The PZT films shows almost no polarization fatigue until 105 cycles and the Pr values begin to decrease after 105 switching cycles. We note that in all the PZT samples, the maximum-decrease-point in the Pr values was observed at near the 106 switching cycles, as marked by the red square box in Fig. 6b. The changing behavior of Pr values after
the 105 cycles was varied depending on the irradiation total dose. It indicates that the fatigue property of the PZT films is affected by the irradiation. The Pr values begin to increase toward its initial values, as marked by dashed red square box shown in Fig. 6b, which is similar to the previously reported papers [2,3,16]. It was noted that the behavior,
generally called by “wake-up” effect, is possibly explained by a reconfiguration of domains during the switching cycling [16]. In addition, as the total dose increases, because more radiation-induced defects can be produced in the films, the increase rate of the Pr value may be reduced with increasing total dose, as marked by dashed red square box
shown in Fig. 6b. These results suggest that radiation-induced defects play an important role in fatigue properties of PZT films.