Abstract
Soft Ni-Mg nano-crystalline ferrites with the general formula Ni1-xMgxFe2O4 (0 <= x <= 1) were synthesized through egg-white method. The precursor decomposition was followed by thermal analysis techniques. The obtained ferrites were characterized by X-ray diffraction, Fourier transform infrared and transmission electron microscopy measurements. X-ray diffraction showed the cubic spinel structure with crystallite size variation within the range 20-45 nm. The different structural data obtained were discussed in the view of ionic radii of the entire ions and their distribution within the lattice. The appropriate suggested cation distribution was then confirmed through Fourier transform infrared as well as electrical and magnetic properties measurements. Transmission electron microscopy exhibited a nano-crystal aggregation phenomenon. The observed size of the spherical particles agrees well with that obtained by X-ray diffraction. Hysteresis loop measurements revealed dilution in the obtained magnetic parameters by Mg-substitution due to the preferential occupancy of Mg2+ ions by the octahedral sites. Ac-electrical conductivity as a function of temperature and frequency exhibited a semi-conducting behavior with conductivity decreases by increasing Mg-content. The change in the slope of the curve indicates the changing in the conduction mechanism from electron hopping to polaron mechanism by increasing temperature. The obtained structural, electrical and magnetic properties were explained based on the cation distribution among tetrahedral and octahedral sites. (C) 2014 Elsevier B.V. All rights reserved.