Dielectric dispersion in PbO-$Bi_2O_3-B_2O_3$ glasses mixed with $TiO_2$

Özet

$[(PbO)_{0.20-x}(Bi_20_3)_{0.40}]:(Ti0_2)x$, $0.0 \leq x\leq 0.02$ glasses were prepared. Dielectric properties (dielectric constant $\varepsilon^{\prime}$, loss tan $\delta$ 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 $TiO_2$ concentration is >0.8 mol% in the glass matrix. The optical absorption spectra of these glasses exhibited bands due to $Ti^{3+}$ ions in the visible region. ESR spectral studies have also indicated that a fraction of $Ti^{4+}$ ions reduced to $Ti^{3+}$ ions. IR spectra of these glasses exhibited bands due to $TiO_4$ and $TiO_6$ structural units. Quantitative studies indicate that as concentration of $TiO_2$ is increased to 0.8 mol% in the glass matrix, a large proportion of titanium ions exist in $Ti^{3+}$ state and has influenced the physical properties of these glasses to a substantial extent.