STUDIES ON THE TEMPERATURE DEPENDENCE OF ELECTROCONDUCTIVITY FOR CRYSTALS OF PHLOGOPITE AND FLUOROPHLOGOPITE. Y.V. Eshova, F.A. Scherbachenko, V.A. Karnakov, N.A. Hlopenko, Irkutsk State University, Irkutsk, Russia

The specific conductivity of natural (phlogopite) and synthetic (fluorophlogopite) micas has been studied as a function of temperature. This allowed to establish activation energies and a nature of charge carriers responsible for current in crystals under investigation.

The conductivity of Phlogopites in the temperature range 300-500 K is associated with aqua-pellicle impregnations and is characterized by activation energy of 0.15-0.20 ev. In the range 500 - 900 K the carriers are loosely bound ions of impurities with activation energy of 0.3- 0.4 ev. Above 900 K the activation energy is about 3.0 ev and the charge carriers are most likely fluorine ions.

Within the considered interval of temperatures specific conductivity of fluorophlogopiles is by two orders of magnitude lower than those of phlogopites. The differences in the magnitude and character of conductivity for these species of mica are explained by a high thermoresistance of fluorophlogopite. The latter is due to a substitution of hydroxygroups by fluorine ions, more firmly bound to lattice, and due to the nearly complete absence of molecular water in fluorophlogopite.