Broadband and strong microwave absorption through heterogeneous interfaces and multiple components in laminated carbonyl iron/FeSiCr@FePO₄ composites

Integrated strategies have been designed to optimize the impedance matching and electromagnetic (EM) loss capabilities of FeSiCr which has become a key factor in expanding EM absorption applications. The integration of four strategies incorporating magnetic–dielectric composites, a flaky morphology, laminated structure, and magnetic/magnetic heterointerfaces was considered a feasible solution. Herein, laminated FeSiCr composites were prepared by embedding ~8-nm carbonyl iron nanoparticles in FeSiCr flakes, followed by a phosphating treatment. The composite exhibited efficient EM absorbing performance through magnetic–dielectric dual loss, enhanced magnetic loss, multiple reflections, reduced permittivity, and enhanced permeability, which helped optimize impedance matching and EM loss. Compared with raw composites, laminated carbonyl iron/FeSiCr@FePO₄ composites achieved an optimal reflection loss of −54.73 dB (an increase of 83%) and an effective absorption bandwidth (EAB) of 6.96 GHz (an increase of 17.6%) owing to their special microstructure. Furthermore, EAB was effectively extended to 12.89 GHz at a thickness of 5.0 mm through a gradient structure design, obtaining radar cross reduction values greater than 10 dB·m² at 10.9–15.2 GHz. This work not only deepens the understanding of magnetic/magnetic heterointerfaces but also enhances the loss capability and expands EAB, thereby contributing to EM absorption applications.