Effects of aluminum substitution on the microstructure and magnetic properties of cobalt ferrites prepared by the co-precipitation precursor

In the current study, Al-substituted cobalt ferrite nanoparticles (NPs), CoFe_2–xAl_xO₄, were synthesized by co-precipitation method. X-ray diffraction patterns for all the prepared ferrite samples confirmed the formation of single-phase cubic spinel structure. The FT-IR spectra show two foremost fundamental absorption bands ranging from about 450 to 600 cm⁻¹. The FE-SEM images confirm the formation of nearly spherical ferrite NPs with an average size of about 25–30 nm. The characteristic feature of magnetic hysteresis loops exhibits the ferrimagnetic nature of all samples. The coercivity of CoFe₂O₄ NPs decreases from 602 Oe to minimum 180 Oe corresponding to Al concentration of x = 0.4. Saturation magnetization values decreases from 81.7 to 26 emu/g and n_B decreases from 3.43 to 0.98 μ_B almost linearly by increasing Al content.