High-Pressure Synthesis of Te-Ge Double-Substituted Skutterudite with Enhanced Thermoelectric Properties.

We synthesized CoSbTeGe ( = 0.5-0.8) using high-pressure, high-temperature conditions at ∼2 GPa and ∼900 K. The microstructure, morphology, and components were characterized via X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction (EBSD). EBSD indicated that the average grain size of CoSbTeGe was 1 μm. Electrical conductivity, Seebeck coefficient, and thermal conductivity were measured from 300 to 800 K. The minimum lattice thermal conductivity of CoSbTeGe was 0.72 W m K, 74% lower than that at 300 K. The introduction of Te and Ge effectively enhanced point effects scattering and location scattering, notably decreasing lattice thermal conductivity. Therefore, the maximum value of CoSbTeGe was 1.13 at 800 K. These results indicate that high pressure combined with multielement substitution optimized the thermoelectric transport properties of skutterudites.