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论文类型： 期刊论文

发表时间： 2014-03-01

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

收录刊物： SCIE、EI、Scopus

卷号： 322

页面范围： 34-40

ISSN号： 0168-583X

关键字： First-principles calculation; Helium; Vacancy; Transition metals

摘要： We report an atomistic study of energetics and configurations of He-He pair in vacancy of bcc transition metals (V, Nb, Ta, Cr, Mo, W, and Fe) using first-principles methods. The results show He-vacancy attractions in the group VB metals are 2-3 times weaker than those in Cr, Mo, W and Fe. The < 1 1 1 > dumbbell configuration for He-He pair in vacancy is the most stable except for V. Calculated formation energies of He-He pair in vacancy of group VB metals (3.2-3.95 eV) are systematically lower than those of group VIB and VIIIB metals (4.25-5.67 eV), while He-He distance for V metal is greater than other metals. He-metal repulsion is stronger than He-He due to longer He-metal distance in metal vacancy. Calculated densities of states provide a reasonable explanation for most stable configuration; thus the stability of He-He pairs depends strongly on the electronic structure of the host and insignificantly on its atomic size. Moreover, the group-specific trends of He-He and self-interstitial configurations are discussed. (C) 2014 Elsevier B.V. All rights reserved.