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The ferroelectric, dielectric, elastic, piezoelectric, and electromechanical properties of tetragonal Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN–PMN–PT) crystals were investigated. The single domain piezoelectric coefficients d33, d15, and d31 were found to be 530, 2350, and -200 pC/N, respectively, with electromechanical coupling factors k33, k15, and k31 being on the order of 0.84, 0.85, and 0.58. The mechanical quality factor Q for longitudinal mode was found to be >700, with high coercive field (Ec) being on the order of 10 kV/cm. The temperature and dc bias electric-field characteristics of single domain tetragonal PIN–PMN–PT crystals were also investigated. In contrast to [001] oriented domain engineered rhombohedral crystals, tetragonal PIN–PMN–PT crystals exhibited broader temperature usage range and higher thermal/electric field stability, with improved coercive field and mechanical quality factor. [ABSTRACT FROM AUTHOR]

High-performance piezoelectrics benefit transducers and sensors in a variety of electromechanical applications. The materials with the highest piezoelectric charge coefficients (d33) are relaxor-PbTiO3 crystals, which were discovered two decades ago. We successfully grew Sm-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (Sm-PMN-PT) single crystals with even higher d33 values ranging from 3400 to 4100 picocoulombs per newton, with variation below 20% over the as-grown crystal boule, exhibiting good property uniformity. We characterized the Sm-PMN-PTon the atomic scale with scanning transmission electron microscopy and made first-principles calculations to determine that the giant piezoelectric properties arise from the enhanced local structural heterogeneity introduced by Sm3+ dopants. Rare-earth doping is thus identified as a general strategy for introducing local structural heterogeneity in order to enhance the piezoelectricity of relaxor ferroelectric crystals. [ABSTRACT FROM AUTHOR]

Abstract: Long‐range ordering of dipoles is a key microscopic signature of ferroelectrics. These ordered dipoles form ferroelectric domains, which can be reoriented by electric fields. Relaxor ferroelectrics are a type of ferroelectric where the long‐range ordering of dipoles is disrupted by cation disorder, exhibiting complex polar states with a significant amount of local structural heterogeneity at the nanoscale. They are the materials of choice for numerous devices such as capacitors, nonlinear optical devices, and piezoelectric transducers, owing to their extraordinary dielectric, electro‐optic, and electromechanical properties. However, despite their extensive applications in these devices, the origins of their unique properties are yet to be fully understood, hindering the design and exploration of new relaxor ferroelectric‐based materials. Herein, the complex polar states and applications of relaxor ferroelectrics are first introduced. Attention is then focused on their electromechanical properties, where the relationship between local structural heterogeneity and the extraordinary electromechanical properties is discussed. Based on the understanding of relaxor ferroelectrics, potential strategies to exploit the local structural heterogeneity to design ferroelectrics for drastically enhancing their electromechanical performances are also discussed. It is expected that this article will stimulate future studies on the important roles of local structural heterogeneity in improving the properties of various functional materials. [ABSTRACT FROM AUTHOR]

Relaxor-PbTiO 3 (PT) based ferroelectric crystals with the perovskite structure have been investigated over the last few decades due to their ultrahigh piezoelectric coefficients ( d 33 > 1500 pC/N) and electromechanical coupling factors ( k 33 > 90%), far outperforming state-of-the-art ferroelectric polycrystalline Pb(Zr,Ti)O 3 ceramics, and are at the forefront of advanced electroacoustic applications. In this review, the performance merits of relaxor-PT crystals in various electroacoustic devices are presented from a piezoelectric material viewpoint. Opportunities come from not only the ultrahigh properties, specifically coupling and piezoelectric coefficients, but through novel vibration modes and crystallographic/domain engineering. Figure of merits (FOMs) of crystals with various compositions and phases were established for various applications, including medical ultrasonic transducers, underwater transducers, acoustic sensors and tweezers. For each device application, recent developments in relaxor-PT ferroelectric crystals were surveyed and compared with state-of-the-art polycrystalline piezoelectrics, with an emphasis on their strong anisotropic features and crystallographic uniqueness, including engineered domain–property relationships. This review starts with an introduction on electroacoustic transducers and the history of piezoelectric materials. The development of the high performance relaxor-PT single crystals, with a focus on their uniqueness in transducer applications, is then discussed. In the third part, various FOMs of piezoelectric materials for a wide range of ultrasound applications, including diagnostic ultrasound, therapeutic ultrasound, underwater acoustic and passive sensors, tactile sensors, acoustic tweezers and ultrasonic motors, are evaluated to provide a thorough understanding of the materials’ behavior under operational conditions. Structure–property–performance relationships are then established. Finally, the impacts and challenges of relaxor-PT crystals are summarized to guide on-going and future research in the development of relaxor-PT crystals for the next generation electroacoustic transducers. [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]

