Structural and magnetic characterizations of Mn-Ni-Zn ferrite nanoparticles

The ferrite samples of Ni0.7-xMnxZn0.3Fe2O4 (where x = 0.0-0.7 in steps of x = 0.1) were synthesized by a sol-gel autocombustion method using nitrates of respective metal ions. The synthesized samples were annealed at 600 degrees C for 4 h. The phase purity of the samples was investigated by X-ray diffraction (XRD). An analysis of XRD patterns reveals the formation of single-phase cubic spinel structure. The crystal lattice constant increases gradually with increasing x from 8.389 to 8.473 angstrom. The cation distribution of constituent ions shows linear dependence of Mn substitution. Based on the cation distribution obtained from XRD data, structural parameters such as lattice parameters, ionic radii of available sites, and the oxygen parameter "u" have been calculated. The trend of theoretically calculated lattice parameter with Mn content matches well with the experimentally obtained values. An initial increase followed by a subsequent decrease of saturation magnetization with increase in x is observed. Possible explanations for the observed structural and magnetic behavior with various Mn content are discussed. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim