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Alternating-current poling (AC-Poling) has attracted wide interests in enhancing piezoelectric performance of ferroelectric single crystals. However, the mechanism of phase transformations and domain morphology underlying AC-Poling has not been thoroughly investigated. In this work, we have systematically studied the AC-poling effect on domain structures and piezoelectric properties in the relaxor ferroelectric single crystals of 0.24Pb(In 1/2 Nb 1/2)O 3 –0.44Pb(Mg 1/3 Nb 2/3)O 3 –0.32PbTiO 3. It is shown that the piezoelectric constant (d 33) and permittivity (ε 33) are greatly enhanced via [001]-AC-poling compared to DC-poling, related to the presence of modified domain configurations as indicated previously. For [110]-oriented specimens, the piezoelectricity through AC-poling is only half as that for the DC-poled single crystals. We attribute this to the transition from the monoclinic-B phase to an orthorhombic phase under AC-poling, confirmed by synchrotron radiation X-ray diffraction and piezo-response force microscopy. The transition to the orthorhombic phase is likely a consequence of lower Gibbs energy. This study on orientation-dependent characteristics of AC-poling for PIN-PMN-PT single crystals will guide the development of AC-poling technology in applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Bending-bending mode piezoelectric actuator with crystal stacks are proposed and evaluated. • Ultrahigh piezoelectric coefficient d 33 of ~10,800 pC/N are achieved in actuation crystal stacks. • Due to high piezoelectricity and bending mode, max velocity is 3.28 mm/s under 130 V pp. • Minimum step resolution of 0.35 µm is demonstrated under 25 V pp driving voltage. [Display omitted] Piezoelectric actuators are important elements for compact actuations with high precision; however, driving voltage reduction is demanding for integration and minimization of precision actuations. In this work, we proposed a bending-bending mode piezoelectric actuator based on multilayered Pb(In 1/2 Nb 1/2)O 3 -Pb(Mg 1/3 Nb 2/3)O 3 -PbTiO 3 (PIN-PMN-PT) single crystals. Ultrahigh apparent piezoelectric coefficient d 33 of ~10,800 pC/N is achieved in four crystal stacks. The crystal stacks are used to fabricate bending-bending mode piezoelectric actuators to reduce driving voltage. Experimental results show that it can produce a maximum traveling velocity of 3.28 mm/s under the driving voltage of 130 V pp at 1000 Hz and minimum step resolution of 0.35 µm with 25 V pp driving voltage. Conventional piezoelectric actuators require driving voltage of ~300 V pp for similar motion velocity. This work demonstrates advantages of crystal stacks in piezoelectric actuators and potential applications in low-voltage precise actuations. [ABSTRACT FROM AUTHOR]

Alternating current (AC) electric field poling (AC-poling) has been actively studied for tailoring the domain configuration of relaxor ferroelectric crystals to further improve their piezoelectric and electro-optical properties. Understanding the change and redistribution of ferroelectric domains under AC electric field is essential for exploring the mechanism of the enhanced piezoelectricity in AC-electric-field-poled (AC-poled) crystals. Despite extensive investigations over recent years, no consensus has yet been reached on this topic. Here, we performed a three-dimensional synchrotron X-ray diffraction study on [001] C -oriented rhombohedral Pb(Mg 1/3 Nb 2/3)O 3 -PbTiO 3 (PMN-PT) ferroelectric crystals to characterize the domain structure variation during the AC-poling process. Our study clearly reveals that the AC electric field has an ability to efficiently merge the ferroelectric domains on both sides of 71o domain walls, leading to a considerable increase of domain size and thus a significant enhancement of electromechanical properties. In addition, this work indicates that, for the AC-poled [001] C -oriented rhombohedral PMN-PT crystal, the most stable state should be the lamellar domain structure with only 109o domain walls and the same volume fractions of the two types of ferroelectric domains on both sides of domain walls, which is expected to benefit the design of high-performance ferroelectric via domain or domain wall engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

The property degradation observed in thin Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) crystals is believed to relate to large domains and subsequent clamping induced by the surface boundary. In this work, the properties were investigated as function of domain size, using controlled poling. The degraded piezoelectric and dielectric properties of thin PMN–PT were found to increase significantly with decreasing domain size. Furthermore, the fine domain structure was found to be stable at 3kVcm−1 after 7.0×105 negative-pulse cycles. These properties make PMN–PT crystals suitable for high-frequency (>20MHz) ultrasound transducers. [Copyright &y& Elsevier]