Decreasing the complex permittivity to enhance microwave absorption properties of flaky FeSiAl/MnZn ferrites composites

MnZn ferrites were prepared by sol-gel combustion method and coated on flaky FeSiAl particles to decrease the complex permittivity. Surface morphology, phase, and element composition were carried out in terms of scanning electron microscope, transmission electron microscope, X-ray diffraction, Raman spectra, and energy-dispersive X-ray spectroscopy, respectively. Soft magnetic properties were measured by vibrating sample magnetometer. The electromagnetic parameter and reflection loss were also assessed by using vector network analyzer. The results show that the complex permittivity of flaky FeSiAl composites can be well decreased by adjusting the amount of MnZn ferrites. The complex permittivity was decreased obviously, but the complex permeability was decreased slightly after coating; thus, the impedance of composites could reach an ideal matching. When the coating amount was 2.5 g sol, the minimum value of reflection loss (RL) decreased to - 24.3 dB at 11.8 GHz, and the bandwidth of RL exceeding - 10 dB reaches to 3.6 GHz.

Automated summary

MnZn ferrites prepared by sol-gel combustion method were coated on flaky FeSiAl particles to decrease the complex permittivity of composites. The coating led to a significant decrease in complex permittivity and a slight decrease in complex permeability, achieving ideal impedance matching. The minimum reflection loss value decreased to -24.3 dB at 11.8 GHz when the coating amount was 2.5 g sol, with a bandwidth exceeding -10 dB reaching 3.6 GHz.