The diffusive behavior of 64Cu in 5N-purity material was studied at 433 to 652C. The results could be described by:

D (cm2/s) = 6.47 x 10-1 exp[-32.27(kcal/mol)/RT]

N.L.Peterson, S.J.Rothman: Physical Review B, 1970, 1[8], 3264-73