Thermal Conductivity of Individual Single-Wall Carbon Nanotubes

Abstract

Despite the significant amount of research on carbon nanotubes, the thermal conductivity of individual single-wall carbon nanotubes has not been well established. To date only a few groups have reported experimental data for these molecules. Existing molecular dynamics simulation results range from several hundred to 6600 W/m K and existing theoretical predictions range from several dozens to 9500 W/m K. To clarify the severalorder-of-magnitude discrepancy in the literature, this paper utilizes molecular dynamics simulation to systematically examine the thermal conductivity of several individual (10, 10) single-wall carbon nanotubes as a function of length, temperature, boundary conditions and molecular dynamics simulation methodology. Nanotube lengths ranging from 5 nm to 40 nm are investigated. The results indicate that thermal conductivity increases with nanotube length, varying from about 10 W/m to 375 W/m K depending on the various simulation conditions. Phonon decay times on the order of hundreds of fs are computed. These times increase linearly with length, indicating ballistic transport in the nanotubes. A simple estimate of speed of sound, which does not require involved calculation of dispersion relations, is presented based on the heat current autocorrelation decay. Agreement with the majority of theoretical/computational literature thermal conductivity data is achieved for the nanotube lengths treated here. Discrepancies in thermal conductivity magnitude with experimental data are primarily attributed to length effects, although simulation methodology, stress, and intermolecular potential may also play a role. Quantum correction of the calculated results reveals thermal conductivity temperature dependence in qualitative agreement with experimental data.

Understanding Divergent Thermal Conductivity in Single Polythiophene Chains Using Green–Kubo Modal Analysis and Sonification

“…Carbon nanotubes were once thought to also possibly exhibit divergence, but calculations performed by Mingo and Broido 29,33 as well as other molecular dynamics (MD) studies [34][35][36][37] confirmed that the thermal conductivity is large but still finite (non-divergent). However, for polymer chains, Henry and Chen 23 discovered that even in a realistic model for the interactions between atoms in a polyethylene (PE) chain, it is possible to observe divergent thermal conductivity.…”

Thermal conductivity and phonon transport in empty and water-filled carbon nanotubes

“…23,27 We note that the systems investigated here are longer than the 10 to 400-nmlong systems typically investigated using MD simulation, as summarized by Mingo and Briodo 21 and Lukes and Zhong. 25 The number of carbon atoms in the CNT ranges from 29,232 ͑for the 200-nm-long, 0.83-nm-diameter CNT͒ to 195,120 ͑for the 1200-nm-long, 1.10-nm-diameter CNT͒ and the equilibrium nearest-neighbor distance is 1.42 Å. 28 Interactions between carbon atoms are modeled using the secondgeneration REBO potential 29 and interactions between water molecules are modeled using the TIP4P/2005 potential.…”

“…1, we define the cross-sectional area of the CNTs to be A c = db, where b͑=0.34 nm͒ is the van der Waals thickness of the CNT surface and d is the CNT diameter. 23,25,26 We fix one layer of carbon atoms at the ends of the CNT to prevent atoms from sublimating. For graphene, we define the cross-sectional area to be A c = wb, where w is the width of the sheet ͑see Fig.…”

Local heating of molecular motors using single carbon nanotubes

“…and are dependent on factors such as chirality, potential, and boundary conditions (Berber et al 2000;Osman and Srivastava 2001;Padgett and Brenner 2004;Lukes and Zhong 2007;Cao and Qu 2012). In addition to these factors, Mingo and Broido (2005) suggested that the calculated thermal conductivity for single-walled nanotubes depends strongly on length, and this theory was subsequently confirmed by the experimental measurement and analytical model of Pop et al (2006).…”