Compositional engineering nanoparticles and microwave absorption tuning of C-coated high-entropy alloy nanoparticles via vapor-phase synthesis

• • C-coated CoNiFeCuCr0.5 nanoparticles achieve RLmin of −63.9 dB at 2.1 mm thickness, enabling >99.999% absorption of incident microwaves, critical for stealth applications requiring minimal signal return. • • Effective absorption bandwidth (EAB) of 5.52 GHz for single-layer coating, and 12.22 GHz for gradient three-layer design, covering entire X-band (8.2–12.4 GHz) and Ku-band (12.4–18 GHz) for broadband radar stealth. • • Simulated RCS values below −20 dBm2 across −85° to 85° angular range, demonstrating omnidirectional stealth capability, reducing detectability by 99% compared to uncoated surfaces. • • Nanoparticle size <10 nm with soft ferromagnetic characteristics, ensuring high surface area for interfacial polarization and magnetic loss, essential for thin, lightweight coatings in aerospace and defense.