Mechanochemical synthesis of ReB_2 powder

摘要

ReB_2 was recently reported to exhibit high hardness and low compressibility, which both are strong functions of its stoichiometry, namely Re to B ratio. Most of the techniques used for ReB_2 synthesis reported 1:2.5 Re to B ratio because of the loss of the B during high temperature synthesis. However, as a result of B excess, the amorphous boron, located along the grain boundaries of polycrystalline ReB_2, would degrade the ReB_2 properties. Therefore, techniques which could allow synthesizing the stoichiometric ReB_2 preferably at room temperature are in high demand. Here, we report synthesis of ReB_2 powders using mechanochemical route by milling elemental crystalline Re and amorphous B powders in the SPEX 8000 high-energy ball mill for 80 h. The formation of boron and perrhenic acids are also reported after ReB_2 powder was exposed to the moist air environment for a 12-month period of time.