Investigation of electric transport in mixed conducting Na2O modified zinc borate glasses for electrode material using broadband dielectric spectroscopy

Abstract

The electrical conductivity of Na2O substituted zinc borate glasses has been studied in the frequency range of 10 mHz to 1 MHz and in the temperature range from 313 to 573 K. The conduction mechanism has been ascertained using the values of the frequency exponent (s) extracted from the fitting of experimental data of the real part of electric conductivity in light of the Almond–West equation. Depending on the glass composition, the ac conduction in the glasses happened via correlated barrier hopping and non-overlapping small polaron tunneling conduction models. The electric modulus studies support the assertion of composition dependent conduction mechanisms. Furthermore, electronic conduction and ionic conduction have been studied from impedance investigations. Equivalent circuit models were used to fit the Nyquist and Bode plots of each sample at the temperatures under consideration. It has been found that the activation energy values calculated from conductivity, electric modulus, and impedance measurements are more or less the same.