Cation distribution and micro level magnetic alignments in the nanosized nickel zinc ferrite

Ni0.5Zn0.5Fe2O4 nanoparticles were synthesized through sol-gel synthesis method. Sintering at elevated temperatures was employed to obtain samples with higher particle sizes. The structural characterization using X-ray diffraction suggests that the three samples possess uniformal cation distribution. The variation of magnetization as a function of applied magnetic field at room temperature is studied using a vibrating sample magnetometer and all the samples found to exhibit nearly zero remanence and zero coercivity suggesting a superparamagnetic behaviour. The variation of magnetizations of the three different samples with temperature was studied by ZFC-FC technique at two different applied fields of 10 Oe and 1000 Oe. In order to study the possibility of structural changes, chemical and coordination differences of iron in the nanocrystalline Ni-Zn ferrite particles, room temperature Fe-57 Mossbauer spectroscopy study was used. The application of 5 T magnetic field at 5 K temperature resolves the two sub spectra and canting angle of 27 degrees and 12 degrees were observed which clearly indicates the noncollinear magnetic alignment in nano crystallites of Ni0.5Zn0.5Fe2O4. The neutron diffraction study was performed at seven different temperatures 20, 50, 100, 150, 200, 250 and 300 K. Rietveld refinement of the neutron diffraction data was performed to deduce the basic structural parameters, cation distribution and micro level magnetic alignments in the nanosized nickel zinc ferrite. (C) 2012 Elsevier B.V. All rights reserved.