Effect of Vacancy Defects on the Vibration Frequency of Graphene Nanoribbons.

Hong Guo,Jing Wang

doi:10.3390/nano12050764

Abstract

Graphene is a type of two-dimensional material with special properties and complex mechanical behavior. In the process of growth or processing, graphene inevitably has various defects, which greatly influence the mechanical properties of graphene. In this paper, the mechanical properties of ideal monolayer graphene nanoribbons and monolayer graphene nanoribbons with vacancy defects were simulated using the molecular dynamics method. The effect of different defect concentrations and defect positions on the vibration frequency of nanoribbons was investigated, respectively. The results show that the vacancy defect decreases the vibration frequency of the graphene nanoribbon. The vacancy concentration and vacancy position have a certain effect on the vibration frequency of graphene nanoribbons. The vibration frequency not only decreases significantly with the increase of nanoribbon length but also with the increase of vacancy concentration. As the vacancy concentration is constant, the vacancy position has a certain effect on the vibration frequency of graphene nanoribbons. For nanoribbons with similar dispersed vacancy, the trend of vibration frequency variation is similar.

Highlights

Graphene has excellent elastic properties and high intrinsic strength [1,2,3,4], as well as extraordinary mechanical [5,6,7], electrical [8,9], and other physical [10,11,12] properties, making it one of the most promising materials in modern technology
Due to the existence of vacancy defects, the bond lengths and bond angles angles generally increased after structure optimization, which led structural to the structural generally increased after structure optimization, which led to the changechange of the of the carbon the vacancies, affecting the structure of the nanoribbons
The results results of show that vacancy defects reduce the vibration frequency of the graphene nanoribbon, and show that vacancy defects reduce the vibration frequency of the graphene nanoribbon, both vacancy concentration and vacancy position have an effect on the vibration frequency and both vacancy concentration and vacancy position have an effect on the vibration freof graphene nanoribbons

Summary

Introduction

Graphene has excellent elastic properties and high intrinsic strength [1,2,3,4], as well as extraordinary mechanical [5,6,7], electrical [8,9], and other physical [10,11,12] properties, making it one of the most promising materials in modern technology. Investigated dislocation, vacancy, and Stone–Wales defects in the semiconductor graphene quantum dot model, showing that mechanical property reduction is close to the experimentally measured values, while the increase in the number of layers does not significantly affect the final results. Nanomaterials 2022, 12, 764 properties of graphene, in which large-sized vacancy defects have a higher tensile modulus and lower fracture strain compared to small-sized vacancy defects. Ng et al [33,34] used molecular dynamics (MD) simulations to study the change in thermal conductivity of graphene under two different chiralities and the relationship between chirality and STW defect density. Lee et al [35] measured the elastic properties and intrinsic fracture strength of freestanding monolayer graphene films using nanoindentation and showed that atomically perfect nanoscale materials could be tested for deformation using mechanical methods over a range well beyond the linear range. We use molecular dynamics simulations to investigate the effects of different defect concentrations and defect locations on the vibration frequency of monolayer graphene

Physical Model and Simulation Method

Discussion

Vibration

Variation

Conclusions