Entropy driven carbon-coated multi-element alloy nanoparticles for enhanced microwave absorption

The development of high-performance microwave absorbers is crucial for mitigating electromagnetic (EM) pollution and interference. Multi-element alloy nanoparticles (MEA NPs) offer a promising platform due to their highly tunable EM properties. This study employs an entropy-driven strategy to systematically engineer the composition and properties of carbon-coated MEA NPs (FeCoNiX@C, where X = Mn, Cr, Mn_0.5Cr, and MnCr) synthesized via chemical vapor deposition. By progressively increasing the elemental complexity through the incorporation of Mn and Cr into the FeCoNi core, the dielectric response, magnetic properties, and polarization relaxation behavior are effectively modulated, thereby enhancing microwave attenuation and optimizing impedance matching. Consequently, the FeCoNiMn@C NPs achieve excellent microwave absorption performance, with a minimum reflection loss of -57.3 dB and an effective absorption bandwidth of 5.20 GHz (8.64-13.84 GHz) at a thickness of 2.7 mm. Furthermore, radar cross-section simulations confirm a significant reduction in scattering, with values below -22 dB m² across all tested angles at 11.2 GHz, demonstrating excellent radar stealth potential. This work highlights the effectiveness of entropy-driven compositional engineering in tuning the EM properties of carbon-coated MEA NPs and provides a viable pathway for the rational design of advanced microwave-absorbing materials.