Densification and magnetic properties of low-fire NiCuZn ferrites

The mixing of (Ni_0.38Cu_0.12Zn_0.50)Fe₂O₄ powders with Bi₂O₃ was performed using the solid-state mixing as well as wet chemical coating processes such as ammonia precipitation coating, urea precipitation coating, and solution coating. Ferrites prepared from the wet chemical coating processes could be densified at a lower sintering temperature without significant impact on the microstructural evolution compared with that prepared by solid-state mixing. In addition, samples prepared from the wet chemical coating process have a higher B_r and B_s and a lower H_c compared with that from solid-state mixing. Considering both the effects of sintering temperature and sintered density (>95% T.D.), ferrites with 1.5wt% Bi₂O₃ addition by ammonia precipitation coating sintered at 900 °C can provide the best permeability and quality factor (191 and 68.2, respectively) among all the cases studied.