Fabrication and electromagnetic wave absorbing properties of the (Hf0.25Zr0.25Nb0.25Ta0.25)C high-entropy ceramics

High-entropy engineering is an effective strategy for developing high properties of the transition-metal carbides, including their mechanical and functional performance, owing to its high-entropy effect, sluggish diffusion effect, sever lattice distortion, and cocktail effect. In this study, a single-phase high-entropy ceramic with a rock-salt crystal structure (Hf0.25Zr0.25Nb0.25Ta0.25)C was fabricated through a solid-phase reaction at 2200 degrees C. The as-obtained, high-entropy ceramic powder exhibited high efficiency electromagnetic-wave-absorption capability. The minimum reflection loss (RL) value reached approximately - 64.38 dB at 16 GHz with a thickness of 4.43 mm. By tuning the thickness of the sample, the total effective absorption bandwidth (RL <= -10 dB) was similar to 4.46 GHz, almost covering the Ku band. The excellent microwave absorption performance was ascribed to the high-entropy effect of the strong dielectric loss of the material as well as the proper impedance matching degree. Thus, high-entropy engineering is expected to be a promising route for developing microwave absorbers with excellent absorption capability.