氧气在铀钼体系表面吸附和解离行为的第一性原理研究  

First-Principles Study of Surface Adsorption and Dissociation Behavior of O_(2) on Uranium-Molybdenum System

作　　者：李俊炜 贾维敏 吕沙沙 王金涛 李正操[1] Li Junwei;Jia Weimin;Lv Shasha;Wang Jintao;Li Zhengcao(School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Xi'an Research Institute of High-Technology,Xi'an 710025,China;College of Nuclear Science and Technology,Beijing Normal University,Beijing 100875,China)

机构地区：[1]清华大学材料学院,北京100084 [2]西安高科技研究所,陕西西安710025 [3]北京师范大学核科学与技术学院,北京100875

出　　处：《稀有金属材料与工程》2023年第5期1650-1660,共11页Rare Metal Materials and Engineering

基　　金：National Natural Science Foundation of China(11975135,12005017);National Basic Research Program of China(2020YFB1901800)。

摘　　要：基于第一性原理探究了氧气分子在铀钼表面的吸附解离行为。在五层γ-U(100)表面构型的基础上,用单个钼原子置换表层的1个高对称点的铀原子,并用4个钼原子置换表层铀原子后,分别建立了γ-U(100)/Mo和γ-U(100)/4Mo模型,计算得到了不同吸附构型下的结构参数、吸附能、Bader电荷、电子结构和表面功函数。结果表明,氧分子在γ-U(100)/Mo和γ-U(100)/4Mo表面为化学吸附,且最稳定的吸附位点为空位平行吸附,吸附能分别为-12.552和-8.661 eV。氧分子在铀钼表面的吸附分为解离吸附和未解离吸附,两者共同组成稳定的吸附行为,同时,解离吸附比未解离吸附更为稳定。Bader电荷结果表明,氧气在吸附过程中,主要与吸附表面最上两层的原子发生电荷转移。电子结构研究表明,O 2s和U 6p轨道发生轻微杂化,O 2p与U 6d、Mo 5s、Mo 4p、Mo 4d轨道发生较强的重叠杂化。本研究为氧分子在铀钼合金表面的吸附提供了机理阐述,并进一步为氧气在铀钼合金表面的腐蚀机理研究提供理论基础。The adsorption and dissociation behavior of O_(2) molecules on U-Mo alloy surface was studied based on the first-principles simulation.One U atom at the highly symmetrical adsorption sites of the top layer was replaced by one Mo atom,and four U atoms at the top layer were replaced by four Mo atoms,resulting in the fact thatγ-U(100)/Mo andγ-U(100)/4Mo slabs were established on the basis of theγ-U(100)slab with five layers.The configuration parameters,adsorption energy,Bader charge,electronic structure,and surface work function were calculated under different adsorption configurations.Results show that the O_(2) molecules are chemically absorbed on theγ-U(100)/Mo andγ-U(100)/4Mo surfaces with the adsorption energy of−12.552 and−8.661 eV,respectively.The most stable adsorption configuration is the hollow horizontal adsorption configuration.The O_(2) molecule adsorption on U-Mo alloy surface can be divided into dissociated adsorption and undissociated adsorption,which jointly contribute to the stable adsorption behavior.In addition,the dissociated adsorption is more stable than the undissociated adsorption.The Bader charge results show that during the oxygen adsorption,the charge transfer mainly occurs at the atoms of the top two layers of adsorption surface.The electronic structure results show that the slight overlapping hybridization occurs in O 2s with U 6p orbitals.Meanwhile,the strong overlapping hybridization occurs in O 2p with U 6d,Mo 5s,Mo 4p,and Mo 4d orbitals.This research clarifies the O_(2) molecule adsorption mechanism on U-Mo alloy surface and provides theoretical basis for the oxidation corrosion mechanism of U-Mo alloy surface.

关 键 词：铀钼合金 解离吸附 轨道杂化 第一性原理 

分 类 号：TG146.8[一般工业技术—材料科学与工程]