Effects of Ultrasonic Agitation on the Structural and Magnetic Properties of CoFe2O4 Nanocrystals

Cobalt ferrite nanocrystals (CoFe2O4) were synthesized by means of ultrasonic agitation and afterward subjected to different annealing temperatures. The structural and morphological properties of the nanocrystals were investigated by means of X-ray diffraction and scanning electron microscopy. The results showed that the samples were composed of CoFe2O4 monophase nanocrystals. The particle size increased with increasing annealing temperatures. Infrared spectroscopy and magnetization showed that the samples exhibited the usual features of CoFe2O4 nanocrystals. Super-paramagnetism was not observed at room temperature. However, the results indicated that the samples could be considered single-domain particles with blocking temperatures greater than 300 K. Both infrared and magnetic results indicated possible diffusion of cobalt ions from tetrahedral to octahedral sites as a function of the annealing temperature.