Development of ultra-thin and high-efficient bi-layer microwave absorbers from Fe3N@C and CoS2 samples

Nowadays, electromagnetic interference (EMI) is one of the pollution that harm human health and electronic devices. Iron nitride (Fe3N) and cobalt sulfide (CoS2) are promising microwave-absorbing materials (MAMs) due to their intriguing properties. In this work, polygonal Fe3N@C and flower-like CoS2 were fabricated, and Fe3N@C showed pretty good magnetic properties. Microwave absorption properties of as-prepared samples were inves-tigated, where Fe3N@C and CoS2 reached minimum reflection loss (RL) of-12 dB and-23 dB, respectively. In addition, Fe3N@C mostly had no effective absorption bandwidth (EAB), whereas Co2S was 2.5 GHz. The better microwave absorption properties of CoS2 compared to Fe3N@C could be explained through the combination of electrical conductivity, C0 values, loss capacity matching, impedance matching, and attenuation constant. It is worth mentioning that both Fe3N@C and CoS2 could not be considered promising MAMs. Therefore, RL curves of bi-layer MAMs made from as-prepared samples were simulated, where CoS2 and Fe3N@C acted as absorption and matching layers, respectively. The simulated Fe3N@C/CoS2 = 0.6 mm/0.6 mm bi-layer absorber could reach an RL of-45 dB and an EAB of 13 GHz, which was superior to the single-layer ones. The fabricated Fe3N@C/CoS2 = 0.6 mm/0.6 mm bi-layer absorber confirmed these excellent properties, which could be a result of the enhancement of complex permittivity, complex permeability, dielectric, and magnetic loss tangents.