Crystalline ferroelectrics with a glassy polarization phase

Abstract

We have studied several different ferroelectric crystal systems where the long range translational symmetry is strongly broken. From measurements of the temperature dependence of the optic index of refraction, n(T), we find that far above the ferroelectric transition temperature, Tc, there is a temperature Td where local polarization occurs. For systems such as PLZT, i.e., (Pb1-3x/2Lax)(Zry;Ti1-y)O3, Td is several hundred degrees above Tc and independent of La-concentration. In this system we can account for Td quantitatively (in terms of Tc of PZT, i.e., zero La concentration). The model emphasizes local polarization effects from clusters of a few unit cells. © 1985 The Japan Society of Applied Physics.