First-principles study on dissolution and diffusion properties of hydrogen in molybdenum
First-principles study on dissolution and diffusion properties of hydrogen in molybdenum
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氢在钼中溶解和扩散特性的第一性原理研究
DOI：
10.1016/j.jnucmat.2010.06.029
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发表时间：
2010-09-15
影响因子：
3.1
通讯作者：
Luo, G. -N.
中科院分区：
文献类型：
--
作者：
Duan, Chen;Liu, Yue-Lin;Luo, G. -N.
采用第一性原理方法，研究了氢(H)在钼（Mo）中的溶解和扩散特性，钼是核聚变托卡马克中面向等离子体材料的潜在候选者之一。结果表明，相对于八面体间隙位和对角线间隙位，单H原子在能量上更有利于位于四面体间隙位。这可以通过电子局域化函数的结果得到证实。Bader电荷分析表明，H与周围Mo之间的键合以离子为主，并伴有少量的共价成分。双H原子倾向于沿（11 - 10）方向在相邻的两个TIS上配对，距离约为0.221 nm，结合能为0.03 eV。这表明氢原子之间存在弱吸引相互作用，这意味着氢的自捕获和H-2分子的形成在本征Mo环境中是相当困难的。结果表明，在典型的600 K温度下，H在ti之间跳跃的扩散势垒为0.16 eV， H在本征流中的溶解浓度为2.6 × 10（-8）。H、D、T的扩散系数因质量不同而不同，分别为1.3 × 10(-7) m(2)/s、9.2 × 10(-8) m(2)/s和7.5 × 10(-8) m(2)/s。(C) 2010 Elsevier B.V.版权所有
Employing a first-principles method, we have investigated dissolution and diffusion properties of hydrogen (H) in molybdenum (Mo), one of potential candidates for plasma facing materials in a nuclear fusion Tokamak. We show that single H atom is energetically favorable sitting at the tetrahedral interstitial site (TIS) instead of octahedral interstitial site and diagonal interstitial site. This can be confirmed by the electron localization function result. Bader charge analysis suggests that the bonding between H and surrounding Mo is mainly ionic mixed with slight covalent component. Double H atoms tend to be paired up at the two neighboring TIS's along the (1 1 0) direction with the distance of similar to 0.221 nm and the binding energy of 0.03 eV. This suggests a weak attractive interaction between H atoms, with the implication that self-trapping of H and thus formation of the H-2 molecules are quite difficult in an intrinsic Mo environment. We demonstrate that the diffusion barrier of H that jumps between the TIS's is 0.16 eV, and the dissolved concentration of H in the intrinsic fvlo is 2.6 x 10(-8) at a typical temperature of 600 K. The diffusion coefficients of H, D, and T are different due to the different masses, which are calculated to be 1.3 x 10(-7) m(2)/s, 9.2 x 10(-8) m(2)/s, and 7.5 x 10(-8) m(2)/s at 600 K. (C) 2010 Elsevier B.V. All rights reserved.