Effective phonon mean free path in polycrystalline nanostructures
Effective phonon mean free path in polycrystalline nanostructures
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DOI：
10.1063/1.4918703
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发表时间：
2015-04-27
影响因子：
4
通讯作者：
Dames, Chris
中科院分区：
文献类型：
--
作者：
Hori, Takuma;Shiomi, Junichiro;Dames, Chris
我们已经计算了平均自由程（MFP）的声子与晶界散射多晶纳米结构，通过开发一个Monte Carlo射线跟踪传输模型，可以应用于任意的几何形状。采用Voronoi图和遗传算法对不同对数正态分布的晶粒尺寸分布进行了计算，结果表明，在平均晶粒尺寸相同（由匹配晶粒体积定义）的情况下，多晶纳米结构的边界散射MFP比简单立方结构的要长20%~ 30%。通过使用Matthiessen规则将联合收割机边界散射与本征声子-声子散射相结合来量化纳米晶硅对热导率的影响。结果表明，导热系数对平均晶粒尺寸的依赖性很强，但对晶粒尺寸分布宽度的依赖性很弱，因此简单立方结构是实际材料多分散晶粒结构的合理近似。(C)2015年AIP Publishing LLC。
We have calculated the mean free path (MFP) of phonons associated with grain boundary scattering in polycrystalline nanostructures, by developing a Monte Carlo ray tracing transmission model that can be applied to arbitrary geometries. The calculations for various log-normal grain-size distributions realized by Voronoi diagrams and genetic algorithms show that the boundary-scattering MFP in a polycrystalline nanostructure is 20%-30% longer than that in a simple cubic structure with the same average grain size (defined by matching grain volumes). The impact on thermal conductivity is quantified for nanocrystalline silicon by using Matthiessen's rule to combine boundary scattering with intrinsic phonon-phonon scattering. The result reveals that the thermal conductivity depends strongly on the average grain size but only weakly on the breadth of the grain-size distribution, and thus, the simple cubic structure is a reasonable approximation for the polydisperse grain structure of actual materials. (C) 2015 AIP Publishing LLC.