Microwave-assisted preparation and characterization of nanoscale rhenium diboride

A simple and efficient microwave-assisted preparation of ReB2-based material is reported utilizing ammonium perrhenate (NH4ReO4), magnesium boride (MgB12) reactants and carbon as an absorber of microwave irradiation. The investigation of microwave irradiated NH4ReO4 + MgB12 + C mixtures, thermal analysis results and electron microscopy examination reveals that Na4ReO4 decomposition produces ReO3 at early stages of the process. The ReO3 then exothermically reacts with MgB12 forming the nanoscale Re3B phase, which converts into ReB2 upon further irradiation. The coupling of microwave energy with exothermic reactions significantly accelerates the formation of ReB2. The product primarily consists of ReB2 as well as B4C and minor carbon phases. Structural characterization reveals that the average particle size of ReB2 is similar to 50 nm.