Hydrothermal Synthesis for Large Barium Titanate Powders at a Low Temperature: Effect of Titania Aging in an Alkaline Solution

Monodisperse and spherical barium titanate (BaTiO 3 ) powders with diameters of 200–470 nm were directly prepared by a low‐temperature hydrothermal method at 90°C. Spherical titania (TiO 2 ) powders, ranging in size from 150 to 420 nm, were initially prepared by a controlled hydrolysis and condensation reaction, aged in a highly alkaline solution for 12 h, and then hydrothermally reacted with barium hydroxide to be converted to BaTiO 3 without a morphological change. The aging step of the TiO 2 , where the surface of TiO 2 was highly densified through elimination of the pores, was indispensable to retain the sizes and shapes of TiO 2 in the resulting BaTiO 3 . This was due to the fact that the formation of BaTiO 3 proceeded by an in situ reaction mechanism. The resulting BaTiO 3 powders exhibited dense and nonporous structures even after calcination at 1000°C.