The Influence of Defect-Induced Amorphization on the Structural and Mechanical Properties of Single Layer Graphene
Ashwin Ramasubramaniam (University of Massachusetts Amherst), Corinne Carpenter (University of Massachusetts Amherst), Dimitrios Maroudas (University of Massachusetts Amherst)
Synthesis, Characterization, and Modeling of Low-Dimensional Nanomaterials
Tue 9:00 - 10:30
Salomon 202
Defect engineering provides a versatile tool for tuning the mechanical, electronic, and chemical properties of graphene, and is an issue of significant current interest. While individual defects in single-layer graphene have been investigated in much detail, collective interactions of multiple defects and their implications for the performance of this material are less well understood. In this work, we address the latter problem via classical molecular-dynamics simulations based on reliable bond-order potentials. We study random distributions of vacancies in a single graphene layer with vacancy concentration and temperature being the key parameters in the analysis. We demonstrate that a crystalline-to-amorphous structural transition -- reminiscent of ion-beam damage experiments on graphene -- occurs at vacancy concentrations of 5-10% leading to complete loss of long-range order in the graphene layer. We conduct a systematic parametric study of this phenomenon accompanied by a detailed analysis of the morphology and electronic structure of these defective sheets. We also present systematic studies of tensile tests on these defective graphene sheets and identify trends for the ultimate tensile strength, failure mode (brittle vs. ductile), and toughness as a function of vacancy concentration. The implications of our findings for tuning the mechanical and electronic properties of single-layer graphene are discussed.