Permeation methods and mass spectroscopy were used to determine H diffusion coefficients in 3N-purity single crystals and polycrystals. The diffusion coefficients (table 88) were independent of the H concentration and could be summarised, for temperatures of between 400 and 1200, by:

D (cm2/s) = 2.0 exp[-17.8(kcal/mol)/RT]

A.P.Kakharov, V.M.Sharapov, E.I.Evko: Fiziko-Khimicheskaya Mekhanika Materialov, 1973, 9[2], 29-33

Table 88

Diffusivity of H in Mo