Ce substituted NiCo2O4 microspheres and nanoflakes: Comparison on magnetic features

NiCo2−xCexO4 (0.0 ≤ x ≤ 0.08) microspheres (MCs) and nanoflakes (NFs) were synthesized hydrothermally. X-ray diffraction analysis confirmed the cubic microstructure of all the samples. The microsphere and nanoflake morphologies of the samples have been confirmed by SEM, along with EDX, TEM and HR-TEM. The magnetic properties of the NiCo2−xCexO4 (0.0 ≤ x ≤ 0.08) MCs and NFs were investigated via magnetization measurements using a vibrating sample magnetometer. Room-temperature magnetization measurements revealed weak ferromagnetic behavior for both MC and NF samples. Low temperature magnetization measurements showed strong ferromagnetic behavior for the different samples. The magnetic parameters for both samples were found to differ substantially at a given temperature, which is accredited to the differences in the morphology of the MC-like and NF-like samples. Room-temperature magnetization measurements revealed antiferromagnetic or paramagnetic behavior for MC samples and weak ferromagnetic character for NF samples. It was also found that the magnetization magnitude decreased with increasing cerium dopant level, when compared to the host product. The changes in magnetization are linked to the effect of introduced cerium ions and their magnetic states, which could generate structural/morphological changes, changes in the size and surface lattice, redistribution of cations among the crystal lattices, changes in magnetic moment, etc.