Effect of Cr3+ substitution on electric and magnetic properties of cobalt ferrite nanoparticles

This work describes the effect of incorporation of Cr3+ into CoFe2O4 nanoparticles on its magnetic and electric properties, prepared by auto combustion method. The samples of CoFe2-xCrxO4 (x = 0, 0.15, 0.3) series were characterized by x-ray diffraction and field emission scanning electron microscopy to find out the average particle size. The substitution of Cr3+ caused a significant reduction in particle size of the modified systems. Room temperature Mossbauer spectroscopy and magnetic characterization were performed. Analysis of extracted parameters concluded that Cr3+ replaced the Fe3+ at B-site (octahedral). The decrease in magnetization at B-site was found responsible for the observed reduced saturation magnetization and coercivity. Impedance spectroscopic analysis has revealed the suppression of electrode-sample surface conduction effect and enhancement of material resistivity. The latter was confirmed by dc resistivity measurement. All these results were explained on the basis of occupancy of Cr3+ at B-site, surface anisotropy potential and reduced particle size.