学术报告预告:6月9日Prof. Li Shi 学术报告会

 

报告题目:Thermal Transport and Thermoelectricity in Nanomaterials

报告人: Prof. Li Shi
Department of Mechanical Engineering and Texas Materials Institute
The University of Texas at Austin

时间:2008年6月9日15:30

地点:理化大楼9004会议室

摘要:
  Thermal and thermoelectric (TE) properties of materials can be
enhanced by engineering nanostructures to manipulate electron and phonon
transport. Characterization of the thermal and TE properties of
nanostructures is challenging and prone to errors. To address this problem,
we have investigated a number of methods based on nanofabricated measurement
devices and scanning probe microscopy. These methods have been employed to
examine various size confinement effects on thermal and TE transport in
nanomaterials including disordered, layered thin films, nanocomposite thin
films, carbon nanotubes, and various semiconducting nanowire systems that
cover a wide range of electron and phonon mean free paths and wavelengths.
Except for carbon nanotubes that have few defects and smooth surface,
suppression of lattice thermal conductivity is commonly observed in most of
these nanostructures. For InSb nanowires and SnO2 nanobelts, the suppression
agrees well with theoretical calculations that assume diffuse phonon-
boundary scattering. For Bi nanowires, however, the total thermal
conductivity was found to be reduced below the calculated minimum lattice
thermal conductivity when the diameter decreases to about 70 nm. In
addition, disordered, layered Wx(WSe2)y and (PbSe)x(WSe2)y thin films
possess not only cross-plane thermal conductivity as low as that of air, but
also increased thermal conductivity anisotropy between the in-plane and
cross-plane directions. Moreover, the large thermal conductivity suppression
and an additional electron filtering effect result in about 10 fold increase
in the in-plane TE figure of merit of InAlGaAs films with embedded ErAs
nanoparticles.

承办单位:合肥微尺度国家实验室,物理系,外事办公室

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