Probing hydrogen interactions with amorphous metals using first-principles calculations

Abstract

Amorphous metals are interesting candidates for use as H(2) purification membranes and occur in some applications of H(2) storage. We introduce a general strategy combining density functional theory and statistical mechanics for quantitatively predicting the properties of interstitial H in amorphous metals. We systematically investigate H solubility in amorphous Fe(3)B, comparing our results with ones for a crystalline material with the same composition. H-H interactions in the amorphous material play a crucial role in determining the net solubility. H solubility in the amorphous and crystalline materials differs by orders of magnitude under conditions relevant for practical H(2) purification membranes. Our results give atomic-level insight into the properties of H in amorphous metals that has not been previously available.

First‐principles investigation of chemical stability and proton conductivity of M‐doped BaZrO3 (M=K, Rb, and Cs)

“…We used one Ba 2+ ion in 2×2×2 unit cells doped by a monovalent dopant, M + , in our calculations. We utilized a quasi‐Newton optimization to find transition states based on initial configurations close to a true transition state . This approach saved computational time and resources, as we did not need the intermediate images (coordinates) required in the Nudged Elastic Band (NEB) method.…”

A semi-empirical methodology to predict hydrogen permeability in amorphous alloy membranes

“…As the hydrogen content increases only sites of relatively high energy states would be available, and it would be more and more difficult to increase the hydrogen solubility with an equal amount of increase of hydrogen pressure. It should be mentioned here that hydrogen-hydrogen interactions can be repulsive at higher hydrogen concentrations [40,41], which may be another reason for the decreased slope in Fig. 1b and c. The extent of increment of hydrogen solubility in the Cu 65 Zr 35 alloy is gentler at low pressures than that in the Cu 50 Zr 50 alloy, which can be explained by the decrease of hydrogen solubility with increasing …”

Characterizing chemical stability and proton conductivity of B-site doped barium hafnate (BaHfO3) and barium stannate (BaSnO3) with first principles modeling

“…Instead of performing Nudged Elastic Band (NEB) calculations, which were used in other theoretical studies to find the transition states for proton transfer and rotation, an efficient way to find the transition states is employed [26][27][28]. When the initial estimated proton position at a transition state is close enough to its true value, this position tends toward the saddle point during a quasi-Newton optimization [26].…”