Hydrothermal synthesis of barium titanate

Barium titanate fine particles were prepared by hydrothermal synthesis. The synthesis was preformed at a temperature between 75 and 180 °C and for 10 min to 96 h. The reactions were carried out in a strong alkaline solution. Ba(OH)₂·8H₂O was used as the Ba-precursor material. Various Ti precursors were used to investigate their effects on the properties of BaTiO₃. The BaTiO₃ powders were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, nitrogen sorption, and differential scanning calorimetry. XRD showed that the as-synthesized BaTiO₃ powders have the BaTiO₃ structure. The particle size of the Ti precursor has a strong influence on the size and morphology of barium titanate. The particle size of BaTiO₃ was the largest when synthesized at 120 °C for 24 h by using anatase TiO₂ (Merck) precursor. The particle size was about 0.1 μm when using TiO₂ (70% anatase and 30% rutile, Degussa P25) or Ti(OH)₄ as the precursor. The BaTiO₃ powder was a porous structure when using Ti(OH)₄ as the precursor. In addition, the particle size and morphology were dependent on the synthesis temperature. At 85 °C, the morphology of the powder was small crystal and an agglomerate of clusters. At 180 °C, the morphology of the powder was large (∼130 nm), uniform, and nearly monodisperse particles. Extending the synthesis time has no significant influence on the size and morphology.