Impact of substituting Cu2+/Ce3+ cations on the structural, magnetic and electrical properties of cobalt nano ferrites

The nano ferrite compounds Co_1-xCu_xFe_2-yCe_yO₄ (with x values of 0.0, 0.25, 0.5, and 0.75, and y values of 0.0, 0.03, 0.06, and 0.09) were synthesized through the sol-gel auto-combustion method. The characteristics of spinel ferrites were tailored by creating nano ferrites with desirable properties, which were then sintered at 1150 °C for 2 h in the presence of rare earth (Ce³⁺) and transition metals (Cu²⁺). They were investigated using dielectric, FTIR, FESEM, XRD, VSM, and DC electrical resistivity experiments. XRD examination verified the samples' cubic spinel structure by measuring the average crystallite size, x-ray density, and lattice constant. FESEM images revealed grain sizes ranging from 41.07 to 156 nm. FTIR spectra in the range of 415 cm⁻¹ to 430 cm⁻¹ further supported the substitution of Cu²⁺/Ce³⁺ ions in the tetrahedral sites, indicated by an increase in the lattice parameter. Measurements of the remanence ratio, saturation magnetization, anisotropy constant, coercivity, and magnetic moment, among other magnetic characteristics, were made. Higher concentrations of Cu²⁺/Ce³⁺ ions were found to considerably reduce magnetic saturation (Ms), coercivity (Hc), and remanence (Mr). These materials were semiconducting because their activation energy varied between 0.52 and 0.62 eV, and their DC resistivity increased with increasing Cu²⁺/Ce³⁺ concentration. Above 1 MHz, the dielectric properties became frequency-independent and decreased with increasing frequency. These ferrites seem highly potential for devices working at high frequency.