Role of phonon dispersion in studying phonon mean free paths in skutterudites
Role of phonon dispersion in studying phonon mean free paths in skutterudites
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DOI：
10.1063/1.4747911
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发表时间：
2012-08
影响因子：
3.2
通讯作者：
M. Zebarjadi;Jian Yang;K. Lukas;B. Kozinsky;Bo Yu;M. Dresselhaus;C. Opeil;Z. Ren;Gang Chen
中科院分区：
文献类型：
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作者：
M. Zebarjadi;Jian Yang;K. Lukas;B. Kozinsky;Bo Yu;M. Dresselhaus;C. Opeil;Z. Ren;Gang Chen
块体材料的实验热导率通常使用德拜近似以及具有拟合参数的弛豫时间的函数形式来建模。虽然这样的模型可以拟合体材料的热导率的温度依赖性，但德拜近似导致实际声子平均自由程的大误差，因此，在考虑了平均自由程的尺寸效应后，用相同的弛豫时间对纳米结构材料热导率的预测是不正确的。Co4Sb12）和完全填充的（LaFe4Sb12）体方钴矿的热导率。我们表明，只有当考虑完全声子色散时，纳米结构样品的理论热导率预测才与不同粒度样品的实验数据一致。
Experimental thermal conductivity of bulk materials are often modeled using Debye approximation together with functional forms of relaxation time with fitting parameters. While such models can fit the temperature dependence of thermal conductivity of bulk materials, the Debye approximation leads to large error in the actual phonon mean free path, and consequently, the predictions of the thermal conductivity of the nanostructured materials using the same relaxation time are not correct even after considering additional size effect on the mean free path. We investigate phonon mean free path distribution inside fully unfilled (Co4Sb12) and fully filled (LaFe4Sb12) bulk skutterudites by fitting their thermal conductivity to analytical models which employ different phonon dispersions. We show that theoretical thermal conductivity predictions of the nanostructured samples are in agreement with the experimental data obtained for samples of different grain sizes only when the full phonon dispersion is considered.