Slow polarization relaxation in non-uniform telluric acid ammonium phosphate crystals

The characteristic features of polarization and spontaneous depolarization kinetics in non-uniform telluric acid ammonium phosphate (TAAP) crystals are investigated by observation of the domain structure using a nematic liquid crystal method. We present experimental results showing the correlation between the internal bias field, responsible for the offset of the hysteresis loop and the backswitching process. The internal field caused by structural disorder accounts for a broad spectrum of energy barriers for domain nucleation. The switching kinetics was analysed in the framework of the nucleation and growth model based on Avrami statistical theory, using the modified Kolmogorov-Avrami-Ishibashi (KAI) model. It has been found that the switching kinetics in TAAP crystals can be approximated by averaging the KAI model over a broad distribution of characteristic domain growth times. The spectra of the distribution of the characteristic domain growth times are derived from the experimental data.