How phonon coherence develops and contributes to heat conduction in periodic and aperiodic superlattices

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences Pub Date : 2025-06-10 DOI:10.1016/j.ijthermalsci.2025.110018

Theodore Maranets, Yan Wang

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引用次数: 0

Abstract

This work investigates the impact of device length on thermal conductivity in periodic and aperiodic superlattices (SLs). While it is well known that thermal conductivity in aperiodic SLs exhibits a weaker dependence on device length compared to periodic SLs, existing literature attributes this behavior to the scattering of coherent phonons by aperiodically arranged interfaces. Through atomistic wave-packet simulations, we show that coherent phonons in aperiodic SLs have spatial extensions limited to a certain number of SL layers, which prevents transmission if the extension is shorter than the device length. Specifically, the disordered interface spacing in aperiodic SLs causes coherent phonons to behave as non-propagative vibrational modes, resulting in diffuse energy transmission. In periodic SLs, however, coherent phonons can propagate across the entire structure, enabling high transmission. The difference between ballistic transport in periodic SLs and diffuse transport in aperiodic SLs is captured in the length-dependence of phonon transmission. These findings provide new insights into phonon coherence and its implications for heat conduction in superlattices, with potential applications in the thermal design of nanostructures.

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声子相干是如何在周期和非周期超晶格中发展和促进热传导的

本文研究了周期和非周期超晶格（SLs）中器件长度对导热系数的影响。众所周知，与周期性SLs相比，非周期SLs中的热导率对器件长度的依赖性较弱，现有文献将这种行为归因于非周期排列界面对相干声子的散射。通过原子波包模拟，我们发现非周期SL中的相干声子的空间扩展仅限于一定数量的SL层，如果扩展短于器件长度，则会阻止传输。具体来说，非周期SLs中无序的界面间距导致相干声子表现为非传播振动模式，从而导致漫射能量传输。然而，在周期性单晶硅中，相干声子可以在整个结构中传播，从而实现高传输。在声子传输的长度依赖性中，捕获了周期性激光激光器的弹道输运与非周期激光激光器的漫射输运之间的差异。这些发现为声子相干性及其对超晶格热传导的影响提供了新的见解，在纳米结构的热设计中具有潜在的应用前景。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Thermal Sciences 工程技术-工程：机械

CiteScore

8.10

自引率

11.10%

发文量

531

审稿时长

55 days

期刊介绍： The International Journal of Thermal Sciences is a journal devoted to the publication of fundamental studies on the physics of transfer processes in general, with an emphasis on thermal aspects and also applied research on various processes, energy systems and the environment. Articles are published in English and French, and are subject to peer review. The fundamental subjects considered within the scope of the journal are: * Heat and relevant mass transfer at all scales (nano, micro and macro) and in all types of material (heterogeneous, composites, biological,...) and fluid flow * Forced, natural or mixed convection in reactive or non-reactive media * Single or multi–phase fluid flow with or without phase change * Near–and far–field radiative heat transfer * Combined modes of heat transfer in complex systems (for example, plasmas, biological, geological,...) * Multiscale modelling The applied research topics include: * Heat exchangers, heat pipes, cooling processes * Transport phenomena taking place in industrial processes (chemical, food and agricultural, metallurgical, space and aeronautical, automobile industries) * Nano–and micro–technology for energy, space, biosystems and devices * Heat transport analysis in advanced systems * Impact of energy–related processes on environment, and emerging energy systems The study of thermophysical properties of materials and fluids, thermal measurement techniques, inverse methods, and the developments of experimental methods are within the scope of the International Journal of Thermal Sciences which also covers the modelling, and numerical methods applied to thermal transfer.