Kinetics of phase transformation at the Curie point of ferroelectric ceramic Ba0.8Sr0.2TiO3

摘要

The temperature dependences of the dielectric permittivity and dielectric loss tangent in the ferroelectric ceramic Ba(0.8)Sr(0.2)TiO(3)have been studied at frequencies from 25 Hz to 120 Hz. It was found that the phase transition at the Curie point (T-C approximate to 338 K) is diffused in the temperature range of similar to 30 K. The temperature dependence of the local order parameter plotted based on dielectric measurement data confirms the diffusion of the phase transition, which begins by the arising of local polar regions at Burns temperature. The revealed dependences of the dielectric loss maximum near theT(C)on the heating rate of the sample and frequency are well explained in the framework of the fluctuation model of low-frequency dielectric losses during a first-order phase transitions.