〈111〉方向单轴应变下金刚石和硅的广义层错能  

Generalized Stacking Fault Energies of Diamond and Silicon under<111>Uniaxial Loading

作　　者：黄丽丽 彭丽 陈实 张红平 李牧 HUANG Lili;PENG Li;CHEN Shi;ZHANG Hongping;LI Mu(College of Engineering Physics,Center for Intense Laser Application Technology,Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology,Shenzhen Technology University,Shenzhen 518118,Guangdong,China;College of Big Data and Internet,Shenzhen Technology University,Shenzhen 518118,Guangdong,China)

机构地区：[1]深圳技术大学工程物理学院,超强激光应用技术研究中心,深圳市超强激光与先进材料重点实验室,广东深圳518118 [2]深圳技术大学大数据与互联网学院,广东深圳518118

出　　处：《高压物理学报》2024年第3期70-79,共10页Chinese Journal of High Pressure Physics

基　　金：国家自然科学基金(12204317,11974321,11972330)。

摘　　要：晶体中原子层面剪切所带来的能量称为广义层错能,它是描述晶体中纳米尺度塑性变形的关键参数,如位错分解、成核和孪晶。在冲击加载过程中,弹塑性转变发生在一维弹性应变之后,因此,单轴应变下的广义层错能对于理解塑性流动的发生具有重要意义。应用基于密度泛函理论的第一性原理,计算了在[111]方向单轴应变下硅和金刚石的glide(111)面的广义层错能面。基于广义层错能面的平移对称性,通过傅里叶级数展开,拟合得到了广义层错能面的表达式,并给出了[110](111)和[112](111)方向的广义层错能曲线。结果表明,随着应变的增加,本征层错能和不稳定层错能出现明显的变化,且不稳定层错能与本征层错能之比减小,说明在<111>方向的单轴应变下晶体中的位错不容易发生分解。该结果解释了在四代光源上开展的位错演化动态实验结果,即沿<111>方向加载的层错信号出现的速度和强度均远不如沿<110>方向和<100>方向加载的结果。The energy caused by atomic level shear in a crystal is called generalized fault energy(GSFE),This is an important material property for describing nanoscale plastic phenomena in crystalline materials,such as dislocation decomposition,nucleation,and twinning.During the shock loading process,the elastoplastic transition occurs after one-dimensional elastic strain,so the generalized stacking fault energy is of great significance in understanding the occurrence of plastic flow.Here,we calculate the generalized GSFE surface of glide(111)surface of silicon and diamond under uniaxial strain in[111]direction by using the first principles of density functional theory.Based on the translation symmetry of GSFE surface,we fit the GSFE surface expression obtained by Fourier series expansion and the generalized stacking fault energy curves for the[110](111)and[112](111)directions are given.With the increase of strain,the intrinsic fault energy(γ_(I))and the unstable fault energy(γ_(us))have obvious changes,and the ratio of the unstable stacking fault energy to the intrinsic stacking fault energy(γ_(us)/γ_(I))decreases indicating that dislocations in crystals are not easily decomposed under uniaxial strain in the<111>direction.This result explains the results of dynamic experiments of dislocation evolution at four generations of light sources that the speed and strength of fault signals loaded along<111>direction are much lower than those loaded along<110>direction and<100>direction.

关 键 词：广义层错能 第一性原理计算 冲击加载 位错 

分 类 号：O521.2[理学—高压高温物理] O344.1[理学—物理]