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 as-synthesized 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.

The core–shell Ni–SiO₂ composite exhibits the best electromagnetic wave absorption in the GHz range with a minimum reflection loss of −40.0 dB, which is superior to those of Ni–TiO₂ and Ni microspheres.

The microwave absorption properties of the core–shell Ni@rutile TiO ₂ composite are superior to those of the Ni@anatase TiO ₂ composite.