Effect of zinc substitution on structural, morphological and magnetic properties of cobalt nanocrystalline ferrites prepared by co-precipitation method

In solid state sintering technology, initial particle size and shape are important factors to determine the properties of the sintered products. The nanoferrites of single phase cubic spinel structure of zinc-substituted cobalt ferrite, Co1-xZnxFe2O4 (x=0.2, 0.4, 0.6 and 0.8) were synthesized by wet chemical co-precipitation method followed by sintering at 1000 and 1100 degrees C for 3h in air. The structural, morphological and magnetic properties of the compositions were estimated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mossbauer spectroscopy (MS) and vibrating sample magnetometer (VSM). The porosity of the compositions was found to vary in the range between 2.7-5.2% at sintering temperature 1000 and 1100 degrees C. The density of the individual sample was observed to decrease with increase in Zn content. The values of the maximum saturation magnetization were found 89.8 and 91.9emu/g for the samples (x=0.2) sintered at 1000 and 1100 degrees C, respectively. The effect of zinc concentration on lattice constant and grain size was examined. Increase in the lattice constant, porosity, ionic radii, the distance between the magnetic ions and bond lengths on tetrahedral and octahedral sites have been observed with the increase of zinc content. Due to zinc incorporation, the movement of iron ions from the tetrahedral site to the octahedral site was revealed by Mossbauer spectroscopy. The zinc substitution has a significant effect on structural and magnetic properties like saturation magnetization, remanent magnetization, coercivity, Curie temperature, etc. of Co1-xZnxFe2O4 ferrite.