Fe/Fe₃O₄@mSiO₂ Core–Shell\nNanostructures for Broad-Band Microwave Absorption

Abstract

Fe/Fe₃O₄ composite particles with\nmesoporous\nsilica (mSiO₂) shells were successfully prepared via solvothermal\nreaction combined with hydrogen-thermal reduction. The introduction\nof mSiO₂ on the surfaces of Fe₃O₄ constructs a ventilated frame and thereafter sustains the dispersion\nof the fine Fe particles that emerge from the reduction reaction.\nThe conversion of Fe₃O₄ to Fe nanoparticles\nenhances the ferromagnetic loss, while the Fe₃O₄/Fe/mSiO₂ interfaces induce an intensified dielectric\nloss. Fe/Fe₃O₄@mSiO₂-500 (FFm-500)\npresents excellent electromagnetic wave-absorbing performances. The\ncoating using FFm-500 as fillers presents a minimum reflection loss\nof −26.81 dB, together with an effective absorption bandwidth\nof 6.66 GHz. The results revealed the key role of mSiO₂ in the synthesis of Fe/Fe₃O₄ nanostructures\nand the unique potential of Fe/Fe₃O₄@mSiO₂ as broad-band EMA fillers.