Cation trivalent tune of crystalline structure and magnetic properties in coprecipitated cobalt ferrite nanoparticles

CoFe2O4, CoBi0.1Fe1.9O4, CoLa0.1Fe1.9O4, and CoAl0.1Fe1.9O4 nanoparticles were successfully synthesized by the coprecipitation method. After annealing at 700 °C for 5 h, the x-ray Diffractometer results confirm that a single phase of cobalt ferrite-based nanoparticles is obtained, which is suitable for ICDD 22-1086. The addition of Bi3+, La3+ and Al3+ ions to the cobalt ferrite nanoparticles modified the crystallite size and lattice constant. Trivalent metal cation substitution tunes the crystallite size which has also been confirmed by measuring the grains with Scanning Electron Microscope images. In the Far Transform Infra-Red curve, the addition of metal ions (Bi3+, La3+, and Al3+) to cobalt ferrite nanoparticles resulted in absorption peaks at the tetrahedral and octahedral sites without any additional absorption peaks. The VSM results showed that saturation magnetization decreased drastically in the presence of trivalent non-magnetic cations, which confirms the replacement of Fe3+ by trivalent non-magnetic cations. The kOe order of the coercive field was obtained in this experiment. The largest coercive field of the cobalt ferrite nanoparticles was obtained with the addition of La3+ ions, i.e. 3.67 kOe suggest to support both Jahn-Teller effect and strain-induced magnetism.