Ultra-low strain hysteresis in BaTiO₃-based piezoelectric multilayer actuators via microstructural texture engineering

Piezoelectric multilayer actuators (MLAs) possess unique advantages of lower driving voltages and more compact structures than bulk ceramic actuators. However, the internal electrode layers in MLAs inevitably weaken the output and result in relatively lower strain. The hysteresis property of piezoelectric ceramics also significantly limits the positioning accuracy of MLAs. In this work, we adopted a synergistic strategy of crystallographic texturing and domain engineering in BaTiO₃-based MLAs to enhance strains by improving piezoelectricity while simultaneously restraining the ultra-low hysteresis. We prepared [001]_c-oriented (Ba_0.95Ca_0.05)(Ti_0.94Zr_0.055Sn_0.005)O₃ (BCTZS) ceramic layers in MLAs through the template grain growth (TGG) method with a texture degree of ∼95%. The textured BCTZS MLAs had a large displacement of 196 nm at 200 V (∼2.4 times that of randomly oriented ones) and achieved ultra-low strain hysteresis (H_s<9%). These almost identical displacement and strain hysteresis in textured MLAs before and after polarization at 200 V indicated better positioning repeatability under various voltage experiences. This finding can be attributed to easier domain switchings, because the high texture degree and the dominant “4O” domain configurations in textured grains accommodated the clamping stress, which decreased the domain wall energy but increased the domain flexibility.