Unveiling Brass-Doped CoSb3-Based Thermoelectric Materials Using Solid-State Reaction

Abstract

Skutterudite (CoSb3)-based thermoelectric materials are regarded as one of the most promising candidates for mid-temperature commercial thermoelectric applications, thanks to their excellent electrical performance and alloy-based attributes. By utilizing techniques such as doping, microstructure design, and high-temperature solid-state reactions, synthesis of Brassx/Co4Sb11.5Te0.5 (x = 0.1, 0.3, 0.5, 0.7, representing wt%) in composite form can be rapidly achieved. XRD analysis indicates that the prepared Brassx/Co4Sb11.5Te0.5 samples primarily exhibit the CoSb3 crystal structure, with the formation of minor impurity phases such as Cu13Te7 and ZnTe. SEM and EDS analyses reveal that the sample is composed of nanoscale equiaxed grains, some of which are micrometer in size, with a large number of microporous structures distributed uniformly, forming abundant grain boundaries. By co-doping with brass and tellurium (Te), the carrier concentration can be effectively regulated, thereby enhancing the power factor of CoSb3-based thermoelectric materials. Meanwhile, the introduction of nanostructures, grain boundaries, and defects optimizes the microstructure of the samples, leading to a reduction in the lattice thermal conductivity of the CoSb3-based thermoelectric materials. At a testing temperature of 781 K, Brass0.1/Co4Sb11.5Te0.5 achieved a maximum power factor of 1.86 mW·m−1·K−2, a minimum lattice thermal conductivity of 1.02 W/(mK), and a maximum thermoelectric figure of merit ZT of 0.81.