Evaluation of domain wall motion in bipolar fatigued lead-zirconate-titanate: A study on reversible and irreversible contributions

Abstract

Mobility of ferroelectric domain walls is a critical factor in the fatigue of piezoelectric ceramics. Here, reversible and irreversible domain wall motion is evaluated for lead-zirconate-titanate both before and after fatigue cycling. To this end, the small-signal permittivity at different levels of bias field is compared to the large-signal permittivity, i.e., the first derivative of the polarization hysteresis loop. While the small-signal permittivity is just determined by the reversible processes due to the small electric excitation field, the large-signal permittivity reflects both reversible and irreversible contributions. The ratio of large- and small-signal permittivity is suggested as measure for the reversible contribution to the overall polarization change. Fatigue leads to a decrease in the small-signal permittivity and hence a general suppression of the reversible processes. Furthermore it causes a shift in the irreversible contributions to higher electric fields and a retarded backswitching when the external electric field is reduced after the maximum field value was reached. This reinforces the notion of bipolar electric fatigue caused by pinned domain walls due to agglomeration of charged defects in the sample bulk.