Synthesis of Nano-Sized Co-Sb Compounds through Solvothermal Routes

Skutterudite materials have received great attention because their promising properties for thermoelectric (TE) applications. Among the family of skutterudites, CoSb3 has been intensively investigated due to its large electrical conductivity and Seebeck coefficient. However, its thermal conductivity is too high to make it an effective TE material. Nanostructuring of CoSb3 has the desirable effects of reducing its lattice thermal conductivity as the point imperfections or grain boundaries can scatter phonons (heat carrier) more effectively than electrons (charge carrier). In this study, nanostructured CoSb3 was synthesized by solvothermal routes using CoCl2·6H2O and SbCl3 as precursors dissolved in anhydrous ethanol with the reaction temperature kept at 240°C. In addition to the CoSb3 phase, other Co-Sb compounds were also formed during the reaction process. In this paper, we investigated the effects of processing parameters, such as concentration of CoCl2·6H2O, SbCl3 and NaBH4 in ethanol and thermal duration of solvothermal synthesis, on the yield of CoSb3 phase.