Microstructure and domain effects in ferroelectric ceramics

Abstract

In tetragonally distorted ferroelectric ceramics a regular domain pattern develops, which allows the grain to keep its shape according to its clamping condition. In coarse grained ceramic the adjustment of the shape is possible in three dimensions, in fine grained ceramic and in thin films a two dimensional adjustment is adequate. Using these rules of 90°-twinning and the minimization of the free energy the domain width decreases with grain size. Irregular domain configurations in small regions of the grain indicate local stress regions.

90°-domain walls can contribute considerably to the dielectric behavior of the ceramic. Aging of the dielectric, elastic and piezoelectric constants result from various processes which are not well known. One of these processes is the clamping of the 90°-domain walls by oriented dipolar defects in the adjacent domains.