MODEL FOR IMPEDANCE OF A SOLID IONIC CONDUCTOR SANDWICHED BETWEEN BLOCKING ELECTRODES

The simplest model for the impedance of an ionic conductor sandwiched between two blocking electrodes is a resistor in series with a capacitor (rc pair) representing the bulk material and the conductor-electrode interface, respectively, and a second capacitor parallel to the rc pair representing the electronic dielectric response of the system. In practice, to describe the experimental data satisfactorily, one needs to replace the interface capacitor with a constant-phase-angle (CPA) element and to add a non-Debye dielectric element parallel to the resistor to represent the local ionic movement. In this paper, some of the existing physical models for the CPA and non-Debye dielectric elements are discussed, and an example is presented for analyzing the impedance data using the resultant circuit model.