Preparation of Fine Tetragonal Barium Titanate Powder by a Microwave–Hydrothermal Process.

A microwave–hydrothermal (MH) process was performed at 240°C to prepare tetragonal BaTiO3 from TiCl4 and Ba(OH)2. No alkali hydroxide was used to avoid contaminations. MH BaTiO3 powder with a c/ a ratio of 1.010 and a mean size of 180 nm was synthesized within only 9 h. The MH BaTiO3 contains a very low concentration of lattice hydroxyl group, associated with a very small lattice strain. The measured density of the MH BaTiO3 is favorably consistent with the theoretical value, and the Ba/Ti stoichiometry determined is 0.996. The formation of a tetragonal structure in BaTiO3 and the particle growth were strongly promoted by the MH process. The effects of lattice defects on the stoichiometry and the determination of transition enthalpy were discussed. [ABSTRACT FROM AUTHOR]