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Is there a ‘ Nano ’ Revolution in Thermal Management and Energy Conversion? Advances in Nanostructure based Thermal Int

Is there a ‘ Nano ’ Revolution in Thermal Management and Energy Conversion? Advances in Nanostructure based Thermal Interface and Thermoelectric Materials Sebastian Volz Laboratoire EM2C UPR CNRS 288, Ecole Centrale Paris Thermal Nanosciences Group - volz@em2c.ecp.fr.

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Is there a ‘ Nano ’ Revolution in Thermal Management and Energy Conversion? Advances in Nanostructure based Thermal Int

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  1. Is there a ‘Nano’ Revolution in Thermal Management and Energy Conversion? Advances in Nanostructure based Thermal Interface and Thermoelectric Materials Sebastian Volz Laboratoire EM2C UPR CNRS 288, Ecole Centrale Paris Thermal Nanosciences Group - volz@em2c.ecp.fr EUROTHERM 2012 – Poitiers, France – September 5th 2012

  2. Heat Transfer Lawsat Small ScalesDeviatefromClassicalOnes Ballistic conduction in air Kn>>1 NEAR FIELD L Radiation When L < the Predominant Photon Wavelength, coupling of Evanescent Surface Waves increasesheat flux. Transition from a regime of propagativewavesemitted by charges motions to a direct electrostatic interaction. STEFAN-BOLTZMANN Conduction « Nano » wire d Convection If Nu<1, heat conduction in air predominates. If Kn>>1 heat conduction becomesballistic. Diffusive to Ballistic transition iswell-known in gases and radiation. European CNRS Network on Thermal Nanosciences and NanoEngineering

  3. Heat carries in solids are SOUND PARTICLES or PHONONs, the quanta of latticevibrationalenergy a i-1 i i+1 Fij = K.(uj- ui) un=u.expi(kna-wt) w PeriodicBoundary Conditions: k = n . 2/L k Density of states

  4. Phonons form a GAS of particles to propagateheat ! Heat Flux: the Phonon Gas w Acoustics: Coherent Phonons Continuouslimit k=>0 Knudsen Transport Applies k Phonon Wien’sWavelength: 3nm (300K) Mean free path: 1-1000nm

  5. Kn>1: Boundaryscatteringpredominates over diffusive scattering L p(, , pol, ) =1/3 C v 

  6. Confinement: Cavity modes appear if L< Wavelength e ikL=e ika=0 Periodicity:e ik(L+x)=e ikx un ~ expi(kna-wt)+ expi(-kna-wt) ~ cos(kna)e-iwt =1/3 C v a STEADY WAVE has ZERO group velocity

  7. The number of phonon modes depends on Dimensionnality k-space Dimension: Number of States /dk: 1D (wire) D(k) ~ 1 =1/3 C v  2D (film/SR) D(k ) ~ k 3D (bulk) D(k) ~ k2

  8. Atnanoscales, thermal resistance arises fromboundaries

  9. Atnanoscales, thermal resistance arises fromboundaries The KEY is to understand phonon transfer at the surface and betweentwosystems

  10. Thermal Resistance is an Ambiguous Concept Relating Equilibrium and Non-Equilibrium Quantities R= (T1-T2)/Q N1 N2 Q ‘Cheating’ Seems Unavoidable Heat Bath T1 Heat Bath T2

  11. Atomic Simulations involve dubious Non-Equilibrium Conditions NEMD - STEADY -Thermostats Parameters -Equilibrium Temperatures: coupling with heat bath? NEMD - TRANSIENT -Thermostat Parameters (weaker) -’Short time’ non-equilibrium -Equilibrium Temperatures at each time step?

