The diffusivity of 110Ag in alumina was studied by using radiotracer methods. It was found that the grain boundary diffusion results could be described by:

D (m3/s) = 9.2 x 10-6 exp[-321(kJ/mol)/RT]

In order to explain the data, it was proposed that there existed a mixed diffusion path in which jumps from structurally unoccupied octahedral sites to Al vacancies were very probable. This was combined with an increased vacancy concentration along grain boundaries.

L.Badrour, E.G.Moya, J.Bernardini, F.Moya: Journal of the Physics and Chemistry of Solids, 1989, 50[6], 551-61