Dynamic dielectric characteristics of the NH4HSO4 ferroelectric within the framework of a two-sublattice pseudospin model

Abstract

Within the framework of the two-sublattice pseudospin model of the deformed NH4HSO4 ferroelectric and using the Glauber approach, we have obtained a system of differential equations for the time-dependent mean values of pseudospins that takes into account the degeneracy of the excited states of the pseudospins. Based on the solutions of this system of equations in the mean-field approximation, the longitudinal dielectric permittivity of a mechanically clamped crystal and the polarization relaxation times are calculated. A satisfactory agreement of the calculated characteristics with the available experimental data in a wide range of temperatures and frequencies is obtained. It is shown that almost one-time relaxational dielectric dispersion takes place in the crystal. It was found that hydrostatic pressure shifts the dispersion region to higher frequencies. The electric field reduces the relaxation time near the upper Curie temperature.