热电复合材料的研究进展

Research progress in thermoelectric composites

热电材料利用固体内部载流子运动特性可实现热能和电能的相互转换,该过程无噪音、无污染,因而热电材料具有广泛而重要的应用前景。热电转换效率依赖于材料本身,不断改善现有热电材料的性能和开发新型高性能的热电材料体系是热电材料领域的重要研究方向。通过复合策略,第二相的种类、含量及微结构调控是设计高性能热电复合材料的关键,如引入第二相所实现的声子散射效应可降低材料的晶格热导率,通过载流子选择性散射的能量过滤效应可提升材料的Seebeck系数,高导电第二相连网引起的渗流效应可提高材料的电导率。本文先介绍复合材料中常见的物理效应,再以几个典型热电材料体系为例介绍复合化实现的微结构调控对电、声输运性能的影响机制.

Thermoelectric materials can realize the direct conversion of heat and electricity by using the internal carrier transport characteristics of solid. This process is noiseless and pollution-free, which has a wide and important potential in application. Thermoelectric conversion efficiency depends on the material itself. Continuously improving the performance of existing thermoelectric materials and developing new high-performance thermoelectric material systems are important research hotpots in the thermoelectric field. The type, content and microstructure control of the second phase are the keys to design high-performance thermoelectric composite materials. Compositing the second phase is an effective strategy to optimize the thermoelectric performance, which can not only reduce the lattice thermal conductivity by introducing phonon scattering centers, but also improve the Seebeck coefficient through the energy filtering effect. Meanwhile, this strategy enhances the conductivity by the percolation effect,owning to form a conductive network in the matrix. This paper first introduces the common physical effects in composites, and then reviews the recent progress of the research on several typical thermoelectric materials. The effects of the second phase on the electrical and thermal transports will be also discussed.