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Dielectrical behaviour of Li2O-ZnO-P2O5 glasses

Structural and dielectrical properties of xLi2O- (40-x)ZnO-60P2O5 glasses, (0 ≤ x ≤ 40), in mol%, have been investigated by DTA, Raman and Impedance Spectroscopy in the frequency range from 0.01 Hz to 4 MHz and temperature range from 298 to 473 K. The systematic change in the variety of properties at 20 mol% Li2O is an after effect of changes in the nature of the oxygen bonds in glass network. The Raman spectra show predominantly metaphosphate structure with barely detectable pyrophosphate units in all investigated glasses. The dielectric permittivity and dielectric strength (Δε = εs – ε∞) as a function of Li2O content, measured at lower temperatures, show a minimum at 20 mol% whereas linearly increase at higher temperatures. This suggests that the dielectric properties are directly related to the thermally stimulated mobility of Li+ ions in the high temperature region. However, the anomaly observed at lower temperatures for glass containing 20 mol% Li2O coincides with the minimum in the glass transition temperature, Tg, and glass forming tendency, (Ts= Tx-Tg). These alterations in physical properties of lithium zinc phosphate glassses are related to the discrete restructuring in glass network due to the changes in the nature of the oxygen bonds.

Dielectrical properties ; Lithium phosphate glasses

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