Dielectric Dispersion in PbO-Bi2O3-B2O3 Glasses Mixed with TiO2

[(PbO)(0.20-x)center dot(Bi2O3)(0.40)center dot(B2O3)(0.40)]:(TiO2)(x), 0.0 <= x <= 0.02 glasses were prepared. Dielectric properties ( dielectric constant epsilon ', loss tan d and a.c. conductivity sigma(ac), over a wide range of frequency and temperature), optical absorption, ESR and IR spectra of these glass materials have been investigated. The dielectric study has revealed that the glasses possess high insulating strength when TiO2 concentration is >0.8 mol% in the glass matrix. The optical absorption spectra of these glasses exhibited bands due to Ti3+ ions in the visible region. ESR spectral studies have also indicated that a fraction of Ti4+ ions reduced to Ti3+ ions. IR spectra of these glasses exhibited bands due to TiO4 and TiO6 structural units. Quantitative studies indicate that as concentration of TiO2 is increased to 0.8 mol% in the glass matrix, a large proportion of titanium ions exist in Ti3+ state and has influenced the physical properties of these glasses to a substantial extent.