Serial sectioning methods were used to study bulk and grain-boundary diffusion in 3N8-purity specimens at 1200 to 1400C. The bulk results could be described by:

D (cm2/s) = 8.94 x 100 exp[-66.73(kcal/mol)/RT]

The grain-boundary results, including interface width and adsorption factor, could be described by:

D (cm3/s) = 2.86 x 10-9 exp[-23.82(kcal/mol)/RT]

A.B.Vladimirov, V.N.Kaigorodov, S.M.Klotsman, I.S.Trakhtenberg: Physics of Metals and Metallography, 1978, 45[5], 1015-23 [Russian edition]