Fracture and progressive failure of defective graphene sheets and carbon nanotubes

Xiao, Jing; Staniszewski, Jeffrey M.; Gillespie, J. W.

doi:10.1016/j.compstruct.2008.06.008

Cited by 118 publications

(68 citation statements)

References 46 publications

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“…Besides, the shear modulus and Poisson’s ration of defective graphene sheet are closely related to the position of SVs, and a pronounced reduction is observed when SVs are in a region of large strain gradient. Another atomistic FEA study [292] indicates that increasing the density of SW defects in graphene can change the Young’s modulus dramatically, particularly when the distance between neighboring defects is smaller than 2 nm (diameter of interaction region of SW defects [293]). Besides, the presence of single SW defects can result in significant reduction of the ultimate strength for graphene sheet, and further strength reductions are predicted for cases where adjacent SW defects are interacting with each other.…”

Section: Disorders In Graphene Structurementioning

confidence: 99%

Structure of graphene and its disorders: a review

Gao

Lee

et al. 2018

Science and Technology of Advanced Materials

487

187

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Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.

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Section: Disorders In Graphene Structurementioning

confidence: 99%

Structure of graphene and its disorders: a review

Gao

Lee

et al. 2018

Science and Technology of Advanced Materials

487

187

View full text Add to dashboard Cite

show abstract

“…Since a higher misorientation angle yields a higher density of dislocation cores at the linear tilt boundary, but also to higher intrinsic strength of the model structures, the authors noted that their results disagree with the fracture me-chanics model, assuming the heptagons of the dislocation cores correspond to Griffith cracks, which would predict graphene sheets to become weaker with an increasing defect density. If the grain boundaries themselves are indeed the weakest point in the lattice, this can be argued to be a reasonable comparison since also Stone-Wales defect consists of pentagons and heptagons and it has been shown to weaken graphene [12]. However, despite similarities between the theoretical models [16,17] and short segments of the actually observed non-decorated boundaries [1][2][3][4][5], it remains unclear whether such infinitely long linear arrangements of dislocation cores can serve as a realistic model for studying mechanical properties of polycrystalline graphene.…”

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confidence: 99%

Mechanical properties of polycrystalline graphene based on a realistic atomistic model

2012

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Graphene can at present be grown at large quantities only by the chemical vapor deposition method, which produces polycrystalline samples. Here, we describe a method for constructing realistic polycrystalline graphene samples for atomistic simulations, and apply it for studying their mechanical properties. We show that cracks initiate at points where grain boundaries meet and then propagate through grains predominantly in zigzag or armchair directions, in agreement with recent experimental work. Contrary to earlier theoretical predictions, we observe normally distributed intrinsic strength (∼ 50% of that of the mono-crystalline graphene) and failure strain which do not depend on the misorientation angles between the grains. Extrapolating for grain sizes above 15 nm results in a failure strain of ∼ 0.09 and a Young's modulus of ∼ 600 GPa. The decreased strength can be adequately explained with a conventional continuum model when the grain boundary meeting points are identified as Griffith cracks.Grain boundaries define the electronic and mechanical properties of polycrystalline materials. Since chemical vapor deposition (CVD) is currently the only way for producing industry-scale graphene membranes, and leads to polycrystalline samples, study of grain boundaries in graphene has become of fundamental importance during the recent years. In a two-dimensional material, such as graphene, the boundaries also have a critical contribution to the chemical reactivity. Because of this, although atomic scale imaging can in principle reveal their exact structure, the boundaries tend to be covered by adsorbates with only short segments available for direct imaging. Nevertheless, experiments [1-6] have revealed meandering serpent-like boundaries which are typically formed from pentagon-heptagon-pairs in the parts not covered by the adsorbates.Mechanical properties of graphene sheets have been a topic of intense research already for two decades in the context of carbon nanotubes (see Ref.[7] for a topical review). More recently, in 2007 [8], Liu and co-workers utilized ab initio calculations to study the elastic moduli and fracture characteristic of graphene. Young's modulus was found to be 1.05 TPa, and failure strain, depending on the pulling direction, 0.194-0.266. Intrinsic strength was estimated to be 110-121 GPa, similarly depending on the pulling direction. The role of pre-existing defects on these properties was also studied [9]. It was noticed that their effect does not depend on the exact atomic structure of the defects but rather on their size. The authors also showed that the intrinsic strength of graphene with crack-like defects can be described with a continuum model using the Griffith formula for defect sizes down to 10Å. Soon after this, Frank et al. used a tip of an atomic force microscope to obtain a Young's modulus of 0.5 TPa for suspended stacks of graphene sheets [10]. A year later, Lee and co-workers reported on several mechanical properties of graphene using a similar technique [11], establishing graphene ...

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“…Computational work has investigated the mechanical properties of graphene in the presence of vacancies [27][28][29][30][31] , bond reconstruction [32][33][34][35] and functional groups 36 . Several studies have also shown the formation and structural evolution of defects in graphene using both experimental 37,38 and theoretical tools [39][40][41][42] .…”

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confidence: 99%

Effect of defects on the intrinsic strength and stiffness of graphene

et al. 2014

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It is important from a fundamental standpoint and for practical applications to understand how the mechanical properties of graphene are influenced by defects. Here we report that the two-dimensional elastic modulus of graphene is maintained even at a high density of sp 3 -type defects. Moreover, the breaking strength of defective graphene is only B14% smaller than its pristine counterpart in the sp 3 -defect regime. By contrast, we report a significant drop in the mechanical properties of graphene in the vacancy-defect regime. We also provide a mapping between the Raman spectra of defective graphene and its mechanical properties. This provides a simple, yet non-destructive methodology to identify graphene samples that are still mechanically functional. By establishing a relationship between the type and density of defects and the mechanical properties of graphene, this work provides important basic information for the rational design of composites and other systems utilizing the high modulus and strength of graphene.

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Fracture and progressive failure of defective graphene sheets and carbon nanotubes

Cited by 118 publications

References 46 publications

Structure of graphene and its disorders: a review

Structure of graphene and its disorders: a review

Mechanical properties of polycrystalline graphene based on a realistic atomistic model

Effect of defects on the intrinsic strength and stiffness of graphene

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