Descriptions of Junctions Between Electronic and Solid Ionic Conductors

Abstract

From a simple experimental viewpoint an electrode can be defined as a location in a chain of electric conductors where the conductivity changes in nature from an electronic to an ionic conductivity. Figure 1 shows a schematic electrode where the ionic conductivity results from the mobility of A+ ions. The transition can occur either as a discontinuity at a phase boundary or even as a gradual change in a single phase material1. The junctions between electronic and solid ionic conductors belong to this group. The originality in their studies arises mainly from the plurality of the descriptions of solid ionic conductors. They are sometimes considered as electrolytes and treated within the scope of the electrochemical formalism. In many respects they can also be considered as semi-conductors.