Cerium doped Mg-Co mixed ferrite nanoparticles; synthesis, magnetic and dielectric study

A series of Ce3+ ion doped magnesium cobalt ferrites, Mg0.5Co0.5Fe2-xCexO4 (0 <= x <= 0.1) having a cubic spinel structure were prepared by the co-precipitation method. Various characterization techniques, including XRD, HR-TEM, ESR and VSM were used to investigate structural and magnetic properties. The lattice constant was observed to be increased with Ce3+ ion concentration as larger ionic radii Ce3+ ion replaced with the lower ionic radii Fe3+ ions. The average crystallite size and lattice parameter lie in the range of 7-14 nm and 8.422-8.365 angstrom respectively. The particle size estimated by HR-TEM is comparable to that of estimated by XRD analysis. Analysis of ESR spectra states that, g-value decreases with Ce3+ ion addition from 5.84 to 4.78. The saturation magnetization and the coercivity decrease with increasing rare-earth content. M-H hysteresis loop shifts from ferromagnetic to a superparamagnetic nature with Ce3+ ion addition. The lower value of squareness factor, less than 0.5 suggests fewer magnetostatic interactions among nanoparticles.