Thermoelectric properties of paracostibite fabricated using chemically synthesized Co–Sb–S nanoparticles as building blocks

Paracostibite (CoSbS) is a promising candidate for n-type thermoelectric materials. In this study, a nanostructured CoSbS pellet was fabricated using chemically synthesized Co–Sb–S nanoparticles as building blocks. The CoSbS pellet showed the highest electrical conductivity (σ = 141 S/cm at 661 K) and lowest thermal conductivity [κ ≅ 2 W/(m K)] among the reported CoSbS. Detailed analysis of the electrical transport process in a wide temperature range (3 K–661 K) revealed the existence of a donor level. At a temperature less than 170 K, the resistivity showed Mott variable-range hopping behavior, while the band conduction became dominant as the temperature increased. Nanograins in the pellet significantly enhanced phonon scattering, resulting in suppression of κ. The maximum dimensionless figure of merit value was 0.05 at 661 K, which is comparable with previously reported values for CoSbS TE materials.