A novel kinetic Monte Carlo simulator was developed to investigate hydrogen diffusion in metals and alloys. The results of the hydrogen diffusion coefficients in palladium, silver, and Pd1-xAgx (x ≤ 0.5) were in excellent agreement with experimental results. Two different diffusion sites, Pd-rich diffusion site and Ag-rich diffusion site, were found to be necessary to explain diffusion behaviors of hydrogen in palladium-silver alloys. Detailed analysis clarified that hydrogen atoms preferentially diffused through the palladium-rich region of palladium-silver alloys at low silver concentrations, and that the hydrogen diffusion process at low silver contents was dominated by the jumps in palladium-rich regions. The migration barrier of hydrogen from Pd-rich diffusion site to Ag-rich diffusion site was estimated to be between 0.40 and 0.45eV.

Development of New Kinetic Monte Carlo Simulator for Hydrogen Diffusion Process in Palladium-Silver Alloys. H.Kurokawa, K.Bada, M.Koyama, M.Kubo, A.Miyamoto: Applied Surface Science, 2005, 244[1-4], 636-9