Nonlinear dielectric properties and temperature stabilization effect near the ferroelectric phase transition in sodium trihydrogen selenite

The ferroelectric phase transition of crystalline sodium trihydrogen selenite has been characterized by domain observations and measurements of electric permittivity, pyroeffect and spontaneous polarization. The first-order character of the phase transition is clearly demonstrated by the phase coexistence and temperature autostabilization. The considerable heating effect at 50 Hz ac field is described. The electric field effect on the temperature variation of the electric permittivity, in the phase transition region, shows a considerable domain structure contribution to the permittivity value. It is demonstrated that the dielectric properties of x- and y-samples can be described by classical dielectric state equations: the set of coefficients has been determined. It is concluded that the x-component of spontaneous polarization plays a predominant role in the phase transition.