Rietveld structure refinement, cations distribution and magnetic features of CoFe₂O₄ nanoparticles synthesized by co-precipitation, hydrothermal, and combustion methods

Cobalt ferrite nanoparticles were synthesized by chemical co-precipitation, hydrothermal and sol gel auto-combustion methods. X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM) were used to investigate the structural characteristics and magnetic properties of cobalt ferrite nanocrystals. X-ray patterns revealed the production of a broad single cubic phase with the average crystallite size of 16, 18 and 178 nm for co-precipitation, hydrothermal and combustion methods, respectively. The FTIR measurements between 400 and 4000 cm^-1 confirmed the intrinsic cation vibrations of spinel structure. The FE-SEM micrographs of the synthesized samples indicated the presence of two distinct groups of grains exhibiting different sizes and, different shapes for hydrothermal route. The results of magnetic hysteresis at a room temperature showed that the magnetic properties depend on the particle size and shape of particles, whereas the role of particle size is more significant.