Positron simulations of defects in tungsten containing hydrogen and helium
Positron simulations of defects in tungsten containing hydrogen and helium
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DOI：
10.1016/j.nimb.2008.11.045
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发表时间：
2009-02-01
影响因子：
1.3
通讯作者：
Yoshiie, T.
中科院分区：
文献类型：
--
作者：
Troev, T.;Popov, E.;Yoshiie, T.
了解钨中含氢或氦缺陷的行为是一个重要的问题。本文用正电子寿命量子力学模拟方法研究了含氢或氦原子的钨中缺陷的性质。在二分量密度泛函理论的局域密度近似下，得到了电子和正电子的波函数。正电子寿命的计算值与电子密度的大小相关。不含氢或氦的空位团簇是活跃的正电子陷阱。空位周围原子的晶格弛豫减小了有效空位体积，降低了空位处的正电子寿命。氢原子和氦原子被晶格空位和纳米空隙捕获在钨中。据确定，正电子寿命取决于纳米空隙内的气体原子的密度。氢和氦的存在下，在较大的纳米空隙显着降低正电子寿命。(C)2008 Elsevier B.V.保留所有权利。
An understanding of the behavior of defects containing hydrogen or helium in tungsten is an important issue. Here the properties of defects in tungsten containing hydrogen or helium atoms have been investigated by model positron lifetime quantum-mechanical simulations. The electron and positron wave functions have been obtained in the local density approximation to the two-component density-functional theory. The calculated values of the positron lifetime correlate with the magnitude of the electron density. The vacancy-clusters without hydrogen or helium are active positron traps. The lattice relaxation of atoms around vacancy reduces the effective vacancy volume and decrease the positron lifetime at a vacancy. The hydrogen and helium atoms are trapped in tungsten by lattice vacancies and nano-voids. It was established that positron lifetime depends on the density of gas atoms inside the nano-void. Hydrogen and helium presence in the larger nano-voids considerably decrease the positron lifetime. (C) 2008 Elsevier B.V. All rights reserved.