Compositional and structural engineering of multicomponent borides hollow microspheres with superior microwave absorption performance

Microwave-absorbing materials with excellent comprehensive performance and high-temperature structural stability are highly favored in practical applications. In extreme environments, boride ultra-high temperature ceramics are considered as promising absorbing materials, however, their high density and poor impedance matching often result in unsatisfactory performance. In this study, based on a multicomponent composition design strategy and hollow microsphere structural engineering, we synthesized multicomponent boride hollow microspheres (MBHMs) for the first time through the well-designed cross-linked network structure and self-assembly of boride nanoparticles. The influence of various elemental compositions on the wave-absorbing properties of the samples was systematically investigated. By fine-tuning the elemental components, the dielectric loss and impedance matching could be easily adjusted, and the optimized samples demonstrated outstanding absorption performances, particularly the (Zr, Hf, Ta)B₂ samples doped with moderate Ti and Cr, which exhibited minimum reflection loss (RL_min) of −53.56 and −68.07 dB, along with effective absorption bandwidth (EAB) of 4.88 and 3.20 GHz, respectively. The excellent performances surpass those of many previously reported absorbers with similar compositions. Furthermore, radar cross-section (RCS) simulation results indicate that such materials exhibit excellent stealth performance in practical applications. This research elucidates that the integration of component design and hollow structure engineering is an effective strategy for developing high-performance microwave-absorbing materials and the findings offer novel perspectives for the advancement of novel lightweight, high-temperature-resistant wave-absorbing materials.