Electrochemical measurements were made of H permeation through multi-layers on Pd substrates. A marked retardation of the permeation was observed at low H contents. In order to decide whether this effect was due to special interface-H states, permeation was modelled on the basis of the bulk properties of the pure metals. This model was able to explain the retardation; which arose from the different free energies of H dissolution in the 2 metals. At higher H contents, a more complicated permeation behavior was observed, and was not yet understood.

Diffusion of Hydrogen through Metallic Multilayers. G.Schmitz, P.Kesten, R.Kirchheim, Q.M.Yang: Physical Review B, 1998, 58[11], 7333-9