Phase development of barium titanate from chemically modified-amorphous titanium (hydrous) oxide precursor

A synthesis procedure for barium titanate involving a chemically modified titanium precursor has been developed. Using a titanium isopropoxide precursor modified with acetylacetone and barium acetate, coprecipitated gels were obtained by addition to a KOH solution. Direct precipitation of cubic BaTiO₃ from such precursor suspensions was obtained under hydrothermal conditions. The pH value was found to be a critical reaction parameter such that production of phase pure BaTiO₃ required high pH (> 13.0), a finding consistent with thermodynamic predictions of the Ba-Ti-H₂O stability system and prior hydrothermal syntheses. It was etermined that phase-pure barium titanatecan be synthesized at temperatures as low as 50 °C and that higher reaction temperatures accelerate the crystallization process. The particle size of the synthesized powder ranged from 50 to 350 nm for the synthesis conditions explored in the current work. It was demonstrated that particle size can be controlled by proper selection of the hydrothermal synthesis conditions such as reaction concentration, temperature, and time. The chemically modified synthesis produces barium titanate more rapidly at lower reaction temperatures than previously reported for similar syntheses.