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Science and Technology of Nuclear Installations
Volume 2017 (2017), Article ID 6547939, 9 pages
https://doi.org/10.1155/2017/6547939
Research Article

First-Principles Study on Various Point Defects Formed by Hydrogen and Helium Atoms in Tungsten

1Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206, China
2Northwest Institute of Nuclear Technology, Xi’an 710024, China
3School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China

Correspondence should be addressed to Qiang Zhao; nc.ude.upecn@oahzq

Received 2 April 2017; Revised 10 July 2017; Accepted 13 July 2017; Published 7 September 2017

Academic Editor: Eugenijus Ušpuras

Copyright © 2017 Qiang Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The different point defects formed by two hydrogen atoms or two helium atoms in tungsten were investigated through first-principles calculation. The energetically favorable site for a hydrogen atom is tetrahedral interstitial site while substitutional site is the most preferred site for a helium atom. The formation energies of two hydrogen or helium atoms are determined by their positions, and they are not simply 2 times the formation energy of a single hydrogen or helium atom’s defect. After relaxation, two adjacent hydrogen atoms are away from each other while helium atoms are close to each other. The reasons for the interaction between two hydrogen or helium atoms are also discussed.