The permeation of H through layered samples was studied by performing transient and steady-state measurements and time-lag experiments. The results for temperatures ranging from 270 to 600C were described by:

D (cm2/s) = 7.5 x 10-3 exp[-10.38(kcal/g-atom)/RT]

Hydrogen Diffusion through (Palladium-Silver)-Tantalum-(Palladium-Silver) Composites. G.L.Holleck: Journal of Physical Chemistry, 1970, 74[9], 1957-61