Enhanced of the Resonant Frequency of NiZnCo Ferrites Induced by Substitution of Fe Ions with Gd Ions

Ni0.55Zn0.3Co0.15GdxFe2-xO4 (x = 0, 0.05, 0.10, 0.15, 0.20) ferrite materials with spinel structure were successfully synthesized by sol-gel self-propagation and microwave sintering technique. The structure and electromagnetic properties of NiZnCo ferrite with Gd substitution are systematically studied. The results show that the substitution of Gd3+ for Fe3+ at the B site changes the electromagnetic properties of NiZnCo ferrite. Among them, the resonant frequency increased from 637 MHz (x = 0.00) to more than 1.5 GHz (x = 0.20), which is 2.5 times higher than that of pure NiZnCo ferrite. Moreover, when the doping amount x = 0.05, the dielectric constant of ferrite is the lowest (epsilon', 37.735), the DC resistivity is the highest (rho, 3.64 x 10(6) Omega.m), and the dielectric loss is the lowest (tan delta, 3.03). In general, the substitution of Gd can make NiZnCo ferrite obtain excellent electromagnetic properties, which provides a reference for high-frequency microwave device materials.