Role of Edge Chirality and Isotope Doping in Thermal Transport and Thermal Rectification in Graphene Nanoribbons

2011 ◽  
Author(s):  
Yan Wang ◽  
Xiulin Ruan
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Graphene Nanoribbons ◽  
Mass Density ◽  
Transport Processes ◽  
Phonon Modes ◽  
Cross Sectional ◽  
Thermal Rectification ◽  
The Difference ◽  
Dynamics Simulations

Thermal transport processes in graphene nanoribbons (GNRs) within and beyond the linear response regime has been studied using classical molecular dynamics simulations. Zigzag-edged GNRs have higher thermal conductivities than armchair-edged ones, and the difference diminishes with increasing width. Analysis on the cross-sectional distribution of heat flux reveals that edge atoms cannot transport thermal energy as efficiently as interior ones. Edge localization of phonon modes reduces thermal transport through edge carbon atoms, especially on armchair edges, which results in a lower thermal conductivity. Isotope (13C) doping can reduce the thermal conductivity of GNRs by 30%–40% by an addition of only ∼20% isotope atoms. The significant reduction in thermal conductivity is partially attributed to phonon localization induced by isotope defects, which is confirmed by phonon mode participation ratio analysis. We also demonstrate that a GNR asymmetric in edge chirality or mass density can generate considerable thermal rectification, which is essential for developing GNR-based thermal management devices.

Thermal Transport in Graphene Supported on Copper

2012 ◽  
Author(s):  
Liang Chen ◽  
Satish Kumar
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Copper Substrate ◽  
Interaction Strength ◽  
Thermal Coupling ◽  
Phonon Modes ◽  
Large Wave ◽  
Relaxation Time Approximation ◽  
Out Of Plane ◽  
Dynamics Simulations

The present study investigates the thermal transport in suspended graphene and graphene supported on copper substrate using equilibrium molecular dynamics simulations, Green-Kubo method and relaxation time approximation (RTA) approach. The thermal coupling between graphene and copper substrate was investigated by varying the interaction strength between the carbon atoms and Cu atoms at the interface. The contribution of different phonon modes to the thermal conductivity of suspended and supported graphene was analyzed in order to elucidate the graphene-substrate thermal interactions. The thermal conductivity of graphene decreases with the increasing strength of the interfacial interaction. The analysis shows that the interactions with copper substrate can reduce the thermal conductivity by up to 44%. The decrease of thermal conductivity is primarily due to the suppression of contribution from out-of-plane acoustic (ZA) phonons in the large wave vector region.

Argon Thermal Conductivity by Anharmonic Lattice Dynamics Calculations

2008 ◽  
Author(s):  
J. E. Turney ◽  
A. J. H. McGaughey ◽  
C. H. Amon
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Lattice Dynamics ◽  
Mode Shapes ◽  
Face Centered Cubic ◽  
Phonon Modes ◽  
Anharmonic Lattice ◽  
The Face ◽  
Face Centered ◽  
Dynamics Simulations

Lattice dynamics calculations are used to investigate thermal transport in the face-centered cubic Lennard-Jones (LJ) argon crystal between temperatures of 20 and 80 K. First, quasi-harmonic lattice dynamics calculations are used to find the frequencies and mode shapes of non-interacting phonons [1]. This information is then used as input for anharmonic lattice dynamics calculations. Anharmonic lattice dynamics is a means of computing the frequency shift and lifetime of each phonon mode due to interactions with other phonons [2]. The phonon frequencies, group velocities, and lifetimes, determined with the lattice dynamics methods, are then used to compute the thermal conductivity. The thermal conductivities predicted by the lattice dynamics methods are compared to predictions from molecular dynamics simulations. The two methods are found to agree well at low temperature but diverge at higher temperatures (i.e., near the melting point). The properties of individual phonon modes are used to identify the modes that dominate thermal transport.

Linear and Nonlinear Thermal Transport in Graphene: Molecular Dynamics Simulations

2011 ◽  
Vol 1347 ◽  
Author(s):  
Bo Qiu ◽  
Yan Wang ◽  
Xiulin Ruan
Keyword(s):  
Molecular Dynamics ◽  
Thermal Transport ◽  
Graphene Nanoribbons ◽  
Ballistic Transport ◽  
Thermal Conductance ◽  
Md Simulations ◽  
Spectral Energy ◽  
Suspended Graphene ◽  
Thermal Rectification ◽  
Dynamics Simulations

AbstractIn this work, we perform molecular dynamics (MD) simulations to study the linear thermal transport in suspended graphene and the nonlinear thermal transport phenomena in graphene nanoribbons (GNR). We use spectral energy density analysis to quantitatively address the relative importance of different types of phonon in thermal transport in suspended graphene. Negative differential thermal conductance (NDTC) and thermal rectification in graphene nanoribbons have been studied using nonequilibrium molecular dyanmics simulations. Ballistic transport regime, sufficient temperature nonlinearity and asymmetry are found to be necessary conditions for the onset of these behaviors.

