Fatigue and failure responses of lead zirconate titanate multilayer actuator under unipolar high-field electric cycling

摘要

Lead zirconate titanate (PZT) multilayer actuators with an interdigital electrode design were studied under high electric fields (3 and 6kV/mm) in a unipolar cycling mode. A 100 Hz sine wave was used in cycling. Five specimens tested under 6kV/mm failed from 3.8 x 10~5 to 7 x 10~5 cycles, whereas three other specimens tested under 3kV/mm were found to be still functional after 10~8 cycles. Variations in piezoelectric and dielectric responses of the tested specimens were observed during the fatigue test, depending on the measuring and cycling conditions. Selected fatigued and damaged actuators were characterized using an impedance analyzer or small signal measurement. Furthermore, involved fatigue and failure mechanisms were investigated using scanning acoustic microscope and scanning electron microscope. The extensive cracks and porous regions were revealed across the PZT layers on the cross sections of a failed actuator. The results from this study have demonstrated that the high-field cycling can accelerate the fatigue of PZT stacks as long as the partial discharge is controlled. The small signal measurement can also be integrated into the large signal measurement to characterize the fatigue response of PZT stacks in a more comprehensive basis. The former can further serve as an experimental method to test and monitor the behavior of PZT stacks.