Diffuse critical point in PLZT ceramics

Abstract

The ferroelectric transition line in the electric-field temperature phase diagram of the canonical relaxor ferroelectric ceramics 9/65/35 PLZT has been studied via polarization and high-resolution heat capacity measurements. The modified calorimetric relaxation measurements show a change of the sample temperature if the applied electric field is sufficiently high to induce a ferroelectric transition. The anomaly in the sample temperature is a consequence of the released excess heat, i.e., latent heat at the transition from the disordered dipolar glass state to the long-range–ordered ferroelectric state. The presence of latent heat supports the well-established physical picture of relaxors according to the so-called dipolar glass scenario. Furthermore, it was found that latent heat decreases with increasing temperature, indicating the existence of a diffuse-type critical point.