Grain boundary diffusion of the tracer in small-grained samples was studied at 760 to 1170K. It was found that the results could be described by:

D (cm2/s) = 3.35 x 10-1 exp[-170.8(kJ/mol)/RT]

A.R.Paul, M.C.Naik, K.N.G.Kaimal: Physica Status Solidi A, 1991, 128[1], 9-19