Doping effect on crystal structure and conduction property of fast oxide ion conductor LaGaO₃-based perovskite

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• 作者：Masahiro Kajitani ; Motohide Matsuda ; Akinori Hoshikawa ; Stefanus Harjo ; Takashi Kamiyama ; Toru Ishigaki ; Fujio Izumi ; Michihiro Miyake
• 刊名：Journal of Physics and Chemistry of Solids
• 出版年：2007
• 期刊代码：69_00223697
• 类别：ch
• 出版时间：May-June 2007
• 卷：68
• 期：5-6
• 页码：758-764
• 文件大小：211 K

摘要

In order to discuss oxide ion conduction mechanism for LaGaO₃-based perovskite compounds, doping effects were investigated using two kinds of solid solutions whose oxygen vacancy concentrations are the same: one is La_0.9Sr_0.1Ga_0.9Mg_0.1O_2.9 with A-site and B-site substitutions and the other is LaGa_0.8Mg_0.2O_2.9 with only B-site substitution. Conductivity measurements showed that La_0.9Sr_0.1Ga_0.9Mg_0.1O_2.9 had a circumstance whereby oxide ion could more easily diffuse in the perovskite structure than in LaGa_0.8Mg_0.2O_2.9. Structural analyses using neutron diffraction found out the following three differences: the first finding was that the saddle point formed by two A-site cations and one B-site cation in La_0.9Sr_0.1Ga_0.9Mg_0.1O_2.9 was larger than that in LaGa_0.8Mg_0.2O_2.9 due to larger displacements of A-site and B-site cations; the second was that the doubly doping with Sr and Mg was more effective for reduction of GaO₆ octahedral tilt angles than the doping with Mg; the last was that La_0.9Sr_0.1Ga_0.9Mg_0.1O_2.9 had larger oxygen displacement than LaGa_0.8Mg_0.2O_2.9. It was considered that these structurally related parameters dominated the high oxide ion conduction in LaGaO₃-based perovskite compounds.