Rapid microwave-assisted synthesis of rare-earth hexaborides powders

Abstract

Rare-earth hexaborides (RB₆) are promising materials for photonic and electronic applications in modern technology. However, the known methods of synthesis of RB₆s are challenging due to their complexities and nuances, usually requiring high temperatures, long synthesis durations and complicated by the use of complex precursors. This paper reports the development of an energy-efficient and straightforward microwave-assisted synthesis (MS) method. The series of rare-earth metal hexaboride powders RB₆ (R = La, Ce, Nd and Sm) have been prepared by the MS method in a dramatically short times (synthesis duration is 10 minutes). For the synthesis, easily available raw materials (lanthanide oxides and boron) were used, although the reactions R₂O₃/B → RB₆ are thermodynamically prohibited (except CeO₂/B system). The x-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis show that all hexaborides are cubic phases with high crystallinity. Although the shapes are similar, the sizes are in the range of 1 to 10 μm. being different for each of the formulations.