Heterointerface regulation of core-shell FeSiAl magnetic powders by in situ oxidation as high-efficiency absorbers

Developing electromagnetic (EM) absorbers that are highly efficient across a wide bandwidth is a significant hurdle in mitigating the growing issue of EM pollution emanating from the increasing prevalence of electronic and telecommunication devices. When considering the applications of absorbers in high-temperature environment, ensuring both structural and chemical stability becomes crucial. Incorporating a magnetic core and dielectric shell within core-shell structures appears to be a promising strategy for addressing this challenge. In this work, we have successfully synthesized the core-shell FeSiAl@oxide composites through in situ oxidation process, which offers a facile route for significantly enhancing their EM absorbing performance by promoting multiple interfacial polarizations and achieving ideal impedance matching. A systematic analysis has been conducted to uncover the morphological and microstructural evolution of the FeSiAl@oxide composites, shedding light on their EM properties. The remarkable EM dissipation capacity of these composites, owing to the strong synergistic effects between magnetic and dielectric losses, has been demonstrated with the minimum absorption of -41.7 dB over an impressive absorption bandwidth of 7.92 GHz at 2.5 mm.