Magnetic properties and cation distribution study of nanocrystalline Ni-Zn ferrites

Nanocrystalline spinel ferrites with general formula Ni1-xZnxFe2O4 (x=0-1.0) were prepared by an oxalate co-precipitation method. Magnetic properties were investigated by means of saturation magnetization, AC susceptibility, cation distribution and Curie temperature measurements. The saturation magnetization increases with increasing concentration of zinc up to x=0.4 and then decreases with increasing zinc concentration. Investigation of the Yafet-Kittel (Y-K) angles shows the existence of Neel's two sublattice model for x <= 0.2 and Y-K model for x >= 0.4 compositions. Variation of normalized AC susceptibility with temperature shows single domain particle nature for the compositions x <= 0.2, whereas multi-domain particle nature for the compositions x >= 0.4. Curie temperatures of the samples decrease with the increase in zinc concentration. Upadhayay's model is used to investigate the cation distribution and hence to calculate the Curie temperature. The composition for x=1 shows paramagnetic behavior at and above room temperature. (C) 2012 Elsevier B.V. All rights reserved.