A short-range structural insight into lithium substituted barium vanadate glasses using Raman and EPR spectroscopy as probes

TL;DR

This study uses Raman and EPR spectroscopy to analyze how lithium substitution affects the local structure and properties of barium vanadate glasses, revealing changes in vanadium coordination and oxygen environment.

Contribution

It provides new insights into the structural modifications in lithium-doped barium vanadate glasses using combined spectroscopic techniques.

Findings

Vanadium exists as distorted VO6 octahedra in the glasses.

Lithium ions prefer planar positions in VO6 octahedra, reducing distortion.

V4+ concentration varies non-monotonically with lithium content.

Abstract

We present a corroborative study of 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 non-bridging 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 homogenous as we increase 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.