Ab initio study of H and He migrations in β-phase Sc, Y, and Er hydrides
Ab initio calculations based on the density functional theory have been performed to investigate the migrations of hydrogen (H) and helium (He) atoms in {beta}-phase scandium (Sc), yttrium (Y), and erbium (Er) hydrides with three different ratios of H to metal. The results show that the migration mechanisms of H and He atoms mainly depend on the crystal structures of hydrides, but their energy barriers are affected by the host-lattice in metal hydrides. The formation energies of octahedral-occupancy H (H{sub oct}) and tetrahedral vacancy (V{sub tet}) pairs are almost the same (about 1.2 eV). It is of interest to note that the migration barriers of H increase with increasing host-lattice atomic number. In addition, the results show that the favorable migration mechanism of He depends slightly on the V{sub tet} in the Sc hydride, but strongly on that in the Y and Er hydrides, which may account for different behaviours of initial He release from ScT{sub 2} and ErT{sub 2}.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1044477
- Report Number(s):
- PNNL-SA-84583; AT6020100; TRN: US201214%%452
- Journal Information:
- Chinese Physics B, Vol. 21, Issue 5
- Country of Publication:
- United States
- Language:
- English
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