Correlation factors for Si diffusion by a vacancy mechanism in the Si sub-lattice of the tetragonal MoSi2 structure were calculated by combining an analytical and a Monte Carlo approach. The ratio of the Si diffusivity perpendicular to the tetragonal axis to that parallel to the tetragonal axis was also deduced. An effect of forward correlation of tracer atom jumps in the Si sub-lattice with the corresponding partial correlation factor of 1.5 appears at small frequencies of Si atom jumps along the tetragonal axis with respect to the jump frequencies in the Si layer perpendicular to the tetragonal axis of the MoSi2 structure. The anisotropy of Si diffusion in MoSi2 measured by Salamon et al. was explained in terms of correlation effects of Si diffusion on its own sub-lattice.

Silicon Diffusion in Molybdenum Disilicide - Correlation Effects. S.Divinski, M.Salamon, H.Mehrer: Philosophical Magazine, 2004, 84[8], 757-72