Synthesis and Magnetic Properties of Cobalt Ferrite (CoFe2O4) Nanoparticles Prepared by Wet Chemical Route

摘要

Magnetic nanoparticles of cobalt ferrite have been synthesized by wetchemical method using stable ferric and cobalt salts with oleic acid as thesurfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM)confirmed the formation of single phase cobalt ferrite nanoparticles in therange 15-48nm depending on the annealing temperature and time. The size of theparticles increases with annealing temperature and time while the coercivitygoes through a maximum, peaking at around 28nm. A very large coercivity(10.5kOe) is observed on cooling down to 77K while typical blocking effects areobserved below about 260K. The high field moment is observed to be small forsmaller particles and approaches the bulk value for large particles.