Electron paramagnetic resonance and electrical conductivity of V₂O₅-ZnCl₂-TeO₂ glasses

Abstract

The electron paramagnetic resonance (EPR) spectra parametersg∥, g⊤, A∥, A⊤.de conductivity. ac conductivity and dielectric constant of V₂O₅-ZnCl₂-TeO₂ glasses in the concentration range 50V₂O₅-XZnCl₂-(50 - X)TeO₃ (X = 0-45) and 40V₂O₅-XZnCl₂-(60 - X)TeO₂ (X = 0-50) are reported. It was observed that the addition of ZnCl₂ initially decreases the V⁴⁺-to-V⁵⁺ ratio, thereby giving well resolved EPR lines. The V⁴⁺-to-V⁵⁺ ratio was found to decrease with increasing X up to 30; however, for higher values of X > 30, electron spectroscopy for chemical analysis of the samples indicate intercalation of ZnCl₂ which results into an increase in the V⁴⁺-to-V⁵⁺ ratio. The value of the V⁴⁺-to-V⁵⁺ ratio for which well resolved lines were found is 0.03 for 50V₂O₅ and 0.04 for 40V₂O₅ glasses. The dc and the ac conductivities as functions of X show a dip which coincides with minima in the V⁴⁺-to-V⁵⁺ ratio; however, the dielectric constant decreases continuously with increasing X. This indicates that the dominant contribution to the dc and the ac conductivities comes from hopping charge carriers, while its contribution to total dielectric polarization is small compared with ionic and electronic polarization.