Synthesis of flower-like CuS hollow microspheres based on nanoflakes self-assembly and their microwave absorption properties

Flower-like CuS hollow microspheres composed of nanoflakes have been successfully prepared via a facile solvothermal method. The crystal structure, morphology and microwave absorption properties of the assynthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and a network analyser. The effects of reaction temperature, concentration of the reagents and reaction time on the structures and morphologies of the CuS products were investigated using XRD and SEM techniques. A plausible mechanism for the formation of hollow architectures related to Ostwald ripening was proposed. The CuS/paraffin composite containing 30 wt% CuS hollow microspheres shows the best microwave absorption properties compared with other CuS/paraffin composites. The minimum reflection loss of -31.5 dB can be observed at 16.7 GHz and reflection loss below -10 dB is 3.6 GHz (14.4-18.0 GHz) with a thickness of only 1.8 mm. The effective absorption (below -10 dB, 90% microwave absorption) bandwidth can be tuned between 6.2 GHz and 18.0 GHz for the absorber with a thin thickness in the range 1.5-4.0 mm. The results indicate that the microwave absorption properties of flower-like CuS hollow microspheres possess the advantages of broad bandwidth, strong absorption, lightweight and thin thickness are superior to those of other absorbing materials.