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 ran ge 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. A ll the dielectric parameters (viz., epsilon', tan delta and sigma (a.c.)) a re found to decrease with the increase in the concentration Of WO3, Dielect ric loss variation with the temperature for the glasses containing WO3 up t o 5 mol % exhibited dipolar relaxation effects. These effects are analysed by a pseudo Cole-Cole plot method. The dielectric breakdown strength, the a ctivation 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 t he structural change in ZnO-WO3-P2O5 glass system with the aid of data on I R spectra and differential thermal analysis of these glasses.