Diffusivity for diffusion between e and g interstitial sites in the C15 AB₂ structure

An exact algebraic expression is derived for the diffusivity for diffusion between interstitial e and g sites in cubic C15 Laves phase AB₂ in terms of four jump rates between interstitial sites. The result is for the low concentration limit of diffusing atoms and is valid for arbitrary positions of the e and g sites. The expression reduces to simple forms in some special cases. Some examples of diffusion of H in C15 intermetallic compounds are discussed.