Effects of Co-substitution on DC-bias-superposition characteristic of the NiCuZn ferrites

Low-temperature-fired Ni(0.5-x)Cu(0.2)Zn(0.3)Co(x)Fe(1.95)O(40) (0.00 <= x <= 0.10, with 0.02 intervals) ferrites were produced by the conventional ceramic technique. Both microstructure and sintering density changed little in samples sintered at 900 degrees C. Saturation magnetic flux density gradually increased with increase in Co-substitution content. Coercive force first decreased with x value and obtained the minimum with x=0.04, then it continuously increased with x value. Permeability presented a fully opposite variation trend compared with coercive force. Furthermore, coercive force had a more important influence on DC-bias-superposition characteristic than that of saturation magnetic flux density. The sample with 0.04 Co-substitution favored to obtain a higher incremental permeability (permeability with magnetic field superposition) under a relatively low superposition magnetic field. And the sample with 0.08 Co-substitution favored to obtain a steady incremental permeability under different superposition magnetic fields. (C) 2010 Elsevier B.V. All rights reserved.