Dielectric characteristics of CuO-Na2O-SiO2 glasses with cole-cole plots technique and ac conductivity study

A series of glasses with formula (SiO₂)_{0.7 ? x} (Na₂O)_0.3(CuO) _x with (0.0 ≤ x ≤ 0.20) were prepared and studied by means of ac measurements in the frequency range 20 kHz-10 MHz at room temperature. The study of frequency dependence of both dielectric constant ?′ and dielectric loss ?″ showed a decrease of both quantities with increasing frequency indicating a normal behavior of dielectrics. Cole-Cole plots are drawn with ?′ and ?″. From the Cole-Cole plot parameters like optical dielectric constant, static dielectric constant, average relaxation time, molecular relaxation time are evaluated. Besides, the ac conductivity were analyzed by considering a power relation σ(ω) = A ω ^s (s ≤ 1). The observed behavior of the ac conduction is treated in terms of the quantum-mechanical tunneling (QMT) model.