A simple framework was developed, for the estimation of equilibrium vacancy concentrations in metal-H systems, by using quantum results for vacancy-H cluster energies. The vacancy formation obeyed Fermi-Dirac statistics with regard to various cluster configurations. The presence of H resulted in equilibrium concentrations of vacancies that were many orders of magnitude higher than the thermodynamic vacancy concentration of the pure metal. This was in agreement with observed changes in the kinetics of the host lattice.

Equilibrium Vacancy Concentration in Pd-H Solid Solutions P.Maroevic, R.B.McLellan: Acta Materialia, 1998, 46[15], 5593-7