热电材料中的晶格热导率

Lattice Thermal Conductivity in Thermoelectric Materials

随着可再生能源及能源转换技术的快速发展,热电材料在发电及制冷领域的应用前景受到越来越广泛的关注。发展具有高热电优值材料的重要性日益突出,如何获得低晶格热导率是热电材料的研究重点之一。本文阐述了热容、声速及弛豫时间对晶格热导率的影响,介绍了本征低热导率热电材料所具有的典型特征,如强非谐性、弱化学键、本征共振散射及复杂晶胞结构等,并分析了通过多尺度声子散射降低已有热电材料晶格热导率的方法,其中包括点缺陷散射、位错散射、晶界散射、共振散射、电声散射等多种散射机制。此外,总结了几种预测材料最小晶格热导率的理论模型,对快速筛选具有低晶格热导率的热电材料具有一定的理论指导意义。最后,展望了如何获得低热导率热电材料的有效途径。

With rapid development of sustainable energies and energy conversion technologies, application prospect of thermoelectric (TE) materials in power generation and cooling has received increasing attention. The requirement of improving TE materials with high figure of merit becomes much more important. How to obtain the low lattice thermal conductivity is one of the main concerns in TE materials. In this review, the influences of specific heat, phonon group velocity and relaxation time on the lattice thermal conductivity are discussed, re-spectively. Several typical features of TE materials with intrinsic low lattice thermal conductivity are introduced, such as strong anharmonicity, weak chemical bonds and complex primitive cells. Introducing multiscale phonon scatterings to reduce the lattice thermal conductivity of known TE materials is also presented and discussed, in-cluding but not limited to point defect scattering, dislocation scattering, boundary scattering, resonance scatter-ing and electron-phonon scattering. In addition, some theoretical models of the minimum lattice thermal con-ductivity are analyzed, which has certain theoretical significance for rapid screening of TE materials with low lattice thermal conductivity. Finally, the efficient ways to obtain the low lattice thermal conductivity for TE property optimization are proposed.