Synthesis and characterization of cobalt ferrite nanoparticles prepared by the glycine-nitrate process

In this research, microstructural evolution and magnetic properties of cobalt ferrite spinel (CoFe2O4) were studied. The ferrite was prepared by the glycine-nitrate process (GNP) followed by calcination process, and subsequent high energy mechanical milling. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and vibration sample magnetometery (VSM) methods. The results showed that the desired high purity spinel phase was formed through a complete combustion reaction using the G/N ratio of 1.48. The as-synthesized powder revealed the coercivity and saturation magnetization of 900 Oe and 62.83 emu/g, respectively. The CoFe2O4 phase was stable after calcination at 500 degrees C for 2 h under argon atmosphere and subsequent milling processes for 2 and 4 h. The highest coercivity value was obtained for the calcined sample (975 Oe), whose average particle size exhibited noticeable conformity with the single magnetic domain size of CoFe2O4 (similar to 40 nm). For the 2 h-milled and 4 h-milled samples, the average particle size was below the single magnetic domain size, causing a significant reduction in coercivity values (820 and 770 Oe, respectively). The saturation magnetization was increased negligibly after the calcination process (63.22 emu/g), while it was raised to 71.47 and 73.98 emu/g after 2 and 4 h milling, probably due to the cationic redistribution during milling.