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Molecular-Dynamics Simulations on Heat Conduction in Peapod

Molecular-Dynamics Simulations on Heat Conduction in Peapod. Fumio Nishimura Takahiro Yamamoto Kazuyuki Watanabe Department of Physics, Tokyo University of Science. 1.Background. High thermal conductivity of CNT. Application of heat sink. Substrate. Chip. Cu: λ = 400W/mK. Carbon nanotube.

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Molecular-Dynamics Simulations on Heat Conduction in Peapod

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  1. Molecular-Dynamics Simulations onHeat Conduction in Peapod Fumio Nishimura Takahiro YamamotoKazuyuki Watanabe Department of Physics, Tokyo University of Science

  2. 1.Background • High thermal conductivity of CNT • Application of heat sink Substrate Chip Cu:λ = 400W/mK Carbon nanotube CNT: λ ~ 2000W/mK IC chip Carbon nanotube bump Substrate FujitsuCo.2005 http://jp.fujitsu.com/group/labs/

  3. 2.Objectives • Thermal conductivity of peapod E. Z. Noya et al, PRB 70, 115416(2004) • higher • lower • Thermal conductanceof peapod isthan empty CNT. G. Wu and B. Li, PRB 76, 085424(2007) Clarify the effect of van derWaals interaction on the thermal conductivity of peapod.

  4. 3.Method • Molecular dynamics • Brennerpotential for covalent bond energy • Lenard-Jones potential for van der Waals interaction W. Brenner,Phys. Rev. B 42, 9458 (1990) J. Che, et al. Theor. Chem. Acc 102, 346 (1999) • Thermostat Nosѐ-Hoover method. Nose, S., J. Chem. Phys. 81, 511 (1984) Hoover, W. G., Phys. Rev. A 31, 1695 (1985)

  5. 3.Method • Direct method • Thermal current

  6. 5.Result • CNT • (10,10)CNT z • Temperature profile • L dependence of thermal current Jth[nW] temperature[K] z[nm] L[nm]

  7. 5.Result • Peapod • C60@(10,10)CNT z • L dependence of thermal current • Temperature profile Jth[nW] temperature[K] • C60 z[nm] L[nm]

  8. 5.Result • Thermal conductance • : thermal current □(10,10)CNT■Peapod Κ[nW/K] L[nm] • Thermal conductance decreases due to C60s.

  9. 5.Result • Thermal current between C60s z z Thermal current does not flows so much through an array of C60s.

  10. 5.Conclusion Ⅰ • Effect of C60s on thermal conductance Thermal conductance of a peapod is lower than a pristine CNT. Because An array of C60 does not open a channel for thermal current but interferes via van der Waals interaction with thermal current flowing through a CNT wall. The present result is compatible with a previous result by G. Wu & B. Li. (PRB 76, 085424(2007))

  11. 5.Conclusion Ⅱ • Single C60 under the temperature gradient If there is no temperature gradient at 300K C60 vibrates around equilibrium position.

  12. 5.Conclusion Ⅱ • Single C60 under the temperature gradient If there is temperature gradient, C60 transfers from hot side to cold side.

  13. 5.Conclusion Ⅱ • Single C60 under the temperature gradient Object Outer CNT Inner CNT • Barreiro, R. Rurali, E.R. Hern´andez, • J. Moser, T. Pichler, L. Forr´o, A. Bachtold, • Science320, 775 (2008)

  14. 6.Future works • Varity structures in thicker peapod • HRTEM image and diffraction pattern • MD simulation result of (35,35)-(40,40)DWNT T. Yamazaki, F. Nishimura, et al. Nanotechnology 19, 045702 (2008)

  15. 5.Conclusion Ⅱ • Single C60 under the temperature gradient

  16. Definition of parameter for VDW • Parameters are respectively defined as and

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