PREPARATION OF WELL-DEFINED COLLOIDAL BARIUM-TITANATE CRYSTALS BY THECONTROLLED DOUBLE-JET PRECIPITATION

A new method for the preparation of well-defined colloidal barium tita nate (BaTiO3) crystals by the controlled double-jet precipitation (CDJ P) technique is described. The process is extremely fast and requires a low temperature (<100 degrees C). The reactants, barium and titanium salts, can be used in high concentrations and the yield is quantitati ve. The stoichiometry of the BaTiO3 particles can be controlled precis ely and reproducibly. The effects of the composition of the reactant s olutions, flow rates, reaction time, and the addition of polymers on t he precipitation process were investigated. The BaTiO3 powders, produc ed by the CDJP technique, sinter to high density at a temperature as l ow as 1200 degrees C and exhibit a relative dielectric constant of 500 0 at 20 degrees C, which is the highest value reported in the literatu re. The grain sizes of the sintered samples are small and uniform, ran ging between 1 and 2 mu m.