Influence of Ni-Cr substitution on the magnetic and electric properties of magnesium ferrite nanomaterials

The effect of variation of composition on the structural, morphological, magnetic and electric properties of Mg1-xNixCrxFe2-xO4 (x = 0.0-0.5) nanocrystallites is presented. The samples were prepared by novel polyethylene glycol (PEG) assisted microemulsion method with average crystallite size of 15-47 nm. The microstructure, chemical, and phase analyses of the samples were studied by the scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray fluorescence (ED-XRF), and X-ray diffraction (XRD). Compositional variation greatly affected the magnetic and structural properties. The high-field regimes of the magnetic loops are modelled using the Law of Approach (LOA) to saturation in order to extract information about their anisotropy and the saturation magnetization. Thermal demagnetization measurements are carried out using VSM and significant enhancement of the Curie temperature from 681 K to 832 K has been achieved by substitution of different contents of Ni-Cr. The dc-electrical resistivity (p(RT)) at potential operational range around 300 K is increased from 7.5 x 10(8) to 4.85 x 10(9) Omega cm with the increase in Ni-Cr contents. Moreover, the results of the present study provide sufficient evidence to show that the electric and magnetic properties of Mg-ferrite have been improved significantly by substituting low contents of Ni-Cr. (C) 2011 Elsevier Ltd. All rights reserved.