Large-stroke low-profile single-crystal piezoelectric actuators

TRS single crystal plates with special crystal orientations and dimensions of 10×5×0.5mm were prepared, and the in-plane strain-electric field behavior was measured using a modified Sawyer-Tower circuit with an LVDT. A d32 coefficient as high as -1600 pm/V was observed which is 60-75% higher than d31 in the conventional cut crystal. The increased performance of this cut can be directly applied to bending mode actuators and other devices that utilize the d31 mode. The strain response was both linear and non-hysteretic up to 15 kV/cm. Large stroke and highly directional strain was also achieved from a quasi-d33 mode single crystal plate with interdigital electrodes (IDE). These were prepared with plate thickness of 0.2 mm, and an effective d33>1000 pC/N was obtained under 10 KV/cm driving field. Both types of plate actuators show at least 5 times larger piezoelectric coefficient than the d31 of PZT materials. Amplified out-of-plane stroke could be easily achieved by integrating the developed thin plate actuators into unimorph, bimorph, or moonie structures.