Department of Mechanical Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States.
Department of Mechanical Engineering and Engineering Science, The University of North Carolina at Charlotte , Charlotte, North Carolina 28223, United States.
Nano Lett. 2017 Jun 14;17(6):3550-3555. doi: 10.1021/acs.nanolett.7b00666. Epub 2017 May 11.
Nanowires of complex morphologies, such as kinked wires, have been recently synthesized and demonstrated for novel devices and applications. However, the effects of these morphologies on thermal transport have not been well studied. Through systematic experimental measurements, we show that single-crystalline, defect-free kinks in boron carbide nanowires can pose a thermal resistance up to ∼30 times larger than that of a straight wire segment of equivalent length. Analysis suggests that this pronounced resistance can be attributed to the combined effects of backscattering of highly focused phonons and required mode conversion at the kink. Interestingly, it is also found that instead of posing resistance, structural defects in the kink can actually assist phonon transport through the kink and reduce its resistance. Given the common kink-like wire morphology in nanoelectronic devices and required low thermal conductivity for thermoelectric devices, these findings have important implications in precise thermal management of electronic devices and thermoelectrics.
最近已经合成了具有复杂形态（如扭结线）的纳米线，并展示了它们在新型器件和应用中的潜力。然而，这些形态对热传输的影响尚未得到很好的研究。通过系统的实验测量，我们表明，碳化硼纳米线中单晶、无缺陷的扭结可以导致热阻增加高达约 30 倍，相比于具有相同长度的直线段。分析表明，这种显著的电阻可以归因于高度聚焦声子的反向散射和扭结处所需的模式转换的综合影响。有趣的是，还发现扭结中的结构缺陷实际上可以通过扭结辅助声子输运并降低其电阻，而不是增加电阻。鉴于纳米电子器件中常见的扭结状线形态以及热电器件所需的低热导率，这些发现对于电子器件和热电器件的精确热管理具有重要意义。
