Electrical conduction in Bi₂O₃-B₂O₃ glassy systems

Five glasses of (Bi₂O₃)_x-(B₂O₃)_1-x, x = 0.06-0.26, have been prepared by melting in an open crucible. The density, thermal analysis and FT-IR spectra were measured. The softening temperature decreased with the bismuth oxide content in the sample. The x-ray diffraction confirmed the amorphous nature for the prepared samples. The molar volume was found to increase with Bi₂O₃ content in the glass matrix. The temperature dependence for the electrical conductivity σ, dielectric constant ε′ and dielectric loss ε″ for these glasses were studied over a temperature range from room temperature to 750 K and frequency from dc to 10⁶ Hz. The mechanism of conduction was found to change with the temperature range of measurements. The electrical conductivity values increased with increasing mol % Bi₂O₃. The ac conductivity increased with frequency according to σ _ac(ω) = Aω ^s, where σ has a value in the range 0.1-0.4 depending on the temperature and composition of the sample. The temperature dependence of the dielectric constant ε′ showed that at relatively lower temperatures the electric dipoles formed in the glasses are frozen and starting to rotate at the softening temperature of the glass. Each of ε′ and ε″ was found to be dependent on the glass composition. The dielectric behaviour could be described according to the Debye-model for all results have been discussed and correlated together.