YAHIA A. Relaxation phenomena in Li2Ge7O15.

The object of researches is the processes of polarization and transfer of charge in dielectric crystals. The aim is to set regularities of the relaxation phenomena, to elucidate the microscopic mechanisms of processes of polarization and transfer of charge in undoped and doped by ions Cr, Mn crystals Li2Ge7O15. The methods are general, as methods of research were used dielectric and impedance the spectroscopy. The processes of volumetric -charge polarization were studied in the DC electric field. The results of the electric measurings are complemented by the study of the EPR spectrums.. The performed researches have allowed to clarify the microscopic mechanisms of the polarization and charge transfer phenomena. It has been shown, that relaxation phenomena in nominally pure and doped Li2Ge7O15 crystals are determined by the processes of various nature: - thermally activated re- orientations of the dipole moments of Cr 3+-Li+ pair centers; - migration mobility of interstitial Li+ ions through the channels of crystal lattice; - accumulation of a charge carriers near to blocking electrodes. It has been demonstrated, that lithium germanate crystal matrix is appropriate for design of new materials with high ionic conductivity. A strong influence of doping ions on lithium heptagermanate electrical properties is registered. It has been shown, that introducing of heterovalent impurities allows to control Li2Ge7O15 electric conductivity in a wide range. Application sphere is the training courses.