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

Abstract

Abstract0.97(Na0.5‐xLixK0.5)(Nb0.89Sb0.11)O3‐0.03CaZrO3 [(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 (d33) 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 d33 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 μm) 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.