The diffusion of 64Cu was studied, in 4N8-purity single crystals, under various hydrostatic pressures. The results for 206 to 326C could be described by:

1.75kbar:     D (cm2/s) = 9.5 x 10-3 exp[-8.8(kcal/mol)/RT]

3 to 9kbar:     D (cm2/s) = 6.18 x 10-2 exp[-10.9(kcal/mol)/RT]

A.Ascoli, G.Poletti: Physical Review B, 1972, 6[10], 3681-4