<br>二维单斜二硫化铼中的移动和固定晶界,Advanced Science

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二维单斜二硫化铼中的移动和固定晶界
Advanced Science ( IF 14.3 ) Pub Date : 2020-10-12 , DOI: 10.1002/advs.202001742
Fangyuan Zheng ₁ , Lingli Huang _{2,

3} , Lok-Wing Wong ₁ , Jin Han ₄ , Yuan Cai ₅ , Ning Wang ₅ , Qingming Deng ₄ , Thuc Hue Ly _{2,

3} , Jiong Zhao ₁

Affiliation

在块体晶体中，位错动力学通常受到孪晶界（TB）或晶界（GB）的阻碍，从而产生众所周知的晶界强化效应。然而，这里发现在二维二硫化铼（ReS ₂ ）中，孪生比位错滑移容易得多。因此，高度移动的 TB 或 GB 被相对固定的位错反向钉扎。由于面内强共价键合，高对称性二维材料（例如由缺陷组成的石墨烯）中的晶界在室温下是不动的。相比之下，在单斜晶系二维 ReS ₂中，可以通过机械负载轻松生成和驱动多种类型的 GB（包括 TB）。通过（原位）原子级透射电子显微镜 (TEM) 表征和密度泛函理论 (DFT) 计算，建立了 2D ReS ₂中 GB 的完整库。 2D ReS ₂的孪晶（剪切）应力估计低至 4-30 MPa，比传统块状材料低一两个数量级。充分阐明此类各向异性二维材料中的晶界结构，尤其是有趣的晶界动力学，对于理解未来二维材料的结构-性能关系和开发应变可调应用至关重要。

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The Mobile and Pinned Grain Boundaries in 2D Monoclinic Rhenium Disulfide

In bulk crystals, the kinetics of dislocations is usually hindered by the twining boundaries (TB) or grain boundaries (GB), rendering the well‐known grain boundary strengthening effects. Nevertheless, here it is found that in 2D rhenium disulfide (ReS₂), twinning is much easier than dislocation slip. Consequently, the highly mobile TBs or GBs are inversely pinned by the relatively immobile dislocations. Due to the strong in‐plane covalent bonding, the GBs in high‐symmetry 2D materials such as graphene which consists of defects are immobile at room temperature. In contrast, in monoclinic 2D ReS₂ several types of GBs (including TBs) can be readily generated and driven by mechanical loading. A complete library of the GBs in 2D ReS₂ is established by the (in situ) atomic‐scale transmission electron microscopy (TEM) characterizations and density functional theory (DFT) calculations. The twinning (shear) stresses for 2D ReS₂ are estimated as low as 4–30 MPa, one or two orders of magnitude lower than the traditional bulk materials. Full elucidation on the GB structures and especially the intriguing GB kinetics in such anisotropic 2D materials are of fundamental importance to understand the structure–property relationships and develop strain‐tunable applications for 2D materials in future.

更新日期：2020-11-19

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