发布时间：2013-10-22
题 目：Heat Transport by Phonons and Phonon-Polaritons in Nanoengineered Materials
报告人：Dr.Jose Ordonez-Miranda(巴黎中央理工学院）
时 间：10月25日（周五），下午2:00-3:00
地 点：南 校区第一实验楼406会 议室
报告摘要：
The blossoming of nanotechnology involving the miniaturization of devices with enhanced rates of operation requires a profound understanding of their thermal performance. This is particularly critical in nanomaterials, in which the heat transport is not described necessarily by the Fourier’s law of heat conduction. In this talk, three approaches beyond the scope of this law are addressed:
1. A new constitutive equation between the heat flux and temperature gradient in the form of a thermal multiple expansion is proposed, where the usual thermal conductivity is just the first thermal pole. This result generalizes the Fourier’s law and various models reported in the literature, and its predictions are in good agreement with the ones of the phonon Boltzmann transport equation.
2. The photothermal signals predicted by this later equation at the illuminated surface of a two-layer system are then analyzed. When the thickness of the illuminated layer is comparable to or smaller than the phonon mean free path, the amplitude and phase of the temperature profile exhibit an non-Fourier oscillatory behavior, which become stronger as the film thickness is scaled down. This is described as the “dance”of phonons at the rhythm of the “music”of the modulated thermal excitation.
3. Finally, Based on the Maxwell’s equations, the heat transport due to surface electromagnetic waves (phonon-polaritons) in polar nano thin films and wires is discussed along with their universal quantum of thermal conductance. It is shown that these heat carriers have the potential to offset the reduction of the phonon thermal conductivity of nanomaterials, due to interface scattering. These three approaches can be applied to perform the thermal characterization and optimization of materials involved in nanoscale electronics and photonics.
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