Fe/Fe<sub>3</sub>O<sub>4</sub>@mSiO<sub>2</sub> Core–Shell Nanostructures for Broad-Band Microwave Absorption
Yuanyuan Zhang, Xue-Yin Sun, Yong Yuan, Wen‐Zhu Shao, Liang Zhen, Jian‐Tang Jiang
Abstract
Fe/Fe 3 O 4 composite particles with mesoporous silica (mSiO 2 ) shells were successfully prepared via solvothermal reaction combined with hydrogen-thermal reduction. The introduction of mSiO 2 on the surfaces of Fe 3 O 4 constructs a ventilated frame and thereafter sustains the dispersion of the fine Fe particles that emerge from the reduction reaction. The conversion of Fe 3 O 4 to Fe nanoparticles enhances the ferromagnetic loss, while the Fe 3 O 4 /Fe/mSiO 2 interfaces induce an intensified dielectric loss. Fe/Fe 3 O 4 @mSiO 2 -500 (FFm-500) presents excellent electromagnetic wave-absorbing performances. The coating using FFm-500 as fillers presents a minimum reflection loss of −26.81 dB, together with an effective absorption bandwidth of 6.66 GHz. The results revealed the key role of mSiO 2 in the synthesis of Fe/Fe 3 O 4 nanostructures and the unique potential of Fe/Fe 3 O 4 @mSiO 2 as broad-band EMA fillers.