Quantitative impedance analysis of solid ionic conductors: Effects of electrode polarization

The dependence of impedance spectra on temperature and sample thickness are analyzed for AgAsS2 as a case example. Using the scaling properties of complex conductivity with thickness and temperature, we discuss the bulk and interfacial properties of the materials. Important physical parameters such as the number of mobile ions, diffusion coefficient in the bulk, and interface are deduced. The influence of the thickness of the sample on conductivity behavior is also discussed. A significant electrode polarization effect is observed even for a low number of localized (accumulated) ions (≈2 × 1017 cm−3) near the interface, which is significantly lower than the number of mobile ions (≈8 × 1021 cm−3) in this test material. The presented analytical method can be widely applied to potentially important ionic conducting systems.