A ZrO₂-wrapped FeSiAl composite with a cotton-like structure for broadband electromagnetic wave absorption

In addition to enhancing impedance matching characteristics, rational structural design can facilitate the absorption of broadband electromagnetic (EM) waves. In this work, ZrO2@FeSiAl composites with a cotton-like structure were prepared through chemical precipitation and heat treatment. With increasing ZrOCl2 content, the chain-like structure gradually evolves into a cotton-like morphology, which not only enhances impedance matching but also enhances dielectric losses due to the introduction of nano-heterogeneous interfaces and defects. At a ZrOCl2 content of 4 wt%, the ZrO2@FeSiAl composites demonstrated a minimum reflection loss (RLmin) of -19.4 dB at 1.85 mm and a maximum effective absorption bandwidth (EAB) of 9.4 GHz, spanning the C-band (5.1-8 GHz) and the X and Ku-bands (11.5-18 GHz). This outstanding broadband EM wave absorption performance arises from the combined effects of dielectric losses and magnetic losses. This achievement sets the stage for the development of FeSiAl-based composites with broadband EM wave absorption capabilities.