Measurements were made of Bi diffusion in thin films. The results for the grain boundaries of thin films could be described by:

D (cm2/s) = 2.43 x 10-4 exp[-0.99(eV)/kT]

The grain boundaries in nanocrystalline material had a higher free energy and volume than those of conventional grain boundaries.

H.J.Höfler, R.S.Averback, H.Hahn, H.Gleiter: Journal of Applied Physics, 1993, 74[6], 3832-9