Dielectric and conductivity relaxation in AgI doped silver selenite superionic glasses

Abstract

Non-Debye relaxation in superionic AgI–Ag2O–SeO2 glasses has been investigated as a function of frequency and temperature. The experimental data have been analyzed in the framework of complex dielectric permittivity and complex electric modulus formalisms. The dielectric permittivity data have been well interpreted using the Havriliak–Negami function. The electric modulus data have been analyzed by invoking Kohlrausch–Williams–Watts function and various parameters describing the relaxation mechanism have been obtained. The temperature and compositional variation in relaxation times and the activation energy, obtained from dielectric permittivity as well as from electric modulus data, have been compared. The low value of stretched exponential parameter implies a highly nonexponential nature of relaxation and is attributed to the correlated ionic motion. The values of the stretched exponential parameter are observed to be independent of temperature as well as composition. Different scaling formalisms have been applied to understand the temperature and compositional dependence of the relaxation mechanism. The scaling of dielectric loss spectra and electric modulus spectra results in master curves, which signifies that the relaxation mechanism is independent of temperature as well as composition.