FeCoCr Nanoalloy/Carbon Composites as Soft-Magnetic Materials for High-Performance Electromagnetic Microwave Absorption

FeCo-based soft-magnetic materials are promising for high-frequency electromagnetic wave absorption but often suffer from high coercivity, poor corrosion resistance, and an impedance mismatch. To address these challenges, we synthesized FeCoCr alloy nanoparticles embedded in a nitrogen-doped carbon matrix via a facile ligand-assisted pyrolysis strategy. The introduction of Cr effectively refines the microstructure, retains the high saturation magnetization (up to 182 emu·g –1 ), lowers coercivity (∼20 Oe), and significantly enhances corrosion resistance. More importantly, the controlled surface oxidation and optimized composition in FeCoCr-0.4 effectively regulate the complex permittivity, achieving excellent impedance matching. Combined with synergistic magnetic and dielectric losses, the composite exhibits outstanding absorption performance with a strong reflection loss of −53.5 dB at 15.2 GHz and a broad effective absorption bandwidth of 7.2 GHz (10.8–18.0 GHz) at a thin thickness of only 1.7 mm. This work provides a feasible composition-regulation strategy for the development of high-performance soft-magnetic absorbers.