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Indexed by:期刊论文

Date of Publication:2013-05-15

Journal:NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

Included Journals:SCIE、EI

Volume:303

Page Number:75-80

ISSN No.:0168-583X

Key Words:Vanadium; Hydrogen; Helium; Vacancy

Abstract:Using first-principles calculations, we investigate the stability and energetics of H-He-vacancy complexes and He-He/He-H/H-H interactions in bulk vanadium to explore the synergetic effect of H and He impurities with vacancy. Inside vacancy space, He prefers to occupy octahedral site rather than vacancy center, different from of the cases of bcc Fe and W. Equilibrium He-H (2.33 angstrom) and H-H (2.45 angstrom) distances in the vacancy are longer than He-He distance (1.75 angstrom) and they exhibit a weak attraction. One He-vacancy complex can trap up to five H atoms and the stable configurations with different amount of trapped H atoms are discussed in details. If a He atom occupies vacancy center, formation of H-2 molecule in the He-vacancy complex is almost impossible. Moreover, formation energy of a new vacancy around the H-He-vacancy complex does not remarkably reduce with increasing number of H atoms. We thus suggest that creation of a new vacancy around the He-complex via H aggregation is thermodynamically difficult. (C) 2012 Elsevier B.V. All rights reserved.