FREQUENCY AND TEMPERATURE DEPENDENCIES OF AC CONDUCTIVITY OF POLYVINYL-ALCOHOL (PVA)-COCL2 COMPOSITES

The a.c. conductivity for polyvinyl alcohol (PVA)-CoCl2 composites pre pared by a casting method has been measured at different frequencies ( 0.1 -1 0 kHz) in the temperature range 300-450 K. At constant temperat ure, the frequency dependence of a.c. conductivity, sigma(omega), was found to fit the established equation sigma(omega) = Aomega(S) quite w ell. On the other hand, the temperature dependence of a.c. conductivit y suggested an electronic hopping conduction mechanism in a thermally assisted electric field. Various theoretical mechanisms have been disc ussed to clarify the conduction processes in these samples. The correl ated barrier hopping (CBH) mechanism, proposed by Elliott, was found t o be the most appropriate one.