Achieving ultra-broadband electromagnetic wave absorption in high-entropy transition metal carbides (HE TMCs)

Electronic devices pervade everyday life, which has triggered severe electromagnetic (EM) wave pollution. To face this challenge, developing EM wave absorbers with ultra-broadband absorption capacity is critically required. Currently, nano-composite construction has been widely utilized to realize impedance match and broadband absorption. However, complex experimental procedures, limited thermal stability, and interior oxidation resistance are still unneglectable issues. Therefore, it is appealing to realize ultra-broadband EM wave absorption in single-phase materials with good stability. Aiming at this target, two high-entropy transition metal carbides (HE TMCs) including (Zr,Hf,Nb,Ta)C (HE TMC-2) and (Cr,Zr,Hf,Nb,Ta)C (HE TMC-3) are designed and synthesized, of which the microwave absorption performance is investigated in comparison with previously reported (Ti,Zr,Hf,Nb,Ta)C (HE TMC-1). Due to the synergistic effects of dielectric and magnetic losses, HE TMC-2 and HE TMC-3 exhibit better impedance match and wider effective absorption bandwidth (EAB). In specific, the exclusion of Ti element in HE TMC-2 endows it optimal minimum reflection loss (RL_min) and EAB of -41.7 dB (2.11 mm, 10.52 GHz) and 3.5 GHz (at 3.0 mm), respectively. Remarkably, the incorporation of Cr element in HE TMC-3 significantly improves the impedance match, thus realizing EAB of 10.5, 9.2, and 13.9 GHz at 2, 3, and 4 mm, respectively. The significance of this study lays on realizing ultra-broadband capacity in HE TMC-3 (Cr, Zr, Hf, Nb, Ta), demonstrating the effectiveness of high-entropy component design in tailoring the impedance match.