Abstract: Pb(In0.5Nb0.5)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIN–PMN–PT) ferroelectric crystals attracted extensive attentions in last couple years, due to their higher usage temperatures range (>30°C) and coercive fields (∼5kV/cm), meanwhile maintaining similar electromechanical couplings (k 33>90%) and piezoelectric coefficients (d 33∼1500pC/N), when compared to their binary counterpart Pb(Mg1/3Nb2/3)O3–PbTiO3. In this article, we reviewed recent developments on the PIN–PMN–PT single crystals, including the Bridgman crystal growth, dielectric, electromechanical, piezoelectric and ferroelectric behaviors as functions of temperature and dc bias. Mechanical quality factor Q was studied as a function of orientation and phase. Of particular interest is the dynamic strain, which related to the Q and d 33, was found to be improved when compared to the binary system, exhibiting the potential usage of PIN–PMN–PT in high power application. Furthermore, PIN–PMN–PT crystals exhibit improved thickness dependent properties, due to their small domain size, being on the order of 1μm. Finally, the manganese acceptor dopant in the ternary crystals was investigated and discussed briefly in this paper. [Copyright &y& Elsevier]

The piezoelectric and dielectric properties of PMN-PT single crystals were significantly enhanced by alternating current electric field poling (ACP). In this work, to investigate the mechanisms of piezoelectric performance enhancement in relaxor ferroelectric single crystals by ACP, a [001]-oriented PIN-PMN-PT single crystal with a diameter of 3 in was grown by the modified Bridgman method, and a series of single crystal samples within 100 mm of the height of the crystal boule were prepared. Compared with their direct current electric field poling (DCP) counterparts, the electrical properties of single crystal samples at different heights by ACP were regularly enhanced. The piezoelectric coefficient d33 and the dielectric constant ɛ33 of the rhombohedral samples both increased by nearly 20%. Based on the results of polarized light microscopy, the domain wall in [001]-poled ACP samples could not be observed along the [001] direction. The brightness of polarized light propagating along the [010] orientation was enhanced after ACP. The domain images of {100} in the DCP and ACP samples were observed by piezoelectric force microscopy. The results showed that the domain size of ACP samples increased. The existence of layered domains can be clearly found in the scanning electron microscopy results of the stress fracture surface of the ACP sample. According to the analysis, the improvement of the piezoelectric performance in ACP samples comes from the elimination of the 71° domain walls. This work demonstrates that certain ACPs can regulate the domain structure and steadily improve the piezoelectric properties of R-phase PIN-PMN-PT single crystals. [ABSTRACT FROM AUTHOR]

Flexoelectricity yields electric polarization through graded strains and exists in various kinds of solid dielectrics but usually with a weak coupling response. In this letter, several Bi-doped Pb(Mg2/3Nb1/3)O3-xPbTiO3 (PMN-xPT) ferroelectric ceramics were prepared and the interplay of their piezoelectricity and flexoelectricity was systematically investigated. The largest flexoelectric response (∼300 μC/m) was 30 times larger than that of pure PMN-PT and was observed in the Bi-doped PMN-32PT, where the after poling piezoelectric coefficients were also the largest (990 pC/N) among all the compositions. This suggests that the apparent flexoelectricity in ferroelectrics is highly related to the bulk piezoelectricity. Therefore, introducing a local structural heterogeneity is considered as a feasible approach to achieve an ultrahigh piezoelectric response while also providing an ultrahigh flexoelectricity. [ABSTRACT FROM AUTHOR]

