Structure, magnetic, and electrical studies on vanadium phosphate glasses containing different oxides

Glass system with molar composition (60% P2O5-30%V2O5-10%X) where X is Li2O, Na2O, K2O, and BaO was prepared. The density and molar volume indicate that the density decreases while the molar volume increases with increasing ionic radius of doped oxides. IR studies reveal the coexistence of V4+ and V5+ ions (act as glass modifier and glass former, respectively). The observed paramagnetic behavior of samples indicates that V4+ > V5+ (the ratio V4+/V4+ + V5+ > 0.52 as obtained from chemical titration analysis). Mott's model of conduction was applied to discuss DC electrical conduction mechanism. The prepared glass exhibits semiconducting behavior. However, Ba ion is the only ion which did not contribute to the ionic conduction. The conductivity increases with decreasing ionic radius of doped oxides due to high mobility due to their small size. The effect of hopping distance on the electrical conduction and magnetic properties were discussed. An attempt was done to determine the expected temperature of Ba ionic conduction and its ionic activation energy.