Vacancy trapping mechanism for multiple hydrogen and helium in beryllium: a first-principles study
Vacancy trapping mechanism for multiple hydrogen and helium in beryllium: a first-principles study
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DOI：
10.1088/0953-8984/24/9/095004
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发表时间：
2012-03
期刊：
影响因子：
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通讯作者：
Pengbo Zhang;Jijun Zhao;B. Wen
中科院分区：
文献类型：
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作者：
Pengbo Zhang;Jijun Zhao;B. Wen
用第一性原理计算研究了Be基质晶格中空位缺陷和气泡形成对H和He的捕获机制。单个He原子倾向于占据空位中心，而H原子则不然。他能比H更容易地从间隙部位向空位分离。H和He都表现出较低的扩散障碍，从一个远程间隙到一个空缺，就他们的扩散障碍内一个完美的Be固体。单空位空间最多可容纳5个H或12个He原子，且Be-He相互作用比Be-H弱得多。进一步讨论了空位中多个H或He原子聚集的物理根源。H和He在空位处捕获的强烈倾向为实验中在材料的空位缺陷处观察到H和He气泡提供了解释。因此，我们认为，空位提供了一个主要的成核位置的气泡内的H和He气体的材料。
The microscopic mechanism for H and He trapping by vacancy defects and bubble formation in a Be host lattice is investigated using first-principles calculations. A single He atom prefers to occupy a vacancy centre while H does not. He can segregate towards the vacancy from the interstitial site much more easily than H. Both H and He exhibit lower diffusion barriers from a remote interstitial to a vacancy with regard to their diffusion barriers inside a perfect Be solid. Up to five H or 12 He atoms can be accommodated into the monovacancy space, and the Be–He interaction is much weaker than Be–H. The physical origin for aggregation of multiple H or He atoms in a vacancy is further discussed. The strong tendency of H and He trapping at vacancies provides an explanation for why H and He bubbles were experimentally observed at vacancy defects in materials. We therefore argue that vacancies provide a primary nucleation site for bubbles of H and He gases inside Be materials.