Phonon scattering at SWCNT–SWCNT junctions in branched carbon nanotube networks

Park, Jungkyu; Lee, Jonghoon; Prakash, Vikas

doi:10.1007/s11051-015-2873-0

Cited by 11 publications

(8 citation statements)

References 29 publications

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“…Although the alteration to the TA phonon mode in Phonon density of states (PDOS) is plotted for PuO 2 with different point defects in Figure 6b. PDOS is obtained directly from MD simulations through velocity auto-correlation using the same potential field at 300K [34]. The shaded area represents the PDOS of stoichiometric PuO 2 .…”

Section: The Effect Of Point Defects On Thermal Transport In Actinidementioning

confidence: 99%

Phonon Scattering and Thermal Conductivity of Actinide Oxides with Defects

et al. 2020

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In the present study, we examine the effect of point defects and fission gases on thermal transport in representative actinide oxides used in modern reactors. In particular, oxygen interstitials and Kr/Xe fission gas bubbles are of primary focus. Reverse non-equilibrium molecular dynamics is employed to investigate thermal transport in UO2 and PuO2 with oxygen interstitials at the defect concentrations of 0.1%, 1%, and 5%. The results show that any alteration to the lattice structures of these fuels reduce their thermal conductivities significantly. For the largest UO2 structure simulated in the present study, for example, 0.1% oxygen interstitials decreased the thermal conductivity by 18.6%. For the case of the effect of fission gas bubbles, serious modification to phonon dispersion in oxide fuels is caused by the presence of a single fission gas bubble, resulting in a large temperature drop in their temperature profiles. The average interfacial thermal resistance across a fission gas bubble (comprised of 30 Kr and/or Xe atoms) is estimated to be 2.1 × 10−9 Km2/W.

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Section: The Effect Of Point Defects On Thermal Transport In Actinidementioning

confidence: 99%

Phonon Scattering and Thermal Conductivity of Actinide Oxides with Defects

et al. 2020

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“…However, the quasi-one-dimensional thermal transport of CNTs has restricted their applications. Therefore, branched CNTs [3,4] have been proposed as alternatives to CNTs. Due to their strong sp2 covalent bonds, branched CNTs exhibit lower thermal resistance than those structures with van der Waals interactions (e.g., CNT bundles [5,6], intermolecular junctions [7][8][9], and CNT networks [10,11]).…”

Section: Introductionmentioning

confidence: 99%

“…Branched CNTs possess topological defects and the possibility of multidirectional thermal transfer in junction regions, whereas pristine CNTs do not. Some studies have examined the influences of the aforementioned phenomena on the thermal transport behavior [3,4,[24][25][26]. The topological defects at the junction area of branched CNTs must satisfy Euler's polyhedral formula [27,28].…”

Section: Introductionmentioning

confidence: 99%

A Thermal Transport Study of Branched Carbon Nanotubes with Cross and T-Junctions

Chen

Chang

2021

Applied Sciences

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This study investigated the thermal transport behaviors of branched carbon nanotubes (CNTs) with cross and T-junctions through non-equilibrium molecular dynamics (NEMD) simulations. A hot region was created at the end of one branch, whereas cold regions were created at the ends of all other branches. The effects on thermal flow due to branch length, topological defects at junctions, and temperature were studied. The NEMD simulations at room temperature indicated that heat transfer tended to move sideways rather than straight in branched CNTs with cross-junctions, despite all branches being identical in chirality and length. However, straight heat transfer was preferred in branched CNTs with T-junctions, irrespective of the atomic configuration of the junction. As branches became longer, the heat current inside approached the values obtained through conventional prediction based on diffusive thermal transport. Moreover, directional thermal transport behaviors became prominent at a low temperature (50 K), which implied that ballistic phonon transport contributed greatly to directional thermal transport. Finally, the collective atomic velocity cross-correlation spectra between branches were used to analyze phonon transport mechanisms for different junctions. Our findings deeply elucidate the thermal transport mechanisms of branched CNTs, which aid in thermal management applications.

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“…Single-walled or multi-walled CNTs are quasi-one dimensional structures, and thermal conduction is limited to one direction. To efficiently transfer energy in all the desired directions, several nanotube structures (e.g., CNT bundles [3,4], pillared graphene [5][6][7], branched CNTs with X-, T-, Y- [8,9] or intermolecular junctions [10][11][12], and CNT networks [11,13]) have been proposed for different purposes. Among these structures, branched CNTs are of special interest for their potential to rectify electric current [14][15][16] or heat [8,17].…”

Section: Introductionmentioning

confidence: 99%

“…Li et al [22] investigated the temperature dependence of thermal rectification in Y-junction CNT. Park et al [9] imposed wave packet on branched CNTs with T-and X-junction and observed the energy transmission, ramification and reflection ratios on branches for the longitudinal acoustic, twisting, transverse acoustic, radial breathing, and flexural optical modes. They discovered that both the nanotube diameter and the junction type would affect phonon scattering, and thus influence the transmission of vibrational energy.…”

Section: Introductionmentioning

confidence: 99%

The Atomistic Study on Thermal Transport of the Branched Cnt

Chen

Chang

2020

J. mech.

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In this research, the thermal transport behavior of the branched carbon nanotube (CNT) with T-junction was investigated using non-equilibrium molecular dynamics simulation. Both symmetric and asymmetric temperature-controlled simulations were imposed to evaluate how the heat flowed inside the branched CNT with three branches of equal length and same chirality. The branch length and strain effects on the heat flow were examined. In addition, the simulated heat flow was compared with the prediction made by conventional thermal circuit calculation based on diffusive phonon transport. The heat was observed to flow straight rather than sideway inside the branched CNT with T-junction under the asymmetric temperature setup; this finding contradicts the conventional thermal circuit calculation. There are two possible explanations for this phenomenon. One is ballistic phonon transport and the other is phonons have different interactions or scattering with the defective atomic configurations at the T-junction. Moreover, the tensile strain could tune the heat flow, a finding that might be useful in thermal management applications.

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Phonon scattering at SWCNT–SWCNT junctions in branched carbon nanotube networks

Cited by 11 publications

References 29 publications

Phonon Scattering and Thermal Conductivity of Actinide Oxides with Defects

Phonon Scattering and Thermal Conductivity of Actinide Oxides with Defects

A Thermal Transport Study of Branched Carbon Nanotubes with Cross and T-Junctions

The Atomistic Study on Thermal Transport of the Branched Cnt

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