Wang Yinlong, Wang Canglong, Meng Zhaocang, Liu Jitao, Li Yuhong, Yang Lei
School of Nuclear Science and Technology, Lanzhou University Lanzhou 730000 China
Institute of Modern Physics, Chinese Academy of Sciences Lanzhou 730000 China
RSC Adv. 2021 Oct 27;11(55):34860-34869. doi: 10.1039/d1ra07023a. eCollection 2021 Oct 25.
Titanium beryllide, BeTi, has been proposed as a prospective neutron multiplier in fusion reactors. First-principles calculations have been performed to investigate the nucleation mechanism of a He bubble in bulk BeTi. Meanwhile, the influence of the presence of H atoms on the nucleation of the He bubble, , the synergistic effect of He and H atoms, has also been investigated. It has been found that the He bubble will initially nucleate around a monovacancy (V). When more He atoms have been implanted, two newly induced vacancies (V and V) could be successively observed. The nucleation of the He bubble will occur around the divacancy of VV and the trivacancy of VVV. Dumbbell structures in the He bubble evolve with the number of implanted He atoms and finally disappear. The presence of H atoms will significantly influence the nucleation of the He bubble. It is interesting that some tetrahedral and octahedral structures have also been observed. The maximal number of H atoms trapped by a He bubble has been obtained. These phenomena could be further explained by the continuous shrinking of the isosurface of charge density. The present results provide a microscopic physical foundation to understand the mechanism of He and H atoms retention in neutron multiplier materials. This investigation could be helpful for the design and fabrication of more promising beryllides which could withstand a severe external environment.
铍化钛（BeTi）已被提议作为聚变反应堆中一种潜在的中子倍增剂。已进行第一性原理计算来研究体相BeTi中氦泡的成核机制。同时，也研究了氢原子的存在对氦泡成核的影响，即氦原子与氢原子的协同效应。研究发现，氦泡最初会在单空位（V）周围成核。当注入更多的氦原子时，会相继观察到两个新诱导产生的空位（V和V）。氦泡的成核将发生在VV双空位和VVV三空位周围。氦泡中的哑铃状结构会随着注入氦原子的数量而演变，最终消失。氢原子的存在会显著影响氦泡的成核。有趣的是，还观察到了一些四面体和八面体结构。已得出氦泡捕获氢原子的最大数量。这些现象可以通过电荷密度等值面的持续收缩得到进一步解释。目前的结果为理解中子倍增剂材料中氦原子和氢原子的保留机制提供了微观物理基础。这项研究有助于设计和制造更有前景的、能承受恶劣外部环境的铍化物。
