Interfacial polarization effects in ionic conductors

The frequency-dependent dielectric response of a simple model ionic conductor has been calculated using boundary conditions that prevent the passage of itinerant ions to or from the sample. The calculation includes the important effects of local fields which lead to an inductive in-phase response in the absence of blocking, and describes the development of interfacial polarization as the applied frequency is decreased. The work allows for the definition of several characteristic frequencies at which the nature of the response changes, including an inductive to capacitive transition in in-phase response at higher values of conductivity. These features enable a separation of vibrational (intrawell) and hopping (interwell) contributions to be made and also make possible an evaluation of the concentration of conducting ions and an estimate of their relaxation times. A brief application of the results using published data for Ag₄RbI₅, Li₄SiO₄, and vitreous LiNbO₃ is also included.