Evolution of phase pure magnetic cobalt ferrite nanoparticles by varying the synthesis conditions of polyol method

Abstract

The mono-dispersed superparamagnetic CoFe2O4 nanoparticles have been prepared by polyol method at different synthesis conditions. The Raman results clearly emphasize that the samples prepared for 3 h reaction time alone have the peaks corresponding to pure CoFe2O4. The percentage of iron content was found to be high for sample prepared for 6 h (72.2%) reaction time compared to sample prepared for 12 h (65.4%). The atomic ratio between Co2+ and Fe3+ for samples prepared in 12 h reaction time is closer to 0.5 as expected from the CoFe2O4 stoichiometry but VSM data shows that sample prepared for 12 h reaction time have low magnetic saturation value. The increase of cobalt content and decrease of saturation value clearly emphasize that some changes have been occurred. Herein, we analyze and propose the possible reaction mechanism that could be occurred in different reaction time and thereby influencing the magnetic properties of the nanoparticles.