Effects of the reaction temperature and Ba/Ti precursor ratio on the crystallite size of BaTiO 3 in hydrothermal synthesis.

Nanocrystalline BaTiO 3 has been prepared by hydrothermal synthesis from titanium isopropoxide and barium hydroxide octahydrate. Reaction conditions including synthesis temperature and Ba/Ti precursor ratio have been explored with the aim of producing BaTiO 3 with small crystallites and a low concentration of defects. It has been found that the crystallite/particle size and tetragonality of the BaTiO 3 samples increase as the synthesis temperature increases; and the crystallite/particle size of BaTiO 3 is also affected by the Ba/Ti precursor ratio. The BaTiO 3 sample synthesised using a Ba/Ti precursor ratio of 2 : 1 at a reaction temperature of 120 °C exhibited homogeneous crystallites of the smallest size of 107 nm. Additionally, the Ba/Ti precursor ratio of 2 : 1 with synthesis temperature of 220 °C was found to produce a smaller concentration of defects in BaTiO 3 .