Diffusion kinetics for migration by bound vacancy pairs in ionic crystals

In this paper we have adapted the Manning diffusion kinetics formalism in random alloys to produce a corresponding formalism to describe diffusion kinetics in ionic crystals with diffusion mediated by vacancy pairs. Tracer correlation factors are expressed in closed form in terms of the sublattice atom-vacancy pair exchange frequencies and the geometric correlation factor. The results are in good agreement with Monte Carlo simulation results also determined in the present study. It is also demonstrated that each correlation factor can be expressed in terms of the ratio of the tracer diffusion coefficients, thus affording an experimental means under certain doping conditions to gain access to the correlation factors.