Effect of the microstructure on the properties of radio-absorbing nickel-zinc ferrites

Abstract

The main approaches and results concerning an increase in the efficiency of broadband radioabsorbing nickel-zinc ferrites are reported. Requirements to the microstructure that ensure the expansion of the radio-absorption frequency range to 30–830 MHz have been developed. The effect of dopants on the frequency dependence of the absorption of electromagnetic waves has been analyzed. The efficiency of the formation of the coarse-grain structure with grain boundary layers having a high dielectric constant has been confirmed. It has been found that both doping with bismuth oxide and the introduction of a coarse-grain fraction of the same composition into a batch before the sintering of the powder enhance the absorbing properties of the ferrites.