Preparation and investigation of hexagonal-tetragonal BaTiO3 powders

Hexagonal-tetragonal co-existing barium titanate powders were prepared by reducing commercial barium titanate powders with their particle size of about 100 nm in a hydrogen atmosphere for 1 h at several temperatures, and the microstructures were observed. It was found that the hexagonal-tetragonal barium titanate powder had a co-existing hexagonal and tetragonal phase in a particle rather than a mixture of two phases in the powder. The hexagonal contents of about 0, 25, 50, 70, 85, and 100 wt % were obtained at temperatures of 1310, 1315, 1320, 1324, 1330, and 1333 degrees C, respectively. The hexagonal phase was returned to the tetragonal phase by annealing at 1200 degrees C in air. A model for the mechanism of a complete transformation of barium titanate polymorph from tetragonal/cubic to hexagonal phases is proposed. (C) 2021 The Ceramic Society of Japan. All rights reserved.

Automated summary

Hexagonal-tetragonal co-existing barium titanate powders were prepared by reducing commercial barium titanate powders with their particle size of about 100 nm in a hydrogen atmosphere at different temperatures, resulting in a single particle containing both hexagonal and tetragonal phases. Different hexagonal contents were obtained by reducing at different temperatures, and the hexagonal phase could be transformed back to the tetragonal phase by annealing in air. A mechanism model for the complete transformation of barium titanate polymorph from tetragonal/cubic to hexagonal phases was proposed.