Reverse non-equilibrium molecular dynamics simulations on the thermal conductivity of three-dimensional graphene nano-ribbon foams

Değirmenci, Ünal; Kırca, Mesut

doi:10.1016/j.jpcs.2019.109130

Cited by 11 publications

(3 citation statements)

References 59 publications

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“…Zhang and Jiang found that the thermal conductivity of ZIF-8 increases slightly when the temperature increases from 300 to 1000 K by performing EMD and NEMD, and they attributed this effect to the improvement of the weakest link part of heat transport in ZIF-8 . Degirmenci and Kirca calculated the thermal conductivity of GNR by performing R-NEMD, and their results showed that the thermal transport can increase by around 5% when the temperature increases from 100 to 700 K. Also, they concluded that the further formation of the covalent bonds between the GNR/GNR-F units establishes a network structure, thereby increasing the energy flow path and the thermal conductivity …”

Section: Resultsmentioning

confidence: 99%

“…40 Degirmenci and Kirca calculated the thermal conductivity of GNR by performing R-NEMD, and their results showed that the thermal transport can increase by around 5% when the temperature increases from 100 to 700 K. Also, they concluded that the further formation of the covalent bonds between the GNR/GNR-F units establishes a network structure, thereby increasing the energy flow path and the thermal conductivity. 50…”

Section: Resultsmentioning

confidence: 99%

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Atomistic Insights into the Anisotropic and Low Thermal Conductivity in Neopentyl Glycol Crystals: A Molecular Dynamics Study

Wang

Sun

et al. 2021

J. Phys. Chem. C

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Neopentyl glycol (NPG) is a promising next-generation environment-friendly refrigerant, because NPG can release huge latent heat during a solid-phase transition from a plastic crystal phase to a true crystal phase. However, NPG has a very low thermal conductivity, which restricts its applications. In this paper, we investigated the mechanisms of thermal transport of an NPG crystal by performing atomistic molecular dynamics (MD) simulations. Our simulation results obtained the thermal conductivities of 0.50, 0.32, and 0.33 W m–1 K–1 at 298.15 K along the a*, b*, and c* directions, respectively, which agree with the experimental results ranging from 0.15 to 0.42 W m–1 K–1. The anisotropy of the thermal conductivity along the three directions is caused by the hydrogen-bond network in NPG. We reveal the reasons for the low thermal conductivity: the large gap between the low-frequency region and the high-frequency region in the phonon spectrum and the ultrashort phonon mean free path (MFP). The effective MFPs are only 1.28, 5.47, and 2.22 nm along the a*, b*, and c* directions, respectively. In addition, we find that the thermal conductivity is insensitive to the temperature from 218.15 to 298.15 K, probably because the ultrashort MFP is insensitive to the temperature. Furthermore, we find that vacancy defects affect the thermal conductivity in an intriguing manner. When the defect concentrations are 2 and 4%, the thermal conductivities along the b* and c* directions increase abnormally with the increase in temperature, which is related to the re-orientation of hydroxyl groups upon the change in temperature. Overall, this work reveals the molecular mechanism of the thermal transport of NPG, which should provide valuable insights in enhancing the thermal conductivity of NPG for the application as an environment-friendly refrigerant.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Atomistic Insights into the Anisotropic and Low Thermal Conductivity in Neopentyl Glycol Crystals: A Molecular Dynamics Study

Wang

Sun

et al. 2021

J. Phys. Chem. C

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“…The RNEMD method is a relatively new simulation technique that was proposed by Müller-Plathe in 1997 [22] as an alternative method for investigating transport phenomena. Originally, it was implemented for transport studies of Lennard-Jones fluids, but later on, it has been applied to more complex systems, such as, carbon and graphene nanosystems [23][24][25][26][27][28]. The RNEMD method has been found to be quite robust for studying thermal transport properties, but also has some issues that have been pointed out in recent works, and improvements have been suggested in some cases [29][30][31][32].…”

Section: Rnemd Simulationsmentioning

confidence: 99%

Heat transport in long-ranged anharmonic oscillator models

Bagchi

2021

Preprint

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In this work, we perform a detailed study of heat transport in one dimensional long-ranged anharmonic oscillator systems, such as the long-ranged Fermi-Pasta-Ulam-Tsingou model. For these systems, the long-ranged anharmonic potential decays with distance as a power-law, controlled by an exponent δ ≥ 0. For such a nonintegrable model, one of the recent results that has captured quite some attention is the puzzling ballistic-like transport observed for δ = 2, reminiscent of integrable systems. Here, we first employ the reverse nonequilibrium molecular dynamics simulations to look closely at the δ = 2 transport in three long-ranged models, and point out a few problematic issues with this simulation method. Next, we examine the process of energy relaxation, and find that relaxation can be appreciably slow for δ = 2 in some situations. We invoke the concept of nonlinear localized modes of excitation, also known as discrete breathers, and demonstrate that the slow relaxation and the ballistic-like transport properties can be consistently explained in terms of a novel depinning of the discrete breathers that makes them highly mobile at δ = 2. Finally, in the presence of quartic pinning potentials we find that the long-ranged model exhibits Fourier (diffusive) transport at δ = 2, as one would expect from short-ranged interacting systems with broken momentum conservation. Such a diffusive regime is not observed for harmonic pinning.

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Nano-foam architectures of polymer and graphene

Kausar¹

2022

Graphene to Polymer/Graphene Nanocomposites

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Reverse non-equilibrium molecular dynamics simulations on the thermal conductivity of three-dimensional graphene nano-ribbon foams

Cited by 11 publications

References 59 publications

Atomistic Insights into the Anisotropic and Low Thermal Conductivity in Neopentyl Glycol Crystals: A Molecular Dynamics Study

Atomistic Insights into the Anisotropic and Low Thermal Conductivity in Neopentyl Glycol Crystals: A Molecular Dynamics Study

Heat transport in long-ranged anharmonic oscillator models

Nano-foam architectures of polymer and graphene

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