Structure, magnetic and positron lifetime studies on CaO-ZrO2-SiO2 glass system doped with vanadium oxide

The structure of CaO-ZrO2-SiO2 glasses doped with V2O5 (0.1-2 mole%) was studied using density and molar volume measurements. It was observed that the molar volume increased while the density decreased with increasing V2O5 content. Magnetic susceptibility measurements showed the diamagnetic behaviour of this glass system. The free volume was probed using ortho-positronium pick-off annihilation lifetime parameters. The mean free volume and fractional free volume have also been calculated from the positron annihilation lifetime data. The overall measured parameters from the structural and/or positron annihilation spectra indicated that the majority of the vanadium ions in the range 0-0.5 mole% of V2O5 are in the V5+ valence state which act as a glass former. On the other hand, the majority of the vanadium ions in the range 0.7-2 mole% of V2O5 are the V3+ and V4+ states acting as a glass modifier.