氢气在γ-U(100)/Mo表面吸附行为的第一性原理研究  

First principles study of hydrogen adsorption and dissociation behavior on γ-U(100)/Mo surface

作　　者：李俊炜 贾维敏 吕沙沙 魏雅璇 李正操 王金涛 Li Jun-Wei;Jia Wei-Min;LüSha-Sha;Wei Ya-Xuan;Li Zheng-Cao;Wang Jin-Tao(Key Lab of Advanced Materials(MOE),School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Xi’an Research Institute of High-Technology,Xi’an 710025,China;Key Laboratory of Beam Technology(MOE),College of Nuclear Science and Technology,Beijing Normal University,Beijing 100875,China)

机构地区：[1]清华大学材料学院先进材料教育部重点实验室,北京100084 [2]西安高科技研究所,西安710025 [3]北京师范大学核科学与技术学院射线束技术教育部重点实验室,北京100875

出　　处：《物理学报》2022年第22期230-241,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11975135,12005017);国家重点基础研究发展计划(批准号:2020YFB1901800)资助的课题。

摘　　要：铀及铀合金贮存环境中的水分子与铀反应会产生氢气(H_(2)_(2)),进而对铀表面产生腐蚀作用.基于密度泛函理论,本文开展了H_(2)在钼(Mo)涂层γ-U(100)表面(U(100)/Mo)吸附行为的第一性原理研究,建立了γ-U(100)及U(100)/Mo表面模型,计算了H_(2)在不同吸附位点下的结构参数、吸附能、Bader电荷、表面功函数、电子态密度.研究结果表明, H_(2)在γ-U(100)和U(100)/Mo表面的吸附主要为物理吸附,在空位平行吸附构型下, H_(2)完全解离成两个H_(2)原子,化学吸附于基底表面. Bader电荷分布结果表明,此时净电荷的变化量大于物理吸附时对应的净电荷变化量. H_(2)在U(100)/Mo表面最稳定吸附构型下(H_(Mo)-Hor)的吸附能小于γ-U(100)表面最稳定吸附构型(H_(U)-Hor)的吸附能,相比于H_(2)在γ-U(100)表面的吸附, H_(2)在U(100)/Mo表面的吸附更稳定.本文为铀合金及其Mo涂层表面氢化腐蚀研究提供了理论依据,为未来开展铀合金表面抗腐蚀研究提供理论基础和实验技术支持.Uranium(U)is one of the most natural radioactive elements widely used in the nuclear industry.In the civilian field,uranium is the most important nuclear fuel in nuclear reactors;militarily,uranium is an important raw material for nuclear weapons.In addition,uranium is also used for radiation shielding and ship ballast due to its high-density properties.Depending on the temperature,U has three kinds of allotrope phases:the orthogonal a phase at temperature below 940 K,the body-centered tetragonal(BCT)βphase at temperature ranging from 940 K to 1050 K,and the body-centered cubic(BCC)γphase at temperature above 1050 K.Compared with the other two structures,the crystal structure ofγphase has good symmetry and excellent mechanical properties.However,γ-U is extremely unstable at low temperature.No matter what heat treatment method is adopted,γ-U will undergo phase transformation and become a phase.It is shown that adding certain alloying elements,such as Mo,Nb,Zr,Ti and Hf,into uranium can stabilizeγ-U to room temperature and improve the mechanical properties of uranium greatly.As an important uranium alloy,γ-U by doping Mo atom has excellent mechanical properties,structural stability and thermal conductivity,and is an important nuclear reactor fuel.However,uranium has special physical and chemical properties due to its complex electronic structure and strong correlation of 5f electrons.Because of its special valence electron structure,it is highly susceptible to chemical and electrochemical reactions of environmental media.After the reaction between uranium and hydrogen,hydrogen embrittlement will occur,and even easily break into powder,which reduces the performance of uranium in service and brings hidden trouble to its storage.With the increase of service life,surface corrosion becomes more serious,and the safety and reliability of U alloys are seriously affected.The adsorption and dissociation of hydrogen on U alloy surface is the primary process of hydrogenation corrosion.Based on density functional theory,

关 键 词：铀合金 第一性原理 化学吸附 涂层 

分 类 号：O647.3[理学—物理化学] TL212[理学—化学]