Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene

TLDR

We measured the elastic properties and intrinsic breaking strength of free‑standing monolayer graphene membranes via nanoindentation in an atomic force microscope. The nanoindentation experiments revealed a nonlinear elastic response with second‑ and third‑order stiffnesses of 340 N m⁻¹ and –690 N m⁻¹, a breaking strength of 42 N m⁻¹ (intrinsic strength 130 GPa for bulk graphite), a Young’s modulus of 1.0 TPa, and established graphene as the strongest material ever measured, demonstrating that atomically perfect nanoscale materials can be tested beyond the linear regime.

Abstract

We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m(-1)) and -690 Nm(-1), respectively. The breaking strength is 42 N m(-1) and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = -2.0 terapascals, and intrinsic strength of sigma(int) = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.