A study of nano-structured Zn-Mn soft spinel ferrites by the citrate precursor method

In the present study, the ZnxMn1-xFe2O4 series of ferrites, where x = 0.1, 0.3, 0.5, 0.7 and 0.9, are prepared by the citrate precursor technique. One set of samples is subjected to the normal pressing technique and the other to the hot-pressing technique. X-ray diffraction (XRD) and scanning electron microscopy techniques are used to study the structural properties of the given series of ferrites. The results are found to be in good agreement. Hot pressing of Zn-Mn ferrites results in improvement of their magnetic and micro-structural properties as it controls simultaneously grain growth and porosity. However, hot pressing of Zn-Mn ferrites results in deterioration of their dc resistivity. The cation distribution has been studied by using x-ray analysis and magnetization. The variation of saturation magnetization and Curie temperature with increasing concentration of Zn2+ ions can be explained on the basis of cation distribution and Neel's two-sublattice models. Mossbauer studies were carried out to confirm the superparamagnetic behaviour of the nanoferrites. The possible mechanisms, models and theories contributing to these results have been discussed.