Synergistic Magnetic-dielectric Loss in In Situ Grown Composites via Molten Salt Etching for Advanced Microwave Absorption

With the rapid advancement of fifth-generation (5G) communication technology, microwave pollution has become increasingly severe, creating an urgent demand for advanced microwave absorption materials. However, materials commonly face challenges such as poor impedance matching and insufficient magnetic-dielectric synergistic loss. This study innovatively proposes a strategy employing multi-component molten salt etching of MAX phases to in situ construct a composite material with magnetic-dielectric synergistic loss properties. This composite features Fe-Co-Ni alloy nanoparticles as the magnetic component and TiC with VC heterojunctions as the dielectric coupling phase. The strategy leverages selective etching of the A-layer atoms within the MAX phases to achieve crystal structure restructuring. Benefiting from the high dielectric loss and interfacial polarization of TiC-VC, coupled with the high saturation magnetization and exchange coupling effects of Fe-Co-Ni, the composite overcomes the limitations imposed by the Snoek effect in traditional magnetic materials at low frequencies, significantly enhancing low-frequency magnetic loss capability. The fabricated composite material, at an ultrathin thickness of 1.5 mm, achieves a minimum reflection loss of −59.1 dB, an effective absorption bandwidth of 5.12 GHz. This research offers a novel approach for designing high-efficiency magnetic-dielectric synergistic absorbing materials for low-frequency applications and paves a new pathway for 5G electromagnetic protection.