Ionic compounds polarons

The intrinsic electrical conductivity of LiFeP04 is of a polaronic type, as in many ionic compounds. The polaron in the present case is linked to the existence of Fe " ions that maintain the charge neutrality in presence of lithium vacancies. According to the Mott formula, the conductivity a(T) is [116] ... 

There are some (Heinze, 1996) to whom the polaron explanation of the ionic introduction of electronic conductivity in organic compounds is specious The roughness factor of 400 would limit the degree of penetration of ions into the interstices of the polymer. However, Li+ or even CIOJ is of course much smaller than the test molecules (large dye molecules) which are generally used to probe the real area. Thus, one might conceive of a model of the polymer that is all fibers, the intercalation being all pervasive. It is obvious that an Li+ ion adsorbed on the surface of a fiber will promote an electron that may indeed be free to move under a field, i.e., to conduct. 

When electrons and electron holes move through polar compounds, such as ionic oxides, they polarise the neighbouring lattice and thereby cause a local deformation of the structure. Such an electron or electron hole with the local deformation is termed a polaron. The polaron is considered as a fictitious single particle. 

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