Towards superior optical and dielectric properties of borosilicate glasses containing tungsten and vanadium ions

Abstract

Transparent glasses of the composition (20–x)V2O5–xWO3–20SiO2–60Li2B4O7, x = 2, 4, 8 and 16 mol %, have been successfully synthesized by a popular melt quenching technique. The main features regarding the structure of these glasses were determined via Fourier transform infrared (FTIR) spectroscopy. The structure change was occurred in the glasses containing 8 and 16 mol% of WO3 which, in turn, decreased non-bridging oxygen (NBO) atoms with further WO3 additions. In addition, the density of these glasses provided higher values with WO3 additions. Optical measurements were achieved through different ranges of wavelength, revealing that the degree of transparency improved, while the absorption decreased, with WO3 additions. Remarkably, the optical transitions of tungsten and vanadium ions embedded in lithium borosilicate glasses were examined. The energy of optical band gaps was decreased by introducing WO3 until 8 mol %, and then increased with further WO3 additions. Furthermore, the conductivity was slightly increased by introducing WO3 until 8 mol %, and then decreased with further WO3 additions, whereas the activation energy demonstrated the opposite behavior with WO3 additions. The dependence of dielectric permittivity, dielectric loss and electrical conductivity on temperatures at varying frequencies was applied. The loss factor revealed a peak that moves towards higher temperature as the frequency increased, indicating the Debye-type relaxation behavior. Finally, the outcomes demonstrated that WO3–V2O5–SiO2–Li2B4O7 glasses are promising optically and electrically tunable materials.