Enhanced Microwave Absorption of Multi-Interface Core–Shell FeSiAl@MnOx@C Composites by Morphology Engineering

The rational manipulation of interfacial properties, composition, and morphology of materials has emerged as an effective strategy for enhancing their microwave absorption performance. The crystal phase composition, microstructure, and electromagnetic properties can be regulated by varying the thermal treatment temperature. The synergistic integration of heterogeneous interfaces, magnetic materials, microstructures, and defect engineering helps optimize impedance matching and enhance polarization and magnetic losses. Herein, multi-interface core–shell FeSiAl@MnO x @C composites with various morphologies demonstrated superior microwave absorption performance. A minimum reflection loss of −56.3 dB is achieved at an absorber thickness of 1.41 mm, and effective absorption bandwidth of 5.0 GHz is obtained at a thickness of 1.59 mm. The radar cross-section reduction value reached 19.448 at an incidence angle of 0°. The excellent microwave absorption performance is due to the synergistic effect of the significant magnetic and dielectric losses and improved impedance matching. This study establishes a foundation for designing next-generation high-performance microwave-absorbing materials with high magnetic losses.