Minimum superlattice thermal conductivity from molecular dynamics
Minimum superlattice thermal conductivity from molecular dynamics
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DOI：
10.1103/physrevb.72.174302
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发表时间：
2005-11-01
影响因子：
3.7
通讯作者：
Chen, MH
中科院分区：
文献类型：
--
作者：
Chen, YF;Li, DY;Chen, MH
利用分子动力学模拟方法研究了超晶格热导率随周期长度的变化规律。对于完全晶格匹配的超晶格，当周期长度为有效声子平均自由程量级时，观察到一个极小值，随着温度的降低和原子间势强度的增加，极小值的位置向更大的周期长度移动。的深度的最小值强烈增强的质量和原子间的潜在的组成材料的比例增加。模拟结果与声子透射系数的计算结果一致，表明在相同的条件下，增加的停止带宽，从而强烈增强布拉格散射的热导率的强烈减少被发现。当非理想界面通过引入4%的晶格失配，最小消失，热导率随周期长度单调增加。这一结果可以解释为什么在大量的实验研究中没有观察到最小热导率。
The dependence of superlattice thermal conductivity on period length is investigated by molecular dynamics simulation. For perfectly lattice matched superlattices, a minimum is observed when the period length is of the order of the effective phonon mean free path. As temperature decreases and interatomic potential strength increases, the position of the minimum shifts to larger period lengths. The depth of the minimum is strongly enhanced as mass and interatomic potential ratios of the constituent materials increase. The simulation results are consistent with phonon transmission coefficient calculations, which indicate increased stop bandwidth and thus strongly enhanced Bragg scattering for the same conditions under which strong reductions in thermal conductivity are found. When nonideal interfaces are created by introducing a 4% lattice mismatch, the minimum disappears and thermal conductivity increases monotonically with period length. This result may explain why minimum thermal conductivity has not been observed in a large number of experimental studies.