Short-Range Structural Insight into Lithium-Substituted Barium Vanadate Glasses Using Raman and EPR Spectroscopy as Probes.

Abstract

We present a corroborative study of the structural characterization of lithium-substituted barium vanadate glasses using Raman and electron paramagnetic resonance (EPR) spectroscopy. Investigation of the thermal and physical properties of these glasses showed a gradual increase in the concentration of nonbridging oxygen. Raman and EPR analysis gave an insight into the changing structure of the glasses. Both the spectroscopic techniques confirmed that vanadium is present in the glasses as distorted VO6 octahedra. From the analysis of both spectroscopic techniques, it is proposed that the lithium ion prefers to occupy planar positions of the VO6 octahedra, thus reducing the tetragonal distortion and making the environment around the network-forming unit in the glass matrix more homogeneous as we increase the lithium content. The concentration of V4+ showed a non-monotonic variation with an increase in Li2O as indicated by Raman studies and confirmed by EPR, which indicates a structural change in the distorted VO6 octahedra.