PZN-PZT flextensional actuator by co-extrusion process

A two-layered flextensional actuator, composed of a piezoelectric layer and a conducting layer, was fabricated by the co-extrusion process. For the piezoelectric layer, newly developed low-temperature sinterable PZN-PZT was used. The conducting layer was fabricated by dispersing 40-50% silver (Ag) particles in the PZN-PZT matrix. For the co-extrusion process, a piezoelectric feedrod and a conducting feedrod were made separately by mixing the PZN-PZT and PZN-PZT/Ag with polymers, respectively. The two feedrods were co-extruded through a reduction die at 105 °C and sintered at 900 °C. High residual stress was developed in the sintered body during the cooling process due to the difference in the coefficient of thermal expansion between the ceramic (PZN-PZT) and the metal (Ag). The residual stress, which bent the specimen into a convex dome shape, was beneficial for achieving an actuator with large displacement.