The Effect of Low Valency Vanadium on the Electrical Conductivities of High Vanadium-Phosphoric Acid Glasses

Abstract

The specific resistance (ρ) at 40°C of V2O5-P2O5-BaO glasses was found to be affected significantly by the chemical composition and the melting condition; ρ changed with the mole ratio of BaO/P2O5 even when the V2O5 content was kept constant. The ρ v. s. BaO/P2O5 curves with a constant V2O5 content, in which the characteristic minimum occured, shifted towards the higher value of BaO/P2O5 when the melting temperature of the glasses was raised.A large amount of low valency vanadium which was considered to be V4+, was found in the glasses. Its amount decreased with increasing BaO/P2O5 and the total amount of vanadium present in the glass, and moreover increased with increase in the melting temperature of the glass. The curve relating ρ with [V4+]/ [total vanadium] had also a minimum. It was however independent of BaO/P2O5 and of the melting temperature of the glasses.Based on the above mentioned results the authors discussed the mechanism of the electrical conduction of the vanadium containing glasses pointing out that it closely resembled that of magnetite. They concluded that the conduction of the glasses was probably due to the valency exchange between V4+ and V5+.