Length-dependent thermal conductivity of an individual single-wall carbon

Length-dependent thermal conductivity of an individual single-wall carbon

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Unformatted text preview: Length-dependent thermal conductivity of an individual single-wall carbon nanotube Zhao Liang Wang, Da Wei Tang, a ! Xiao Bo Li, and Xing Hua Zheng Institute of Engineering Thermophysics, Chinese Academy of Science, Beijing 100080, China Wei Gang Zhang Institute of Process Engineering, Chinese Academy of Science, Beijing 100080, China Li Xin Zheng and Yuntian T. Zhu Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Ai Zi Jin, Hai Fang Yang, and Chang Zhi Gu Institute of Physics, Chinese Academy of Science, Beijing 100080, China s Received 11 May 2007; accepted 15 August 2007; published online 21 September 2007 d The thermal conductivity of single-wall carbon nanotubes s SWCNTs d is predicted to increase with length, but this has never been proved experimentally because of limitations in previous measurement methods. Here, the authors report the measurement of the length-dependent thermal conductivities of individual SWCNTs on a Si substrate using a four-pad 3 v method. An increase in thermal conductivity with length was observed at room temperature, which is consistent with a theoretical prediction that considers higher order three-phonon processes. When SWCNTs are longer than the phonon mean path, they showed dissipative thermal transport. The observed increase of thermal conductivity with length makes SWCNTs ideal for thermal management. © 2007 American Institute of Physics . f DOI: 10.1063/1.2779850 g Theoretical and experimental studies have shown that single-wall carbon nanotubes s SWCNTs d have outstanding thermal and electrical transport characteristics, which makes them good candidates for applications in integrated circuits as microtransistors, probes of atomic force microscope s AFM d , and thermal interface materials in thermal manage- ment. Although the thermal properties of millimeter-sized carbon nanotube mats and packed carbon nanofibers have been measured, the measurement on an individual nanotube has been a challenge. A “thermal conductance” technology, 1 – 4 a T-type nanosensor, 5 and a 3 v method 6 – 8 have been utilized to measure the thermal conductivities of multiwall carbon nanotubes s MWCNTs d and the temperature-dependent thermal conductance of individual SWCNTs. However, it is not easy for these technologies to measure the length-dependent thermal conductivity of indi- vidual MWCNT or SWCNT because of difficulties in sample preparation, including synthesis and suspension of MWCNTs or SWCNTs. The four-pad 3 v method 8 has an advantage over other methods because it has no contact resistance prob- lem and much reduced spurious signals, but the suspension of nanotubes is still a big challenge. For these reasons, ex- perimental study on length-dependent thermal conductivity of individual SWCNTs has been rare....
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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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Length-dependent thermal conductivity of an individual single-wall carbon

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