INTERFACES IN SOLID IONIC CONDUCTORS - EQUILIBRIUM AND SMALL-SIGNAL PICTURE

The interface of an ionic conductor to a solid neighbouring phase is considered. First the equilibrium picture is presented. The interface is divided into core and space charge region. It is assumed that the materials parameters, such as defect standard potentials and defect mobilities, behave as step functions. The interaction with an insulator or a parent metal as second phases is briefly discussed. On the basis of the equilibrium picture the interfacial impedance is modelled in a novel manner. The interfacial resistance is derived analytically and an exact method is proposed to calculate the space charge capacitance. In the experimental part a new impedance technique is presented: It is especially sensitive to interfacial responses and allows for scanning of the electrical properties from the boundary to the bulk by changing the frequency.