Factors controlling magnetic properties of CoFe₂O₄ nanoparticles synthesized by chemical co-precipitation: Modeling and optimization using response surface methodology

CoFe₂O₄ nanoparticles were synthesized by a low temperature co-precipitation method. In the present research, size-controlled CoFe₂O₄ was achieved by systematically tailoring the supersaturation condition during the nucleation and crystal growth processes. In order to investigate the size properties of synthesized particles, the experimental design was done using central composite method (CCD) of response surface methodology (RSM). For this purpose, the temperature, pH, and feeding rate of reactant solutions were selected as influential factors. Based on designed runs, the various responses such as hydrodynamic size of particles, size distribution, crystallite size, and magnetic size were evaluated by dynamic light scattering (DLS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Based on the results, the quadratic polynomial model was fitted for each response that could predict the response amounts. In following, the study of factors effects was carried out using software that showed the flow rate, temperature, and their interactions had higher effectiveness. Finally, by optimizing, the maximum average crystallite size were gained in maximum amounts of temperature (100 °C) and pH (13) value and minimum feeding rate of initial reactant (1 ml/min). The coercivity of cobalt ferrite nanoparticles reached 2029 Oe at optimal synthesis conditions.