  12. EquilibriumTemperatureCorrelationdefines Thermal Resistance FLUCTUATIONAL THERMODYNAMICS INTERNAL SCATTERING ACF NEGLECTED (?) τau JAP, 108, 094324, 2010

  13. A Flux based Thermal Conductance can be equivalently derived -Interfacial Thermal Resistance only depends on Interactions between Atoms of both Sub-Systems -Temperatures involved in the definition of resistance are the Temperatures of the Interacting Atoms

  14. Nanostructures have exceptional thermal conductivities Carbon Nanotubes 2400-3000 W/mK@RT SiliconNanowires 1-3 W/mK@RT

  15. Nanostructures canbeused to taylor thermal conductivity Thermal Interface Materials: Increase Thermoelectricity: Decrease

  16. Can Carbon Nanotubes beused as Thermal Interface Materials? Use Carbon Nanotube Pellets D Isotropy L J

  17. Isotropic Pellet Thermal Conductivity is promising but…. Chalopin, Volz, Mingo, Journal of AppliedPhysics, 105, 084301, (2009)

  18. …Measured Thermal Conductivity is more than disappointing Prasher, Hu, Chalopin, Mingo, Lofgreen, Volz, Cleri, Keblinski, Phys. Rev. Lett.,102, 105901, 2009

  19. CNT Orientation is drastically affecting thermal conductivity Volkov and Zhigilei Phys. Rev. Lett. 104, 215902 (2010)

  20. Use of Hybrid Charges Imposes Isotropy Bozlar, He, Bai, Chalopin, Mingo and Volz, Advanced Materials, 21, 1, (2009)

  21. Vertically aligned CNTs appears as the optimized option Applying pressure? CNT-Superstrate contact resistance cancels performances

  22. Thermal Conductance isincreasedwhenapplying Pressure Chalopin, Srivastava, Mingo, Volz, submitted to APL

  23. Transmission shows the opening of inelasticchannels whenincreasing pressure Harmonic Green Functions Fluctuations Anharmonic Green Functions

  24. Introducing a polymer layer at contact reduces thermal resistance HLK5 2.5mm2K/W Introducing Covalent Bonds ShouldIncrease Conductance

  25. CNT-HLK5resistanceis three times lowerthan CNT-PEMA one Ni, LeKhahn, Bai, Divay, Chalopin, Lebarny,, Volz Appl. Phys. Lett. 100, 193118 (2012)

  26. CONCLUSION on Thermal Interface Materials Ni, LeKhahn, Bai, Divay, Chalopin, Lebarny,, Volz Appl. Phys. Lett. 100, 193118 (2012)

  27. Collaborators: Team: Y. Chalopin (CNRS) T. Antoni (Ass. Prof.) T. Dumitrica (Inv. Prof.) Pdocs: J. Ordonez O. Pokropivny PhDs: Y. Ni, S. Xiong, L. Tranchant W. Kassem, J. Jaramillo Ramière, H. Han B. Latour, J. Soussi Abroad G. Chen (MIT) H. Ban (Utah U.) C.W. Chang (National Taiwan Uniiversity) B. Kim (U Tokyo) H. Fujita (U Tokyo) H. Kawakatsu (U. Tokyo) Y. Kosevich(Semenov Inst. Moscow) M. Kazan (U Américaine de Beyrouth) Rajabpour(U Teheran) Y. Ciumakov (Moldova) France: N. Mingo (CEA-LITEN) E. Ollier (CEA-LITEN) A. Ziaei (Thales R&T) L. Divay (Thales R&T) P. Cortona (SPMS, Ecole Centrale Paris) H. Dammak (SPMS, Ecole Centrale Paris) J. Bai (SPMS, Ecole Centrale Paris) L. Aigouy (LPM, ESPCI) B. Palpant (LPQM, ENS Cachan) S. Merabia (LPMNC, U Lyon) P. Chantrenne (MATTEIS, U Lyon) D. Lacroix (LEMTA, U Nancy) J. Amrit (LIMSI, U Orsay) B. LePioufle (SATIE, ENS Cachan) D. Fourmy (Centre de Génétique Mol., Gif) K. Termentzidis (LEMTA, Nancy France) European CNRS Network Thermal Nanosciences and NanoEngineering 2007 2010 THANK YOU FOR YOUR ATTENTION

  28. QMNTIA 2013 Quantitative Micro and Nano Thermal Imaging and Analysis 10-12 July 2013 Reims, France GRESPI Université de Reims-Champagne-Ardenne http://qmntia2013.univ-reims.fr/ qmntia2013@univ-reims.fr

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