Synthesis, structural characterization, and magnetic properties of Ce and Sb doped Co-Ni-Cd-Cu ferrite nanoparticles

This research studies the effect of rare-earth Cerium (Ce) and metalloid Antimony (Sb) doping on the structural and magnetic properties of Co-Ni-Cd-Cu-ferrite, prepared by the co-precipitation method. The composition of the samples is Co_0.3Ni_0.3Cd_0.2Cu_0.2Fe_1.8Ce_0.2-xSb_xO₄ with 0<x < 0.12. XRD revealed the phase formation of spinel structure with minority of hematite phase. Upon doping, the crystallite sizes decreased, and the lattice constant increased. The FTIR spectra showed two vibrational frequency bands of tetrahedral and octahedral sites. SEM and TEM analyses indicated the formation of cubic shapes with rounded-edge particles. The sample's polycrystalline nature was revealed by concentric circles in SAED. EDX revealed homogeneous distribution of elements and XPS indicated multivalent Ce and Sb³⁺ replacing Fe³⁺ ions. VSM measurements depicted narrow hysteresis loops at low magnetic field, revealing weak-ferromagnetic nature. Then, they were fitted to five models of the law of approach-to-saturation. The model with equation $M=M_s\left(1-\frac{1}{15}\times \frac{H_A^2}{H^{\frac{1}{2}}\left(H^{\frac{3}{2}}+H_R^{\frac{3}{2}}\right)}\right)+\chi H$, was well-fitted to the experimental data.