Large Stroke and Low Profile Single Crystal Piezoelectric Actuators

TRS single crystal plates with special crystal orientations and dimensions of 10 × 5 × 0.5 mm 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.