EFFECTS OF THE RARE-EARTH IONS ON SOME PROPERTIES OF A NICKEL-ZINC FERRITE

The effect of Fe substitutions by rare-earth ions on magnetic and elec trical properties of a Ni-Zn ferrite prepared by the classical method is investigated. A set of seven compounds with formula Ni0.7Zn0.3Fe1.9 8R0.02O4, where R = Yb, Er, Dy, Th, Gd, Sm or Ce, was prepared. Emphas is is placed on current experimental results of bulk magnetic measurem ents and transport phenomena. The results obtained reveal that, by int roducing a relatively small amount of R2O3 instead of Fe2O3, an import ant modification of both the structure and the magnetic and electrical properties can be obtained. We explain the influence of the rare-eart h ions as an effect of the ionic radius. This assumption is supported by the lattice constant measurements. The best results from the viewpo int of magnetic and electrical characteristic acceptable for high freq uencies were obtained for R ions with a large radius and with a stable valence of 3+ such as Gd in our work.