Structural and electromagnetic properties of Ni0.5Zn0.5HoxFe2-xO4 ferrites

Ni-Zn ferrites with a nominal composition of Ni0.5Zn0.5HoxFe2-xO4 (x = 0-0.06) were prepared by conventional solid state reaction through using analytical-grade metal oxides powders as raw materials. The phase composition, microstructure, magnetic properties and dielectric performance of the as-prepared samples were investigated. The doped Ho3+ ions could enter into the crystal lattice of the resultant spinel ferrites, causing the expansion of the unit cell, reaching a saturated state when x = 0.015; and the additional Ho3+ ions would form a foreign HoFeO3 phase at the grain boundary. The grain size and densification of the samples initially decreased after a small amount of Ho3+ ions was doped, but then increased with more Ho3+ ions added. The saturation magnetization decreased gradually with increasing substitution level of Ho3+ ions. The Curie temperature and coercivity raised initially and declined later with increasing content of Ho3+ ions in the samples, reaching their maximums of 305 °C with x = 0.015 and 2.99 Oe with x = 0.03, respectively. The variation of complex permeability versus Ho3+ ions substitution level presented an opposite trend to that of coercivity. The dielectric loss increased slightly after the introduction of a small amount of Ho3+ ions, but reduced significantly with more Ho3+ ions doped.