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 electrical properties of a Ni-Zn ferrite prepared by the classical method is investigated. A set of seven compounds with formula Ni_0.7Zn_0.3Fe_1.98R_0.02O₄, where R identical to Yb, Er, Dy, Tb, Gd, Sm or Ce, was prepared. Emphasis is placed on current experimental results of bulk magnetic measurements and transport phenomena. The results obtained reveal that, by introducing a relatively small amount of R₂O₃ instead of Fe₂O₃, an important modification of both the structure and the magnetic and electrical properties can be obtained. We explain the influence of the rare-earth ions as an effect of the ionic radius. This assumption is supported by the lattice constant measurements. The best results from the viewpoint of magnetic and electrical characteristic acceptable for high frequencies were obtained for R ions with a large radius and with a stable valence of 3+ such as Gd in our work.