Abstract
In this study, the mechanical and thermal properties of graphene were systematically investigated using molecular dynamic simulations. The effects of temperature, strain rate and defect on the mechanical properties, including Young’s modulus, fracture strength and fracture strain, were studied. The results indicate that the Young’s modulus, fracture strength and fracture strain of graphene decreased with the increase of temperature, while the fracture strength of graphene along the zigzag direction was more sensitive to the strain rate than that along armchair direction by calculating the strain rate sensitive index. The mechanical properties were significantly reduced with the existence of defect, which was due to more cracks and local stress concentration points. Besides, the thermal conductivity of graphene followed a power law of λ~L0.28, and decreased monotonously with the increase of defect concentration. Compared with the pristine graphene, the thermal conductivity of defective graphene showed a low temperature-dependent behavior since the phonon scattering caused by defect dominated the thermal properties. In addition, the corresponding underlying mechanisms were analyzed by the stress distribution, fracture structure during the deformation and phonon vibration power spectrum.
Highlights
Due to its excellent mechanical, thermal and other physical properties, Graphene (Gr) has attracted great attention from researchers since it was first prepared by Geim and Novoselov [1] in 2004
Experimental studies have proven that Gr presents superior thermal conductivity (TC) of ∼4840–5300 W/mK [2], which is far more than other common thermal management materials, such as copper (~400 W/mK), silver (~429 W/mK), etc
The pristine structure would be destroyed by the existence of defects, which have a significant impact on the mechanical and thermal properties of Gr
Summary
Due to its excellent mechanical, thermal and other physical properties, Graphene (Gr) has attracted great attention from researchers since it was first prepared by Geim and Novoselov [1] in 2004. The pristine structure would be destroyed by the existence of defects, which have a significant impact on the mechanical and thermal properties of Gr. For instance, by using Raman spectral, Zandiatashbar et al [10] found thatNtahneomYaoteurianlsg2’0s19m, 9o, xdFuOlRusPEoEfRGRErVwIEaWs maintained and fracture strength decreased by only ~124o%f 15even at a high concentration of sp3-type defects; it decreased significantly with the existence of vaca[n10c]yfoduenfedctth. C. TToo iinnvveessttiiggaattee tthhee eeffffeecctt ooff ddiiffffeerreenntt ddeeffeeccttss,, GGrrwwiitthhtthhrreeeeccoommmmoonnttyyppeessooffddeeffeeccttss,,nnaammeelylySSVV,, DDVV aanndd SSWW,, wwaass ccoonnssttrruucctteedd ((aass sshhoowwnn iinn FFiigguurree 22)). The sum of added/removed energy is equal to zaetro0.,0t3h.uDs uthreintgottahleenNeErgMyDissciomnusleartvioedn.s,Tthheeheenaetrfgluiexs arleomnogvtehde xfr-odmiretchtieocnoJlxdcbanatbheaenxdpraedsdsed btoy:the hot bath as a function of time were calculated. Once the steady-state temperature profile awlohnegrethEeishtehaet falcucxumwauslarteeadcheneedr,gtyh,et TisCthceousilmd ubleatciaolncutilmateedinbNy VFoEuerniesremlabwle: and A is the cross-section area obtained by the width multiplied by thickness.
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