Microwave Synthesis And Characterization Of CoSb₃ And CoS₂

We introduce the principle and superiority of solid-state microwave sintering on the preparation of functional materials, and present two samples using temperature-controlled hybrid-microwave method. CoSb₃/SiC composites as well as CoS₂ with suitable reaction temperature and synthesis time were characterized. The structure, composition and morphology of prepared samples were studied. The result reveals that: compared to conventional processes, microwave heating technology has the advantages include: convenience to use; rapid and uniform heating; reducing energy consumption; safety as well as environmentally friendly. The main contents and results are as follows:?1? One-step microwave synthesis and thermoelectric properties of CoSb₃ and CoSb₃/SiC compositesSkutterudite CoSb₃ and CoSb₃/SiC composites were successfully prepared by one-step microwave heating, with the procedures greatly simplified and preparation period significantly shortened from several days to several hours. The unique microstructure including the inter-granular and intra-granular precipitates combined with high porosity of the microwave-synthesized samples lead to very low thermal conductivity, which compensates the loss in electrical conductivity and results in comparable figure of merit ZT value with those reported for undoped CoSb₃ from conventional method with high energy consumption and lengthy synthesis time. These results demonstrate the feasibility of high efficient and economical synthesis of CoSb₃-based compounds and promising ZT enhancement by use of microwave technique, which can also be utilized for fabricating other thermoelectrical materials.?2? Transport and magnetic properties of cobalt disulfide prepared by solid state hybrid microwave heating and hot PressingSingle phase cobalt disulfide CoS₂ was synthesized by temperature-controlled solid state hybrid microwave heating. The structure, composition and morphology of the obtained samples were studied using X-ray diffraction?XRD?, energy dispersive X-ray spectroscopy?EDX? and high resolution transmission electron microscopy?HRTEM?. The loose CoS₂ polycrystalline precursor was then hot pressed to dense bulk sample. The subsequent transport and magnetic properties measurements reveal the ferromagnetic Curie temperature at the magnetic transition near 128 K. Our results suggest that the magnetic transition in CoS₂ is susceptible to the preparation conditions and the microstructure of the samples.