Enhanced piezoelectric properties of barium titanate single crystals with different engineered-domain sizes

For tetragonal barium titanate (BaTiO3) single crystals, an electric field (E-field) applied along the 111c direction can induce an engineered-domain configuration in these crystals. In this study, such engineered-domain configurations of different domain sizes were induced in BaTiO3 single crystals, and their piezoelectric properties were investigated as a function of domain size. Prior to this study, the dependences of the domain configuration on the temperature and E-field were investigated using a polarizing microscope in order to understand the optimum poling condition for fine- and coarse-domain configurations. We found that above the Curie temperature (TC) of 132.2 °C, when an E-field above 6.0kV∕cm was applied along the 111c direction, an engineered domain with a fine-domain configuration appeared. Moreover, it was also found that this fine-domain configuration remained stable at room temperature without the E-field. On the other hand, the coarse-domain configuration was obtained upon poling at just below TC. Finally, the piezoelectric properties of 31 resonators with different domain sizes of 40–5.5μm were measured. As a result, it was found that the piezoelectric properties, such as d31 and k31, increased significantly with decreasing domain size.