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The piezoelectric actuator is a kind of actuation device that acts through the 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, microelectromechanical systems, and so on. Piezoelectric materials are the core materials for piezoelectric actuators. In this review, recent developments in high-performance piezoelectric materials (HPMs) are introduced, including relaxor ferroelectric crystals, textured ceramics, piezoelectric metamaterials, and so on. 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. [ABSTRACT FROM AUTHOR]

Relaxor-PbTiO3 (PT-based) ferroelectric single crystals are important for many piezoelectric applications because of their outstanding performances. In order to expand their usage and avoid the failure during application, frequency dependence of coercive fields EC for [001]- and [011]-poled rhombohedral Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals was investigated from the frequency of 1 Hz to 300 kHz by using hysteresis loop measurement (frequency: from 1 Hz to 2 kHz) and a critical value method (frequency: from 5 to 300 kHz). The results showed that the coercive field EC, remnant polarization Pr, and saturation polarization Ps strongly depended on the crystal orientation and frequency. Compared with the [001]-poled crystals, the [011]-poled PIN-PMN-PT single crystals possessed higher EC, Pr, and Ps at the same testing frequencies. With increasing frequency from 1 Hz to 300 kHz, the coercive fields EC of the [001]- and [011]-poled PIN-PMN-PT single crystals increased from 4.0 and 4.8 kV/cm to 11.5 and 14.9 kV/cm, respectively. Moreover, the frequency dependence of the coercive fields was found to be consistent with the growth kinetics model, where the coercive fieldsEC were proportional to ƒβ. This work benefits to the design of piezoelectric devices based on PIN-PMN-PT single crystals operated at high frequencies and high driving fields. [ABSTRACT FROM AUTHOR]

We developed a high-power piezoelectric characterization system that was used to study the high-field properties of (1-x-y)Pb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3) O3-xPbTiO3 (PIN-PMN-PT) relaxor ferroelectric single crystals and PZT-4 piezoelectric ceramics. The impedance spectrum of 31 modes was measured under constant voltage by the high-power piezoelectric system. From measuring the resonance and antiresonance frequencies, the high-field behaviors of the electromechanical coupling coefficients, elastic compliances, and piezoelectric coefficients of the PIN-PMN-PT crystals were determined and compared with commercial PZT ceramics. By fitting the equivalent circuit parameters under large electric fields, the mechanical quality factors of the PIN-PMN-PT single crystals and PZT-4 ceramics were calculated as well. The results showed that the mechanical quality factor of the PZT-4 is higher than that of PIN-PMN-PT, and the mechanical quality factors of the PZT-4 and PIN-PMN-PT both decrease sharply first and then decrease slowly with increasing the electric field. The tensile strengths of PIN-PMN-PT crystals and PZT-4 ceramics were also determined by the impedance method, where we found that the tensile strengths of PIN-PMN-PT crystal and PZT-4 ceramic were 19.6 and 76.4 MPa, respectively. The 31-mode vibrators of PIN-PMN-PT crystals and PZT-4 ceramics can be driven by the largest electric field of 33 and 65 V/mm under resonance frequency, respectively. [ABSTRACT FROM AUTHOR]

Perovskite ferroelectrics (PFs) have been the dominant piezoelectric materials for various electromechanical applications, such as ultrasonic transducers, sensors, and actuators, to name a few. In this review article, the development of PF crystals is introduced, focusing on the crystal growth and piezoelectric activity. The critical factors responsible for the high piezoelectric activity of PFs (i.e., phase transition, monoclinic phase, domain size, relaxor component, dopants, and piezoelectric anisotropy) are surveyed and discussed. A general picture of the present understanding on the high piezoelectricity of PFs is described. At the end of this review, potential approaches to further improve the piezoelectricity of PFs are proposed. [ABSTRACT FROM AUTHOR]