Hydrothermal Synthesis of Bismuth Titanate Powders

Bismuth titanate was synthesized under hydrothermal conditions from an amorphous bismuth–titanium precursor gel. The gel was formed by mixing a bismuth acetate complex with titanium butoxide and then adding the solution dropwise into 6M NaOH. The resulting gel suspension was reacted under hydrothermal conditions at temperatures ranging from 160° to 200°C to form crystalline bismuth titanate. The gel crystallization kinetics increased with temperature, which resulted in 100% crystalline bismuth titanate in 5 h at 200°C. Wavelength-dispersive spectroscopy data indicated that sodium was incorporated into bismuth titanate during processing, and X-ray diffractometry suggested that the powder was composed of the Bi5Ti4O15 phase. Transmission electron microscopy micrographs showed that the gel particles decomposed to 100–200 nm crystalline bismuth titanate particles during hydrothermal processing.