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Nanotubes as Robust Thermal Conductors

IB-2335

APPLICATIONS OF TECHNOLOGY:

  • Thermal management in design and operation of integrated circuits
  • Flexible electronics
  • Composites subject to mechanical strain (e.g., aerospace industry)
  • Phonon filters for use in spectrometers, acoustic imaging, and cavity resonators
  • Acoustic isolation of RF resonators and sensors
  • Information carriers in combination with solid-state thermal rectifiers and tunable thermal links

ADVANTAGES:

  • Robust heat conductivity far exceeds that of other materials
  • Better thermal conductor than diamond; not compromised by imperfections
  • Thermal properties hold up under extreme deformation
  • Lightweight, pliable, with excellent tensile strength

ABSTRACT:

Multiwall nanotubes of carbon (CNT) and of boron nitride (BNNT) have a very high thermal conductance at room temperature.   Their twin properties of high thermal conductivity along the axial direction and poor thermal conductivity in the radial direction provide an excellent heat conduction channel that can confine heat currents on the nano scale.

Alex Zettl and Chih-wei Chang of Lawrence Berkeley National Laboratory have determined that CNT and BNNT are also highly efficient under conditions of severe mechanical deformation (at angles of more than 130 degrees).   This means that they can function not only as sensitive nanoelectromechanical devices but also as robust broadband phonon waveguides conducting heat through phonons, or quantized soundwaves, around corners.   In addition to their use in thermal links, their light weight, stiffness, and tensile strength (50 times greater than steel) show promise for flexible electronics and composites subject to mechanical strain.  

Nanotubes may also be used as synthetic acoustic bandgap (ABG) materials, making it possible to control the propagation and distribution of acoustic waves or phonons.   ABGs on this scale can provide acoustic isolation of microfabricated devices such as radio frequency resonators and sensors, and miniature acoustic waveguides can be used for ultrasound and signal processing.   As ABGs are produced at smaller sizes operating at higher frequencies, applications in thermal management and engineering the thermal noise distribution of a material become feasible.   Defected acoustic crystals can potentially be used as "mirrors" for micro-cavities, providing higher frequency selectivity than competing technologies.

While phonon transmission is only minimally affected by deformation, electron transmission is more significantly affected.   Coupling the two allows phonon signals to be used to carry information.

STATUS:

  • Patent pending. Available for licensing or collaborative research.

To learn more about licensing a technology from LBNL see http://www.lbl.gov/Tech-Transfer/licensing/index.html.

FOR MORE INFORMATION:

C. W. Chang, D. Okawa, H. Garcia, A. Majumdar, A. Zettl, "Nanotube Phonon Waveguide," Physical Review Letters 99: 045901-1 04590-4 (2007).

REFERENCE NUMBER: IB-2335

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