Tunable electromagnetic and broadband microwave absorption of SiO2-coated FeSiAl absorbents

Abstract SiO2-coated FeSiAl absorbents were prepared by StOber method. The microstructure, complex permittivity and complex permeability of the samples synthetized with different tetraethyl orthosilicate (TEOS) content were systematically explored. The results show that the microwave absorption properties of the SiO2-coated FeSiAl absorbents were enhanced significantly by controlling the TEOS content. The sample synthetized with 10 ml TEOS exhibits the minimum reflection loss of -21.4 dB at 11.1 GHz and the effective absorption bandwidth of 3.8 GHz in 8.6-12.4 GHz. The superior microwave absorption performance was attributed to the multi-effects of the effective transmission channel, dielectric loss, and magnetic loss. Therefore, the introduction of insulating layer in ferromagnetic absorbents can be qualified as favorable absorbents for broadband and efficient microwave absorption.