Effect of Variable Oxidation States of Vanadium on the Structural, Optical, and Dielectric Properties of B 2 O 3 -Li 2 O-ZnO-V 2 O 5 Glasses.

In the present study, the effect of variable vanadium oxidation states on the structural, optical, and dielectric properties of vanadium oxide containing lithium borate glasses has been investigated. Electron paramagnetic resonance studies indicate that vanadium in these glasses is mostly in the V4+ state, having a tetragonal symmetry. As the glass composition of V2 O5 increases, tetragonality also increases at the cost of octahedral symmetry. The photoluminescence (PL) spectra of these glasses are dominated by zinc oxide transition, whereas the peaks pertaining to the vanadyl group are not visible in the PL spectra. The optical absorption spectra show a single wide absorption band, which is attributed to V4+ ions in these glasses. The ac conductivity of the glasses increases with an increase in vanadium content. The highest electrical conductivity observed is ∼10-5 S cm-1 at 250 °C for the glass with 2.5 mol % V2 O5 . Electrical conductivity is dominated by electron conduction, as indicated by the activation energy calculation.