Investigating the influence of barium oxide on bismuth borovanadate glasses: physical, structural, optical, and dielectric properties

Abstract

This study involved the systematic synthesis and characterization of glasses with the nominal composition \(60{\text{V}}_{2} {\text{O}}_{5} - 20{\text{B}}_{2} {\text{O}}_{3} - \left( {20 - {\text{x}}} \right){\text{Bi}}_{2} {\text{O}}_{3} - {\text{xBaO}}\) (x = 0–20 mol%), employing the traditional melt-quench technique. The absence of crystallinity in the synthesized glasses was verified through XRD and SEM analyses. The substitution of elements with higher molecular weights by those with lower molecular weights resulted in a systematic decrease in density (4.08–3.27 \(\frac{{{\text{gm}}}}{{{\text{cm}}^{3} }}\)). A similar trend was observed in various other physical properties, such as molar volume (52.98–46.97 \(\frac{{{\text{cm}}^{3} }}{{{\text{mol}}}}\)), crystalline volume (47.97–43.50 \(\frac{{{\text{cm}}^{3} }}{{{\text{mol}}}}\)), interionic distance (1.20–0.73 \({\text{cm}}^{ - 1}\)), and polaron radius (4.83–2.96 \({\text{cm}}^{ - 1}\)). FTIR and Raman spectroscopic studies showed that the addition of BaO as a modifier dopant causes a structural transformation, converting \({\text{VO}}_{5}\) units to \({\text{VO}}_{4}\) units. \({\text{Bi}}_{2} {\text{O}}_{3}\) exhibited a dual functionality within the glass structure, serving as a modifier in all samples and contributing to network formation at concentrations up to 10 mol%. The optical investigation reveals a non-monotonic dependence of the optical band gap on BaO concentration, characterized by an initial increment up to 10 mol% and a subsequent decrement at higher concentrations (15 and 20 mol%). A analogous trend is observed in the dielectric properties, exhibiting an initial augmentation up to 10 mol% followed by a diminution at higher concentrations. The present glass system exhibits a remarkably high dielectric constant, with values attaining the order of \(10^{10}\). This exceptional dielectric property renders these glasses highly suitable for applications as dielectric layers in capacitor devices, where high energy storage density and efficient charge separation are requisite.