The structure and magnetic properties of NiCuZn ferrites sintered via a two-step sintering process

Fine powders of Ni0.4CuxZn0.6-xFe2O4, where 0aecurrency sign x aecurrency sign0.25, were prepared by sol-gel auto-combustion method. A two-step sintering process and the traditional final-stage sintering process have been adopted to produce NiCuZn ferrite toroidal specimens. The densification, microstructure, and magnetic properties of the ferrites have been investigated. It has been found that the sample produced by a two-step sintering process has a higher sintered density than the sample produced by the traditional final-stage sintering process, and the former gives rise to a higher initial permeability, especially when x = 0.15. Both the two sintering processes have no impact on Curie temperature which is only dependent on Cu-substituted content. The two-step sintering process is an effective method to produce high-density ferrites with improved soft magnetic properties. [GRAPHICS]