Preparation of Superparamagnetic Cobalt Ferrite Nanoparticles with High Saturation Magnetization by Temperature-Controlled Co-Precipitation Method

Abstract

In this study, the effect of reaction temperature on the properties of cobalt ferrite nanoparticles was investigated. X-ray diffraction analysis and Fourier transform infrared spectroscopy confirmed that synthesized nanoparticles are cobalt ferrite. Particle sizes and shapes were determined by a transmission electron microscope, and magnetic measurements were done using a vibrating sample magnetometer. The average particle size varies in the range of 5.7 - 10.7 nm as the temperature is raised from 30 to 80°C. With that, there is a transition from ferrimagnetic to superparamagnetic behaviors at 40°C. The critical size of cobalt ferrite nanoparticles for the superparamagnetic limit with zero coercivity is found to be around 6 nm, and its saturation magnetization value is 25.4 emu/g. This value is impressive higher compared to that in the other studies with similar preparation conditions.