Ce³⁺-doped nanocrystalline cobalt–zinc spinel ferrite: microstructural, magnetic, and optical characterizations

A series of Ce³⁺ ions-doped cobalt–zinc spinel cubic ferrite nanoparticles with the general formula Co_0.5Zn_0.5Ce_xFe_2–xO₄ (x = 0.00, 0.03, 0.06 and 0.09) were synthesized using soft chemical co-precipitation route. The synthesized nanoferrites were in single-phase as ensured by the X-ray diffractograms. Average crystallite sizes were 16 nm, 12 nm, 10 nm, and 07 nm with increasing Ce content as determined using Scherrer’s formula. A significant enhancement in coercivity (H_C) and decrement in saturation magnetization (M_S) was observed in field-cooled (9 T) low-temperature (3 K) hysteresis loops with increasing Ce content. A correlation between the mean crystallite size of the synthesized nanoparticles and disordered surface spins has been established. The increment in Ce³⁺ ions substitution also favored the onset of superparamagnetic behavior as confirmed by the room temperature hysteresis loops. The blocking temperature was reduced with the increase of Ce³⁺ ions content which makes the nanoparticles a suitable candidate for various biomedical applications. The indirect optical bandgaps were observed to increase gradually with the increasing Ce content due to the nanosize effect.