Dedicated preparation for in situ transmission electron microscope tensile testing of exfoliated graphene

Abstract

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.

Fracture Toughness Characteristics of Stacked Bilayer Graphene via Far‐Field Displacement Measurements

“…[1][2][3][4][5] Among various types of nanomaterials, DOI: 10.1002/smll.202302499 one-atom-thick graphene exhibits remarkable mechanical properties, e.g., in-plane Young's modulus of as high as ≈1 TPa and mechanical strength of as high as 100-130 GPa owing to its sp 2 bonding and honeycomb crystalline structure. [1,6,7] Based on its high intrinsic strength and stiffness, graphene has been used extensively as a strengthening and reinforcing nanofiller in composites, [2,8] and suspended 2D materials have been actively used in the field of nanoelectromechanical systems to improve the device yield. [9] In many of the above applications, the mechanical properties of graphene is of primary concern, or directly linked to the safe and reliable operations of the graphene-based devices.…”