Preparation of pod-like 3D Ni _0.33 Co _0.67 Fe ₂ O ₄ @rGO composites and their microwave absorbing properties

The ferrite/reduced graphene oxide (rGO) composites have attracted increasing attention due to the combination of the dielectric loss of rGO and the magnetic loss of ferrites. In this paper, pod-like 3D Ni _0.33 Co _0.67 Fe ₂ O ₄ @rGO composites were prepared using a solvothermal reaction followed by cold quenching. The structures and morphologies of as obtained composites were characterized using X-ray diffractometer, Raman microscope, photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The Ni _0.33 Co _0.67 Fe ₂ O ₄ microspheres with a diameter of 100–150 nm were wrapped in rGO rolls due to the shrinkage of rGO in liquid nitrogen. The rGO sheets with ferrite microspheres wrapped in form the pod-like 3D network morphology. The minimum reflection loss of as-prepared composites reaches −47.5 dB and the absorption bandwidth (RL<−10 dB) is 5.02 GHz. The composites show much better absorbing performances than pure Ni _0.33 Co _0.67 Fe ₂ O ₄ microspheres and Ni _0.33 Co _0.67 Fe ₂ O ₄ -rGO mixture formed by mechanically blending of cold quenched pure rGO and ferrite microspheres.