稲熊 宜之

Perovskite-type oxides with a chemical formula of ABO3 exhibit various functional properties. Among them, lithium ion-conducting oxides with A-site deficient perovskite-type structure such as La2/3－xLi3xTiO3 show fast lithium ion conductivity of 10－5 to 10－3 S/cm at room temperature. The high conductivity is attributable to the percolation-controlled diffusion of lithium ions in the vicinity of A-site via vacancy. In this report, recent research on perovskite-type lithium ion-conducting oxides are reviewed in terms of crystal structure including microstructure, and chemical bond. The relationship among structure, chemical bond, especially second-order Jahn-Teller effect attributable to the covalent bond between B ion with d0 electronic configuration and O ion, and lithium-ion diffusion are discussed.