Morphology-controlled synthesis and growth mechanism of lead-free bismuth sodium titanate nanostructures via the hydrothermal route

Lead-free bismuth sodium titanate (Bi0.5Na0.5TiO3, BNT) perovskite nanostructures including nanoplates, nanocubes and nanowires were synthesized by a facile hydrothermal method without any additives or templates. The crystallization and morphologies of the hydrothermal derived BNT were controlled by simply adjusting the reaction time and NaOH concentration, which were examined by XRD, SEM, TEM and HRTEM techniques in detail. The BNT nanoplates of 400 nm in length and several nanometers in thickness were obtained at 200 degrees C for 48 h with NaOH concentration of 8-12 M. The uniformly BNT cubes of 1-2 mu m in length were synthesized at 200 degrees C with NaOH concentration of 16-18 M for 36-48 h. The BNT nanowires with 50-100 nm in diameter and more than 5 mu m in length were obtained when the holding time was prolonged to 60 h. The probable growth mechanisms of the BNT nanostructures with various morphologies were proposed.