ВЕСТНИК ВГУ, Серия физика, математика, 2002, ¹ 1 UDC 537.266 DISPERSION OF DIELECTRIC PERMEABILITY IN POLYDOMAIN FERROELECTRICS © 2002 г. <...> A. S. Sidorkin, A. S. Sigov Voronezh State University Moscow Institute of Radioelectronic Engineering The parameters of the equation of the domain wall motion for its translational movement KH2PO4 crystal at the frequencies 107 defects. <...> PO4 have been calculated: the effective mass of the wall connected with involving in motion of the bulk of ferroelectric through the piezoeffect, the coefficient of the quasielastic force effecting on the wall and connected with the change of charging state on the surface of the material at the displacement of domain boundary and the effective resistance to the motion of domain boundary in crystal with defects. <...> On the basis of the equation of motion for the domain wall the value of its shift is determined in dependence on the amplitude and frequency of external electrical field. <...> The obtained results are compared with the experimental data. <...> Rather low-frequency dispersion crystals KH2 Hz can be explained by inertial properties of domain 3 at the frequencies : 10 Hz in According to numerous experimental data the dispersion of dielectric permeability and tangent of the dielectric losses angle in ferroelectrics besides the so-called soft mode [1] is connected with the motion of domain boundaries [2]. <...> Dispersion of a resonant type observed in ferroelectrics with perovskite-type structure in the megaherz range of frequencies [3], and dispersion of relaxation type noted in the kiloherz range in numerous crystals of KH2 radiation [4] is also related to the same class of phenomena. <...> They depend on the inertial properties of the boundaries [5] as on the materials themselves [6, 7], on the forces arising at the displacement of domain boundaries from their equilibrum positions [810], and, finally, on the mobility of the boundary determined by dissipative processes in the ideal material [11, 12] as well as by the interaction of the moving boundary with defects of the crystal lattice [1315]. <...> In the initial state in the absence of external field the charges on the surface of ferroelectric are compensated as a rule at the expense of the bulk or surface conductivity. <...> The applying of external electric field results in appearance of the pressure on the domain walls. <...> Being displaced under this pressure the domain boundaries break the balance of charges on the surface of ferroelectric. <...> It results in the increase of electrostatic energy of the crystal and, hence, the appearance of quasielastic returning force effecting <...>