Measurement of thermal conductivity of individual multiwalled carbon

Measurement of thermal conductivity of individual multiwalled carbon

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Measurement of thermal conductivity of individual multiwalled carbon nanotubes by the 3- v method Tae Y. Choi and Dimos Poulikakos a ! Laboratory of Thermodynamics, Institute of Energy Technology, ETH Zurich, CH-8092 Zurich, Switzerland Joy Tharian and Urs Sennhauser Electronics/Metrology Laboratory, Swiss Federal Laboratories for Materials Testing and Research, CH-8600 Duebendorf, Switzerland s Received 1 February 2005; accepted 17 May 2005; published online 29 June 2005 d The thermal conductivity of individual multiwalled carbon nanotubes s outer diameter of , 45 nm d was obtained by employing the 3- method. To this end, the third-harmonic amplitude as a response to the applied alternate current at fundamental frequency s d is expressed in terms of thermal conductivity. A microfabricated device composed of a pair of metal electrodes 1 m m apart is used to place a single nanotube across the designated metal electrodes by utilizing the principle of dielectrophoresis. The multiwalled carbon nanotube was modeled as a one-dimensional diffusive energy transporter and its thermal conductivity was measured to be 650–830 W/mK at room temperature. © 2005 American Institute of Physics . f DOI: 10.1063/1.1957118 g Since the discovery of carbon nanotubes s CNTs d , 1 many researchers directed their efforts to understand and character- ize their unique properties. These researches have reported remarkable electrical, 2 mechanical, 3 and thermal 4 properties related to their unique structure and small size, making them the ideal material for various engineering applications, such as sensors, 5 actuators, 6 energy storage systems, 7 and nanoelectronics. 8 Of particular interest in this letter is the thermal conductivity of CNTs. Thermal conductivity of single-walled CNTs was theo- retically predicted to be higher than that of monocrystalline diamond. 4,9 There have been a few attempts to measure ther- mal conductivity of single-walled CNT bundles. 10–12 One study showed that the measured values of thermal conduc- tivity were at around 30 W/mK, which is two orders of mag- nitude lower than the theoretically predicted value. 10 These drastically reduced values result from the boundary phonon scattering between individual nanotubes in the bundle. It is dif±cult to measure the correct thermal conductivity due to the uncertainty of the thermal resistance in the tube-tube junctions and the ±lling factor of CNTs in the bundles. Therefore, it is desirable and necessary to investigate indi- vidual CNTs in order to achieve accurate and reliable data. Thermal conductivity of a single multiwall CNT s MWCNT d has been measured, by using an indirect thermal conductance technique. 13
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This note was uploaded on 03/18/2012 for the course PHYSICS 303 taught by Professor Ihn during the Spring '12 term at Swiss Federal Institute of Technology Zurich.

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Measurement of thermal conductivity of individual multiwalled carbon

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