Achieving better impedance matching by a sulfurization method through converting Ni into NiS/Ni3S4 composites

Herein, we synthesized metallic Ni through a simple chemical reduction process. Unfortunately, the Ni showed poor microwave absorption performance because of the inferior impedance matching properties. To overcome this, a sulfurization method was employed to obtain a novel microwave absorber-NiS/Ni3S4 composite. The nickel sulfide composites displayed much better microwave absorption abilities than the metallic Ni. The reflection loss (RL) values that exceeded -10 dB were observed in the frequency range 13.8-18.0 GHz (a broad microwave absorption bandwidth of 4.2 GHz) with a thickness of only 1.8 mm. Besides, the minimum RL value was as high as -43.0 dB at 9.1 GHz with the thickness of 2.4 mm. On the basis of high dielectric loss, good impedance matching properties, as well as stronger interfacial polarization effect, it can be concluded that NiS/Ni3S4 composites possess strong-absorption properties and have great potential for application as light microwave absorbers.