剪切形变下磷烯的力学和热学性能  

Mechanical and thermal properties of phosphorene under shear deformation

作　　者：李婷 毕晓月 孔婧文 Li Ting;Bi Xiao-Yue;Kong Jing-Wen(School of Physics and Electronic Technology,Liaoning Normal University,Dalian 116029,China)

机构地区：[1]辽宁师范大学物理与电子技术学院,大连116029

出　　处：《物理学报》2023年第12期214-222,共9页Acta Physica Sinica

基　　金：辽宁省科技厅博士启动基金(批准号:2021-BS-200);大连市科技创新基金(批准号:2022JJ12GX023);辽宁师范大学2022年高端科研成果培育资助计划(批准号:22GDL002)资助的课题。

摘　　要：磷烯是一种新型的二维半导体材料,近年来得到了研究者们的广泛关注.通过分子动力学模拟对磷烯在剪切形变下的力学和热学性能进行了系统探究.磷烯的剪切力学呈现出各向同性的特点,沿扶手椅与锯齿方向的剪切模量均约为22 GPa.磷烯的断裂强度和极限应变对温度十分敏感,高温会显著削弱磷烯抗剪切形变的能力.无应变时磷烯沿锯齿与扶手椅方向热导率的各向异性比为2.83.当对磷烯施加剪切应变时,磷烯沿扶手椅方向的热导率随着剪切应变的增大而减小,但是剪切应变对磷烯锯齿方向热导率的影响则相对较弱.通过对磷烯的声子态密度分析发现,剪切形变主要对其柔性声子模式的振动特性具有显著影响,使高频声子发生了红移.同时,剪切形变的存在会严重改变晶格的非简谐振动,继而在不同程度上对磷烯声子间的散射产生重要的影响.磷烯声子态密度的改变以及声子散射通道的变化共同决定了其在剪切形变下的导热特性.Phosphorene,a new two-dimensional material beyond graphene,has received increasing attention in recent years owing to its superior physical properties of significant utility.Herein we carry out molecular dynamics simulations to systematically study the mechanical and thermal properties of phosphorene under shear loadings.It is found that the shear modulus of phosphorene is about 22 GPa in both the armchair direction and zigzag direction.The fracture strength and ultimate strain of phosphorene can be significantly reduced owing to stronger thermal vibrations of atoms at a higher temperature.The thermal conductivity of pristine phosphorene at room temperature is obtained,specifically,it is 18.57 W·m^(-1)·K^(-1) along the armchair direction and 52.52 W·m^(-1)·K^(-1) in the zigzag direction.When either an armchair-or a zigzag-oriented shear strain is applied,the armchair-oriented thermal conductivity decreases monotonically with the strain increasing.Whereas the zigzag-oriented thermal conductivity exhibits a non-monotonic behavior.The strain-induced redshift occurs in the high-frequency phonons of out-of-plane flexural modes in the phonon density of states of the sheared phosphorene.In addition,the buckled structure of phosphorene will lead the deformation characteristics under the shear strain differ from those of the planar structure such as graphene,which has a significant influence on the lattice anharmonicity and phonon scattering.It is believed that the interplay between the shift of phonon density of states and the change of phonon scattering channels results in the unique thermal transport behavior of phosphorene under shear deformation.The findings provide an insight into the understanding of the mechanical and thermal properties of phosphorene,and have significance for the future applications in phosphorene-based novel devices.

关 键 词：磷烯 剪切形变 热导率 分子动力学 

分 类 号：TB34[一般工业技术—材料科学与工程]