Diffusivity in single crystals was measured by using secondary ion mass spectrometry at 2195 to 2461K. The results could be described by:

D (cm2/s) = 4.0 x 100 exp[-137(kcal/mol)/RT]

The results were explained in terms of the Lazarus-LeClaire vacancy mechanism.

S.M.Klotsman, G.N.Tatarinova, A.N.Timofeev: Materials Science Forum, 1987, 15-18, 457-62

The best linear fits to the solute diffusion data ([5] to [25]) yield:

H (sd): Ln[Do] = 1.49E – 21 (R2 = 0.87); W(sd): Ln[Do] = 0.33E – 16.1 (R2 = 0.63)