ON THE PHENOMENOLOGY OF DIFFUSE PHASE-TRANSITIONS IN PLZT

PLZT x/65/35 in the composition range of 7<xs10 shows a diffuse phase transition (DPT). The DPT is correlated with the occurrence of anomalies in the susceptibilities above “Tc”. These anomalies can be ascribed to the influence of a local polarization1. The relaxor behaviour of the PLZT-material can be seen in the dielectric relaxation with very low relaxation frequencies2. Here, on the basis of the free energy, we discuss the case of a material with DPT in general. It is shown that the various phases in the phase diagram can easily be explained. Above all, it is demonstrated that in the case of PLZT in absence of an electrical field no paraelectric-ferroelectric phase transition happens. © 1991, Taylor & Francis Group, LLC. All rights reserved.