The role of terbium cation substitution on the magnetic properties of cobalt ferrite nanoparticles

Terbium substituted cobalt ferrite nanoparticles with composition of CoFe2−xTbxO4 (x=0–0.5 in a step of 0.1) were prepared employing a reverse micelle process. The effect of Tb3+ cations substitution on structural and magnetic properties of cobalt ferrite nanoparticles was investigated. X-ray diffraction and field-emission scanning electron microscopy evaluations demonstrated that the single phase spinel ferrites with a narrow size distribution were obtained. Mössbauer spectroscopy was used to determine the site preference of constitutive elements. The results confirm the preference of terbium cations for tetrahedral sites. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples at room temperature. It was found that with an increase in terbium content, the coercive field decreases while the saturation of magnetization increases. Magnetic dynamics of the samples was studied by measuring ac magnetic susceptibility versus temperature. The phenomenological Neel–Brown and Vogel–Fulcher models were employed to distinguish between the interacting or non-interacting system. Results exhibited that there is a strong interaction among fine particles. ► Fine particles single phase of CoFe2−xTbxO4 (x=0–0.5) were prepared by a reverse micelle method. ► With an increase in terbium amount, the coercive field decreases while the saturation of magnetization increases. ► Terbium cations were distributed in the tetrahedral and octahedral sites,however, their preference is in tetrahedral sites. ► The blocking temperature increases with an increase in terbium concentration in synthesized samples.