Reduction behavior of PZN-PZT piezoelectric ceramics reduced by graphite under high temperature

The reduction behavior of PZN-PZT piezoelectric ceramics was preliminary, studied for developing of the so called RAINBOW device with ultrahigh induced displacement based on this material. Multilayer microstructure was observed in the cross section of reduced samples. Fracture morphology, phase constitution and electric conductive type of every layer were studied with the help of SEM, XRD and electric conductivity measuring methods. An explanation of the reduction process and mechanism of PZN-PZT ceramic reduced by graphite under high temperature was proposed. It was believed that the reduction first happens at grain bourndary, then at the inner part of grains. With the increasing of reduction extent, the variation of electric conductive types of different layers follows the sequence of insulator,semiconductor and metal. XRD results showed that the original crystal stucture of PZN-PZT solid solution retains in the layers with lower level reduction, while it is completely destroyed in highly reduced layers.