Vanadyl ions influence on spectroscopic and dielectric properties of glass network

Melt quenching derived (in air) transparent glasses containing 30LiF10SrO(60 − x)B2O3xV2O5, with 0 ⩽ x ⩽ 1.0 (mol%) were investigated for physical, spectroscopic measurements, viz., optical absorption, electron spin resonance (ESR) and FTIR along with dielectric properties (dielectric constant ε′, loss tan δ, conductivity σac, etc.). The results were analyzed to correlate with each other in the light of local environment and oxidation states of vanadyl ion in the glass network. The observed blue shift in 3T1g(F) → 3T2g(F) and red shift in 2B2g → 2Eg transitions and decrease in Δg∥/Δg⊥ values up to V8 indicates that the decrease in tetragonality of the vanadium site. The increase in area of optical absorption peak, ESR signal intensity and in the relative value of ac conductivity up to 0.8 mol% of V2O5 doped glasses is due to the predominant presence of V4+ and V3+ ions. Beyond this concentration, the redox ratio V4+/V5+ is found to decrease. By the gradual replacement of B2O3 by V2O5 up to 0.8 mol% the semi conducting nature of the glass network is found to increase due to increase of BO3 structural units beyond this concentration insulating strength of glass matrix is increased.