Core-shell FeNi@SiO2 composite with enhanced microwave absorption performance

Abstract

In this work, a core-shell FeNi@SiO2 composite is constructed by modified Stöber method. Through adjusting the content of Tetra-Ethyl OrthoSilicate (TEOS) to control the thickness of the SiO2 shell, four FeNi@SiO2 powder samples with different SiO2 mass fractions were prepared, where magnetic FeNi@SiO2 microsphere with the core of FeNi is completely coated by SiO2. Herein, the electromagnetic parameters of the composites are effectively tuned by the combination of magnetic FeNi with dielectric SiO2. Results show that when the mass fraction of SiO2 is 35 %, the prepared FeNi@SiO2 powder sample exhibits good absorption performance, the minimum reflection loss (RL) reaches − 36.25 dB at 2.6 mm with the effective absorption bandwidth (RL<−10 dB) of 6 GHz (9.5–15.5 GHz) at 2.0 mm. It is believed that its good absorbing performance originates from the synergistic effect of the conductivity loss, dielectric polarization loss and magnetic loss of core-shell FeNi@SiO2 composite. This work provides a versatile strategy for FeNi@SiO2 composite with unique core-shell structures on excellent and tunable microwave absorption performance.