Bal_alnMO_<5.5> (M = Sc, Gaとln)とBaLaln_<2-x>Sc_xO_<5.5>(x=0.1,0.2と0.3)の酸化物イオン導電性について

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Solid solutions of BaLaIn_2O_<5.5> and BaLaInMO_<5.5> that formed by partial replacement of In by Sc and Ga have a cubic perovskite structure. The Sc^<3+> - and Ga^<3+> -doped compounds, which had almost the same electrical conductivities, exhibited lower conductivities than the parent compound BaLaIn_2O_<5.5> in the temperature range from 573 to 1273 K. The Ga compound showed a transference number, t_i, of unity at both high and low oxygen partial pressures in the temperature range from 973 to 1273 K. As for the Sc compound kept at 973-1273 K, a t_i of nearly unity was observed at low oxygen partial pressure, while the t_i was slightly lower than unity at high oxygen partial pressures at higher temperatures. The In compound had a t_i of almost unity at high oxygen partial pressure, whereas the number decreased to a value less than 0.9 at low partial pressures of oxygen. The stepwise increase in the Sc content from 0.1 to 1.0 in BaLaIn_<2-x>Sc_xO_<5.5> caused a monotonic decrease in conductivity. The decrease in conductivity and the increase in activation energy caused by Sc^<3+> and Ga^<3+> doping were ascribed to the partial ordering of originally disordered oxygen vacancies and a decrease in the size of the triangle formed by two A-site cations and one B-site cation, through which the oxide ion proceeds, respectively.
社団法人日本セラミックス協会の論文
2003-10-01