Preparation and microwave absorption properties of Ni(Co/Zn/Cu)Fe₂O₄/SiC@SiO₂ composites

Ni(Co/Zn/Cu)Fe₂O₄/SiC@SiO₂, a microwave absorber, was prepared by the sol–gel method. The phase structure and the morphology of the microwave absorbers were characterized by X-Ray Diffraction (XRD) and scanning electron microscopy (SEM), respectively. Laser sizer (LS) and X-ray photoelectron spectroscopy (XPS) analysis show the core–shell structure of SiC@SiO₂. Coaxial method was used to measure the microwave absorption properties of the prepared composites in the frequency range of 2–18 GHz. When 70 wt% SiC is wrapped by 30 wt% SiO₂, and 50 wt% NiFe₂O₄ is added into 50 wt% SiC@SiO₂, the as-prepared powders are found to have advanced microwave absorption properties with a minimum reflection loss (RL) of −32.26 dB at about 6.08 GHz, and the available bandwidth is approximately 2.1 GHz when the RL is below −10 dB.