Electrical conductivity of vanadium phosphate glasses containing ZnO or GeO2

Abstract

Glasses containing up to 80 mol% V2O5 were obtained when ZnO : P2O5 or GeO2 : P2O5 was 1 in the mole ratio. The temperature dependence of dc conductivity, σ, was exponential with σ = σ0/Texp (-W/k Τ), σ and W of glasses containing the same amount of V2O5 were affected slightly by the kind of the additive oxides ZnO or GeO2, when V2O5 ⪆ 50 mol%. In this region, σ0 varied slightly with the change of V2O5 content, and the hopping conduction was adiabatic. When V2O5 ⪅ 50 mol%, adiabatic approximation could not be valid for the hopping conduction. σ0 and the transition probability decreased remarkably with decreasing V2O5 content, σ and W of the glasses containing the same amount of V2O5 depended on the kind of the additive oxides. The relationship between the anionic molar volume or Tg and V2O5 content indicated that the glass structure changed at V2O5 ≈ 50 mol%. The conduction mechanism was discussed in relation to the glass structure.