Einstein-Townsend relation

The concepts of ionic mobility ui, m /s-V) and effective ionic mobility ( f, m /s-V) are introduced as representative parameters of electromigration (ionic migration). The effective ionic mobility defines the velocity of the ionic species under the effect of a unit electric field, which can be theoretically estimated using the Nemst-Townsend-Einstein relation (Holmes, 1962). Ionic mobility is related to the ionic valence (z,) and molecular diffusion coefficient (Z) m /s) of species as follows ... 

The term K, called the mobility coefficient, like the diffusion coefficient D, is unique at a fixed temperature for a given combination of an ion and neutral gas molecules of the supporting atmosphere. The relation between the diffusion coefficient and weak-fleld ion mobility shown in Equation 10.5, known as the Einstein equation, and is sometimes called the Nemst-Townsend relationship ... 

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