P_O2 dependence of valence number of Co in LaGaO₃ and its influence on partial electronic and oxide ionic conductivity

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• 作者：Ishihara ; Tatsumi ; Ishikawa ; Shinji ; Ando ; Masaki ; Nishiguchi ; Hiroyasu ; Takita ; Yusaku
• 关键词：LaGaO₃ perovskite oxide ; Partial electronic conduction ; Valence number ; Tracer diffusion ; Mobility
• 刊名：Solid State Ionics
• 出版年：2004
• 期刊代码：96_01672738
• 类别：ch
• 出版时间：September 30, 2004
• 卷：173
• 期：1-4
• 页码：9-15
• 文件大小：380 K

摘要

Partial electronic and oxide ionic conductivity in Co doped LaGaO₃ was investigated with a polarization method and it was seen that the partial electronic conductivity became significant with increasing temperature. P_O2 dependences of the partial electron and hole conductivities at 1173 K are almost proportional to P_O2^芒芒芒1/4 and P_O2^1/4, respectively, in accordance to Wagner's theory. On the other hand, P_O2 dependences of electron and hole conductivities deviate from those of Wagner's theory and became much smaller as temperature decrease. The small P_O2 dependence of the partial electronic conductivity could be explained by extrinsic electrons or holes originating from oxidation or reduction of cobalt. In order to explain the small P_O2 dependence, average valence numbers of Co were measured by redox titration. It was seen that the P_O2 dependence of the Co valence number is similar to those of partial electron and hole conduction. Consequently, the small P_O2 dependence of partial electronic conduction could be assigned to the small P_O2 dependence of the valence number of Co.