The migration of 57Co across (00•1) Al2O3 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 to treat the experimental results. The Arrhenius plot exhibited a break, at about 900C, in the surface diffusion of 57Co. At higher temperatures, vapor transport appeared to be the predominant diffusion mechanism. At lower temperatures, ionic transport predominated.

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