Hydrothermal synthesis of BaTiO3 nano/microcrystals

The results of the hydrothermal preparation of BaTiO3 fine powders are reported. The effects of the reaction temperature, the molar ratio of Ba/Ti in the precursors, the chemical form of the precursors on the phase composition, and the size and morphology of the products have been determined. Perovskite-type BaTiO, crystallite forms more easily as the temperature, basicity, and Ba:Ti ratio in the precursor increase. BaTiO3 microcrystals (150 to 300 nm) were synthesized through the hydrothermal reaction of commercial TiO2 with a Ba(OH)(2) aqueous solution. The hydrothermal reaction of a 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 turned out to be a 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. The lattice constant, a, decreased with an increase in the reaction temperature. These abnormal crystallographic features are assumed to result from lattice defects caused by OH incorporated in the perovskite lattice.