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

Abstract

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.

The effect of electrical conductivity on the polarization behavior of the relaxor–ferroelectric Sr0.33Ba0.67Nb2O6

“…In such crystals asymmetric hysteresis loops about D-E axes have been observed, with a built-in internal bias field, defined as a shift of the hysteresis loop on the E axis. The preferential orientation of the polarization is connected with the site-specific nature of domain nucleation and non-random distribution of domains over the crystal surface [23]. The specific features of the hysteresis loop observed for the crystal sample examined can serve as direct verification of the concept of local random fields existing due to structural disorder of the SBN crystal.…”

Dynamics of the domain structure in non-uniform ferroelectric crystals

“…There is observed an essential difference between the domain kinetics observed in inhomogeneous crystal samples and homogeneous ones. In a homogeneous crystal sample, the switching curves taken at different electric fields typically saturate at the same value, so that they relate to the complete polarization reversal [7]. In the examined inhomogeneous region of the crystal sample, the saturation value of the switching polarization increases with the electric field increase.…”

“…On analyzing the switching process in a homogeneous crystal sample [7], the kinetics of polarization switching in external electric field has been well described by the Avrami function i.e., the expression of the same form as KWW function, with exponential coefficient ranging from 1 to 2. In that case the exponential coefficient could express the spatial dimensionality of the domain growth, which should take the integer value of 2 for two-dimensional domain growth (circular domains as shown in figure 2(a)) and the value of 1 for one-dimensional domain growth (as shown in figure 4).…”

Domain nucleation and growth in relaxor-ferroelectric Sr0.58Ba0.42Nb2O6doped with chromium and ytterbium

“…Therefore, the observed P(t) behaviour in the SBN crystal sample results from a superposition of many different relaxation times of relaxing domains. The spectra of the relaxation time distribution can be drawn from experimental data [8,29].…”