Piezoelectric actuators is a kind of actuation devices that acts through inverse piezoelectric effect. Due to advantages of high precision, low power consumption, compact size and flexible structure design, they have a wide range of applications in optics, robotics, micro-electromechanical systems, etc. Piezoelectric materials are the core materials for piezoelectric actuators. In this review, recently developments on high-performance piezoelectric materials are introduced, including relaxor ferroelectric crystals, textured ceramics, piezoelectric metamaterials, etc. The advances of piezoelectric actuators are introduced in this review based on the developments of those piezoelectric materials, where the relationship between the figure of merits of materials and the performance of actuators is also discussed. Finally, we present outlooks and challenges for piezoelectric materials and actuators.

The figure-of-merits of ferroelectrics for transducer applications are their electromechanical coupling factor and the operable temperature range. Relaxor-PbTiO₃ferroelectric crystals show a much improved electromechanical coupling factork₃₃(88~93%) compared to their ceramic counterparts (65~78%) by taking advantage of the strong anisotropy of crystals. However, only a few relaxor-PbTiO₃systems, for example Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃, can be grown into single crystals, whose operable temperature range is limited by their rhombohedral-tetragonal phase transition temperatures (T_rt: 60~120 °C). Here, we develop a templated grain-growth approach to fabricate -textured Pb(In_1/2Nb_1/2)O₃-Pb(Sc_1/2Nb_1/2)O₃-PbTiO₃(PIN-PSN-PT) ceramics that contain a large amount of the refractory component Sc₂O₃, which has the ability to increase theT_rtof the system. The highk₃₃of 85~89% and the greatly increasedT_rtof 160~200 °C are simultaneously achieved in the textured PIN-PSN-PT ceramics. The above merits will make textured PIN-PSN-PT ceramics an alternative to single crystals, benefiting the development of numerous advanced piezoelectric devices.

Ferroelectric materials have been widely used in various electromechanical devices, from ultrasonic transducers and actuators to mechanical energy harvesters. The key performance metrics of these devices, such as sensitivity, efficiency, and bandwidth of ultrasonic transducers, are largely determined by the piezoelectric properties. This Review highlights recent research progress in improving the piezoelectricity of ferroelectric materials and offers potential strategies for further enhancement to meet the ever-increasing demands for high-performance piezoelectric devices and systems. It provides insights into the future development of ferroelectrics to address the increasing demands of emerging applications, including photoacoustic imaging and piezoelectric fans and motors in integrated circuit–enabled electronic devices. Additionally, it emphasizes the need to consider environmental impacts across the entire life cycle of ferroelectrics, from sourcing and manufacturing to usage and disposal.