The T was introduced into samples by using a nuclear reaction method in order to avoid surface effects. It was found that the results could be described by:

D (cm2/s) = 2.1 x 10-3 exp[-46.6(kJ/mol)/RT]

at temperatures of between 133 and 415C.

W.Kunz, H.Munzel, U.Helfrich, H.Horneff: Zeitschrift fur Metallkunde, 1983, 74[5], 289-93