In-plane lattice thermal conductivities of multilayer graphene films

Wei, Zhiyong; Zhang, Ni; Bi, Kedong; Chen, Minhua; Chen, Yunfei

doi:10.1016/j.carbon.2011.02.051

Cited by 168 publications

(94 citation statements)

References 32 publications

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“…For the pristine graphene sheet, the extrapolation gives k ? = 774 W/mK, which is in agreement with recent NEMD calculations on the same potential model [16,32,34]. The large deviation from linearity at the maximum concentration (10 % silicon atoms) is related to the Thermal conductivity reduction in graphene with silicon impurity 1195 resolution of conductivity, i.e., the conductivity value is so small that the inverse value appears large.…”

Section: Resultssupporting

confidence: 89%

“…(5). There are three conjectures on the behavior of the thermal conductivity: (1) As in MD simulation, the bulk thermal conductivity is usually estimated by the Matthiessen's rule preferred in general bulk (three dimensional) materials , which assumes a finite k at infinite length [31,32]; (2) the k diverges in lower dimensions especially with logarithmic law (log dependence) for two dimensional lattices, which, in graphene, is known to be valid up to L \ *9 lm, and then diverges [35]; and (3) the k follows log dependence when L is smaller than about 100 lm, and for longer L, it converges when the thermal transport reaches the diffusive regime [36].…”

Section: Resultsmentioning

confidence: 99%

“…The Newtonian equation is discretized in time using the Verlet algorithm with a fixed time step of Dt = 0.2 fs for both NEMD and EMD, and both methods have previously been systemically applied to silicon bonds with the Tersoff potential [31]. The procedure used by Wei et al [32] is employed for NEMD calculations, where the half-sized domain, which is used for time-saving purposes, is the only difference from general NEMD calculations. The atomic arrangement of carbon and silicon is depicted in Fig.…”

Section: Methodsmentioning

confidence: 99%

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Thermal conductivity reduction in graphene with silicon impurity

Lee

2015

Appl. Phys. A

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We present a molecular dynamics investigation on the thermal conductivity of silicon-doped graphene and the resulting change in phonon properties. A significant reduction in the thermal conductivity is observed in the presence of silicon impurity even at a small concentration of silicon atoms. Conductivity values continued to decrease with an increase in silicon concentration. The increase in the scattering rate, which is measured by the reduction or broadening of the peaks of the van Hove singularities, is the most significant factor contributing to the large conductivity reduction. An analysis with scattering time models shows that the mass displaced by the silicon impurity plays a significant role in reducing the conductivity, especially at a moderate concentration. The nonmass effect, which comes from the change of the sp 2 C-C bonds to the sp 3 Si-C bonds, is less strong or comparable with the mass change effect. For high impurity concentrations, the shape of the graphene is severely distorted and the irregularity of the ripples increases, which could contribute to the reduction in conductivity.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Thermal conductivity reduction in graphene with silicon impurity

Lee

2015

Appl. Phys. A

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“…This is considered to be due to interlayer interactions and vibrational restrictions from neighboring layers, which limits the free vibration of the graphene sheets and imposes resistance on phonon transport. [45] Therefore, we believe that the thermal transport properties of our rGO fibers are not an indication of the in-plane thermal conductivity of the individual layers due to the tangled nature of the rGO sheets in the fiber and lattice defects that are introduced during GO sheet synthesis and subsequent reduction processes. These effects further contribute to the lower thermal conductivity measurements compared to pristine graphene.…”

Section: Thermal Conductivitymentioning

confidence: 94%

Scalable One‐Step Wet‐Spinning of Graphene Fibers and Yarns from Liquid Crystalline Dispersions of Graphene Oxide: Towards Multifunctional Textiles

Jalili

Aboutalebi

Esrafilzadeh

et al. 2013

Adv Funct Materials

387

426

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. (2013). Scalable one-step wet-spinning of graphene fibers and yarns from liquid crystalline dispersions of graphene oxide: towards multifunctional textiles. Advanced Functional Materials, 23 (43), 5345-5354.Scalable one-step wet-spinning of graphene fibers and yarns from liquid crystalline dispersions of graphene oxide: towards multifunctional textiles AbstractKey points in the formation of liquid crystalline (LC) dispersions of graphene oxide (GO) and their processability via wet-spinning to produce long lengths of micrometer-dimensional fibers and yarns are addressed. Based on rheological and polarized optical microscopy investigations, a rational relation between GO sheet size and polydispersity, concentration, liquid crystallinity, and spinnability is proposed, leading to an understanding of lyotropic LC behavior and fiber spinnability. The knowledge gained from the straightforward formulation of LC GO "inks" in a range of processable concentrations enables the spinning of continuous conducting, strong, and robust fibers at concentrations as low as 0.075 wt%, eliminating the need for relatively concentrated spinning dope dispersions. The dilute LC GO dispersion is proven to be suitable for fiber spinning using a number of coagulation strategies, including non-solvent precipitation, dispersion destabilization, ionic cross-linking, and polyelectrolyte complexation. One-step continuous spinning of graphene fibers and yarns is introduced for the first time by in situ spinning of LC GO in basic coagulation baths (i.e., NaOH or KOH), eliminating the need for post-treatment processes. The thermal conductivity of these graphene fibers is found to be much higher than polycrystalline graphite and other types of 3D carbon based materials. New insights are provided into the processing of liquid crystalline graphene oxide (GO) dispersion (containing large GO sheets) demonstrating a facile and scalable production of GO and reduced GO fibers and yarns with exciting properties such as high thermal conductivity. These results provide a universal platform for the development of solution-based processing methods, properties, and applications of liquid crystalline GO-based architectures. AbstractIn the present work, we address key points in the formation of liquid crystalline (LC) dispersions of graphene oxide (GO) and their processability via wet-spinning to produce long lengths of micron dimensional fibers and yarns. Based on rheological and polarized optical microscopy investigations, a rational relation between GO sheet size and polydispersity, concentration, liquid crystallinity and spinnability is proposed leading to the understanding of 2 lyotropic LC behavior and fiber spinnability. The knowledge gained from our straightforward formulation of LC GO "inks" in a range of processable concentrations enabled us to spin continuous conducting, strong and robust fibres at concentrations as low as 0.075 wt. % eliminating the need for relatively concentrated spinning dope dispersions. This concentration is the lowest ever rep...

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“…15,16 In additional to posing resistance to thermal transport in the direction that is normal to the vdW interface, phonon behavior at vdW interfaces could also have important effects to energy flow in the direction parallel to the vdW interface. For example, it has been shown that the in-plane thermal conductivity of multi-layer graphene 17 or supported graphene 8 is lower than that of suspended single-layer graphene, [17][18][19][20][21] which has been attributed to the interlayer phonon scattering or that between the supported graphene and the substrate. 17,[19][20][21][22] On the contrary, Guo et al's 23 and Ong et al's 24 results show that the coupling force plays an positive role in the enhancement of thermal conductivity.…”

mentioning

confidence: 99%