Thermal Resistance by Transition Between Collective and Non-Collective Phonon Flows in Graphitic Materials
Thermal Resistance by Transition Between Collective and Non-Collective Phonon Flows in Graphitic Materials
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DOI：
10.1080/15567265.2019.1575497
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发表时间：
2018-12
影响因子：
4.1
通讯作者：
Sangyeop Lee;Xun Li;Ruiqiang Guo
中科院分区：
文献类型：
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作者：
Sangyeop Lee;Xun Li;Ruiqiang Guo
石墨材料中的声子表现出比umklapp散射（U散射）更强的法向散射（N散射）。强烈的N-散射导致集体声子流，不像U-散射占主导地位的相对常见的情况。如果石墨材料具有有限的尺寸并且与发射具有非集体分布的声子的热库和冷库接触，则N-散射将石墨材料和热库之间的界面附近的非集体声子流改变为集体声子流。我们研究了在非集体声子流和集体声子流之间的转变过程中的N-散射热阻。Peierls-Boltzmann输运方程的Monte Carlo解表明，石墨材料中的N-散射在100、200和300 K时分别使弹道情况下的热通量减少约15%、30%和40%。这明显大于具有类似德拜温度（~2300 K）的德拜晶体的~ 5%的减少。我们关联的N-散射的热通量的大幅度减少与非线性色散和多声子分支与石墨材料的不同群速度。
ABSTRACT Phonons in graphitic materials exhibit strong normal scattering (N-scattering) compared to umklapp scattering (U-scattering). The strong N-scattering cause collective phonon flow, unlike the relatively common cases where U-scattering is dominant. If graphitic materials have finite size and contact with hot and cold reservoirs emitting phonons with non-collective distribution, N-scattering change the non-collective phonon flow to the collective phonon flow near the interface between graphitic material and a heat reservoir. We study the thermal resistance by N-scattering during the transition between non-collective and collective phonon flows. Our Monte Carlo solution of Peierls-Boltzmann transport equation shows that the N-scattering in graphitic materials reduce heat flux from the ballistic case by around 15%, 30%, and 40% at 100, 200, and 300 K, respectively. This is significantly larger than ~ 5% reduction of Debye crystal with similar Debye temperature (~2300 K). We associate the large reduction of heat flux by N-scattering with the non-linear dispersion and multiple phonon branches with different group velocities of graphitic materials.