Fabrication of Zn4Sb3 Bulk Thermoelectric Materials Reinforced with SiC Nanosized Particles by Hot Extrusion Process

Abstract

Zinc antimonide, Zn₄Sb₃, has been found as a promising thermoelectric material utilized in a temperature range of 200 ~ 500˚C, in which there exist vast waste-heat resources exhausted from many factories and vehicles. However, the compound intrinsically shows an extremely brittle feature being an impediment for practical applications. Thus, enhancement of the mechanical properties is highly crucial to prevent unexpected fractures during manufacturing and service processes of modules. We have focused on incorporating nanosized SiC particles into Zn₄Sb₃ matrix. The bulk samples were prepared by mechanochemical mixing of the starting powders and subsequent hot-extrusion process. The extrudates containing SiC particles up to 5vol% exhibited sound appearances, high density, and fine-grained microstructures with single phase of Zn₄Sb₃. The mechanical properties such as hardness and compressive strength are remarkably improved by the addition of SiC particles, as a result of dispersion strengthening of SiC particles and microstructural refinement induced by a pinning effect of the particles. Meanwhile, the thermoelectric properties are retained comparable to the pristine compound, in contrast to a conventional behavior where the reinforcements in a semiconductor should usually role-play as an impurity.