Electrical Charge Transfer in Complex Oxides

The electrophysical properties (temperature-frequency dependence of conductivity and dielectric constant, current of depolarization) of complex oxide single crystals (Ca-Ga-Ge-garnet, Ca-Ga-germanate, Pb-, Ca-, Cd-tungstates) are analyzed. The experimental results for different crystallographic axes were obtained in the frequency range 10-$10^{5}$ Hz and temperature range 290-650 K. The main parameters of conductivity and depolarization currents are determined. The nature of polarization charge induced by applied external field is discussed using the model of polarization at hopping exchange of charge between complex dipolar defects and space-inhomogeneous distribution of charge in the sample. Existence of small polarons in the crystals is considered.