The migration of 57Co across (00•1) surfaces was investigated by using the edge source method. The surface diffusion parameter, D, where  was the segregation factor, D was the surface diffusion coefficient, and  was the thickness of the high-diffusivity layer, was determined at temperatures ranging from 750 to 1200C. The Whipple solution was used for treating the experimental results. The Arrhenius plot exhibited a break, at about 900C, in the surface diffusion of 57Co upon the (00•1) plane. At higher temperatures, vapor transport appeared to be the predominant diffusion mechanism. At lower temperatures, ionic transport predominated. The apparent activation energy for ionic transport was calculated to be 120kJ/mol.

E.P.Macey, V.S.Stubican: Journal of the American Ceramic Society, 1993, 76[2], 557-9