Study on the effect of sol–gel parameters using the Taguchi technique to achieve the optimal crystallite size and magnetic properties of cobalt ferrite powders

Abstract

Nanostructured cobalt ferrite powders were prepared using the sol–gel process to obtain the optimal crystallite size and magnetic properties. The effect of sol–gel parameters, including the pH value, the mole ratio of ethylenediaminetetraacetic acid (EDTA) to metal ions, the mole ratio of ethylene glycol (EG) to metal ions and the heat-treatment temperature on the crystallite size and the magnetic properties of the samples, was investigated by Taguchi statistical experiments. By using three different levels for each process parameter, nine unique experiments were defined based on an L9 orthogonal array. From the analysis of the powder X-ray diffraction patterns, the crystallite size was calculated by the most intense peak (311) using the Scherrer formula. The results showed that the crystallite size is in the range of 16–39 nm, depending on the different levels of each parameter. The magnetic properties of the samples were carried out using the vibrating sample magnetometer (VSM) and magnetic parameters, such as the saturation magnetization (MS) and coercivity (HC) obtained from the VSM data. The analysis of variance showed that the optimum values of the parameters to obtain the optimal crystallite size and magnetic properties have occurred at the heat-treatment temperature of 1023 K, EDTA-to-metal ions molar ratio equal to 1.67, EG-to-metal ions molar ratio of 3.33 and pH = 6.