Preparation of BaTiO3 by the hydrothermal method

The results of hydrothermal preparation of BaTiO3 fine powders are reported. The effects of the reaction temperature, the molar ratio of BaTi in the precursors, the chemical form of the precursors on the phase composition, the size and the morphology of the products are presented. The higher the temperature, the higher the basicity and the greater the molar ratio of BaTi in the precursor, the easier the formation of the perovskite type BaTiO3 crystallite will be. It was found that BaTiO3 microcrystals(150–300 nm) could be synthesized through the hydrothermal reaction of commercial TiO2 with Ba(OH)2 aqueous solution, while the hydrothermal reaction of the newly prepared Ti(OH)4 gel with the Ba(OH)2 solution produced highly crystallized, well dispersed perovskite type BaTiO3 crystallites with very fine (< 100 nm) particles. The newly prepared Ti(OH)4 gel proved to be suitable precursor for the hydrothermal preparation of BaTiO3 fine powders. X-ray diffraction (XRD) of the hydrothermal BaTiO3 powders reveals a simple cubic perovskite structure. Above that, the lattice constant decreased with the increase of the reaction temperature. These abnormal crystallographic features are assumed to result from lattice defects, due to OH− incorporation in the perovskite lattice.