Preparation of pod-like 3D Ni0.33Co0.67Fe2O4@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 Ni0.33Co0.67Fe2O4@ 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 Ni0.33Co0.67Fe2O4 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 Ni0.33Co0.67Fe2O4 microspheres and Ni0.33Co0.67Fe2O4-rGO mixture formed by mechanically blending of cold quenched pure rGO and ferrite microspheres.