Ab-initio calculations of the hydrogen–uranium system: Surface phenomena, absorption, transport and trapping

✍ Scribed by Christopher D. Taylor; R. Scott Lillard

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 877 KB
• Volume: 57
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2009.06.055

✦ Synopsis

Density functional theory was applied to the initial steps of uranium hydriding: surface phenomena, absorption, bulk transport and trapping. H adsorbs exothermically to the (0 0 1) surface, yet H absorption into the bulk is endothermic, with off-center octahedral absorption having the lowest absorption energy of 0.39 eV, relative to molecular H 2 . H absorption in interstitial sites causes a local softening of the bulk modulus. Diffusion of H in unstrained a-U has a barrier of 0.6 eV. The energy of H absorption adjacent to the chemical impurities C, S, Si was lowered by an amount proportional to the size of the impurity atom, and the resulting lattice strain Si > S > C. Thus, impurities may promote hydriding by providing surfaces or prestrained zones for H uptake.