Optical, magnetic and dielectric properties of CaO-B2O3-V2O5 glasses

Abstract

In this present study, glass materials belonging to the CaO-B₂O₃-V₂O₅ system with different concentrations of V₂O₅ were elaborated using the melt-quenching process. The main aim of this paper is to investigate the optical, magnetic and dielectric characteristics of these vitreous materials, and thus determine the impact of vanadium oxide. The optical parameters of the elaborated glassy samples, including the cut-off wavelength, band gap, Urbach energy, refractive index and molar refraction, are investigated in this work. The observed variations in cut-off wavelength, gap energy and refractive index indicated an increase in non-bridging oxygen atoms (NBO) with increasing V₂O₅ content, which results in the conversion of BO₃ to BO₄ units. Urbach's energy values indicate that the glass samples with a higher vanadium content exhibit a more stable and uniform glass structure. The introduction of V₂O₅ increased the refractive index and molar refraction. Furthermore, the magnetic properties revealed the paramagnetic behavior for all the glasses studied. Diamagnetic behavior at higher temperatures was also observed for two glasses, CBV1 and CBV2, as the content of V₂O₅ decreased. The transition from diamagnetic to the paramagnetic state observed for CBV1 and CBV2 indicates the transformation of V⁵⁺ to V⁴⁺. The dielectric parameters of glass samples CBV2 and CBV3 increase at higher temperatures, with CBV3 exhibiting a transition between the ferroelectric and the paraelectric phases. Moreover, the study of conductivity reveals the semiconducting nature of the studied glasses. The activation energy decreased with rising vanadium oxide content.