Selective Formation of Zigzag Edges in Graphene Cracks

Fujihara, Miho; Inoue, Ryosuke; Kurita, Rei; Taniuchi, Toshiyuki; Motoyui, Yoshihito; Shin, Shik; Komori, Fumio; Maniwa, Yutaka; Shinohara, Hisanori; Miyata, Yasumitsu

doi:10.1021/acsnano.5b03079

Cited by 23 publications

(18 citation statements)

References 41 publications

(90 reference statements)

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“…The attachment process is activated by the barrier E att . The second term reflects the detachment rate from the flake perimeter L which is assumed to consist of zig‐zag edges in agreement with the literature . Here, ν g indicates the vibrational frequency of carbon atoms at the graphene flake perimeter (which equals typically about 10 13 1/s) and the desorption barrier amounts E det .…”

Section: Resultsmentioning

confidence: 79%

Understanding the Reaction Kinetics to Optimize Graphene Growth on Cu by Chemical Vapor Deposition

et al. 2017

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Understanding and controlling the growth kinetics of graphene is a prerequisite to synthesize this highly wanted material by chemical vapor deposition on Cu, e.g. for the construction of ultra-stable electron transparent membranes. It is reviewed that Cu foils contain a considerable amount of carbon in the bulk which significantly exceeds the expected amount of thermally equilibrated dissolved carbon in Cu and that this carbon must be removed before any high quality graphene may be grown. Starting with such conditioned Cu foils, systematic studies of the graphene growth kinetics in a reactive CH 4 /H 2 atmosphere allow to extract the following meaningful data: prediction of the equilibrium constant of the graphene formation reaction within a precision of a factor of two, the confirmation that the graphene growth proceeds from a C(ad)-phase on Cu which is in thermal equilibrium with the reactive gas phase, its apparent activation barrier and finally the prediction of the achievable growth velocity of the growing graphene flakes during chemical vapor deposition. As a result of the performed study, growth parameters are identified for the synthesis of high quality monolayer graphene with single crystalline domains of 100-1000 μm in diameter within a reasonable growth time.

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Section: Resultsmentioning

confidence: 79%

Understanding the Reaction Kinetics to Optimize Graphene Growth on Cu by Chemical Vapor Deposition

et al. 2017

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“…One-dimensional (1D) materials have historically been one of the most extensively studied classes of materials due to their diverse physical and chemical properties [3][4][5][6][7][8][9][10][11][12][13][14]. The breakthrough of single-layer graphene [15], initialized by Konstantin Novoselov and Andre Geim in 2004, has triggered exceptional interest in two-dimensional (2D) materials in the form of a single-atom-thick or polyhedral-thick layer with either covalent or ionic bonding in the plane and van der Waals bonding out of plane [16][17][18][19][20][21][22][23][24][25][26][27]. Beyond graphene, semiconducting transition metal dichalcogenides (TMDs) have also attracted significant research interest [28][29][30][31][32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Mechanical testing of two-dimensional materials: a brief review

Al-Quraishi

Kauppila

et al. 2020

International Journal of Smart and Nano Materials

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Two-dimensional (2D) materials have dominated nanoscience for the last two decades. Among all 2D materials, graphene, MoS 2 , and h-BN are extremely popular and have been tentatively scaled up to fabricate nanocomposites, energy storage devices, flexible electronics, etc., ex situ and in situ mechanical characterization of 2D crystals can help us understand their mechanical behavior and measure their mechanical properties, which are of great significance in both fundamental science and practical engineering. To date, a great effort has been devoted to both theoretical and experimental mechanics with a focus on unveiling mechanical behaviors and quantifying mechanical properties. Beyond original research, several insightful review works have been published with a specific focus on the mechanics of 2D materials. To have a complementary contribution to the overview of the mechanics of 2D materials, we would like to review the developed experimental techniques being used to mechanically characterize 2D materials. The working mechanism and associated advantages and disadvantages of the techniques will be briefly discussed. Based on the existence of arguments in mechanical properties and behaviors of 2D crystals, and immature mechanical characterization of 2D materials, more intensive and comprehensive studies are expected toward a full understanding of these novel and promising materials.

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“…The fracture toughness of monolayer graphene was quantitatively measured by in situ TEM with supportive molecular dynamics simulations, suggesting pure brittleness10. The cracks in monolayer graphene are along the preferable zigzag edge11. Meanwhile, several types of basal plane dislocations, or ‘zero-dimensional' dislocations, can emerge and are mobile in graphene or TMD121314, especially at high temperature or under electron beam irradiation, indicative of the easier dislocation dynamics in 2D form than in bulk.…”

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confidence: 99%

Dynamical observations on the crack tip zone and stress corrosion of two-dimensional MoS2

Zhao

Cichocka

et al. 2017

Nat Commun

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Whether and how fracture mechanics needs to be modified for small length scales and in systems of reduced dimensionality remains an open debate. Here, employing in situ transmission electron microscopy, atomic structures and dislocation dynamics in the crack tip zone of a propagating crack in two-dimensional (2D) monolayer MoS 2 membrane are observed, and atom-to-atom displacement mapping is obtained. The electron beam is used to initiate the crack; during in situ observation of crack propagation the electron beam effect is minimized. The observed high-frequency emission of dislocations is beyond previous understanding of the fracture of brittle MoS 2 . Strain analysis reveals dislocation emission to be closely associated with the crack propagation path in nanoscale. The critical crack tip plastic zone size of nearly perfect 2D MoS 2 is between 2 and 5 nm, although it can grow to 10 nm under corrosive conditions such as ultraviolet light exposure, showing enhanced dislocation activity via defect generation.

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Selective Formation of Zigzag Edges in Graphene Cracks

Cited by 23 publications

References 41 publications

Understanding the Reaction Kinetics to Optimize Graphene Growth on Cu by Chemical Vapor Deposition

Understanding the Reaction Kinetics to Optimize Graphene Growth on Cu by Chemical Vapor Deposition

Mechanical testing of two-dimensional materials: a brief review

Dynamical observations on the crack tip zone and stress corrosion of two-dimensional MoS2

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