The effect of the base composition and microstructure of nickel-zinc ferrites on the level of absorption of electromagnetic radiation

Аннотация

Promising absorbing materials include Ni—Zn ferrites, as they quite intensively absorb electromagnetic waves in the frequency range from 50 to 1000 MHz. The electromagnetic properties of Ni—Zn ferrite absorbing materials obtained by different technological methods were studied in this paper. A model making it possible to evaluate the dielectric permeability of the ferrite material, depending on the microstructure parameters and electrophysical properties of grain boundaries, was proposed. The influence of base composition and microstructure on the amount of absorption of electromagnetic radiation by Ni—Zn ferrite absorbing materials was determined. It was stated that the increase of the content of excess Fe₂O₃ to 51.0 mol % leads to the shift of the frequency range of the absorption of electromagnetic radiation towards lower frequencies. It can be explained by the increase of the dielectric and magnetic permeability of ferrite. Moreover, the introduction of an excess of Fe₂O₃ in the grinding stage of the synthesized burden is more efficient. It was revealed that increasing the sintering temperature to 1350°C also shifts the frequency range of absorption of electromagnetic radiation towards lower frequencies. Probably it is caused by the increase of the dielectric and magnetic permeability of ferrite and the shift of the resonance frequency of domain walls as a result of the formation of a coarse-grained structure.