波纹石墨烯中的负泊松比。

Negative Poisson's ratio in rippled graphene.

机构信息

State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China 710049.

State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China 710049.

出版信息

Nanoscale. 2017 Mar 23;9(12):4135-4142. doi: 10.1039/c6nr07911c.

DOI:10.1039/c6nr07911c

PMID:28281710

Abstract

In this work, we perform molecular dynamics (MD) simulations to study the effect of rippling on the Poisson's ratio of graphene. Due to the atomic scale thickness of graphene, out-of-plane ripples are generated in free standing graphene with topological defects (e.g. heptagons and pentagons) to release the in-plane deformation energy. Through MD simulations, we have found that the Poisson's ratio of rippled graphene decreases upon increasing its aspect ratio η (amplitude over wavelength). For the rippled graphene sheet η = 0.188, a negative Poisson's ratio of -0.38 is observed for a tensile strain up to 8%, while the Poisson's ratio for η = 0.066 is almost zero. During uniaxial tension, the ripples gradually become flat, thus the Poisson's ratio of rippled graphene is determined by the competing factors of the intrinsic positive Poisson's ratio of graphene and the negative Poisson's ratio due to the de-wrinkling effect. Besides, the rippled graphene exhibits excellent fracture strength and toughness. With the combination of its auxetic and excellent mechanical properties, rippled graphene may possess potential for application in nano-devices and nanomaterials.

摘要

在这项工作中，我们进行了分子动力学（MD）模拟，以研究波纹对石墨烯泊松比的影响。由于石墨烯的原子级厚度，在具有拓扑缺陷（例如七边形和五边形）的自由-standing 石墨烯中会产生面外波纹，以释放面内变形能。通过 MD 模拟，我们发现，随着波纹石墨烯的纵横比 η（幅度与波长之比）的增加，其泊松比减小。对于波纹石墨烯片，当 η = 0.188 时，在拉伸应变高达 8%的情况下，观察到负泊松比为-0.38，而 η = 0.066 的泊松比几乎为零。在单轴拉伸过程中，波纹逐渐变平，因此波纹石墨烯的泊松比由石墨烯的固有正泊松比和由于去皱效应引起的负泊松比的竞争因素决定。此外，波纹石墨烯表现出优异的断裂强度和韧性。波纹石墨烯具有各向异性和优异的机械性能，因此可能在纳米器件和纳米材料中有应用潜力。