Diameter-dependent thermal conductivity of carbon nanotubes

Carbon nanotubes are uniquely featured by the nanoscale tubular structure with a highly-curved surface and defined chirality. The diameter and chirality fundamentally determine their stability and electrical and thermal properties. Up to now, the relationship between the intrinsic thermal conductivity and the atomic features of CNTs has not been established, due to the challenges in precise measurements and characterizations. In this work, we develop a micro electro-thermal device enabling simultaneous thermal measurements by Raman spectroscopy and atomic structural characterization by transmission electron microscopy for individual CNTs. The influence of diameter and chirality is systematically investigated. In addition, the temperature dependence of the thermal conductivity was extracted from parameter optimization of finite-element modeling. It is found that the thermal transport of CNTs depends mainly on the diameter, while the chiral angle has no significant influence. Along with increasing diameter, the room temperature thermal conductivity increases and eventually approaches the limit of flat graphene.