Influence of WO₃ on dielectric properties of zinc phosphate glasses

Abstract

Dielectric constant ɛ', loss tan δ and a.c conductivity σ_a.cof 40 ZnO-xWO₃-(60-x) P₂O₅ (with 0 ≤ x ≤ 15) glasses are studied as a function of frequency (in the range 10²-10⁵ Hz) and temperature (range 30-300°C). The dielectric breakdown strengths of these glasses are also measured in the air medium. All the dielectric parameters (viz., ɛ', tan δ and σ_a.c) are found to decrease with the increase in the concentration of WO₃. Dielectric loss variation with the temperature for the glasses containing WO₃up to 5 mol % exhibited dipolar relaxation effects. These effects are analysed by a pseudo Cole-Cole plot method. The dielectric breakdown strength, the activation energy for a.c conduction are found to decrease with increase in concentration of WO₃. These results have been used to throw some light on the structural change in ZnO-WO₃-P₂O₅ glass system with the aid of data on IR spectra and differential thermal analysis of these glasses.