Impedance spectroscopy studies of fresnoites in BaO-TiO₂- SiO₂ system

The electrical properties of the fresnoite BaO-TiO₂-SiO ₂ system were studied over a range of amorphous and crystalline microstructures using as-quenched glass (BTS-gl), partially crystallized glass (BTS-pc, heat treated at 740°C for 100 min) and fully crystallized glass ceramic (BTS-gc, heat treated at 750°C for 180 min). Combination of impedance and moduli plots along with equivalent circuit models were utilized in an attempt to understand the contributions arising from different regions in the glass ceramic, i.e. the glassy matrix, crystalline phase, and crystal-glass interface region. Electrical conductivity of the samples exhibited frequency dispersions at different temperatures suggesting localized motion of ions. The activation energies calculated from dc resistivity-temperature plots (E _dc) and relaxation frequency-temperature plots (E_f) seem to increase as the degree of crystallinity increases suggesting that ionic transport becomes more difficult in crystallized glasses.