Hi-Fi Stake Piezo Single Crystal Actuator

Abstract

High fidelity (Hi-Fi) piezoelectric single crystal stake actuators are presented in this work. They are made of multiple rectangular d32 mode lead-based relaxor ferroelectric (notably Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) and Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT)) single crystals bonded along their long edges with the aid of compliant polymeric edge guides into a square or polygonal pipe-like construction. Due to the highly stable engineered domain structure and high piezoelectricity of single crystal active materials, the actuators exhibit large linear displacement responses with negligible (<1%) hysteresis. Prototypes of square-pipe stake actuators were first fabricated and their phase transformation curves under different applied voltages, axial compressive loads and temperatures were established. Based on the information obtained, a range of Hi-Fi stake actuators with external square cross-sections of 5 × 5 mm2, 7.5 × 7.5 mm2 and 10 × 10 mm2, each of 4 different overall lengths of 15, 28, 41 and 54 mm, were further designed and fabricated using either PZN-PT or PIN-PMN-PT single crystals (both with TRO ≈ 110–125 °C) of 0.4 mm in crystal thickness. The stroke for the longest stake actuator fabricated (L = 54 mm) reaches −58 µm at 240 V. The working conditions, over which these Hi-Fi stake actuators remain linear with negligible hysteresis, were established for a total load of up to 10 kg and use temperature of up to 40 °C.