Microstructural Characteristics and Magnetic Properties of Gadolinium-Substituted Cobalt Ferrite Nanocrystals Synthesized by Hydrothermal Processing

Gadolinium substituted cobalt ferrite nanocrystals with composition of CoFe_2−xGd_xO₄ (x = 0–0.04 in a step of 0.01) were prepared by a hydrothermal process and without subsequent annealing. X-ray diffraction, field-emission scanning electron microscopy, and vibrating sample magnetometer were used to investigate the effect of Gd³⁺ cation substitution on structural Characteristics and magnetic properties of cobalt ferrite nanocrystals. The X-ray diffraction analysis demonstrated that single phase spinel ferrites were obtained. The FE-SEM micrographs of the synthesized samples indicated the presence of two distinct groups of grains exhibiting different sizes and, more important, different shapes. The results of magnetic hysteresis at a room temperature showed that with an increase in gadolinium content, the coercive field decreased from 1250 Oe for x = 0 to 450 Oe for x = 0.03. In addition, it was observed that with substitutions of gadolinium cations, the values of saturation magnetization decreased.