Abstract: Nanocomposite structure is one of the promising directions towards advanced bulk thermoelectric materials. An n-type CoSb₃ nanocomposite consisting nano- and micro-sized grains was prepared by in~situ solvothermal synthesis and hot pressing. Using CoCl₂ and SbCl₃ as precursors, NaBH₄ as reductant, and ethanol as solvent, the start materials together with micro-grained n-type CoSb₃ powders prepared by melting/annealing method were put into an autoclave and reacted at 250℃ for 72h. The bulk nanocomposite was prepared by hot pressing the as-synthesized products. The introduction of nanocomposite structure can reduce the thermal conductivity efficiently by interface scattering and increase the Seebeck coefficient by quantum confinement due to the nanoscale constituents, thereby improve the thermoelectric performance. It is shown that the composite has a doped semicondoctor behavior with good electrical properties. The phonon scattering is efficiently enhanced by the composite micro-/nano-structure, which reduces the thermal conductivity to 2.0-2.3W·m^-1·K^-1 in the nanocomposite. The highest dimensionless figure of merit obtained in the present work reaches 0.5 at 600K.

Key words: CoSb₃, solvothermal synthesis, nanocomposite, thermoelectric materials