分子动力学模拟研究孪晶界对单层二硫化钼拉伸行为的影响  

Molecular dynamics simulations for tensile behaviors of mono-layer MoS2 with twin boundary

作　　者：邵宇飞[1] 孟凡顺[2,3] 李久会 赵星[2] Shao Yu-Fei;Meng Fan-Shun;Li Jiu-Hui;Zhao Xing(Institute of Applied Physics and Technology,Liaoning Technical University,Huludao 125105,China;College of Sciences,Liaoning University of Technology,Jinzhou 121001,China;College of Materials Science and Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]辽宁工程技术大学应用物理与技术研究所,葫芦岛125105 [2]辽宁工业大学理学院,锦州121001 [3]东北大学材料科学与工程学院,沈阳110819

出　　处：《物理学报》2019年第21期241-248,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51801091);辽宁省自然基金(批准号:201602360,20180550484)资助的课题~~

摘　　要：孪晶界是单层过渡金属二硫族化物材料中的一种重要结构缺陷.本文通过分子动力学模拟结合Stillinger-Weber势函数研究单轴拉伸过程中孪晶界对单层MoS2力学行为的影响.结果表明:1)孪晶界能够诱发裂纹在孪晶界附近形核,并促使裂纹沿界面扩展,从而降低晶体的断裂应变;2)温度的升高能够加剧孪晶界附近的裂纹形核过程,从而进一步减弱单层MoS2的断裂强度和断裂应变;3)孔洞能够造成应力集中,从而进一步触发断裂过程,但孪晶界能够阻碍孔洞应力场的扩散,从而延缓单层MoS2材料的断裂过程;4)孪晶片层间距对单层MoS2断裂应变具有重要影响,特别是对于含孔洞的单层MoS2材料,材料断裂应变能够随着片层间距的减小而显著提高.Grain boundary(GB)plays a key role in determining the electrical and mechanical properties of mono-layer transition metal dichalcogenide(TMDC),however it is still a challenge to uncover the GB-mediatedTMDC material experimentally.In this paper,the effect of twin boundary on the tensile behaviors of mono-layer MoS2 is investigated by using the molecular dynamics simulation combined with the Stillinger-Weberpotential.Mono-layer MoS2 model under the varied size and temperature condition is adopted.Stresscalculation is performed by using Virial theorem.The results are obtained as follows.1)Twin boundarypromotes the brittle fracture of an undefected mono-layer MoS2 sheet by inducing the nucleation of the cracknear boundaries,thus the fracture strength and strain are weakened.2)Increasing the ambient temperaturefrom 1 K to 600 K,the crack nucleation process near the twin boundary is intensely accelerated,and thefracture strength and strain are further declined.3)Twin lamellar spacing also plays an important role in thetensile process of mono-layer MoS2,and the specimen with dense twin boundary,especially with void,showshigher fracture strain.4)Stress analysis at an atomic level outlines the stress concentration caused by voids andthe shielding effect of twin boundary.Because of the interactions between voids and twin boundary,the fracturestrength and strain of a voided mono-layer MoS2 sheet can be greatly improved.

关 键 词：单层二硫化钼 孪晶界 力学性能 分子动力学 

分 类 号：O77[理学—晶体学] O614.612