Revealing the Pressure-Induced Softening/Weakening Mechanism in Representative Covalent Materials  

作　　者：Tengfei Xu Shihao Zhang Dominik Legut Stan Veprek Ruifeng Zhang 徐腾飞;张世毫;Dominik Legut;Stan Veprek;张瑞丰(School of Materials Science and Engineering,Beihang University,Beijing 100191,China;Center for Integrated Computational Engineering(International Research Institute for Multidisciplinary Science)and Key Laboratory of High-Temperature Structural Materials&Coatings Technology(Ministry of Industry and Information Technology),Beihang University,Beijing 100191,China;IT4Innovations,VSB-Technical University of Ostrava,17 listopadu 2172/15,70800 Ostrava,Czech Republic;Department of Chemistry,Technical University Munich,Lichtenbergstr 4,D-85747 Garching,Germany)

机构地区：[1]School of Materials Science and Engineering,Beihang University,Beijing 100191,China [2]Center for Integrated Computational Engineering(International Research Institute for Multidisciplinary Science)and Key Laboratory of High-Temperature Structural Materials&Coatings Technology(Ministry of Industry and Information Technology),Beihang University,Beijing 100191,China [3]IT4Innovations,VSB-Technical University of Ostrava,17 listopadu 2172/15,70800 Ostrava,Czech Republic [4]Department of Chemistry,Technical University Munich,Lichtenbergstr 4,D-85747 Garching,Germany

出　　处：《Chinese Physics Letters》2021年第5期51-59,共9页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China (Grant No.51672015);the National Key Research and Development Program of China (Grant Nos.2016YFC1102500 and 2017YFB0702100);the 111 Project (Grant No.B17002);and the Fundamental Research Funds for the Central Universities;supported by the European Regional Development Fund in the IT4Innovations National Supercomputing Center—Path to Exascale Project (Grant No.CZ.02.1.01/0.0/0.0/16 013/0001791);within the Operational Programme for Research,Development and Education,and by the Large Infrastructures for Research,Experimental Development,and Innovation Project (Grant No.e-INFRA CZ-LM2018140) by the Ministry of Education,Youth,Sport of the Czech Republic。

摘　　要：Diamond, cubic boron nitride(c-BN), silicon(Si), and germanium(Ge), as examples of typical strong covalent materials, have been extensively investigated in recent decades, owing to their fundamental importance in material science and industry. However, an in-depth analysis of the character of these materials' mechanical behaviors under harsh service environments, such as high pressure, has yet to be conducted. Based on several mechanical criteria, the effect of pressure on the mechanical properties of these materials is comprehensively investigated.It is demonstrated that, with respect to their intrinsic brittleness/ductile nature, all these materials exhibit ubiquitous pressure-enhanced ductility. By analyzing the strength variation under uniform deformation, together with the corresponding electronic structures, we reveal for the first time that the pressure-induced mechanical softening/weakening exhibits distinct characteristics between diamond and c-BN, owing to the differences in their abnormal charge-depletion evolution under applied strain, whereas a monotonous weakening phenomenon is observed in Si and Ge. Further investigation into dislocation-mediated plastic resistance indicates that the pressure-induced shuffle-set plane softening in diamond(c-BN), and weakening in Si(Ge), can be attributed to the reduction of antibonding states below the Fermi level, and an enhanced metallization, corresponding to the weakening of the bonds around the slipped plane with increasing pressure, respectively. These findings not only reveal the physical mechanism of pressure-induced softening/weakening in covalent materials, but also highlights the necessity of exploring strain-tunable electronic structures to emphasize the mechanical response in such covalent materials.

关 键 词：red service Revealing the Pressure-Induced Softening/Weakening Mechanism in Representative Covalent Materials 

分 类 号：TB321[一般工业技术—材料科学与工程]