Kim Kangsik, Yoon Jong Chan, Kim Jaemin, Kim Jung Hwa, Lee Suk Woo, Yoon Aram, Lee Zonghoon
School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919, Republic of Korea.
Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan Metropolitan City, 44919, Republic of Korea.
Appl Microsc. 2019 Apr 29;49(1):3. doi: 10.1007/s42649-019-0005-5.
Graphene, which is one of the most promising materials for its state-of-the-art applications, has received extensive attention because of its superior mechanical properties. However, there is little experimental evidence related to the mechanical properties of graphene at the atomic level because of the challenges associated with transferring atomically-thin two-dimensional (2D) materials onto microelectromechanical systems (MEMS) devices. In this study, we show successful dry transfer with a gel material of a stable, clean, and free-standing exfoliated graphene film onto a push-to-pull (PTP) device, which is a MEMS device used for uniaxial tensile testing in in situ transmission electron microscopy (TEM). Through the results of optical microscopy, Raman spectroscopy, and TEM, we demonstrate high quality exfoliated graphene on the PTP device. Finally, the stress-strain results corresponding to propagating cracks in folded graphene were simultaneously obtained during the tensile tests in TEM. The zigzag and armchair edges of graphene confirmed that the fracture occurred in association with the hexagonal lattice structure of graphene while the tensile testing. In the wake of the results, we envision the dedicated preparation and in situ TEM tensile experiments advance the understanding of the relationship between the mechanical properties and structural characteristics of 2D materials.
石墨烯作为最具前景的材料之一，因其先进的应用而备受广泛关注，这得益于其卓越的机械性能。然而，由于将原子级超薄二维（2D）材料转移到微机电系统（MEMS）器件上存在挑战，关于石墨烯在原子水平的机械性能的实验证据很少。在本研究中，我们展示了成功地将稳定、清洁且独立的剥离石墨烯薄膜通过凝胶材料干式转移到推挽（PTP）器件上，该器件是一种用于原位透射电子显微镜（TEM）单轴拉伸测试的MEMS器件。通过光学显微镜、拉曼光谱和TEM的结果，我们证明了PTP器件上高质量的剥离石墨烯。最后，在TEM拉伸测试过程中，同时获得了与折叠石墨烯中扩展裂纹相对应的应力 - 应变结果。石墨烯的锯齿形和扶手椅形边缘证实，在拉伸测试时，断裂与石墨烯的六边形晶格结构相关。基于这些结果，我们设想专门的制备和原位TEM拉伸实验将推动对二维材料机械性能与结构特征之间关系的理解。
