Thermodynamic and Kinetic Description of the Second Order Phase Transitions

Abstract

A thermodynamic and kinetic description of phase transitions for the model of ferroelectrics on the basis of kinetic equations for the distribution function of values of the "order parameter", coordinates and time is discussed. For one-domain ferroelectrics the self-consistent approximation for the first moment is used. The kinetic equation is reduced to the relaxation Ginsburg–Landau equation. The susceptibility is governed by the Curie law and there is an increase in heat capacity. Calculations are carried out for one-domain and polydomain ferroelectrics. In the first case the self-consistent approximation for the first moment is used. In the second one the self-consistent approximation for the second moment is carried out. In the last case there is a jump in susceptibility. The heat capacity is governed by the Curie law. It is shown also that the Ornstein–Zernike formula is valid not for the space correlator of fluctuations, but only for the temporal spectral density of the space correlator at zero frequency. In the kinetic theory of the phase transition all physical characteristics at the critical point have finite values. Thus, the problem of "infinities" is absent.