[001]-texturing of (K, Na)NbO3-based piezoceramics with a pseudocubic structure and their application to piezoelectric devices

0.96(K0·5Na0.5-zLiz) (Nb0·92Sb0.08)O3-0.04(Ca0·5Sr0.5)ZrO3 [(KN0.5-zLz)NS-CSZ] piezoceramics (0 ≤ z ≤ 0.04) were aligned in the [001] orientation using 3% (in mole) NaNbO3 templates with a large Lotgering factor (>97%). Their crystal structures transformed from the orthorhombic-pseudocubic (OP) structure to the orthorhombic-tetragonal-pseudocubic (O-T-P) structure with an increasing z. The P structure was interpreted as a rhombohedral R3m structure. The piezoelectricity of the compositions increased after [001]-texturing, and the enhancement was proportional to the O phase quantity. The composition (z = 0.03) exhibited the highest piezoelectric constant (d33; 670 pC/N) and electromechanical coupling factor (kp; 0.56). Piezoelectric energy harvesters were produced using the untextured and textured samples (z = 0.03). The textured harvester delivered a large power density of 26.6 mW/mm3, which was larger than that of the untextured harvester owing to the enhanced kp and d33 × g33 of the textured piezoceramic. A multilayer actuator was produced using the textured sample (z = 0.03), and it exhibited a large acceleration (44.2 G) and displacement (±3,730 μm) at ±25 V. Therefore, the [001]-textured (KN0.47L0.03)NS-CSZ piezoceramic is suitable for piezoelectric energy harvesters and actuators.