Enhancement of Cobalt Ferrite Properties through Rare Earth Ion Doping

Cobalt ferrite, a prominent magnetic nanomaterial, has attracted huge interest for its exceptional physical and chemical properties. These characteristics make it an ideal candidate for a myriad of advanced applications. Particularly, the properties of cobalt ferrite can be finely tuned by manipulating the cation distribution within its structure. This study explores the impact of substituting Fe3+ ions with rare earth (RE3+) ions—specifically Lanthanum (La), Europium (Eu), Cerium (Ce), and Gadolinium (Gd)—whose ionic radii are larger than that of Fe3+. This replacement, even in minimal amounts, significantly affects the physical and chemical properties of cobalt ferrite, primarily due to induced structural distortions and lattice strain. In the present work, we have doped the ferrite crystal lattice with these rare earth (RE) elements using the sol–gel method. The structural and magnetic properties of the resulting samples are analyzed by different characterization techniques, including powder X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) complemented by Energy Dispersive X-ray Spectroscopy (EDX), Raman spectroscopy, and Differential Scanning Calorimetry/Thermogravimetric Analysis (DSC/TGA). Additionally, the magnetic properties of the synthesized nanomaterials were evaluated using a Vibrating Sample Magnetometer (VSM). This research reveals a systematic decrease in saturation magnetization values, with pure CFO (CoFe2O4) displaying approximately 74.96 emu/g, and varying reductions observed upon substitution with rare earth (RE) metal ions (La3+, Ce3+, Eu3+, Gd3+; x = 0.0 and 0.1). Furthermore, the introduction of rare earth (La, Gd) dopants correlates with an elevated coercivity (Hc) value, emphasizing the influence on crystal unit symmetry and magneto-crystalline anisotropy.