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

Abstract

Multilayer prototype actuators were demonstrated using (Bi 1/2 Na 1/2 )TiO 3 [BNT]-based ceramics as active layers and Pt as internal electrodes. One of the BNT-based solid solutions, 0.68(Bi 1/2 Na 1/2 )TiO 3 0.04(Bi 1/2 Li 1/2 )TiO 3 0.28(Bi 1/2 K 1/2 )TiO 3 (BNLKT428) 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°C. The total number of layers was 10 and the active layer thickness was 125 µm for the sintered body. The final compact dimensions were approximately 5 © 5 © 2 mm 3 . From the SEM observation, there were no apparent delaminations around the interface between Pt electrodes and active BNLKT layers. The large electricfield-induced strain at 70 kV/cm was 0.17% and the longitudinal dynamic displacement at the same electric field was 2.1 µm.

Bismuth Sodium Titanate Based Materials for Piezoelectric Actuators

“…After decomposition at 835 °C, even the formation of the intermetallic compound Pd x Bi y was observed. Thus, the use of silver-palladium alloy together with Bismuth-based ceramics was generally excluded and the first multilayer sample described by Nagata, et al [156] contained platinum electrodes. In a study by Schütz, et al [157] it was shown that the bismuth-palladium reaction does not take place if the presence of free Bi 2 O 3 in the ceramic is avoided.…”

Influence of tetragonality on crystal orientation induced by a strong magnetic field and on the piezoelectric properties of the (Bi_0.5, Na_0.5)₁₋<i>_x</i>Ba<i>_x</i>TiO₃ ceramic system

“…1)19) These ceramics have a perovskite crystal structure and form a solid solution with other alkaline or alkaline-earth cations, and improvements in their properties are possible by means of the preparation of solid solutions. 13)19) Takenaka et al 4)15) have reported extensively on systematic studies of the (Bi 0.5 , Na 0.5 ) 1¹x Ba x TiO 3 (BNBT) ceramic system. In this system, BNBT has a morphotropic phase boundary (MPB, x = 0.060.07) with a rhombohedral and tetragonal crystal structure, in which comparably large displacements can be achieved both by polarization and phase transformations.…”

Diffusion behavior of Ag electrodes into (Bi_1/2Na_1/2)TiO₃ ceramics

“…We demonstrated MLCA using (Bi 1/2 Na 1/2 )TiO 3 (BNT)-based ceramics as the active layers and Pt electrodes as the inner electrodes. 22) Then, the prototype of BNT-based actuator indicated a large displacement, and we could not observe any apparent delamination around the interface between Pt electrodes and active layers. Normally, the AgPd electrodes have been widely used for the PZT-based MLCAs, considering cost efficiency.…”