Synthesis of monodispersed barium titanate nanocrytals-hydrothermal recrystallization of BaTiO3 nanospheres

A hydrothermal recrystallization scheme has been developed to produce pure, well-controlled characteristics in terms of size, morphology, and monodispersity of barium titanate (BaTiO3) nanocubes from low-temperature aqueous synthesized (LTAS) BaTiO3 nanospheres suspensions. The BaTiO3 powders, produced by the LTAS technique, show a cubic structure at room temperature and a spherical morphology. BaTiO3 particles, in purely cubic phase as synthesized, underwent a phase transition to pseudotetragonal phase by hydrothermal recrystallization at different temperatures for 3 h. As a result, the sizes of BaTiO3 crystallites changed from around 30±5 to 80±10 nm. With increasing hydrothermal recrystallization temperature, the lattice constant, c and a parameters decreased, as well as the tetragonality (c/a-1) and particle sizes increased, respectively. Higher recrystallization temperatures clearly favored particle growth. These crystallographic features are assumed to result from the release of lattice defects caused by −OH groups incorporated in perovskite lattice and size factors. Its chemical analysis determined that the Ba/Ti atomic ratio was 1.000±0.003, which implies the formation of barium and titanate vacancies simultaneously in the crystallites. The hydrothermal converted nanocubes of barium titanate may open up unique niches of applications in industry.