Fabrication and characterization of piezoelectric ceramic actuators with functional gradients

We fabricated a PZT/ZnO piezoelectric ceramic actuator with graded distribution of piezoelectric coefficient and resistivity through the thickness. There were tremendous differences of electric properties between its two sides, but these properties changed gradually in the transition region. The PZT composition was determined from authors´ previous work. ZnO ceramics was tailored by adding dopants, such as Al and Mn ions, respectively. The microstructure of the sample profile and composition distribution through the thickness was examined by electron probe microanalysis, verifying the existence of gradient microstructure developed from the diffusion of Zn²⁺. The resistivity of ZnO layer is more than ten magnitudes lower than that of PZT layer. This made the PZT layer be more effectively poled and suffered nearly all the driving voltage. Displacement curves of the PZT/ZnO Functionaly Gradient Piezoceramic Actuator (FGMPA) were investigated. The results show that tip displacement of the actuator is higher than that of La-PZT/Fe-PZT FGMPA for the same geometrical dimensions and applied voltage.