分形结构纳米复合材料热导率的分子动力学模拟研究∗

摘要

Sierpinski carpet fractal structure is introduced into the construction of Si/Ge nanocomposites in this paper so as to regulate and control the thermal conductivity of the nanocomposites. Non-equilibrium molecular dynamics simula-tion is applied to investigate the thermal conduction performance of nanocomposites embedded with fractal structure. Effects of the silicon atom percent, axial length and cross-sectional dimensions on the thermal conductivity of nanocom-posites embedded with fractal structure are analyzed and compared with the corresponding nanocomposites embedded with traditional rectangular structure. It is indicated that, owing to the enhanced scattering at the Si/Ge interfaces of nanocomposites embedded with fractal structure, their thermal conductivity are lower than that embedded with rectan-gular structure, thus providing an effective way to improve the thermoelectric efficiency. And it is also demonstrated that the thermal conductivity of nanocomposites embedded with fractal structure are affected by the silicon atoms percent, axial length and cross-sectional size. The thermal conductivity is first decreased and then increased with the increase of Si atom percent. In addition, the increase in axial length of nanocomposites may lead to the enhancement of thermal conduction.%提出了一基于Sierpinski分形结构的Si/Ge纳米复合材料结构，以调控纳米复合材料的热导率。采用非平衡分子动力学方法模拟研究了分形结构Si/Ge纳米复合材料的导热性能，给出了硅原子百分比、轴向长度以及截面尺寸对分形结构纳米复合材料热导率的影响规律，并与传统矩形结构进行了对比。研究结果表明，分形结构纳米复合材料增强了Si/Ge界面散射作用，使得热导率低于传统矩形结构，这为提高材料的热电效率提供了有效途径。 Si原子百分比、截面尺寸、轴向长度皆对分形结构纳米复合材料热导率存在着重要影响。纳米复合材料热导率随着Si原子百分比的增加呈先减小后增加的趋势，随轴向长度的增加则呈单调增大趋势。