Influence of WO3 on dielectric properties of zinc phosphate glasses

Dielectric constant epsilon', loss tan delta and a.c conductivity sigma (a.c.) of 40 ZnO-xWO(3)- (60-x) P2O5 (with 0 less than or equal to x less than or equal to 15) glasses are studied as a function of frequency (in the range 10(2)-10(5) Hz) and temperature (range 30-300 degreesC). The dielectric breakdown strengths of these glasses are also measured in the air medium. All the dielectric parameters (viz., epsilon', tan delta and sigma (a.c.)) are found to decrease with the increase in the concentration Of WO3, Dielectric loss variation with the temperature for the glasses containing WO3 up 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.