Ionic conduction and dielectric relaxation of the superionic conductor Ag 2HgI 4

Abstract

Complex conductivity spectra of Ag 2HgI 4 in the radio and microwave frequency range reveal distinctive features separating the ionic conducting α-phase from electronic conducting β-phase. In the α-phase, a power law conductivity spectrum, a relaxation-like permittivity spectrum, together with thermal activation effects, are indicative of hopping transport with a distribution of hopping times. Single-particle kinetics are thought to play a dominant role in the long time scale since many of the observed structures can be explained by a model based on jump diffusion. In the β-phase, a non-dispersive permittivity and the lack of thermal activation effects suggest that the observed response is the long-wavelength tail of an infrared vibrational mode.