Dielectric properties of $Li_{0.003}Na_{0.997}NbO_3$ ceramics

Abstract

Temperature, frequency and time dependencies of dielectric permittivity and pyroelectric current of $Li_{0.003}Na_{0.997}NbO_3$ ceramics have been presented. Investigation of the pyroeffect reveals the existence of the local dipoles in a temperature range above the temperature of the maximum of the dielectric permittivity, $T_m$. The observed dispersion of the dielectric permittivity for this material and its time dependence, can be connected with the existence of these dipoles. The occurrence of these dipoles can be associated with a large local deformation accompanying the substitution of individual Li- by Na-ions and with imperfections of the polycrystal.