Synthesis of nano/micro ternary magnetic particles with different Co content and their electromagnetic absorbing properties

To comprehend the influence of Co element content on the microwave absorption properties of FeCoNi alloy particles, five sets of nano/micro FeCoNi alloy particles with varying Co element contents were fabricated with chemical liquid deposition. The microstructure, static magnetic characteristics, and microwave absorption performance were studied. The results shown that the synthesized FeCoNi alloy particles exhibited spherical morphology and face-centered cubic crystal structure, with the average particle size increasing from 150 nanometers to 500 nanometers as the Co element content rose. All five sets of samples presented soft magnetic properties, with the saturation magnetization fluctuating between 97.1–129.5 emu/g and coercivity ranging from 40.4–280.3 Oe. As the frequency of electromagnetic waves increased, the real part of the complex permittivity of the alloy particles demonstrated minimal variation, while the imaginary part exhibited dielectric loss absorption peaks in the frequency ranges of 10–16 GHz, 10–14 GHz, and 8–10 GHz/13–16 GHz. The imaginary part of the complex permeability initially increased and then decreased with the frequency rose. All the samples exhibited distinct Debye semicircles and polarization relaxation losses within the samples. The sample with Co content of x = 0.8 Fe₁Co_0.8Ni₁ achieved the maximum effective absorption bandwidth 5.36 GHz at thickness of 1.5 mm and the maximum reflection loss |RLmax| 32.5 dB at thickness of 2.2 mm for relatively good impedance matching and excellent combination of magnetic loss and dielectric loss.