Effects of Process Variables on Properties of CoFe(2)O(4) Nanoparticles Prepared by Solvothermal Process

Controlling the morphology and magnetic properties of CoFe(2)O(4) nanoparticles is crucial for the synthesis of compatible materials for different applications. CoFe(2)O(4) nanoparticles were synthesized by a solvothermal method using cobalt nitrate, iron nitrate as precursors, and oleic acid as a surfactant. The formation of CoFe(2)O(4) nanoparticles was systematically observed by adjusting synthesis process conditions including reaction temperature, reaction time, and oleic acid concentration. Nearly spherical, monodispersed CoFe(2)O(4) nanoparticles were formed by changing the reaction time and reaction temperature. The oleic acid-coated CoFe(2)O(4) nanoparticles inhibited the growth of particle size after 1 h and, therefore, the particle size of CoFe(2)O(4) nanoparticles did not change significantly as the reaction time increased. Both without and with low oleic acid concentration, the large-sized cubic CoFe(2)O(4) nanoparticles showing ferromagnetic behavior were synthesized, while the small-sized CoFe(2)O(4) nanoparticles with superparamagnetic properties were obtained for the oleic acid concentration higher than 0.1 M. This study will become a basis for further research in the future to prepare the high-functional CoFe(2)O(4) magnetic nanoparticles by a solvothermal process, which can be applied to bio-separation, biosensors, drug delivery, magnetic hyperthermia, etc.