Conduction in Ionic Materials

For ionic materials, conductivity is equal to the sum of electronic and ionic contributions 

Both cations and anions in ionic materials possess an electric charge and, as a consequence, are capable of migration or diffusion when an electric field is present. Thus, an electric current results from the net movement of these charged ions, which are present in addition to current due to any electron motion. Anion and cation migrations are in opposite directions. The total conductivity of an ionic material o-totai is thus equal to the sum of electronic and ionic contributions, as follows  

Either contribution may predominate, depending on the material, its purity, and temperature. A mobility may be associated with each of the ionic species as follows  

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Funke K, Cramer C, Wihner D (2005) Concept of mismatch and relaxation for self-diffusion and conduction in ionic materials with disordered structures. In Karger J, Heitjans P (eds) Diffusion in condensed matter. Springer, Berlin, pp 857-893... 

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