THEORETICAL CONSIDERATION CONCERNING DIFFUSION-COEFFICIENT MEASUREMENTS BY POTENTIAL STEP CHRONOAMPEROMETRY FOR INSERTION COMPOUNDS

The diffusion coefficient of inserted ions in a host compound is often determined by the potential step method assuming that the induced transitional current shows a Cottrell-type dependency, Theoretically, however, such a dependency does not necessarily hold for the usual setup of measurements, especially when a sample insertion compound has considerable resistivity. In this paper, we derive, as strictly as possible, a theoretical I-t relationship compatible with a situation for usual measurements. The Cottrell equation is a special case of the relationship thus derived.