Three different methods are studied for the preparation of fine-grained BaTiO3 by homogeneous precipitation: (1)Hydrolysis of barium and titanium alkoxide precursors, in which the required water is generated by an esterification reaction; (2)Precipitation of a barium¿titanium complex as a result of thermal decomposition of Ba-EDTA; (3)Precipitation of a barium and titanium complex by the increase of pH caused by the hydrolysis of urea. The properties of powders, prepared via these methods, and their sintering behaviour are as follows: (1)The esterification method results in a powder with medium average aggregate size of about 3 ¿m and a sintered density of 90% which is higher than the value obtained with the other precipitation methods. The considerable differences, in hydrolysis rate between the barium and titanium precursors used, lead to second phase formation; (2)The complexation method gives the most promising results; 1 ¿m sized spherical aggregates were obtained which consist of smaller particles. Sintered densities obtained were up to 88% and the method can be optimised further to obtain values in excess of 95%; (3)The urea method results in large irregular aggregates and is found to be unsuitable for the preparation of BaTiO3 ceramics.
van der Gijp, S., Emond, M. H. J., Winnubst, A. J. A., & Verweij, H. (1999). preparation of BaTiO3 by homogeneous precipitation. Journal of the European Ceramic Society, 9(19), 1683-1690. https://doi.org/10.1016/S0955-2219(98)00274-X