Atomic-Scale Layer-by-Layer Deposition of FeSiAl@ZnO@Al2O3 Hybrid with Threshold Anti-Corrosion and Ultra-High Microwave Absorption Properties in Low-Frequency Bands

Developing highly efficient magnetic microwave absorbers (MAs) is crucial, and yet challenging for anti-corrosion properties in extremely humid and salt-induced foggy environments. Herein, a dual-oxide shell of ZnO/Al₂O₃ as a robust barrier to FeSiAl core is introduced to mitigate corrosion resistance. The FeSiAl@ZnO@Al₂O₃ layer by layer hybrid structure is realized with atomic-scale precision through the atomic layer deposition technique. Owing to the unique hybrid structure, the FeSiAl@ZnO@Al₂O₃ exhibits record-high microwave absorbing performance in low-frequency bands covering L and S bands with a minimum reflection loss (RL_min) of -50.6 dB at 3.4 GHz. Compared with pure FeSiAl (RL_min of -13.5 dB, a bandwidth of 0.5 GHz), the RL_min value and effective bandwidth of this designed novel absorber increased up to ~ 3.7 and ~ 3 times, respectively. Furthermore, the inert ceramic dual-shells have improved 9.0 times the anti-corrosion property of FeSiAl core by multistage barriers towards corrosive medium and obstruction of the electric circuit. This is attributed to the large charge transfer resistance, increased impedance modulus |Z|_{0.01 Hz}, and frequency time constant of FeSiAl@ZnO@Al₂O₃. The research demonstrates a promising platform toward the design of next-generation MAs with improved anti-corrosion properties.