Research had suggested that diffusion via vacancy-pairs could make an important contribution to cation diffusion in fluorite-related oxides, such as yttria-stabilized zirconia. A combination of analytical development and Monte Carlo computer simulation was used here to analyze various diffusion correlation effects for cation and oxygen ion diffusion via tightly bound vacancy-pairs in the fluorite structure. It was shown that the application of sum-rule relationships provided exact expressions for the collective correlation functions. It was also shown that a formalism inspired by the Manning diffusion kinetics formalism gave accurate expressions for tracer correlation factors when tested against Monte Carlo simulation results. It was also shown that the tracer correlation factors followed the impurity-form, thereby simplifying an interpretation of the diffusion isotope effect.

Correlation Effects for Cation Diffusion via Vacancy-Pairs in Fluorite-Related Oxides. I.V.Belova, D.Samuelis, M.Martin, G.E.Murch: Philosophical Magazine, 2006, 86[23], 3559-67