Application of electrical conductivity for determining the chemical diffusivity in transition-metal compounds

Electrical conductivity is a very convenient means for determining chemical diffusivity in transition metal compounds. Misinterpretation may however occur about its actual significance in such nonequilibrium measurements. A detailed analysis is provided here about the application of electrical conductivity and the development of specific diffusion models in regard to Wagner's theory. One major exception is the simultaneous diffusion of both cations and anions within their respective sublattices. Results on two typical oxides, TiO₂ and CoO, are briefly discussed.