Ultrafast Synthesis of Te-Doped CoSb₃ with Excellent Thermoelectric Properties

An efficient technique to prepare high-ZT skutterudites is described. Nearly single-phase Te-doped CoSb3–xTex ingots are synthesized by microwave processing for 5 min, and materials with 98% relative density are produced after spark plasma sintering for 5 min. The phase composition, grain size, and microstructure are studied, and the electrical and thermal transport mechanisms are examined systematically. In addition, the phonon scattering mechanism is examined. Our results show that 5–10 mol % Te is desirable for CoSb3–xTex, and the power factors can be maximized by balancing the Seebeck coefficient and conductivity. Abundant edge and screw dislocations are observed, and an ultralow lattice thermal conductivity of 1.04 W m–1 K–1 is observed from CoSb2.95Te0.05 at 773 K on account of the combined effects of boundary and dislocation scattering. CoSb2.95Te0.5 shows the highest ZT of 1.06 at 773 K, and even larger values can be achieved at a higher temperature. The preparation technique described here has many advantages associated with the properties and efficiency and great potential in the research and production of TE materials.