Sun Yufei, Wang Yujia, Wang Enze, Wang Bolun, Zhao Hengyi, Zeng Yongpan, Zhang Qinghua, Wu Yonghuang, Gu Lin, Li Xiaoyan, Liu Kai
State Key Laboratory of New Ceramics and Fine Processing & Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China.
Center for Advanced Mechanics and Materials, Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing, 100084, China.
Nat Commun. 2022 Jul 6;13(1):3898. doi: 10.1038/s41467-022-31685-7.
The rise of twistronics has increased the attention of the community to the twist-angle-dependent properties of two-dimensional van der Waals integrated architectures. Clarification of the relationship between twist angles and interlayer mechanical interactions is important in benefiting the design of two-dimensional twisted structures. However, current mechanical methods have critical limitations in quantitatively probing the twist-angle dependence of two-dimensional interlayer interactions in monolayer limits. Here we report a nanoindentation-based technique and a shearing-boundary model to determine the interlayer mechanical interactions of twisted bilayer MoS. Both in-plane elastic moduli and interlayer shear stress are found to be independent of the twist angle, which is attributed to the long-range interaction of intermolecular van der Waals forces that homogenously spread over the interfaces of MoS. Our work provides a universal approach to determining the interlayer shear stress and deepens the understanding of twist-angle-dependent behaviours of two-dimensional layered materials.
扭曲电子学的兴起使学界更加关注二维范德华集成结构中与扭曲角相关的特性。阐明扭曲角与层间力学相互作用之间的关系对于二维扭曲结构的设计十分重要。然而，当前的力学方法在定量探测单层极限下二维层间相互作用的扭曲角依赖性方面存在关键局限性。在此，我们报告一种基于纳米压痕的技术和一个剪切边界模型，以确定扭曲双层二硫化钼的层间力学相互作用。发现面内弹性模量和层间剪应力均与扭曲角无关，这归因于分子间范德华力的长程相互作用，该相互作用均匀地分布在二硫化钼的界面上。我们的工作提供了一种确定层间剪应力的通用方法，并加深了对二维层状材料扭曲角相关行为的理解。
