Improvement in magnetic behaviour of cobalt doped magnesium zinc nano-ferrites via co-precipitation route

Nanoparticles of spinel ferrites have attracted huge interest in various technological applications due to their distinct magnetic behaviour. These magnetic nanoparticles acquire surface and finite size effects. We report an improvement of magnetic characteristics in Co2+ substituted Mg-Zn nano-ferrites synthesized by co-precipitation route. Physical properties have been investigated for Mg0.5Zn0.5-xCoxFe2O4 (x = 0, 0.125, 0.250, 0.375, 0.500) nano ferrites using XRD, FTIR, FESEM, EDS, VSM, photoluminescence and UV spectroscopy. Single phase cubical spinel structure has been observed. A phase transition from superparamagnetic to ferrimagnetic behaviour for x > 0.125 has been observed. Saturation magnetization has been found to be enhanced. Frequency dependent dielectric behaviour shows normal dispersion. Absorption spectra show a shift in position of maximum absorption towards longer wavelength with increasing Co2+ content. Photoluminescence spectroscopy has also confirmed the red shift in band edge emission with increasing Co2+ content. Some theoretical parameters, using proposed cation distribution, like theoretical lattice parameter, oxygen positional parameter, bond length etc., have also been calculated and found to support our experimental results. (C) 2016 Elsevier B.V. All rights reserved.