Fractional factorial design applied to optimize experimental conditions for preparation of ultrafine lanthanum-doped strontium titanate powders

Abstract

A fractional factorial design was implemented to optimize the experimental conditions for the preparation of ultrafine lanthanum-doped strontium titanate from titanyl acylate precursors. The effects of preparation conditions such as the molar ratio of acetic acid to titanium alkoxide, the water to titanium alkoxide ratio, pH value, the reaction temperature, and stirring speed were systematically studied by using Taguchi orthogonal array design. Results indicated that the effects of the reaction temperature and stirring speed on the reaction were the key variables influencing the average particle size of powders obtained. By combining the optimal settings of the two influential processing variables, it was possible to obtain an ultrafine powder with a particle size of about 340 Å. This was put to a test in the laboratory, and a polycrystalline, narrow size distribution ultrafine SrTiO3 powder that had a particle size of about 380 Å and readily sintered at 1150–1250 °C was obtained.