Diffusion of interstitial hydrogen plays a key role in potential uses for amorphous metals as membranes for hydrogen purification. It was shown how first-principles-based methods could be used to characterize the diffusion of interstitial H in amorphous metals using amorphous Fe3B as an example. The net transport of interstitial H was governed by the transport diffusion coefficient that appears in Fick’s law. This diffusion coefficient was strongly dependent on the interstitial concentration, and was not equal to the self-diffusion coefficient except at dilute interstitial concentrations. Under conditions of practical interest, the concentrations of interstitial H in amorphous metals were non-dilute so methods to determine the transport diffusion coefficient must be used if net mass transport was to be described. It was shown how kinetic Monte Carlo simulations of interstitial H diffusion that used rates derived from first-principles calculations could be used to assess both self- and transport diffusion coefficients of H in amorphous metals. These methods could be helpful in efforts to screen amorphous metal alloys as potential membranes for hydrogen purification.

Self-Diffusion and Macroscopic Diffusion of Hydrogen in Amorphous Metals from First-Principles Calculations. S.Hao, D.S.Sholl: Journal of Chemical Physics, 2009, 130[24], 244705