Structural and Electrical Properties of PZT/ZnO Piezoelectric Ceramic Composites with Resistivity Gradient

La-PZT/Al-ZnO piezoelectric ceramics with gradients of resistivity and piezoelectric modulus were fabricated by using a powder metallurgical process. They are a kind of monolithic Piezoelectric Actuator with Functional Gradients (FGMPA), which can effectively reduce or smooth its interfacial stress concentration and requires much lower driving field than that of La-PZT/Fe-PZT FGMPA. The distributions of composition, phase-and microstructure were examined respectively by using electron probe microanalysis (EPMA), X-ray Diffraction (XRD) and scanning electron microscopy (SEM). Results show that the gradient distributions of structural and electrical properties are mainly caused by the diffusion and aggregation of Zn ions in the PZT layer. It is also the main cause of reducing the resistivity in partial gradient PZT region adjacent to ZnO layer. The existence of ZnO in the PZT region as a second phase was detected by XRD.