Hits:

Indexed by:期刊论文

Date of Publication:2013-09-01

Journal:Conference on Nuclear Materials (NuMat)

Included Journals:SCIE、EI、CPCI-S

Volume:440

Issue:1-3

Page Number:557-561

ISSN No.:0022-3115

Abstract:Using first-principles methods, we have investigated the microscopic mechanism for He trapping in two kinds of vacancy defects (monovacancy and 9-atom void) inside vanadium host lattice. In the monovacancy, single He prefers to occupy the octahedral site near vacancy rather than vacancy center. Inside vacancy defects, the He-He equilibrium distances range in 1.6-2.2 angstrom. After more He atoms are incorporated, the magnitude of trapping energy decreases and the host lattice expand dramatically. A monovacancy and 9-atom void can host up to 18 and 66 He atoms, respectively, with internal pressure up to 7.5 and 19.3 GPa. The atomic structures of selected He clusters trapped in vacancies are compared with the gas-phase clusters. The strong tendency of He trapping at vacancies and 9-atom voids provides an explanation for experimentally observed He bubble formation at vacancy defects in metals. (C) 2013 Elsevier B.V. All rights reserved.