The effect of rippling on the mechanical properties of graphene

作     者：Guillermo Lopez-Polin Cristina Gomez-Navarro Julio Gomez-Herrero Guillermo Lopez-Polin;Cristina Gomez-Navarro;Julio Gomez-Herrero

作者机构：Instituto de Ciencia de Materiales de MadridCSICMadrid E 28049Spain Departamento de Física de La Materia CondensadaUniversidad Autónoma de MadridMadridE-28049Spain IFIMAC Condensed Matter Physics Center(IFIMAC).Universidad Autónoma de MadridMadridE-28049Spain 

出 版 物：《Nano Materials Science》 (纳米材料科学（英文版）)

年 卷 期：2022年第4卷第1期

页      面：18-26页

核心收录：

学科分类：0821[工学-纺织科学与工程] 081702[工学-化学工艺] 08[工学] 0817[工学-化学工程与技术] 0805[工学-材料科学与工程（可授工学、理学学位）] 0801[工学-力学（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：financial support from the Spanish MINECO through PID2019-106268 GB-C31 from Comunidad de Madrid (S2018/NMT-4511, NMAT2D-CM) support from the Spanish Ministry of Science and Innovation, through the "María de Maeztu" Programme for Units of Excellence in R&D (CEX2018-000805-M) support from the Spanish Ministry of Science and Innovation for the Jd C Fellowship FJCI-2017-32370. 

主　　题：Graphene Mechanical properties Atomic force microscopy Defects Ripples Stmain 

摘      要：Graphene is the stiffest material known so far but, due to its one-atom thickness, it is also very bendable.Consequently, free-standing graphene exhibit ripples that has major effects on its elastic properties. Here we will summarize three experiments where the influence of rippling is essential to address the results. Firstly, we observed that atomic vacancies lessen the negative thermal expansion coefficient(TEC) of free-standing graphene.We also observed an increase of the Young s modulus with global applied strain and with the introduction of small density defects that we attributed to the decrease of rippling. Here, we will focus on a surprising feature observed in the data: the experiments consistently indicate that only the rippling with wavelengths between 5 and 10 nm influences the mechanics of graphene. The rippling responsible of the negative TEC and anomalous elasticity is thought to be dynamic, i.e. flexural phonons. However, flexural phonons with these wavelengths should have minor effects on the mechanics of graphene, therefore other mechanisms must be considered to address our observations. We propose static ripples as one of the key elements to correctly understand the thermomechanics of graphene and suggest that rippling arises naturally due to a competition of symmetry breaking and anharmonic fluctuations.