Effect of Bi3+ on the physical, mechanical, and dielectric properties of cadmium silicate glasses for energy storage devices.

Glasses with the composition of (60 - X)CdO-XBi2O3-40SiO2 (X = 0, 7.5, 15, and 30 mol%) were synthesized by melt-quenching. Their physical properties and FTIR spectra confirmed that the network strength weakened with the increase in CdO substitution by Bi2O3. The incorporation of Bi2O3 disrupts Si-O-Si bonds, forming non-bridging oxygen atoms that increase the molar volume and reduce the packing density. Dielectric spectra (0.1 Hz-10 MHz and 30-150 °C) showed increased permittivity and dielectric loss with Bi2O3 addition, strong frequency/temperature dependence, and thermally activated mid-frequency relaxations. The AC conductivity increased with the frequency: gradually (0.1-10 Hz), moderately (10 Hz-100 kHz), and sharply (1-10 MHz). The permittivity ranges are 18-27 (X = 0), 17-45 (X = 7.5), 17-55 (X = 15), and 24-65 (X = 30), with maxima at 0.1 Hz and over a temperature range of 30-150 °C. Doped samples exhibited conductivity shoulders coinciding with loss peaks. Mechanical moduli and microhardness decreased with Bi2O3 addition, confirming network softening. These glasses combined high dielectric performance and thermal stability, with potential for reprocessing, making them suitable for power-electronics components used in applications such as electric mobility, solar inverters, and wind-turbine converters.