Electric-field-induced strain for (Bi1/2Na1/2)TiO3-based lead-free multilayer actuator

Multilayer prototype actuators were demonstrated using (Bi1/2Na1/2)TiO3 [BNT]-based ceramics as active layers and Pt as internal electrodes. One of the BNT-based solid solutions, 0.68(Bi1/2Na1/2)TiO3-0.04(Bi1/2Li1/2)TiO3-0.28(Bi1/2K1/2)TiO3 (BNLKT4-28) has been selected as the an active layer and it showed a relatively large piezoelectric strain constant d(33) of 130 pC/N and a high depolarization temperature T-d of 226 degrees C. The total number of layers was 10 and the active layer thickness was 125 mu m for the sintered body. The final compact dimensions were approximately 5 x 5 x 2 mm(3). From the SEM observation, there were no apparent delaminations around the interface between Pt electrodes and active BNLKT layers. The large electric-field-induced strain at 70 kV/cm was 0.17% and the longitudinal dynamic displacement at the same electric field was 2.1 mu m. (C) 2010 The Ceramic Society of Japan. All rights reserved.