The Green’s function technique was used to determine the isothermal transient ionic current caused by the application of a constant potential across an ion conductor which initially contained the ions under consideration. The analysis included migration, diffusion, and space-charge effects as contributions to the ionic motion. Furthermore, the relative importance of diffusion and space-charge effects as current limiters was

investigated. It was found that ion concentrations as low as some 1016 to 1017/cm3 were sufficient to make space-charge effects the dominant contribution to the decay of the isothermal transient ionic current at low applied electric fields (about 104V/cm). It was concluded that such effects should be taken into consideration when the isothermal transient ionic current method was used to determine conduction parameters.

Theoretical Derivation of the Isothermal Transient Ionic Current in an Ion Conductor - Migration, Diffusion and Space-Charge Effects. G.Frenning, M.Strømme: Journal of Applied Physics, 2001, 90[11], 5570-5