electron holes with decreasing p(O2).

    Original languageEnglish
    Pages (from-to)16433-16438
    Number of pages6
    JournalJournal of Physical Chemistry C
    Volume115
    Issue number33
    DOIs
    Publication statusPublished - 2011 Aug 25

    ASJC Scopus subject areas

    • Physical and Theoretical Chemistry
    • Electronic, Optical and Magnetic Materials
    • Surfaces, Coatings and Films
    • Energy(all)

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