Influence of Ce³⁺ ion doping on structural, morphological, magnetic, dielectric and optical properties of Mg_0.5Ni_0.5Fe_2-xCe_xO_{4 (0 < x < 0.1) ferrite nanoparticles synthesized via coprecipitation method}

In this work the effect of Ce3+ ion doping on microstructure, crystallite size, magnetic, optical and dielectric characteristics of Mg0.5Ni0.5Fe2-xCexO4 (0 <= x <= 0.1) ferrite nanoparticles are discussed which are synthesized by using the co-precipitation method. The X-ray diffraction analysis confirms the cubic phase of all the synthesized samples and further confirmation of ferrite structure is supported by Fourier transformed infrared spectroscopy characteristic peaks. The crystallite size was determined in the range of 6 nm to 12 nm with increasing lattice parameter value from 8.347 angstrom to 8.359 angstrom on increasing Ce3+ ion doping. High-resolution transmission electron microscopy analysis confirms the spherical shape of the nanoparticles with agglomeration. Magnetic hysteresis curves analysis reveals that saturation magnetization of the Mg-Ni ferrite nanoparticles decreases with increasing Ce3+ ion concentration. Vibrating sample magnetometer analysis confirms the superparamagnetic nature of the synthesized samples. Electron spin resonance spectroscopy confirmed the reduction in g-value and spin relaxation time with increasing Ce3+ ions doping. The band gap increases from 1.79 eV to 2.59 eV with increasing Ce3+ ion doping. The magnetic properties of the synthesized samples make these nanoparticles a potential candidate for the synthesis of ferrofluids and biomedical application. Dielectric study confirms the decrease in dielectric constant (epsilon ' ) and loss tangent (tan delta) against increasing frequency with increasing Ce3+ ion concentration making the nanoparticles a potential candidate for the high frequency applications.