Interaction between impurity nitrogen and tungsten:a first-principles investigation  

作　　者：Liu Yue-Lin Jin Shuo Zhang Ying 刘悦林;金硕;张颖(Department of Physics,Yantai University,Yantai 264005,China;Department of Physics,Beijing University of Aeronautics and Astronautics,Beijing 100191,China)

机构地区：[1]Department of Physics,Yantai University,Yantai 264005,China [2]Department of Physics,Beijing University of Aeronautics and Astronautics,Beijing 100191,China

出　　处：《Chinese Physics B》2012年第1期346-351,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.50871009 and 51101135);the National Magnetic Confinement Fusion Program,China(Grant No.2009GB106003)

摘　　要：We investigate the stability, diffusion, and impurity concentration of nitrogen in intrinsic tungsten single crystal employing a first-principles method, and find that a single nitrogen atom is energetically favourable for sitting at the octahedral interstitial site. A nitrogen atom prefers to diffuse between the two nearest neighboring octahedral interstitial sites with a diffusion barrier of 0.72 eV. The diffusion coefficient is determined as a function of temperature and expressed a.s D（N） = 1.66 ~ 10-7 exp（-O.72/kT）. The solubility of nitrogen is estimated in intrinsic tungsten in terms of Sieverts＇ law. The concentration of the nitrogen impurity is found to be 4.82 ~ 10-16 /~ 3 at a temperature of 600 K and a pressure of 1 Pa. A single nitrogen atom can easily sit in an off-vacancy-centre position close to the octahedral interstitial site. There exists a strong attraction between nitrogen and a vacancy with a large binding energy of 1.40 eV. We believe that these results can provide a good reference for the understanding of the behaviour of nitrogen in intrinsic tungsten.We investigate the stability, diffusion, and impurity concentration of nitrogen in intrinsic tungsten single crystal employing a first-principles method, and find that a single nitrogen atom is energetically favourable for sitting at the octahedral interstitial site. A nitrogen atom prefers to diffuse between the two nearest neighboring octahedral interstitial sites with a diffusion barrier of 0.72 eV. The diffusion coefficient is determined as a function of temperature and expressed a.s D（N） = 1.66 ~ 10-7 exp（-O.72/kT）. The solubility of nitrogen is estimated in intrinsic tungsten in terms of Sieverts＇ law. The concentration of the nitrogen impurity is found to be 4.82 ~ 10-16 /~ 3 at a temperature of 600 K and a pressure of 1 Pa. A single nitrogen atom can easily sit in an off-vacancy-centre position close to the octahedral interstitial site. There exists a strong attraction between nitrogen and a vacancy with a large binding energy of 1.40 eV. We believe that these results can provide a good reference for the understanding of the behaviour of nitrogen in intrinsic tungsten.

关 键 词：TUNGSTEN NITROGEN DIFFUSION FIRST-PRINCIPLES 

分 类 号：O483[理学—固体物理]