Abstract: The increasing challenges of electromagnetic interference and radiation pollution urgently demand the development of advanced electromagnetic wave absorption materials with excellent high-temperature stability. Medium- and high-entropy ceramics, owing to their tunable compositions and unique high-entropy effects, have attracted growing attention. In this work, novel core-shell structured (Zr, Ta, Ti)C@C ceramics were successfully synthesized via a combination of polymer-derived ceramics method and solvothermal reaction. The microstructural evolution, carbon shell formation mechanism, dielectric properties, and electromagnetic wave absorption performance of (Zr, Ta, Ti)C@C were systematically investigated. The results show that the (Zr, Ta, Ti)C/paraffin composites achieve a minimum reflection loss (RL_min) of -57.19 dB at a thickness of 1.92 mm, with an effective absorption bandwidth (EAB) of 3.62 GHz at a filler loading of 40 wt.%. With the formation of the carbon shell, (Zr, Ta, Ti)C@C/paraffin composites maintains an outstanding RL_min of -57.11 dB and achieves full X-band coverage with only 20 wt.% filler loading. The construction of the carbon shell effectively enhances interfacial polarization and dielectric loss, optimizes impedance matching, and thus significantly boosts the electromagnetic wave absorption performance. This study provides a promising strategy for designing high-performance core-shell structured medium-entropy ceramics for electromagnetic absorption applications.

Key words: Medium-entropy ceramics, Core-shell structure, Polymer-derived ceramics method, Electromagnetic wave absorption