Electromagnetic wave absorption properties of high-entropy carbide ceramics: The role of Fe content in (Hf_(1-X)/4Zr_(1-X)/4Nb_(1-X)/4Ta_(1-X)/4Fe_X)C compositions

Transition metal carbide high-entropy ceramics, due to their narrow absorption bandwidth, face limitations in widespread application. However, by introducing magnetic elements into these ceramics, the absorption bandwidth can be significantly improved. Achieving an equimolar solid solution through solid-state reactions, though, remains challenging. In this study, the polymer-derived ceramic method was successfully applied to incorporate Fe at various molar ratio into high-entropy carbide ceramics, specifically (Hf_(1-X)/4Zr_(1-X)/4Nb_(1-X)/4Ta_(1-X)/4Fe_X)C (X = 0.10, 0.14, 0.16, 0.18, and 0.20). It was found that high-entropy carbide ceramics with a face-centered cubic (FCC) rock salt structure could be successfully prepared in this system along with the increasing Fe content. Moreover, samples with 50 % powder content in (Hf_0.2Zr_0.2Nb_0.2Ta_0.2Fe_0.2)C, pyrolyzed at 1800^oC, exhibit excellent microwave absorption performance and broader effective absorption bandwidth. Specifically, the minimum reflection loss (RL_min) is −61.62 dB at a thickness of 3.16 mm at a frequency of 10.77 GHz. These experimental findings suggest that (Hf_0.2Zr_0.2Nb_0.2Ta_0.2Fe_0.2)C high-entropy ceramics hold significant potential as structure-function integrated materials, with wide-ranging applications, particularly in electromagnetic interference shielding under extreme environment applications.