(410d) Diffusive Heat Transfer in Isolated, Free-Standing, Single-Walled Carbon Nanotubes

Carbon nanotubes show potential for thermal devices and heat management applications, albeit their thermal properties often remain poorly characterized. For example, room temperature axial thermal conductivity values reported from experiments span at least 5 orders of magnitude. This significant spread is partially due to challenges in accurately quantifying the different contributions to heat transfer at the nanoscale as well as in correctly identifying the type of CNT under study. Using Raman spectroscopy, we here measure isolated, single-walled CNTs in vacuum, reducing heat transfer pathways to the minimum. We show that a simple heat transfer equation based on Fourier’s law can be applied to determine the axial thermal conductivity as only free parameter. We quantify the spread in this parameter extracted from repeated measurements on multiple free-standing segments of the same chirality tube to be on the order of 30 %. We attribute this variation to differences in the concentration of defects that act as scattering sites for phonons. A further reduction in thermal conductivity is observed upon filling the tube interior with water. Taking these extrinsic effects into account using Matthiessen’s rule, we extract lower bounds for the intrinsic axial thermal conductivity of our single-walled CNTs typically on the order of several 100 W/(m K). The contactless platform discussed here represents a means to the statistically robust assessment of diffusive heat transfer in CNTs, laying the basis for more reliable systematic investigations on the thermal properties of these and related nanomaterials.