The migration of 57Co across (110) 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. Ionic transport predominated over the entire temperature range. This was explained in terms of a weak bond between Co-vapor species and the NiO surface. The results suggested that the surface diffusion of Co2+ ions on NiO at 750C was some 7 orders of magnitude faster than volume diffusion while, at 1200C, it was some 5 orders of magnitude faster than volume diffusion. The activation energies were 139 and 227kJ/mol, for surface and volume diffusion, respectively.

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