Thermal‐Driven Structure‐Phase Cooperative Evolution of Magnetic Micro‐Flower on Biomass‐Derived Carbon for Exceptional Microwave Absorption and Radar‐Infrared Stealth

Abstract The collaborative design of structure‐phase evolution represents a promising strategy for constructing high‐performance electromagnetic wave absorption (EMA) materials. Nevertheless, challenges remain in realizing customized EMA performance and deeper loss mechanism analysis. Here, through gradient temperature pyrolysis, NiFe layered double hydroxide (NiFe‐LDH) micro‐flower undergoes dynamic structure‐phase cooperative evolution on the biomass‐derived carbon (BC) layer, triggering vacancies, defects, and magnetic media to enhance multi‐polarization relaxation and gradient magnetic coupling effects. The multiphase coexisting NiO/NiFe ₂ O ₄ /Ni/Ni ₃ Fe@BC (S700) exhibits customized dual‐band EMA properties, integrating the EMA characteristics of both metal oxides and alloys, which owns the minimum reflection loss (RL) of −67.44 dB at 2.773 mm (C band) and the RL of −60.3 dB at only 1.754 mm with the wide effective absorption bandwidth (EAB) of 6.7 GHz (Ku band). Additionally, radar cross‐section (RCS) simulations display that S700 owns exceptional omnidirectional radar stealth capacity. The minimum RCS value can reach −45.99 dB m ² at the plane wave angle of 60°. And the prepared S700/acrylic resin shows good infrared stealth performance. This pioneering work provides valuable insights for the rational design and development of EMA materials with compatible radar‐infrared stealth ability.