The permeation response of the gases under the influence of an oscillating pressure was determined in order to deduce the diffusion coefficient. The results which were obtained at 673 to 973K by using this method could be described by the expressions:

D:     D (m2/s) = 5.08 x 10-7 exp[-39.6(kJ/mol)/RT]

H:     D (m2/s) = 6.60 x 10-7 exp[-40.4(kJ/mol)/RT]

The isotope dependence of the surface effect was such that equilibration of the gas-phase and the solid-solution occurred more rapidly in the case of H.

Measurement of Permeation of Hydrogen Isotopes Through Nickel by Oscillating Pressure Change. A.Tahara, Y.Hayashi: Journal of the Japan Institute of Metals, 1984, 48[12], 1152-6

Table 100

Parameters for H Isotope Diffusion in

Ni Single Crystals at 670 to 1270K