Experiments were performed on single crystals at 1073 to 1446K, and the data could be described by:

D (cm2/s) = 1.28 x 103 exp[-4.58(eV)/kT]

The high pre-exponential factor and activation enthalpy could not be attributed to a specific diffusion mechanism.

J.N.Mundy, H.A.Hoff, J.Pelleg, S.J.Rothman, L.J.Nowicki, F.A.Schmidt: Physical Review B, 1981, 24[2], 658-65