The kinetic characteristics of polarization of relaxor ferroelectrics

SBN crystals doped with rare-earth metal ions were studied to show that relaxor ferroelectrics had pronounced anomalies, which manifested themselves by the noncoincidence of the trajectories of the first several cycles of dielectric hysteresis loops, the absence of an unambiguous coercive field, and other special features of the kinetics of polarization. These anomalies were related to structural disorder of the crystals and a random internal electric field distribution and could only be observed in constant and quasi-static electric fields. A phenomenological analysis of the thermal activation stages of polarization relaxation was performed. The spectra of the energy distribution of potential barriers were reproduced in the approximation of their independence. Electric conductivity was shown to, play an important role in the formation of giant barriers. (C) 2001 MAIK "Nauka/Interperiodica".