Monolayer and bilayer polyaniline C3N: two-dimensional semiconductors with high thermal conductivity

Nanoscale ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 4301-4310 ◽  
Author(s):  
Yang Hong ◽  
Jingchao Zhang ◽  
Xiao Cheng Zeng
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Md Simulation ◽  
Transport Processes ◽  
High Thermal Conductivity ◽  
Two Dimensional

Lateral and flexural thermal transport processes in monolayer and bilayer C3N are systematically investigated using MD simulation.

scholarly journals Thermal Transport in Graphene Oxide Films: Theoretical Analysis and Molecular Dynamics Simulation

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 285 ◽  
Author(s):  
Yi Yang ◽  
Dan Zhong ◽  
Yilun Liu ◽  
Donghui Meng ◽  
Lina Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Graphene Oxide ◽  
Molecular Dynamics Simulation ◽  
Thermal Transport ◽  
Oxide Films ◽  
Vacancy Defect ◽  
Transport Processes ◽  
Dynamics Simulation ◽  
Great Promise

As a derivative material of graphene, graphene oxide films hold great promise in thermal management devices. Based on the theory of Fourier formula, we deduce the analytical formula of the thermal conductivity of graphene oxide films. The interlaminar thermal property of graphene oxide films is studied using molecular dynamics simulation. The effect of vacancy defect on the thermal conductance of the interface is considered. The interfacial heat transfer efficiency of graphene oxide films strengthens with the increasing ratio of the vacancy defect. Based on the theoretical model and simulation results, we put forward an optimization model of the graphene oxide film. The optimal structure has the minimum overlap length and the maximum thermal conductivity. An estimated optimal overlap length for the GO (graphene-oxide) films with degree of oxidation 10% and density of vacancy defect 2% is 0.33 μm. Our results can provide effective guidance to the rationally designed defective microstructures on engineering thermal transport processes.

scholarly journals Anomalous strain effect on the thermal conductivity of low-buckled two-dimensional silicene

2020 ◽  
Author(s):  
Bin Ding ◽  
Xiaoyan Li ◽  
Wuxing Zhou ◽  
Gang Zhang ◽  
Huajian Gao
Keyword(s):  
Thermal Conductivity ◽  
Strain Effect ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Heat Management ◽  
Anomalous Effect ◽  
Long Wavelength ◽  
Two Dimensional Materials ◽  
Dynamics Simulations ◽  
Energy Conversion Devices

Abstract The thermal conductivity of two-dimensional materials, such as graphene, typically decreases when tensile strain is applied, which softens their phonon modes. Here, we report an anomalous strain effect on the thermal conductivity of monolayer silicene, a representative low-buckled two-dimensional (LB-2D) material. ReaxFF-based molecular dynamics simulations are performed to show that biaxially stretched monolayer silicene exhibits a remarkable increase in the thermal conductivity, by as much as 10 times the freestanding value, with increasing applied strain in the range of [0, 0.1], which is attributed to increased contributions from long-wavelength phonons. A further increase in strain in the range of [0.11, 0.18] results in a plateau of the thermal conductivity in an oscillatory manner, governed by a unique dynamic bonding behavior under extreme loading. This anomalous effect reveals new physical insights into the thermal properties of LB-2D materials and may provide some guidelines for designing heat management and energy conversion devices based on such materials.

scholarly journals Reduction of Lattice Thermal Conductivity in PbTe Induced by Artificially Generated Pores

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Jae-Yeol Hwang ◽  
Eun Sung Kim ◽  
Syed Waqar Hasan ◽  
Soon-Mok Choi ◽  
Kyu Hyoung Lee ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pore Structure ◽  
Transport Properties ◽  
Thermoelectric Materials ◽  
Thermal Transport ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Phonon Modes ◽  
Thermal Transport Properties

Highly dense pore structure was generated by simple sequential routes using NaCl and PVA as porogens in conventional PbTe thermoelectric materials, and the effect of pores on thermal transport properties was investigated. Compared with the pristine PbTe, the lattice thermal conductivity values of pore-generated PbTe polycrystalline bulks were significantly reduced due to the enhanced phonon scattering by mismatched phonon modes in the presence of pores (200 nm–2 μm) in the PbTe matrix. We obtained extremely low lattice thermal conductivity (~0.56 W m−1 K−1at 773 K) in pore-embedded PbTe bulk after sonication for the elimination of NaCl residue.

Structure, Mechanical Properties, and Thermal Transport in Microporous Silicon Nitride Via Parallel Molecular Dynamics

1995 ◽  
Vol 408 ◽  
Author(s):  
Andrey Omeltchenko ◽  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Silicon Nitride ◽  
Elastic Constants ◽  
Thermal Transport ◽  
Entire System ◽  
Amorphous Silicon Nitride ◽  
Parallel Molecular Dynamics ◽  
Dynamics Simulations

AbstractMolecular dynamics simulations are performed to investigate structure, mechanical properties, and thermal transport in amorphous silicon nitride under uniform dilation. As the density is lowered, we observe the formation of pores below ρ = 2.6 g/cc and at 2.0 g/cc the largest pore percolates through the entire system. Effects of porosity on elastic constants, phonons and thermal conductivity are investigated. Thermal conductivity and Young's modulus are found to scale as ρ1.5 and ρ3.6, respectively.

Mode-Wise Thermal Conductivity of Bismuth Telluride

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Yaguo Wang ◽  
Bo Qiu ◽  
Alan J. H. McGaughey ◽  
Xiulin Ruan ◽  
Xianfan Xu
Keyword(s):  
Thermal Conductivity ◽  
Bismuth Telluride ◽  
Thermal Transport ◽  
Phonon Dispersion ◽  
Relaxation Times ◽  
Phonon Modes ◽  
Time Resolved ◽  
Transport Control ◽  
Reported Data ◽  
Phonon Properties

Thermal properties and transport control are important for many applications, for example, low thermal conductivity is desirable for thermoelectrics. Knowledge of mode-wise phonon properties is crucial to identify dominant phonon modes for thermal transport and to design effective phonon barriers for thermal transport control. In this paper, we adopt time-domain (TD) and frequency-domain (FD) normal-mode analyses to investigate mode-wise phonon properties and to calculate phonon dispersion relations and phonon relaxation times in bismuth telluride. Our simulation results agree with the previously reported data obtained from ultrafast time-resolved measurements. By combining frequency-dependent anharmonic phonon group velocities and lifetimes, mode-wise thermal conductivities are predicted to reveal the contributions of heat carriers with different wavelengths and polarizations.

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