Improving polarization of piezoelectric materials in low electric field

Piezoelectric materials can be used as actuators and sensors by poling that applies an electric field while heating from the outside. However, there is a risk of dielectric breakdown due to poling piezoelectric materials. The closer to the Curie temperature, the closer the coercive field is to zero, and the voltage required for polarization is reducing. Therefore, we measured the hysteresis loop of the piezoelectric material and poling while lowering the temperature from around the Curie temperature by the manufactured temperature controllable device (Cooling poling treatment). Then compared with results of poling while lowering the temperature from below the Curie temperature and the results of poling at a constant temperature below the Curie temperature, which is a normal poling treatment. As a result, higher piezoelectric performance was obtained at a voltage of 10% by performing the cooling poling while lowering the temperature from around the Curie temperature with the manufactured temperature controllable device. Furthermore, it was found that the piezoelectric performance was improved after the cooling poling from above Curie temperature.