Thermal and electrical transport in multi-walled carbon nanotubes

Thermal and electrical transport properties of multi-walled carbon nanotubes (MWNTs), which were prepared by microwave plasma,chemical vapor deposition technique, were investigated using pulsed photothermal reflectance and the two-terminal I-V methods. The effective thermal conductivity in the nanotube axis direction was around 200 W/mK at room temperature, and it was independent on the nanotube length. By comparing the thermal conductivity with the electrical conductivity, heat transport was found to be dominated by phonons instead of electrons. On the other hand, the electrical conductivity of the MWNT films exhibited anisotropic characteristics with respect to the nanotube axis and the electron transport was diffusive rather than ballistic. (C) 2004 Elsevier B.V. All rights reserved.