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首页> 外文期刊>Physical review >Ab initio computational study on the lattice thermal conductivity of Zintl clathrates [Si_(19)P_4]Cl_4 and Na_4[Al_4Si_(19)]
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Ab initio computational study on the lattice thermal conductivity of Zintl clathrates [Si_(19)P_4]Cl_4 and Na_4[Al_4Si_(19)]

机译:Zintl包合物[Si_(19)P_4] Cl_4和Na_4 [Al_4Si_(19)]的晶格热导率从头算计算研究。

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摘要

The lattice thermal conductivity of silicon clathrate framework Si_(23) and two Zintl clathrates, [Si_(19)P_4]Cl_4 and Na_4[Al_4Si_(19)], is investigated by using an iterative solution of the linearized Boltzmann transport equation in conjunction with ab initio lattice dynamical techniques. At 300 K, the lattice thermal conductivities for Si_(23), [Si_(19)P_4]Cl_4, and Na_4[Al_()4Si_(19)] were found to be 43 W/(m K), 25 W/(m K), and 2 W/(m K), respectively. In the case of Na_4[Al_4Si_(19)], the order-of-magnitude reduction in the lattice thermal conductivity was found to be mostly due to relaxation times and group velocities differing from Si_(23) and [Si_(19)P_4]Cl_4. The difference in the relaxation times and group velocities arises primarily due to the phonon spectrum at low frequencies, resulting eventually from the differences in the second-order interatomic force constants (IFCs). The obtained third-order IFCs were rather similar for all materials considered here. The present findings are similar to those obtained earlier for some skutterudites. The predicted lattice thermal conductivity of Na_4[Al_4Si_(19)] is in line with the experimentally measured thermal conductivity of recently synthesized type-Ⅰ Zintl clathrate Na_8[Al_8Si_(38)] (polycrystalline samples).
机译:结合线性玻尔兹曼输运方程的迭代解,研究了硅包合物骨架Si_(23)和两种Zintl包合物[Si_(19)P_4] Cl_4和Na_4 [Al_4Si_(19)]的晶格热导率。从头算格动力学技术。在300 K时,发现Si_(23),[Si_(19)P_4] Cl_4和Na_4 [Al _()4Si_(19)]的晶格热导率分别为43 W /(m K),25 W /( m K)和2 W /(m K)。在Na_4 [Al_4Si_(19)]的情况下,发现晶格热导率的数量级降低主要是由于弛豫时间和基团速度不同于Si_(23)和[Si_(19)P_4] Cl_4。弛豫时间和基团速度的差异主要是由于低频处的声子谱引起的,最终是由二阶原子间原子力常数(IFC)的差异引起的。对于此处考虑的所有材料,获得的三阶IFC都非常相似。目前的发现与先前从某些方钴矿获得的发现相似。 Na_4 [Al_4Si_(19)]的预测晶格热导率与最近合成的Ⅰ型Zintl包合物Na_8 [Al_8Si_(38)](多晶样品)的实验测量热导率一致。

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  • 来源
    《Physical review》 |2016年第5期|054310.1-054310.11|共11页
  • 作者单位

    Department of Chemistry, University of Jyvaeskylae, PO Box 35, FI-40014, Finland;

    Department of Chemistry, Aalto University, FI-00076 Espoo, Finland;

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