The diffusion coefficients of the isotopes in 3N5-purity material were determined by using gas-phase, ion and electrochemical permeation techniques at temperatures of between 240 and 970K. The data could be described by the expressions:

D:     D (m2/s) = 3.35 x 10-8 exp[-0.052(eV)/kT]

H:     D (m2/s) = 3.35 x 10-8 exp[-0.035(eV)/kT]

The results indicated that, although the diffusivity of H in Fe could be expressed by an equation of Arrhenius type, the isotope dependence was not of classical type within the present temperature range.

Y.Hayashi, H.Hagi, A.Tahara: Zeitschrift for Physikalische Chemie, 1989, 164[1], 815-20

Figure 3

Diffusivity of H in Fe