ELECTRON-PARAMAGNETIC-RESONANCE AND ELECTRICAL-CONDUCTIVITY OF V2O5-ZNCL2-TEO2 GLASSES

The electron paramagnetic resonance (EPR) spectra parameters g(paralle l to), g(perpendicular to), A(parallel to), A(perpendicular to), dc co nductivity, ac conductivity and dielectric constant of V2O5-ZnCl2-TeO2 glasses in the concentration range 50V(2)O(5)-XZnCl2-(50 - X)TeO2 (X = 0-45) and 40V(2)O(5)-XZnCl2-(60 - X)TeO2 (X = 0-50) are reported. It was observed that the addition of ZnCl2 initially decreases the V4+-t o-V5+ ratio, thereby giving well resolved EPR lines. The V4+-to-V5+ ra tio was found to decrease with increasing X up to 30; however, for hig her values of X > 30, electron spectroscopy for chemical analysis of t he samples indicate intercalation of ZnCl2 which results into an incre ase in the V4+-to-V5+ ratio. The value of the V4+-to-V5+ ratio for whi ch well resolved lines were found is 0.03 for 50V(2)O(5) and 0.04 for 40V(2)O(5) glasses. The dc and the ac conductivities as functions of X show a dip which coincides with minima in the V4+-to-V5+ ratio; howev er, the dielectric constant decreases continuously with increasing X. This indicates that the dominant contribution to the de and the ac con ductivities comes from hopping charge carriers, while its contribution to total dielectric polarization is small compared with ionic and ele ctronic polarization.