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

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 de-
gree 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 tem-
peratures at varying frequencies was applied. The loss factor revealed a peak that moves towards higher tem-
perature 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.