Fundamental study about shape memory piezoelectric actuator

In the field of FeRAM research, the imprint electrical field is serious problem for data storage operation. On the other hand, we propose to modify conventional piezoelectric actuator to a shape memory actuator using this imprint electrical field in this paper. The principle of shape memory piezoelectric actuator is based on the electrical field imprint and utilizes the polarization reversal, which is totally different from the conventional piezoelectric actuators. This shape memory piezoelectric actuator can be operated using a pulse voltage, so that small energy consumption and small voltage operation can be realized. The imprint electrical field was induced by treatment with a high electrical field of 3.5 kV/mm in a 150degC environment. Long time treatment resulted in a large electrical field imprint, and the imprint direction was dependent on the direction of the applied electrical field. After treatment for four hours, the shape memory actuator was driven using a pulse voltage. The actuator had two stable positions that were dependent on the piezoelectric polarization, and could be maintained without the use of an external electrical field. The ferroelectric materials have versatile properties such as piezoelectric effect, nonlinear permittivity and nonlinear optical refractive index. Not only the piezoelectric effect, but the other functional properties can obtain memory properties with the control of the imprint electrical field.