Crystallographic orientation effects of hydrogen diffusion in α-uranium from DFT: Interpreting variations in experimental data

Abstract

Experimental values of hydrogen diffusion coefficients in bulk α-uranium obtained at elevated temperatures have significant scatter, leading to dramatic differences in extrapolated diffusion coefficients at room temperature. Previous density functional theory (DFT) calculations predicted higher diffusion barriers than experiments, suggesting hydrogen diffusion through undefected bulk is not possible. In this manuscript DFT calculations of hydrogen diffusion coefficients as a function of crystallographic orientation in α-uranium are reported. The findings explain previous discrepancies, show that diffusion of hydrogen through bulk uranium is consistent with experiments, and suggest a reasonable value for room temperature diffusion coefficient based on proposed pathway.