Effects of ZnO on Dielectric Properties and Electrical Conductivity of Ternary Zinc Magnesium Phosphate Glasses

Five different compositions of the ternary system (ZnO)_x(MgO)₃₀(P₂O₅)_70-x containing 8, 10, 13, 15 and 18 moL% of ZnO were prepared by the melt quenching technique. The complex permittivity studies were presented in the frequency range of 0.01 Hz to 1 MHz and over the temperature range of 303-573 K. The empirical data were analyzed by means of the curve-fitting technique based on Havriliak-Negami model. A small broad dipolar relaxation peak was well described at frequencies between 10³ and 10⁶ Hz within the range of temperatures studied, while at low frequency the spectrum was dominated by dc conduction which was evidence by 1/ω slope in the loss factor versus frequency plot. With increasing ZnO concentration, the dielectric (ε′) and dielectric strength (Δε) both show an increasing trend while the dc conduction behaved in the opposite direction. The excessive zinc ions occupying interstitial position rather than substitutional position among the glass network and increases of the compactness of the glass structure have been suggested to be the reason behind the declining values of the dc conduction.