A model delineating the dielectric spectra of a relaxor PLZT obtained by impedance analyzer

Abstract

The origin of the dielectric responses of relaxor ferroelectrics, featured by a signal dispersion according to the measurement frequency, were investigated systematically using a canonical relaxor Pb0.92La0.08(Zr0.65Ti0.35)0.98O3 (PLZT 8/65/35) ceramic. By scanning complex dielectric permittivity over a frequency range from 10 mHz to 10 MHz as a function of temperature from 0°C to 100°C, we revealed that the complex dielectric permittivity spectra obtained from an impedance analyzer are a consequence of a convolution of at least three distinct relaxation processes, featured by the unique relaxation time and distribution. The complex dielectric permittivity spectra at each measurement temperature were deconvoluted by the application of a series of Havriliak‐Negami relaxation models, resulting in three distinguished processes; namely, slow, intermediate, and fast process. We identified that the fast process is responsible for the overall magnitude of capacitance with little influence on the dielectric loss, the intermediate mainly for the thermal evolution of the capacitance, and the slow mainly for the thermal evolution of the loss. With this model, we successfully rationalized the characteristics of the relaxor behavior such as the frequency dispersion of the dielectric maxima, the disparity in peak positions of real and imaginary parts, and the unique feature during aging, so‐called a “dip.”