Fine powders of Barium titanate (BaTiO3) were hydrothermally prepared and heat treated at various temperatures from 400 oC to 1200 oC for 1 hour. The as-prepared and heat-treated powders were characterized by thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray diffractometry (XRD). All these powders were identified as tetragonal phase by Raman spectroscopy. The XRD results show that the tetragonality or c/a ratio in heat-treated BaTiO3 powders increases with heat treatment temperature. This suggests that lattice water and lattice vacancies suppress the phase transition from cubic to tetragonal in hydrothermal BaTiO3 powders, but do not prevent it completely.

Keywords: Crystal structure, Lattice defects, Hydrothermal, Barium titanate, powder