Fabrication and Performances of Piezoelectric Functional Gradient BLF-xPT Ceramic Actuators by the Tape Casting Method

(1 − x)(Bi_0.85La_0.15)FeO₃₋xPbTiO₃(BLF-xPT, x = 0.38, 0.40, 0.415 and 0.43) piezoelectric functional gradient ceramic actuators in disk and bar shapes were fabricated by the tape casting method where the gradient distribution was arranged according to d₃₃. Electric-induced displacement of about 2.38 μm was achieved in the center of the gradient disk actuator along the thickness direction, nearly three times higher than single-component ceramic, with bending displacement of about 17.05 μm occurring at the tip of gradient bar actuator. The simulation of modal analysis and admittance spectrum demonstrated that the bar actuator could produce the bending vibration at 1039 Hz and thus produce enlarged displacement due to the bending deformation of gradient structure. Furthermore, the harmonic response analysis indicated that the maximum stress at the clamped side is of about 344 MPa in the gradient bar actuator under voltage of 220 V at the resonance condition, revealing 12% reduction relative to the bulk bar actuators. Moreover, the lowest stress area at the interfaces between ceramic and metal for gradient bar actuator is relatively larger than that for bulk bar actuators. Our results indicated that gradient piezoelectric actuators with large displacement and low vibration frequency have great potential for underwater acoustic applications.