Influence of the Microstructure on Some Microwave Properties of Substituted Nickel Ferrites

The influence of the substituents on the microstructure of nickel ferrites from the system NiCaCuCoZnMnAlFeO4 + y SiO2 where 0 ≦ x1 ≦ 0.02; 0 ≦ x2 ≦ 0.3; 0 ≦ x3 ≦ 0.06; 0 ≦ x4 ≦ 0.5; 0 ≦ x5 ≦ 0.06; 0 ≦ x6 ≦ 0.2; 1.8 ≦ x7 ≦ 2; 0 ≦ y ≦ 0.3 wt%; x6 + x7 = 2; is investigated. Electrical resistance measurements are performed by a complex impedance method which permits the evaluation of the contributions due to the resistance of the bulk material and the grain boundaries. It is found that the dielectric and resonance magnetic losses can be improved to a certain degree by the average grain size. [Russian Text Ignored].