Ultrasound measurements on doped PZT with diffuse phase transition

Abstract

Doped PZT (e. g. PLZT 8/65/35) shows a diffuse phase transition with a broad maximum of the dielectric constant at the temperature T_C. The spontaneous polarization of the poled material vanishes in a relatively small temperature region (at T_t). Ultrasound measurements as a function of temperature give as a result a small anomaly near T_C and a pronounced minimum at T₁, a temperature below T_t for the unpoled material. Poled samples show, as a function of temperature, a modified sound velocity, which changes significantly at T₁. These measurements and investigations of the sound velocity as a function of the electric field as well as further properties, especially the behaviour of the remanent polarization, can be explained by a model based on interacting microdomains.