PuGa合金中H吸附行为的第一性原理研究

    First-Principle of Adsorption Behavior of H Atom in PuGa Alloy

    • 摘要: 在氢气氛下,PuGa合金会发生氢化腐蚀反应,这会影响材料结构,导致PuGa合金相关性能下降。由于PuGa材料的高辐射性、相关实验技术及条件的制约,难以通过大规模的实验手段对此进行研究。因此,针对H在PuGa合金(111)面及体相内的吸附行为机制进行了第一性原理模拟研究,分析H在PuGa合金中的电子结构及吸附作用过程。研究发现H原子在PuGa体相中倾向吸附于包含Ga原子的四面体间隙,其吸附能为-0.75 eV,而在(111)面上倾向吸附于Pu原子周围,其最大吸附能绝对值为0.62 eV。H在Ga原子邻近吸附位具有较低的扩散能垒,尤其是在表面上其反应能垒小于0.3 eV。本工作从原子尺度理解揭示H在材料表面的吸附行为机理,为降低H对材料结构及性能的影响提供理论指导。

       

      Abstract: PuGa alloy shows hydrogenation corrosive reaction exposed in a hydrogen atmosphere, which affects material microstructures and decreases the related performance. Considering the high toxicity and radioactivity of PuGa alloy, experimental conditions and technical constraints, it is difficult to study this project through experimental method. Therefore, first-principle simulations were applied to study the adsorption behavior of H atom in PuGa alloy and on (111) surface, which included the electronic structure of PuGa alloy and the adsorption process of H. Hydrogen atom prefers to adopt in tetrahedral-Pu3Ga site in PuGa bulk with an adsorption energy of -0.75 eV. In contrast, on the PuGa alloy (111) surface, hydrogen atom prefers to adopt in fcc/hcp-Pu3 site with the maximum absolute value of the adsorption energy of 0.62 eV. H atom has a lower diffusion barrier at the adjacent adsorption sites of Ga atom, especially a barrier energy less than 0.3 eV on the surface. In this study, the mechanism of H atom adsorption behaviors on the material surface is revealed in atomic scale, and can provide the theoretical support to reduce the influence of H on the material structures and properties.

       

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