Process Analysis and Mechanism Investigation of Low Temperature Synthesis of Nanoscale Calcium Hexaboride Powder

The synthesis of nanoscale CaB6 powder via the low-temperature chemical reaction of Calcium chloride (CaCl2) with Sodium Borohydride (NaBH4) in a vacuum has been investigated in this study. The reaction temperature was determined by differential scanning calorimetry and thermogravimetric analysis (DSC and TG). The crystallization process was provided by studying the influence of heat preservation time on the crystal particle morphologies in a vacuum. X-ray diffraction (XRD) was used to investigate the phase and structure of CaB6. The characterization of microstructure was performed by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The elemental analysis was conducted by X-ray photoelectron spectroscopy (XPS). It is concluded that CaB6 nanoparticles can be successfully prepared under low temperatures at 500 °C. The results showed that 2 hours of heat preservation time in a vacuum is enough for the reaction to complete at this temperature. The average size of crystal grains is 25.1 nm with high crystallinity and cubic shape, with particle size at 20–100 nm. A longer heat preservation time of more than 2 hours will make CaB6 particles connected together to form hard aggregations; that is, the sintering process occurs under this temperature. However, the crystal grain size changed unobviously, prolonging the holding time due to the high chemical stability of CaB6. The atomic ratio of B to Ca is 5.37:1, less than but close to its stoichiometric ratio of 6:1. The synthesis process and mechanism were investigated in this paper. If you are looking for high quality, high purity, and cost-effective Calcium hexaboride, or if you require the latest price of Calcium hexaboride, please feel free to email contact mis-asia.