Two-Step Hydrothermal Synthesis of Well-Dispersed (Na0.5Bi0.5)TiO3 Spherical Powders

(Na0.5Bi0.5)TiO3 (NBT) powders that have well-dispersed, uniform particle size and well-developed spherical shape were successfully prepared by a two-step hydrothermal synthesis method. Nanosized TiO2 powders were firstly synthesized by a hydrothermal method, and then the TiO2 particles are used as a raw material to synthesize NBT powders. It was found that by using the TiO2 nanoparticles as Ti source, the well-dispersed spherical NBT powders with about 200 nm in size could be obtained at 200°C for 4 h with a low mineralizer concentration of 6 mol/L NaOH in the second step. The formation of spherical NBT powders can be explained by first generating nuclei on the surface of TiO2 nanoparticles via in situ crystallization mechanism and then crystal growing and agglomerating by dissolution-recrystallization mechanism.