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.

中文翻译：

---

石墨材料中集体和非集体声子流之间转变的热阻

摘要 与 umklapp 散射（U 散射）相比，石墨材料中的声子表现出强烈的法向散射（N 散射）。与 U 散射占主导地位的相对常见情况不同，强烈的 N 散射会导致集体声子流。如果石墨材料具有有限的尺寸并且与发出非集体分布的声子的冷热储层接触，则 N 散射会将非集体声子流改变为石墨材料和储热层之间界面附近的集体声子流。我们通过在非集体和集体声子流之间的过渡期间通过 N 散射来研究热阻。Peierls-Boltzmann 传输方程的蒙特卡罗解表明，石墨材料中的 N 散射使弹道情况下的热通量在 100、200 和 100% 时分别降低了约 15%、30% 和 40%。和 300 K，分别。这明显大于具有相似德拜温度 (~2300 K) 的德拜晶体的~5% 减少。我们将 N 散射引起的热通量的大幅减少与石墨材料的非线性色散和具有不同群速度的多个声子分支联系起来。