Nanocrystalline Zn1−x Co0.5xNi0.5x Fe2O4 ferrites: Fabrication via co-precipitation route with enhanced magnetic and electrical properties

• Zn1−xCo0.5xNi0.5xFe2O4 nano-ferrites were fabricated in the range 20–50 nm.
• XRD and FTIR confirmed the cubic spinal structure.
• Six fold increase in Hc was observed for Zn0.25Co0.375Ni0.375Fe2O4.

Co and Ni substituted znic ferrite nanoparticles (Zn1−xCo0.5xNi0.5xFe2O4) (0.00≤x≥0.75) were synthesized by co-precipitation method. X-ray diffraction and Fourier transform infrared spectroscopy confirmed the single phase spinel structure. The lattice constant decreased with the increased Co and Ni contents. The bulk density was found less as compared to the X-ray density and this difference was explained in terms of porosity. The crystallite size was calculated by Scherrer's formula and found in the range 20–50 nm. Two prominent stretching bands were observed in FTIR spectra around 400–600 cm−1. These two bands confirmed the spinel structure of the prepared nanoparticles. The saturation magnetization was found to increase upto x=0.60 from 1.31 emu/g to 81.2 emu/g then it decreased for x=0.75 to the value of 75.1 emu/g. The coercivity and retentivity were found in the range 35.36–226.125 Oe and 0.0135–19.8 emu/g, respectively. Dielectric parameters were decreased with the increased Ni–Co contents. About nine fold increase in the DC-electrical resistivity was obtained for the Zn0.25Co0.375Ni0.375Fe2O4 (2.8979×1010 Ω cm) as compared to the ZnFe2O4 (0.2974×1010 Ω cm) nanoparticles.