ZnO and CuO crystal precipitation in sintering Cu-doped Ni-Zn ferrites. II. Influence of sintering temperature and sintering time

This paper presents a study of the precipitation of ZnO and CuO crystals during the sintering of Cu-doped Ni-Zn ferrites. The nature of the resulting crystal precipitates were analysed using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), confirming the findings of a previous paper (Part I). This study examines the influence of sintering temperature and sintering time of the thermal cycle on their formation, and on their microstructure and electromagnetic properties. The same two consecutive chemical reactions proposed in Part I can be used to explain the bulk precipitation and subsequent re-dissolution of the zinc and copper oxides observed during sintering. The effect of these crystal precipitates on the final properties of this type of soft ferrite was also analysed, revealing a deterioration in its electromagnetic performance.