Optimization of the microwave absorption properties of FeSiCr@Fe 2 O 3 core‐shell nanoparticles by controlling the thickness and crystallinity of Fe 2 O 3 shell

Abstract Fe 2 O 3 ‐coated FeSiCr(FeSiCr@Fe 2 O 3 ) nanoparticles were prepared by plasma arc discharge method and oxidation heat treatment process, and the crystallinity of Fe 2 O 3 was improved by vacuum heat treatment. By adjusting the oxidation temperature, Fe 2 O 3 shell layer is formed on the surface of FeSiCr nanoparticles. The thickness of the Fe 2 O 3 shell layer increases with the increase of oxidation temperature. The complex permittivity () and complex permeability () show a trend of first increasing and then decreasing. When the oxidation temperature is 125°C, the minimum reflection loss (RL min ) of FeSiCr@Fe 2 O 3 nanoparticles is calculated to be −23.7 dB at 11.2 Ghz ( d = 2.2 mm). With the increase of the temperature of vacuum heat treatment, the crystallinity of Fe 2 O 3 shell keeps increasing. The real and imaginary values ( and ) of the complex permittivity of FeSiCr@Fe 2 O 3 nanoparticle increase with the increase of the crystallinity of Fe 2 O 3 shell, and the basically remains unchanged. When the vacuum heat treatment temperature is 150°C, the FeSiCr@Fe 2 O 3 nanoparticle obtains RL min of −49.9 dB at 15.9 Ghz ( d = 1.7 mm). And the corresponding effective absorption bandwidth within 1‐18 GHz (RL ≤ −10 dB) is 5.9 GHz. The improved microwave performance is due to the interface polarization of the core‐shell structure, and the synergistic effect between FeSiCr and Fe 2 O 3 also helps to balance the electromagnetic parameters.