Hydrothermal synthesis of nano-size zirconia using commercial zirconia powder: process optimization through response surface methodology

A hydrothermal method for preparation of nano-size zirconia has been studied to optimize the effective parameters (precursor concentration, temperature and time) using response surface methodology (RSM). The synthesized zirconia samples were characterized through X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) analyses to identify mean nanoparticles size of the zirconia powders and molar fraction of monoclinic and tetragonal (or cubic) crystalline phases. Since, tetragonal and cubic phases are more valuable for the technological applications than the monoclinic phase, improving synthesis of tetragonal and cubic crystalline phases has been considered. The analysis of the primary experimental data through RSM method for optimization of the parameters showed that a precursor concentration of about 0.0092 mol L–1, a reaction temperature of 150 °C and a reaction time of 83.18 h are the optimum process conditions which give a mean zirconia nanoparticles size of ~23 nm and a high molar fraction of tetragonal (or cubic) crystalline phases (~70%) simultaneously.