Microwave-hydrothermal synthesis of tetragonal barium titanate

Tetragonal barium titanate with c/a ratio of 1.0093 and average particle size of 240 nm was synthesized by the microwave-hydrothermal (MH) method at 240 °C in only 12 h. Temperatures above 200 °C were first introduced to the MH process in this study, since the temperature has a critical effect on the formation of tetragonal BaTiO3, shown by the experiments here. Hydrous titanium oxide and Ba(OH)2 were used as precursors, without halide anions and alkali-metal cations to avoid contamination. The kinetics of tetragonal phase formation in BaTiO3 was considerably promoted in the MH processing, in comparison with the conventional hydrothermal (CH) route.