The interplay of intra- and inter-layer interactions in bending rigidity of ultrathin 2D materials
The interplay of intra- and inter-layer interactions in bending rigidity of ultrathin 2D materials
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DOI：
10.1063/5.0146065
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发表时间：
2023-04
影响因子：
4
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连续介质力学在计算单层和少层二维货车德瓦耳斯（van der Waals）晶体片的弯曲刚度时失效，因为它们的层状原子结构的独特特征在于强的面内键合与弱的层间相互作用。在这里，我们阐明了原始的单层和多层二硫化钼（MoS2），石墨烯和六方氮化硼（hBN）的弯曲刚度是如何由它们的结构几何形状和层内和层间的键合相互作用。这些二维材料在平面衬底上的自折叠构象的原子力显微镜实验表明，MoS2的弯曲刚度显着超过石墨烯或hBN的可比层，尽管其拉伸模量低得多。即使在每厚度的基础上，发现MoS2具有与hBN相似的弯曲刚度，并且比石墨烯刚性大得多。密度泛函理论计算表明，这种高的抗弯刚度的MoS2是由于其大的层间厚度和强的层间剪切，占主导地位的弱面内键合。
Continuum mechanics break down in bending stiffness calculations of mono- and few-layered two-dimensional (2D) van der Waals crystal sheets, because their layered atomistic structures are uniquely characterized by strong in-plane bonding coupled with weak interlayer interactions. Here, we elucidate how the bending rigidities of pristine mono- and few-layered molybdenum disulfide (MoS2), graphene, and hexagonal boron nitride (hBN) are governed by their structural geometry and intra- and inter-layer bonding interactions. Atomic force microscopy experiments on the self-folded conformations of these 2D materials on flat substrates show that the bending rigidity of MoS2 significantly exceeds those of graphene or hBN of comparable layers, despite its much lower tensile modulus. Even on a per-thickness basis, MoS2 is found to possess similar bending stiffness to hBN and is much stiffer than graphene. Density functional theory calculations suggest that this high bending rigidity of MoS2 is due to its large interlayer thickness and strong interlayer shear, which prevail over its weak in-plane bonding.