The thermal conductivity and thermal rectification of carbon nanotubes studied using reverse non-equilibrium molecular dynamics simulations

Abstract

The thermal conductivity of single-walled and multi-walled carbon nanotubes has been investigated as a function of the tube length L, temperature and chiral index using non-equilibrium molecular dynamics simulations. In the ballistic-diffusive regime the thermal conductivity follows a L(alpha) law. The exponent alpha is insensitive to the diameter of the carbon nanotube; alpha approximately 0.77 has been derived for short carbon nanotubes at room temperature. The temperature dependence of the thermal conductivity shows a peak before falling at higher temperatures (>500 K). The phenomenon of thermal rectification in nanotubes has been investigated by gradually changing the atomic mass in the tube-axial direction as well as by loading extra masses on the terminal sites of the tube. A higher thermal conductivity occurs when heat flows from the low-mass to the high-mass region.

A review of thermal rectification observations and models in solid materials

“…In 2009 Alaghemandi et al performed non-equilibrium molecular dynamics simulations of carbon nanotubes where an asymmetry was present due to a non-uniform mass distribution [42]. In the first case the mass of the carbon atoms were varied along the length resulting in a mass or density gradient along the tube.…”

“…to think about what devices can be fabricated, what quantities can be measured and whether the theoretical [15] Al/SS thermal warping 0.67 Rogers [17] Al/SS thermal potential barrier 0.1 Powell et al [19] Al/SS thermal warping 0 Clausing [20] SS/Al thermal strain 0.2 Lewis and Perkins [21] Al/SS thermal warping 0.41 O'Callaghan et al [27] varied thermal warping 0.13 Stevenson et al [23] varied thermal warping 0.21 Chang et al [5] CNT and BNNT non-uniform mass loading 0.034 Kobayashi et al [38] varied bulk thermal conductivity 0.18 [4] 1D chain nonlinear lattice 0.33 Li et al [81] 1D chain nonlinear lattice 0.98 Hu et al [82] 1D chain nonlinear lattice 1.0 Lan et al [75] 1D chain nonlinear lattice 1.0 Hopkins and Serrano [88] 1D chain asymmetric mass loading and defect 0.29 Yang et al [48] graphene asymmetric ribbons 0.6 Hu et al [49,55] graphene asymmetric ribbons 0.47 Alaghemandi et al [42,44] CNT non-uniform mass loading 0.17 Hu et al [79] water/silica interface transmission 0.21 Roberts and Walker [74] argon/krypton interface transmission 0.13 Wu and Li [46] CNH asymmetric CNT 0.55 Yang et al [47] CNC asymmetric CNT 0.46 Wu and Li [56] CNT CNT interface 0.39 systems can be realized in the lab. In fact, experimental study of thermal rectification is said to be ongoing in quite a few research labs.…”

“…Unfortunately in many of these reports the mechanism that causes thermal rectification does so by reducing the transport (in one direction more than the other), which can make it difficult to maintain high levels of conduction. In some of these studies, specifically the work with the asymmetric CNTs and graphene [5,56,47,46,49,55,42,44,48], the transport appears to be increased in one direction and decreased in the opposite which makes these ideal materials for thermal rectification applications.…”

Microwave absorption properties of MWCNT-SiC composites synthesized via a low temperature induced reaction

“…[19][20][21][22] Meanwhile, the nanoparticles constituting the SiC spheres could be repeatedly polarized under an alternating EM field, leading to strong interfacial polarization relaxation loss and Ohmic loss, and consequently to the enhancement in dielectric properties. 21,23 Furthermore, CNTs have good electric conductivity, 24,25 their bonding to the SiC spheres could also increase the microwave attenuation.…”

Heat conduction in graphene flakes with inhomogeneous mass interface

“…The mass interface can be implemented by two methods. One is to load external heavy and thermal insulating molecules upon the carbon atoms [11][12][13][14]. The other one is to use different ratio of isotope substitutions [27][28][29] which is demonstrated possible in experiment by chemical vapor deposition growth of graphene on metal [30].…”