The motion of the domain boundaries in crystals of KH2PO4group

The lateral motion of 180-degree domain walls in ferroelectrics is considered. The motion is realized by the thermofluctuational nucleation and subsequent spreading of the reverse domain nucleuses on the domain wall. The energy and the velocity of the lateral walls of nucleus for different orientations, energies and dimensions of the critical nucleus are determined. Different avelocity regimes of the lateral motion of domain wall are analysed. The results of general analysis are applied to the case of strong temperature dependence of the barrier height in periodic potential relief of the domain walls, connected to co-ordinate dependence of the wall's energy. Strong dependence on the temperature of mobility of the domain boundaries, obtained here, explains the pnenomenon of domain structure “freezing” in crystals of KH2PO4 group, The dependence of the “freezing” temperature on the amplitude of the measuring field is calculated.