Unipolar and sesquipolar electrical fatigue in PZT

Electrical fatigue is an issue of application for piezoinjectors for diesel engines, for piezomotors and for many other actuator systems. Further, electrical fatigue is a topic, where complex defect interactions occur and where basic scientific questions need to be solved. Key events are: migration of electronic charge carriers in the bulk or as injected through the electrodes, reorientation of defect dipoles, domain wall movement and the interaction of the three above. Selected loading scenarios also lead to microcracking with attendant changes of local field distribution. The experiments presented were performed on discs of soft PZT under unipolar and sesquipolar loading. Measurements of the hysteresis of strain, polarization, dielectric coefficient and piezoelectric coefficient give insight into various interacting phenomena.