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首页> 外文期刊>Physical review >Bond deformation paths and electronic instabilities of ultraincompressible transition metal diborides: Case study of OsB_2 and IrB_2
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Bond deformation paths and electronic instabilities of ultraincompressible transition metal diborides: Case study of OsB_2 and IrB_2

机译:超不可压缩过渡金属二硼化物的键变形路径和电子不稳定性:以OsB_2和IrB_2为例

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摘要

The energetically most stable orthorhombic structure of OsB_2 and IrB_2 is dynamically stable for OsB_2 but unstable for IrB_2. Both diborides have substantially lower shear strength in their easy slip systems than their metal counterparts. This is attributed to an easy sliding facilitated by out-of-plane weakening of metallic Os-Os bonds in OsB_2 and by an in-plane bond splitting instability in IrB_2. A much higher shear resistance of Os-B and B-B bonds than Os-Os ones is found, suggesting that the strengthened Os-B and B-B bonds are responsible for hardness enhancement in OsB_2. In contrast, an in-plane electronic instability in IrB_2 limits its strength. The electronic structure of deformed diborides suggests that the electronic instabilities of 5d orbitals are their origin of different bond deformation paths. Neither IrB_2 nor OsB_2 can be intrinsically superhard.
机译:OsB_2和IrB_2的能量最稳定的正交结构对于OsB_2动态稳定,但对于IrB_2则不稳定。两种二硼化物在其易滑系统中均具有比其金属同类物低的剪切强度。这归因于OsB_2中金属Os-Os键的面外弱化和IrB_2中的面内键分裂不稳定性,促进了容易滑动。发现Os-B和B-B键的抗剪切强度比Os-Os的高得多,这表明增强的Os-B和B-B键可提高OsB_2的硬度。相反,IrB_2中的平面电子不稳定性限制了其强度。变形二硼化物的电子结构表明5d轨道的电子不稳定性是它们不同键变形路径的​​起源。 IrB_2和OsB_2都不是本质上超硬的。

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  • 来源
    《Physical review》 |2014年第9期|094115.1-094115.6|共6页
  • 作者单位

    School of Materials Science and Engineering, and International Research Institute for Multidisciplinary Science, Beihang University,Beijing 100191, P. R. China,Theoretical division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA,Department of Materials Science and Engineering, Iowa State University, Ames, IA50010, USA;

    Nanotechnology Centre, VSB-Technical University of Ostrava, CZ-708 33 Ostrava, Czech Republic;

    Theoretical division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA,State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001,P. R. China & Synfuels China, Beijing 100195, P. R. China;

    Department of Chemistry, Technical University Munich, Lichtenbergstr. 4, D-85747 Garching, Germany;

    Department of Materials Science and Engineering, Iowa State University, Ames, IA50010, USA;

    Theoretical division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA;

    Geophysical Laboratory, Carnegie Institution of Washington, NW Washington, DC 20015, USA,Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, P. R. China;

    HiPSEC, Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154, USA;

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  • 正文语种 eng
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  • 关键词

    theory of crystal structure, crystal symmetry; calculations and modeling; other inorganic compounds;

    机译:晶体结构理论;晶体对称性;计算和建模;其他无机化合物;

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