Structure-Thermal Relationships of Carbon Nanotubes

1. Structure-Thermal Relationships of Carbon Nanotubes Daniel C. Ralph, Cornell University, ECCS - 0335765 • Defect concentration appears to increase with number of walls • Thermal contact resistance per unit length obtained for three as-grown multi-walled carbon nanotubes (MWCNTs) is in the range of 78 – 585 mKW-1 at room temperature • Intrinsic thermal conductivity for three MWCNTs is in the range of 42 – 343 Wm-1K-1; the calculated phonon mean free path correlates well with the TEM observed defect concentration • Large thermal contact resistance limits effective  for as-grown SW and DW CNTs to ~ 600 Wm-1K-1 at room temperature In CNTs, high axial thermal conductivity and electron mobility is expected for defect-free nanotubes, as long-range crystalinity along the axial direction and negligible boundary scattering in unconstrained nanotubes allow heat and charge carriers to flow with ease. We have been able to demonstrate a capability for establishing the structure-thermal property relationship of different types of individual CNTs using a suspended microthermometer device fabricated at MRC to allow for a fundamental understanding of thermal transport processes in these materials. Pettes, M.T., and Shi, L., Adv. Funct. Mater.19, 3918 (2009). (a) SEM image of the suspended micro-device for thermal conductance measurements of carbon nanotubes. (b) SEM image of the two central membranes of the micro-device. (c) SEM and (d) transmission electron microscopy (TEM) image of SWCNT sample S1 bridging the two membranes. (e) Nanoarea Electron Diffraction pattern for S1 The diameter and chiral angle are determined to be 2.33 ± 0.02 nm and 20.44 ± 0.2o, respectively. (f) Equatorial oscillations (solid line) along EE' in (e) and calculation (dashed line) for a (22, 12) SWCNT are in good agreement. M. Pettes, Li Shi. Univ. of Texas. Work performed at U. Texas Austin MRC