S-filled and Te-doped CoSb3 materials prepared by HPHT method with ultra-low thermal conductivity.

In this paper, a series of S 0. 0 5 Co4Sb 1 1. 6 Te 0. 4 samples were prepared by high pressure and high temperature (HPHT) method under different pressures. The synthesis time was shortened from several days to 0.5 h. Te doping and S filling simultaneously optimized the thermal and electrical transport properties of the CoSb3 materials. We found a porous architecture containing rich grain boundaries, different grain sizes, nano- to micrometer-sized pores, and a large number of dislocations, which can scatter a wide spectrum of phonons. Seebeck coefficient α , electrical resistivity ρ , and thermal conductivity κ were measured between 295 K and 773 K. The minimum thermal conductivity of S 0. 0 5 Co4Sb 1 1. 6 Te 0. 4 synthesized at 3.0 GPa was 1.23 Wm − 1  K − 1 , and its maximum zT value reached 1.07 at 773 K, especially the lattice thermal conductivity was as low as 0.49 Wm − 1  K − 1 . [ABSTRACT FROM AUTHOR]