Dielectric dispersion and spectroscopic investigations on Na2SO4–B2O3–P2O5 glasses mixed with low concentrations of TiO2

A series of Na2SO4–B2O3–P2O5 glasses doped with different concentrations of TiO2 (0 to 1.0 mol%) have been synthesized. Dielectric properties (over a range of frequency and temperature) and a variety of spectroscopic (optical absorption, IR, Raman and ESR) properties of these glasses have been investigated. The values of dielectric parameters viz., dielectric constant, loss and ac conductivity at any frequency and temperature are observed to increase with the concentration of TiO2. The optical absorption and ESR spectral studies have pointed out that a part of titanium ions do exist in Ti3+ state in addition to Ti4+ state especially in the samples containing higher concentration of TiO2. The increase of dielectric constant with the concentration of TiO2 is explained on the basis of space charge polarization due to increasing concentration of various bonding defects in the glass network. The dielectric relaxation effects exhibited by these glasses are quantitatively analyzed by pseudo Cole–Cole method and the spreading of relaxation times is established. The ac conductivity is observed to increase with increasing content of TiO2, the mechanism responsible for such increase is well explained based on the modifying action of Ti3+ ions.

► The glasses of composition (40 − x)Na2SO4–30B2O3–30P2O5: xTiO2 with 0 ≤ x ≤ 1.0 mol% were synthesized.
► Dielectric and spectroscopic properties were investigated.
► The studies revealed decrease of insulating character of the glass with increase of TiO2 content.