Investigation into phase formation of Nickel—Zinc ferrites by hydroxide coprecipitation

It was found that in the case of solutions which contain Ni 2+-, Zn 2+- and Fe 3+-ions in the molar ratio of Ni xZn 1−xFe 2O 4 ( x=0–1) a quantitative precipitation is possible. In the primary precipitation product, besides β-FeOOH. there is already a ferrite phase rich in zinc. Ageing the precipitate, the β-FeOOH phase is transformed into ferrite, and the ferrite is crystallized. When the isolated powder is tempered at 350°C, further crystal growth occurs and the disturbances in the lattice are stopped. Using XRD, Mössbauer spectroscopy and thermal analysis the formation process of Ni 0·5Zn 0·5Fe 2O 4 was investigated. The influence of ageing of the precipitates in aqueous suspension and of tempering of the isolated solids on the formation of ferrite is described.