A NEW CHEMICAL ROUTE FOR THE PREPARATION OF FINE FERRITE POWDERS

Precursors to MFe(2)O(4) [spinels ferrites; where M=Ni(II), Co(II) and Zn(II)] have been prepared by the evaporation of polyvinyl alcohol added mixed metal nitrate solution, in presence and absence of urea. The precursor materials have low ignition temperature and are spontaneously combustible at low temperatures (250 degrees C to 400 degrees C). The heat liberated through the process is sufficient for the crystallization of the desired ferrite phase. The urea added process resulted in finer, superparamagnetic particles (12-17 nm) compared to the process without urea (particle size 25-30 nm). The ultrafine ferrite powders obtained have been characterized by X-ray powder diffraction (XRD), thermal gravimetry (TC), differential scanning calorimetry (DSC), infrared spectroscopy (IR), transmission electron microscopy (TEM) and room temperature magnetic measurement studies.