Interfacial engineering of core–shell structured FeCoNi@SnO2 magnetic composites for tunable radar-infrared compatible stealth

Radar-Infrared (IR) compatible camouflage is challenging as the spectral requirements for two bands differ or even collide with each other. Hence, the development of compatible stealth materials is urgently needed. This study employed a simple method to synthesize core–shell FeCoNi@SnO2 composite materials (MCCMs) with different alloy and SnO2 thicknesses. The unique interfacial engineering, the synergistic effect between multiple components, and the low IR emissivity of SnO2 allow this material to excel in radar-IR compatible stealth. Notably, the electromagnetic (EM) parameters, microwave absorption (MA) capacity, and IR radiation characteristics can be tuned by adjusting the atomic ratios and outer layer thickness, resulting in excellent MA performance along with low IR emissivity. Thereinto, the product has an effective absorption bandwidth (EAB) of 7.20 GHz at 1.20 mm and reflection loss (RL) of −53.54 dB at 5.80 GHz. The core–shell FeCoNi@SnO2 MCCM modified by the SnO2 layer can enhance the EAB and RL values to 8.12 GHz (1.61 mm) and −65.55 dB (11.08 GHz) due to the increased interface polarization. Furthermore, thanks to the strong IR reflection of the SnO2 layer, the obtained composites achieve an IR emissivity of approximately 0.50. This work provides a straightforward for developing radar-IR compatible stealth materials.