Preparation of well-defined colloidal barium titanate crystals by the controlled double-jet precipitation

A new method for the preparation of well-defined colloidal barium titanate (BaTiO₃) crystals by the controlled double-jet precipitation (CDJP) technique is described. The process is extremely fast and requires a low temperature (<100 °C). The reactants, barium and titanium salts, can be used in high concentrations and the yield is quantitative. The stoichiometry of the BaTiO₃ particles can be controlled precisely and reproducibly. The effects of the composition of the reactant solutions, flow rates, reaction time, and the addition of polymers on the precipitation process were investigated. The BaTiO₃ powders, produced by the CDJP technique, sinter to high density at a temperature as low as 1200 °C and exhibit a relative dielectric constant of 5000 at 20 °C, which is the highest value reported in the literature. The grain sizes of the sintered samples are small and uniform, ranging between 1 and 2 μm.