Ultrafast microwave-assisted solvothermal synthesis and characterization of near-spherical CoSb3 nanopowders

Near-spherical shape CoSb3 nanopowders have been rapidly synthesized by a microwave-assisted solvothermal method. The use of a microwave-assisted solvothermal method saves 99% of the dwell time compared to conventional solvothermal and hydrothermal methods. The effects of composition and processing parameters such as temperature and dwell time on the formation process of CoSb3 nanopowders were investigated. It is found almost pure CoSb3 can be synthesized at 280 °C with n (Co2+):n (Sb3+) = 1:3.5 for 20 min. The Rietveld refinement result indicates that the amount of CoSb3 phase is 95%. The microstructure characterization and analysis results show that the final products consist mainly of nearly spherical particles with an average diameter of approximately 33 nm. Meanwhile, high-density grain boundaries and dislocations are also found in the as-obtained CoSb3 nanopowders, which can contribute to the decrease of thermal conductivity by phonon scatterings.