Synthesis of Magnetic Nanoparticles of Fe3O4 and CoFe2O4 and Their Surface Modification by Surfactant Adsorption

Fe₃O₄ and CoFe₂O₄ magnetic nanoparticles have been synthesized successfully in aqueous solution and coated with oleic acid. The solid and organic solution of the synthesized nanoparticles was obtained. Self-assembled monolayer films were formed using organic solution of these nanoparticles. The crystal sizes determined by Debye-Scherre equation with XRD data were found close to the particle sizes calculated from TEM images, and this indicates that the synthesized particles are nanocrystalline. Especially, EDS, ED, FT-IR, TGA/DTA and DSC were used to characterize the nanoparticles and the oleic acid adsorption, and it was found that oleic acid molecule on the Fe₃O₄ nanoparticle is a bilayer adsorption, while that on CoFe₂O₄ nanoparticle is single layer adsorption. The superparamagnetic behavior of the nanoparticles was documented by the hysteresis loop measured at 300 K.