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首页> 外文期刊>Physical review >Lattice thermal conductivity reduction in Bi_2Te_3 quantum wires with smooth and rough surfaces: A molecular dynamics study
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Lattice thermal conductivity reduction in Bi_2Te_3 quantum wires with smooth and rough surfaces: A molecular dynamics study

机译：具有光滑和粗糙表面的Bi_2Te_3量子线的晶格热导率降低：分子动力学研究

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摘要

Using molecular dynamics simulations, we have predicted the thermal conductivity of Bi_2Te_3 nanowires with diameters ranging from 3 to 30 nm with both smooth and rough surfaces. It is found that when the nanowire diameter decreases to the molecular scale (below 10 nm, or the so-called "quantum wire"), the thermal conductivity shows significant reduction as compared to bulk value. On the other hand, the thermal conductivity for the 30-nm-diam nanowire only shows less than 20% reduction, in agreement with recent experimental data. Also, the thermal conductivity of nanowires shows a weaker temperature dependence than the typical T~(-1) trend, consistent with experimental observations. This is attributed to the strong boundary scattering of phonons. An analytical model is developed to interpret the molecular dynamics data, and the model suggests that phonon softening in thin nanowires and strong phonon scattering on the rough surface are the two major mechanisms leading to the thermal conductivity reduction. Our results indicate that Bi_2Te_3 nanowires need to be in the molecular scale (diameter below 10 nm) in order to achieve better ZT than the bulk phase.
机译：使用分子动力学模拟，我们预测了直径为3到30 nm且具有光滑和粗糙表面的Bi_2Te_3纳米线的热导率。发现当纳米线直径减小到分子尺度时（低于10nm，或所谓的“量子线”），与体积值相比，热导率显示出显着降低。另一方面，与最近的实验数据一致，直径为30 nm的纳米线的热导率仅降低了不到20％。而且，纳米线的导热性与典型的T〜（-1）趋势相比，对温度的依赖性更弱，这与实验观察一致。这归因于声子的强边界散射。建立了解析模型来解释分子动力学数据，该模型表明，细纳米线中的声子软化和粗糙表面上的强声子散射是导致热导率降低的两个主要机理。我们的结果表明，Bi_2Te_3纳米线必须处于分子尺度（直径小于10 nm）才能获得比本体相更好的ZT。

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  • 来源
    《Physical review》 |2011年第3期|p.035312.1-035312.7|共7页
  • 作者

    Bo Qiu; Lin Sun; Xiulin Ruan;

  • 作者单位

    School of Mechanical Engineering and the Birck Nanotechnology Center,Purdue University, West Lafayette, Indiana 47907-2088, USA;

    School of Mechanical Engineering and the Birck Nanotechnology Center,Purdue University, West Lafayette, Indiana 47907-2088, USA;

    School of Mechanical Engineering and the Birck Nanotechnology Center,Purdue University, West Lafayette, Indiana 47907-2088, USA;

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  • 正文语种 eng
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  • 关键词

    semiconductor compounds;

    机译：半导体化合物;

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