Impedance Spectroscopy on Solid State Electrochemical Sensors and Devices: Potentials and Pitfalls

In this contribution recent exemplary applications of impedance spectroscopy in characterization of solid state electrochemical devices will be presented. Serial electrical and electrochemical processes, each modeled as a RC parallel element, can be most successfully distinguished in conventional impedance plane representation, where the associated capacitance values are different by orders of magnitude. In the presence of short-circuiting grain boundary phase in Mg-Zr-O-N specimens, micro-contact impedance spectroscopy is employed to extract the bulk crystal conductivity. Ionic conduction responsible for the leakage current in CaF₂ thin films on Si substrates can be unambiguously revealed by modulus spectroscopy. A general transmission line model is applied to describe a model mixed ionic and electronic conductor Ag₂S with semi-blocking electrode conditions.