ZnO and CuO crystal precipitation in sintering Cu-doped Ni–Zn ferrites. I. Influence of dry relative density and cooling rate

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 Zn- and Cu-containing crystal precipitates was determined by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The influence of the dry relative density of the body and the cooling rate on the occurring precipitates was also studied. Two consecutive chemical reactions are put forward, which explain the bulk precipitation of the zinc and copper oxides in the specimen during sintering, and their re-dissolution during cooling.