Multilayer Actuator Composed of PZN–PZT and PZN–PZT/Ag Fabricated by Co-Extrusion Process

A multilayer ceramic actuator composed of piezoelectrically active Pb(Zn1/3Nb2/3)0.2–Pb(Zr0.5Ti0.5)O0.8 (PZN–PZT) layers and electrically conducting PZN–PZT/Ag layers was fabricated by the co-extrusion process. For the piezoelectric layers, PZN–PZT, which is sinterable at a low temperature (9001C), was used. For the conducting layers, a PZN–PZT/Ag composite, made by mixing silver particles with the PZN–PZT matrix, was employed. For the co-extrusion process, piezoelectric and conducting feedrods were made by mixing the PZN–PZT and PZN–PZT/Ag, respectively, with a thermoplastic polymer. The initial feedrods, which were composed of five 3 mm-thick PZN– PZT layers, two 1.5 mm-thick PZN–PZT layers, and six 1 mmthick PZN–PZT/Ag layers, were co-extruded through a 24 mm 2 mm reduction die at 1051C to produce continuous multilayered green sheets. The sheets were stacked, warm pressed, and sintered at 9001C for 4 h after binder burnout. The sintered multilayer actuator showed distinct layers without any reaction products or cracks at the interface. The thicknesses of the piezoelectric and conducting layers were about 200 and 70 lm, respectively. The displacement of the multilayer actuator, composed of 40 piezoelectric layers (with a total height of 10.8 mm), was about 10 lm at an applied voltage of 500 V.