The dependence of the hydrogen concentration in metals on the surface impurities

Abstract

In a recent paper we have shown that there is a difference in the concentration of hydrogen set up in a metal when it is exposed to a flux of atomic hydrogen as compared to the same flux of molecular hydrogen. Whereas in the case of molecular hydrogen one reaches an equilibrium situation in which the resulting concentration is a bulk property given by Sievert's law totally independent of the condition of the surface, in the case of an atomic flux the resulting steady state concentration becomes a surface dependent property governed to a large extent by the condition of the surface and the resulting surface potentials. In this paper I extend the model to the more realistic case of energetic hydrogen atoms which are implanted into the metal and discuss the consequences. Furthermore, I compare the interaction of the plasma with metals to electrolytic hydrogen charging and point out the similarities. Also in this case, due to surface impurity layers, one obtains high concentrations of hydrogen.