Structural and piezoelectric properties of textured NLKNS-CZ thick films and their application in planar piezoactuator

Abstract

0.97(Na0.5-xLixK0.5)(Nb0.89Sb0.11)O-3-0.03CaZrO(3) [(N0.5-xLxK)(NS)-CZ] piezoceramic (x = 0.325) has a pseudocubic-tetragonal-orthorhombic (PC-T-O) multi-structure. The PC structure formed in this piezoceramic was identified as the R3m rhombohedral structure. This piezoceramic showed the large piezoelectric charge constant (d(33)) of 515 pC/N due to the PC-T-O multi-structure. The NaNbO3 (NN) templates were used to texture the (N0.5-xLxK)(NS)-CZ thick films along the (001) direction, and the textured thick film (x = 0.0375) had a large Lotgering factor of 95.6%. The PC-T-O multi-structure was observed in this thick film (x = 0.0375), but the thick film (x = 0.0325) showed a PC-O structure owing to the diffusion of the NN templates into the thick film. The textured thick film (x = 0.0375) exhibited an increased d(33) of 625 pC/N because of the PC-T-O multi-structure and the lineup of grains along the [001] direction. A textured thick film (x = 0.0375) was used to fabricate a planar-type actuator to confirm its applicability to electrical devices. This actuator exhibits large acceleration (580.3 G) and displacement (150 mu m) at a low electric field of 0.2 kV/mm with a short response time of 3.0 ms. Therefore, the (N0.5-xLxK)(NS)-CZ thick films are excellent lead-free piezoceramics.