Conductivity and defect concentrations

If the total conductivity of a material is made up of contributions from cations, anions, electrons, and holes, equations such as (6.1), for ionic conductivity, must be extended to include the electronic defects  

O — Ocation T Oanion T O electrons T Ofooles = ca 5rap,a + ccqc[Lc + csqe xe + ch hFh 

The fraction of the conductivity that can be apportioned to each charge carrier, its transport number, is defined by 

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