Strain engineering for thermal conductivity of single-walled carbon nanotube forests |
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| Affiliation: | 1. College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China;2. Key Lab of Advanced Transducers and Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China;3. Key Lab of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China;4. College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China;1. International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan;2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;3. Collaborative Innovation Center of Quantum Matter, Beijing 100190, China;1. Institute of Solid State Physics of RAS, Chernogolovka, Moscow region 142432, Russia;2. Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;3. Chemical Engineering Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;1. Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, National Laboratory of Solid State Microstructures, Nanjing 210093, PR China;2. Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, PR China;3. Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, PR China |
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| Abstract: | We perform classical molecular dynamics simulations to investigate the mechanical compression effect on the thermal conductivity of the single-walled carbon nanotube (SWCNT) forest, in which SWCNTs are closely aligned and parallel with each other. We find that the thermal conductivity can be linearly enhanced by increasing compression before the buckling of SWCNT forests, but the thermal conductivity decreases quickly with further increasing compression after the forest is buckled. Our phonon mode analysis reveals that, before buckling, the smoothness of the inter-tube interface is maintained during compression, and the inter-tube van der Waals interaction is strengthened by the compression. Consequently, the twisting-like mode (good heat carrier) is well preserved and its group velocity is increased by increasing compression, resulting in the enhancement of the thermal conductivity. The buckling phenomenon changes the circular cross section of the SWCNT into ellipse, which causes effective roughness at the inter-tube interface for the twisting motion. As a result, in ellipse SWCNTs, the radial breathing mode (poor heat carrier) becomes the most favorable motion instead of the twisting-like mode and the group velocity of the twisting-like mode drops considerably, both of which lead to the quick decrease of the thermal conductivity with further increasing compression after buckling. |
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