Statistical mechanical calculations were made, of the effects of H-vacancy interactions, by using an energy-level spectrum for decorated vacancies that was deduced from effective-medium calculations. The presence of H atoms led to the generation of large concentrations of vacancies, and this led to a measurable increase in Pd self-diffusion in H-doped crystals. The equilibrium of Pd with H2 gas at increasing pressure led to a large increase in vacancy formation. This was clearly true for total H concentrations of up to 0.1, but its validity at high concentrations was not demonstrated quantitatively.

R.B.McLellan, L.Yang: Acta Metallurgica et Materialia, 1995, 43[6], 2463-7