Effect of preparation conditions on formation of nanophase Ni–Zn ferrites through hydrothermal technique

Nanophase Ni1xZnxFe2O4 (x=0, 0.5, 1.0) samples were prepared by chemically precipitating hydroxides followed
by hydrothermal processing. The products were characterized by X-ray diffraction and M.ossbauer spectroscopy.
Ferrite formation was found to be quite sensitive to the procedures adopted for preparing the hydroxide slurry prior to
hydrothermal treatment. Nickel ferrite could be prepared in pure phase by co-precipitation as well as by mixing
separately precipitated hydroxides. However, Ni0.5Zn0.5Fe2O4 could only be prepared by co-precipitation. Leaving
small amount of sodium in the slurry seems to obstruct pure phase formation of Ni0.5Zn0.5Fe2O4 and results in partial
formation of a-Fe2O3. A similar effect is observed in zinc ferrite.