Sintering studies of hydrothermal NiZn ferrites

The isothermal sintering behavior of submicrometer-sized (<50 nm) powders of Ni0.38Zn0.53Fe2.09O4, prepared by hydrothermal process, was investigated under different sintering conditions. The powders were characterized by chemical analysis, energy-dispersive spectrometry (EDS), X-ray powder diffraction and scanning electron microscopy. The powders were compacted uniaxially with polyvinylalcohol and sintered at different times and temperatures, under constant heating and cooling rates. The characterization of the ceramic bodies was conducted by X-ray diffraction, optical and scanning electron microscopy, helium picnometry and EDS. The investigations showed high density ferrites with different porosity and microstructures depending on the sintering conditions. The results have been explained in terms of a qualitative model, which indicates the relative influence of the densification and grain growth rates. (C) 1997 Elsevier Science Ltd.