Synthesis of CaB ₆ powders via mechanochemical reaction of Ca/B ₂O ₃ blends

The synthesis of CaB ₆ powders by mechanochemical processing was investigated in the present study. The synthesis was carried out using stoichiometric amounts of Ca/B ₂O ₃ powder blends as low cost raw materials. Milling was performed at room temperature in a high energy ball-mill using hardened steel vial and balls with a constant ball-to-powder weight ratio (10:1). The effect of milling duration on the production efficiency of CaB ₆ powders was investigated. Milled powders were leached by different HCl concentrations under the effect of ultrasonic stirring. The final product was obtained after repeated centrifuging, decanting, washing and drying treatments. Phase and microstructural characterization investigations of the milled and leached powders were carried out by X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) whereas supernatant liquid was characterized by Atomic Absorption Spectrometry (AAS). The best results for the preparation of CaB ₆ powders were obtained from the 6h milled and repeated leached (2 and 0.5M HCl solution) powders.