MECHANICAL STRAIN AND PIEZOELECTRIC PROPERTIES OF PZT STACKS RELATED TO SEMI-BIPOLAR ELECTRIC CYCLIC FATIGUE

摘要

PZT stacks that have an inter-digital internal electrode configuration were tested to more than 10~8 cycles. A 100-Hz semi-bipolar sine wave with a field range of +4.5/-0.9 kV/mm was used in cycling with a concurrently applied 20 MPa preload. Significant reductions in mechanical strain and piezoelectric coefficients were observed during the cycling depending on the measuring condition. Extensive surface discharges were also observed. These surface events, as well as related breakdown, resulted in the erosion of external electrode and the outcrop of internal electrode, which partially accounted for the observed reductions. The results from this study demonstrate the feasibility of using a semi-bipolar mode to drive a PZT stack under a mechanical preload and illustrate the potential fatigue performance of the stack in service.