Design and fabrication of (Hf _0.25Zr _0.25Ta _0.25Nb _0.25)C–SiC ceramics with improved microwave absorbing properties via PDC route

The development of advanced and efficient microwave-absorbing materials through the precise regulation of dielectric loss and impedance matching remains a significant challenge. In this study, (Hf_0.25Zr_0.25Ta_0.25Nb_0.25)C-SiC (HEC-SiC) biphasic ceramic powders were synthesized via a single-source-precursor route. The SiC content was systematically controlled by adjusting the amount of methyltrimethoxysilane. The resulting polymer-derived HEC-SiC composite exhibited a unique microstructure, with nano-sized SiC particles uniformly distributed throughout the HEC matrix. As a result, the HEC-SiC-2 composite, containing approximately 21.21 wt.% SiC, achieved a minimum reflection loss value (<em>RL_min</em>) of -54.28 dB at 12.39 GHz with a thickness of 3.14 mm. The superior microwave attenuation capability is attributed to optimized impedance matching, enhanced interfacial polarization between the HEC matrix and nano-sized SiC, and the dipole polarization induced by defects within the HEC. This study offers a novel strategy for the fabrication of high-entropy ceramic-SiC biphasic composites with excellent microwave absorbing properties, paving the way for application in electromagnetic interference shielding and stealth technologies.