EFFECT OF THE BASE COMPOSITION AND MICROSTRUCTURE ON THE LEVEL OF ABSORPTION OF ELECTROMAGNETIC RADIATION IN NICKEL−ZINC FERRITE

Promising absorbing materials include Ni—Zn−ferrites, as they quite intensively absorb electromagnetic waves in the 50 MHz to 1000 MHz frequency range. In this paper we have studied the electromagnetic properties of Ni—Zn ferrite absorbing materials obtained in different technological modes. We propose a model that allows one to evaluate the dielectric constant of the ferrite material depending on the parameters of the microstructure and electrical properties of grain boundaries. Influence of base composition and microstructure on the level of absorption of electromagnetic radiation by Ni—Zn ferrite absorbing materials has been found. An increase in Fe₂O₃ excess to 51 % has been found to shift the frequency interval of electromagnetic radiation absorption towards lower frequencies, and this effect can be explained by an increase in the dielectric and magnetic constants of ferrite. Introduction of excess Fe₂O₃ in step 2 of grinding proved to be more efficient. An increase in the sintering temperature to 1350 °C also provides for a shift of electromagnetic radiation absorption frequency interval towards lower frequencies, which can be explained by an increase of the dielectric and magnetic constants of ferrite and resonance frequency shift of domain walls due to the formation of a coarse−grained structure.