Microstructure and magnetic properties of cobalt ferrite nano powder prepared by solution combustion synthesis

In this study, cobalt ferrite nanoparticles (CoFe2O4NPs) were prepared by solution combustion synthesis using urea and glycine as fuels. The magnetic properties of the CoFe2O4 powders were modified by using various amounts of extra fuel (above the stoichiometric value). Thermodynamic calculations indicates that as the extra fuel increases, the amount of gases produced and the adiabatic flame temperature (Tad) rise. To investigate effect of urea, glycine and amount of extra fuel on the structural and magnetic properties of CoFe2O4 powders, the produced samples were studied by using X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), thermogravimetric analysis and differential scanning calorimetry (TGA-DSC), and Brunauer-Emmett-Teller (BET) technique. XRD results of the produced sample indicated that the single phase CoFe2O4with an average crystallite size between 17 and 33 nm was synthesized. By using two different type of fuel, the specific surface area of the produced powders were increased from 1.6 (glycine fuel) to 56.2 m2/g (urea fuel). By changing the type of fuel and the amount of extra fuel, the CoFe2O4 coercivity (Hc) ranges between 870 and 1667.8Oe and the saturation magnetization (Ms) varies between 31.6 and 83.7 emu/g. The solution combustion synthesized CoFe2O4 powders exhibit a hard ferrimagnetic behavior. Based on the results, Urea is the proper fuel for producing cobalt ferrite nanoparticles (with a particle size less than 100 nm) and in case of using glycine, the minimum amount of this fuel should be 2 times the stoichiometric amount.