The effect of calcining temperature on the magnetic properties of the ultra-fine NiCuZn-ferrites

In this study, the ultra-fine NiCuZn-ferrite was prepared by a coprecipitation method. The magnetic properties were investigated in terms of calcining temperature. The ferrite powders, Ni_0.206Cu_0.206Zn_0.618Fe_1.94O_4−δ, were initially heat treated at various temperatures of 300-750 °C, and then sintered at the final temperature of 900 °C. The average particle size calculated by a XRD pattern and confirmed by a transmission electron microscope (TEM) micrograph was 7.5 nm. The calcining temperature was an important factor for microstructures and magnetic properties of the sintered ferrite. Scanning electron microscope (SEM) micrographs showed a uniform grain growth with small pores and high densification at the calcining temperature of 450 °C. From the results of magnetic property measurements, the ferrite calcined at 450 °C showed higher initial permeability (170) and quality factor (72) than those of other calcining temperatures.