Understanding Microstructural Effects on Long Term Electrical Fatigue in Multilayer PZT Actuators

In this study, multilayered PbTixZr1-xO3 (PZT) samples were produced by tape-casting and subsequent sintering at temperatures in the range of 1175 °C to 1325 °C. Sintering times were 6 and 24 minutes. Samples were poled and additionally electrically fatigued by long-term exposure (≈10 cycles) to cyclic electric fields. The parameters of initial and remnant polarization were estimated from hysteresis loops. Changes in the crystallographic microstructure as a function of sintering temperature TS were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to gain insight on fatigue mechanisms and their prevention. The microstructural results, such as domain reorientation and amount of secondary phases, explained the results of electrical observations. We found that grain sizes and internal strains were major influence factors on device performance. Domain wall movement was facilitated in samples processed at TS less than 1250 °C, and such samples were more resistant to electrical fatigue. With increasing TS, a tradeoff between higher device performance power and lower device degradation with usage time was observed.