The diffusive behavior of Cu in 4N7-purity material was studied at 890 to 1015C. The results could be described by:

D (cm2/s) = 1.25 x 100 exp[-2.10(eV)/kT]

K.Höhne, R.Sizmann: Physica Status Solidi A, 1971, 5[3], 577-89