Ferrimagnetic Ni 2+ doped Mg-Zn spinel ferrite nanoparticles for high density information storage

In the present paper, Ni2+ doped Mg0.5Zn0.5−xNixFe2O4 (x = 0, 0.125, 0.250, 0.375, 0.500) ferrite samples prepared by co-precipitation route have been characterized by XRD, FT-IR, FE-SEM, VSM, UV Visible and PL spectroscopy for various physical properties. A transition from superparamagnetic behavior (x = 0) to soft ferrimagnetic nature (x > 0) with Ni2+ addition has been reported. With reduction in crystallite size, ferrite nano-particles have shown an increase in coercivity with lower saturation magnetization. An increase in remanence ratio with Ni2+content has been observed. The optical band gap of the prepared samples has been calculated using Tauc plots and have been found to increase with increase in Ni2+content from 4.50 eV (x = 0) to 5.60 eV (x = 0.500). The PL spectra show band edge emission at lower energy than optical band gap energy for all samples. A cation distribution has been proposed and based on this some theoretical parameters have been calculated which supports our experimental results. Modest values of coercivity and saturation magnetization indicates that these materials may be used in high density information storage devices.