Hydrogen behaviors in molybdenum and tungsten and a generic vacancy trapping mechanism for H bubble formation
Hydrogen behaviors in molybdenum and tungsten and a generic vacancy trapping mechanism for H bubble formation
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钼和钨中的氢行为以及 H 气泡形成的通用空位捕获机制
DOI：
10.1016/j.jnucmat.2012.12.008
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发表时间：
2013-03-01
影响因子：
3.1
通讯作者：
Lu, Guang-Hong
中科院分区：
文献类型：
--
作者：
Sun, Lu;Jin, Shuo;Lu, Guang-Hong
本文采用带零点能量修正的第一性原理方法和分子动力学方法研究了氢(H)在钼（Mo）和钨(W)中的俘获行为。发现空位处的H俘获总体上满足“最优电荷密度”规则，单空位在Mo和w的空位中心形成一个H-2分子，同时捕获14h。另一方面，MD模拟表明温度降低了空位处捕获H的数量。我们进一步提出了金属中H泡形成的一般空位捕获机制。H原子首先会饱和空位（或其他空位型缺陷）的内表面，形成一个“屏蔽层”，可以屏蔽进一步被捕获的H与周围金属原子之间的相互作用。这导致在空位中心形成H-2分子，这可以认为是H泡成核的初级阶段。(C) 2012 Elsevier B.V.版权所有
We investigate the trapping behaviors of hydrogen (H) in molybdenum (Mo) and tungsten (W) using a first-principles method with a zero point energy correction as well as the molecular dynamics (MD) method. The H trapping is found to generally satisfy the "optimal charge density" rule at the vacancy, and a monovacancy is shown to simultaneously trap 14 H with a H-2 molecule formed at the vacancy center in both Mo and W. On the other hand, the MD simulation shows the temperature decreases the number of trapped H at the vacancy. We further propose a generic vacancy trapping mechanism for H bubble formation in metals. The H atoms will first saturate the internal surface of the vacancy (or other vacancy-type defects) to form a "screening layer", which can screen the interaction between the further trapped H and the surrounding metal atoms. This leads to the formation of H-2 molecule at the vacancy center, which can be considered as the preliminary stage of H bubble nucleation. (C) 2012 Elsevier B.V. All rights reserved.