Effect of sub-coercive degradation on the local piezoelectric properties in lead zirconate titanate ceramics

Abstract

Lead zirconate titanate (PZT) is a widely recognized piezoelectric ceramic exhibiting excellent dielectric and ferroelectric properties over a wide range of temperature and frequency, making it desirable for applications such as capacitors, piezoelectric transducers, and actuators. Being subjected to repeated electrical loading in various applications, a progressive decrease in the functionality can happen, leading to device failure over time. Therefore, understanding degradation phenomena in all aspects is of importance to expand the lifespan of electronic devices. Despite of many studies focusing on the macroscopic properties of ferroelectrics related to degradation, such as switchable polarization, little is known about the change on local ferroelectric and piezoelectric properties and the domain structure induced by degradation. This paper reports the effect of sub-coercive electrical cycling on local static and dynamic piezoelectric properties for PZT ceramic using piezoresponse force microscopy (PFM). The piezoelectric properties are probed along the three sample directions (x, y, z) to gain comprehensive insights into the local domain orientation throughout the bulk PZT sample which is then compared with microscopically measured piezoelectric coefficients. The PFM results are analyzed with respect to changes in domain orientation (depolarization) as well as to reduction on piezoelectric material response (degradation) to identify the origin of the degradation behavior. Our results directly show a strong depolarization effect in the direction of the applied electric field because of sub-coercive cycling although it leads to small or even no degradation in directions perpendicular to the applied electric field. However, the latter is associated with a notable change in dynamic polarization switching properties which are strongly tied to the local domain structure. Our study shows that the origin of the degradation can be identified by analyzing the statistical change of local piezoelectric properties.