Criteria for diffusion by a site-interchange mechanism

Criteria are established for evaluating whether self-diffusion in a material may be occurring by a site-interchange diffusion mechanism. The criteria include comparisons between defect formation and migration energies for the site-interchange model and a normal vacancy diffusion model. These criteria are applied to some material systems to illustrate their utility. A siteinterchange diffusion mechanism is probably occurring in lithium niobate, but this mechanism is not operative in silicon carbide or in some III-V compound semiconductors.