Characterization of Physical and Structural Properties in a Quaternary Li2O-B2O3-Bi2O3-V2O5 Glass System

Borate-based glasses modified with alkali oxides are of considerable interest due to their tunable structural and optical properties, which are important for optical and energy storage applications. In this work, glasses with a novel nominal composition of xLi2O-(75-x) B2O3—20Bi2O3—5V2O5, in which (x ¼ 5, 10, 15, 20, 25 mol %) were produced using the traditional melt-quenching technique to investigate the effect of substituting the glass former B2O3 with the modifier Li2O. The structural and optical properties were examined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and UV—visible spectroscopy. The XRD analysis confirms the amorphous nature of the samples produced. The density increased from 2.955 to 3.499 g/cm3 with increasing Li2O content, while the molar volume decreased, indicating compaction of the borate network due to lithium ions' network-modifying role. Optical investigations demonstrated a shift of the absorption edge towards shorter wavelengths with increasing Li2O content. The optical band gap of lithium-modified borate glasses can be tuned by adjusting the lithium content. The indirect optical band gap values range from 2.13 to 2.52 eV, with a maximum at x ¼ 15 mol %, and the Urbach energy analysis indicated that this mixture exhibited a more homogeneous structure. FTIR analysis confirmed the presence of BO3 and BO4 structural units in the glass, and the addition of Li2O enhanced the asymmetric stretching vibrations of BO3. This study found that Li2O concentration significantly influences the structure, density, and optical properties of borate glasses, with x ¼ 15 mol % regarded as the best composition. Further investigations employing electrochemical methods, such as cyclic voltammetry (CV) and impedance spectroscopy, are recommended to evaluate their practical application and productivity.