Meyer-Neldel relation

Fig. 7.3. Measured values of the conductivity prefactor a, versus the conductivity activation energy, showing the Meyer-Neldel relation. Data from sever different laboratories are shown (Tanielian 1982).

The Meyer-Neldel relation is a statement that the temperature dependence data for different samples all intersect at the same value of conductivity, Og, at the temperature 7 x 600 K. There is still no completely satisfactory explanation of why this occurs. 

Therefore, within the linear approximation, the conductivity activation energy Eg measures the value of ( tr— )g and the prefactor contains the additional factor exp(y/k). The temperature dependence of the energies accounts for the Meyer-Neldel relation provided that... 

A more detailed analysis of the conductivity data is needed to explain the prefactor and to understand the Meyer-Neldel relation. The magnitudes of Yp and Yg depend on the location of the Fermi energy, the density of states distribution and the thermal state of the material. There are three situations which can be analyzed easily. 

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