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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]

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]