Acoustic emission in PZT under bipolar electric driving and uniaxial mechanical stress

The acoustic emission (AE) from ferroelectrics has at least two possible so urces, switching and microcracking. Both components have to release a disti nct amount of elastic energy in a brief time span to generate the burst lik e AE. Whether ferroelectric switching on its own can generate AE is not ful ly understood. Furthermore the internal discharges in pores or microcracks can be an AE source. An easy way to suppress the ferroelastic switching com ponent is to apply uniaxial mechanical stress parallel to the switching dir ection. This publication deals with the acoustic emission behavior of comme rcial ferroelectric-ferroelastic PZT ceramics under constant uniaxial load and concurrent electric hysteresis measurements. Both the coercive field an d the remanent polarization decrease under compressive mechanical stress. M echanical loading causes a stronger decrease in the AE activity and the dis sipated AE-energy than in the remanent polarization. The threshold polariza tion for the occurrence of AE decreases with the mechanical load. Discharge s in pores and microcracks can be discarded as AE sources.