層状構造強誘電体の欠陥構造と機能

抄録

Ferroelectric materials with layered structure have attracted a great deal of attention in technological and scientific points of view because of their high Curie temperature and large spontaneous polarization. The current status and problems of representative layered ferroelectric material, Bi₄Ti₃O₁₂, are briefly reviewed. Piezoresponse force microscopy observations reveal that the clamping of 90° domain walls is the origin of poor polarization properties of Bi4Ti3O12 crystals. The origin of the domain clamping is suggested to be the strong interaction between oxygen vacancies and 90° domain walls. High-pressure-oxygen sintering is shown to be effective processing for obtaining high-quality Bi₄Ti₃O₁₂-based devices with superior polarization properties.