Anisotropic thermal conductivity of graphene wrinkles

Wang, Chao; Liu, Y.; Li, Li; Tan, He‐Ping

doi:10.1039/c4nr00423j

Cited by 87 publications

(61 citation statements)

References 37 publications

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“…This is in good agreement with Ref. 32,33 . This PDOS peak broadening effect may also be explained as the phonon scattering enhancement by the mass density difference.…”

Section: Resultssupporting

confidence: 94%

Mechanisms governing phonon scattering by topological defects in graphene nanoribbons

et al. 2015

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Understanding phonon scattering by topological defects in graphene is of particular interest for thermal management in graphene-based devices. We present a study that quantifies the roles of the different mechanisms governing defect phonon scattering by comparing the effects of ten different defect structures using molecular dynamics. Our results show that phonon scattering is mainly influenced by mass density difference, with general trends governed by the defect formation energy and typical softening behaviors in the phonon density of state. The phonon scattering cross-section is found to be far larger than that geometrically occupied by the defects. We also show that the lattice thermal conductivity can be reduced by a factor of up to ~30 in the presence of the grain boundaries formed by these defects.

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“…This is in good agreement with Ref. 32,33 . This PDOS peak broadening effect may also be explained as the phonon scattering enhancement by the mass density difference.…”

Section: Resultssupporting

confidence: 94%

Mechanisms governing phonon scattering by topological defects in graphene nanoribbons

et al. 2015

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“…Then, the origin of the observed wrinkle to filament-like morphology evolution could be ascribed to the steady deformation of the GO sheets triggered by the creation of structural defects [29][30][31] and chemical functionalization [32]. Besides thermal fluctuations, the development of extremely high temperature gradients in reduced regions due to the presence of different intrinsic defect sites in GO sheet could significantly contribute to the formation of a stress-induced bending, the arrangement of the wrinkles and the formation of resonant features [33][34][35]. In a similar way, prominent corrugation of multiwall carbon nanotubes shells induced by UV laser radiation has been recently observed [36].…”

Section: Resultsmentioning

confidence: 97%

Laser-induced chemical transformation of graphene oxide–iron oxide nanoparticles composites deposited on polymer substrates

Pino

György

Logofatu

et al. 2015

Carbon

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A B S T R A C TUltraviolet laser irradiation of films composed of graphene oxide (GO) and GO-magnetite (Fe 3 O 4 ) nanoparticles deposited on polydimethylsiloxane substrates is carried out. The irradiations are performed in vacuum and ammonia-rich gas environments. Electron and scanning probe microscopies reveal a rippling process in GO sheets as the accumulation of laser pulses proceeds, being the effect more pronounced with the increase of laser fluence. X-ray photoelectron spectroscopy analyses point to laser-induced chemical reaction pathways in GO completely different depending on the environment and the presence or absence of Fe 3 O 4 nanoparticles. It is demonstrated that GO-based films with diverse type of oxygen-and nitrogen-containing chemical groups can be obtained by means of laser irradiation processes. The sheet resistance of these materials is also correlated to their structure and composition.

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“…Wrinkling is a common phenomenon that is seen on graphene grown by the chemical vapor deposition (CVD) method because of the strain induced by the different thermal expansion coefficient mismatch between graphene and the metal substrate . There has been a great interest in understanding the wrinkling of graphene since graphene wrinkles may affect its extraordinary properties such as electrical mobility, band gap opening, local charge accumulation, anticorrosion degradation, mechanical strength, thermal conductivity, charge storage enhancement, and strain sensitivity . Hence, understanding the wrinkling mechanisms of graphene is important for many applications.…”

Section: Introductionmentioning

confidence: 99%

Wrinkling of graphene because of the thermal expansion mismatch between graphene and copper

Ogurtani

Senyildiz

Büke

2018

Surface & Interface Analysis

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Well-defined bundles of wrinkles are observed on the graphene-covered copper by using atomic force microscopy after chemical vapor deposition process. Their numerical analyses are performed by employing a set of formula deduced from classical elasticity theory of bent thin films with clamped boundary conditions. Here they are imposed by the banks of trenches associated with the reconstructed copper substrate surfaces, which suppress lateral movements of graphene monolayers and induce local biaxial stress. The wrinkling wavelength (λ) and amplitude (A) are both measured experimentally (λ = 100-160 nm and A = 2.5-3 nm) and calculated numerically (λ = 167 nm and A = 3.0 nm) and found to be in good agreement. Wrinkle formation is attributed to the nonhydrostatic compression stresses induced on the graphene by the linear thermal expansion coefficient difference between graphene and copper during cooling. These mismatch stresses, which are varying strongly with the temperature, create temperature-dependent wrinkling wave formation that decreases in wavelength and increases in amplitude upon cooling below the crossover temperature of 1233 K, at which both values of linear thermal expansion coefficient are equal.

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Anisotropic thermal conductivity of graphene wrinkles

Cited by 87 publications

References 37 publications

Mechanisms governing phonon scattering by topological defects in graphene nanoribbons

Mechanisms governing phonon scattering by topological defects in graphene nanoribbons

Laser-induced chemical transformation of graphene oxide–iron oxide nanoparticles composites deposited on polymer substrates

Wrinkling of graphene because of the thermal expansion mismatch between graphene and copper

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