Nuclear absorption techniques were used to measure the permeation of 119mSn through polycrystalline Pb foils. The delay in the arrival of the radiotracer at the other surface was related to diffusion along an average high-angle grain boundary. This process was described, at 34 to 90C, by:

D (cm2/s) = 1.1 x 10-3 exp[-0.47(eV)/kT]

D.Gupta, D.R.Campbell: Philosophical Magazine, 1980, 42[4], 513-26