Nano-size effects on the quantum paraelectric SrTiO₃ fine particles

Abstract

Nano-size effects on the dielectric and soft mode behaviors in the quantum paraelectric SrTiO₃ were studied. Nanocrystalline SrTiO₃ particles were prepared by the sol-gel method, and the particle sizes were controlled by treating temperatures. The sizes were determined to be from 12 to 44 nm using Scherrer's formula. The transition temperatures from classical paraelectric to quantum paraelectric phase were increased for the smaller sizes of the particles. Soft mode behaviors of fine particles were investigated by Raman scattering. The soft mode frequencies of the smaller sizes of the particles were higher than those of the larger ones in the low temperature. The soft mode behaviors were agreed with dielectric results through the Lyddane-Sachs-Teller relation.