Synthesis and characterization of high-entropy diboride microfibers

High-entropy diboride (HEB) microfibers are in great demand for structural and functional applications in extreme conditions. Here, we synthesize (Hf, Ta, Nb, Mo, Ti)B 2 HEB microfibers through a two-step technique involving thermal decomposition of polymers and subsequent boro/carbothermal reduction for the first time. Specifically, polymer precursor microfibers are first decomposed at a moderate temperature of 773 K, followed by a high-temperature calcination at 2273 K to promote boro/carbothermal reduction. The resulting HEB microfibers, with a diameter of approximately 1 µm, exhibit a polycrystalline structure and high-compositional uniformity from nanoscale to microscale. This work opens up a new way to synthesize innovative HEB microfibers.