Compared with the state-of-the-art Pb(Zr,Ti)O3 ceramics, relaxor-PbTiO3 (PT) based ferroelectric single crystals possess much higher piezoelectricity, thus receiving considerable attention from the ferroelectric community. Recently, it was found that the alternating current electric field poling (AC-poling) could further improve the piezoelectricity of [001]-poled rhombohedral (R) relaxor-PT single crystals. In this work, we investigated the domain structures and electromechanical properties of alternating current electric field poled (AC-poled) relaxor ferroelectric Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIN–PMN–PT) crystals with different orientations and phase structures, including [001]-oriented R PIN–PMN–PT (23/47/30), [011]-oriented R PIN–PMN–PT (23/47/30), and [001]-oriented monoclinic (MC) PIN–PMN–PT (22/44/34) single crystals. We found that the piezoelectric coefficient (d33), free dielectric permittivity (ɛ33T/ɛ0), and clamped dielectric permittivity (ɛ33S/ɛ0) for AC-poled [001]-oriented R PIN–PMN–PT (23/47/30) crystals were improved by 24.4%, 22.6%, and 8.5%, respectively, when compared with the direct current electric field poled (DC-poled) counterparts. This phenomenon is attributed to the increase of domain size according to the observations from polarized light microscopy. Nevertheless, for [011]-poled R PIN–PMN–PT and [001]-poled MC PIN–PMN–PT crystals, the dielectric permittivities and piezoelectric coefficients were decreased a bit by AC-poling, being attributed to the depolarization phenomenon caused by the AC electric field. This work demonstrates that impacts of AC-poling on the properties of ferroelectrics are highly related to the orientation and phase of ferroelectric crystals. [ABSTRACT FROM AUTHOR]

The low uniformity in properties of relaxor ferroelectric crystals is a long‐standing issue in the ferroelectric community, which limits the available volume of the entire crystal boule. The aim of this study is to develop a relaxor ferroelectric crystal with improved property uniformity and excellent piezoelectricity. To this end, Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 is doped with Nd2O3 (Nd–PIN–PMN–PT) to improve the crystal performance. Along the crystal boule, the piezoelectric coefficient d33 varies from 2800 to 3500 pC N−1, and the dielectric constant ranges from 8400 to 9800, with variations of 25% and 16%, respectively. Such high property uniformity results in over 75% available volume of the crystal boule, compared to 30–50% for undoped crystals grown by Bridgman method. At the electric field of 1 kV cm−1, the converse piezoelectric response is up to 4780 pm V−1. In addition, its Curie temperature (TC) and coercive field (EC) are above 150 °C and 3 kV cm−1, respectively. Compared with Pb(Mg1/3Nb2/3)O3–PbTiO3 crystal (d33: 1500 pC N−1, TC: 135 °C, EC: 2.3 kV cm−1), the larger piezoelectricity, the higher TC and EC, and improved uniformity make Nd–PIN–PMN–PT crystals promising candidates for advanced piezoelectric applications. [ABSTRACT FROM AUTHOR]

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]

The electrostrictive effect was investigated in Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) relaxor ferroelectric crystal, a representative high performance piezoelectric material, with respect to orientation, temperature, and composition. The electrostrictive coefficients Q11C, Q12C, and Q44C of PMN-xPT (x = 0.25-0.37) crystals were found to be on the order of 0.055, -0.024, and 0.020 m4/C2, respectively. The maximum and minimum Q33* were found to be along <100> and <111> directions, being about 0.055 and 0.014 m4/C2, respectively, showing a strong anisotropic behavior, which is inherently associated with the oxygen-octahedra structure. In contrast to piezoelectric and dielectric responses, the electrostrictive coefficients Q are found to be insensitive to the ferroelectric phase transition, no matter it is induced by the temperature or composition. [ABSTRACT FROM AUTHOR]

Traditional piezoelectric adaptive lenses (ALENS) are fabricated by piezoceramics with transparent liquids as the filling media. However, it is challenging to achieve high focal sensitivity and long-time robustness because of the low piezoelectricity of ceramics as well as the evaporation and leakage of the liquids. To overcome the above-mentioned issues, we design a piezoelectric lens based on a radial extension-arching mode by using polydimethylsiloxane films and Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIMNT) relaxor ferroelectric single crystals to replace the transparent liquids and Pb(Zr, Ti)O3 (PZT) ceramics, respectively. Due to the ultrahigh piezoelectric properties (d33 ∼ 1500 pC N−1 and d31 ∼ 730 pC N−1) of the PIMNT crystals and the optimized radial extension-arching structure, an ultrahigh focal sensitivity (8.5 cm V−1 and a fast response time (∼102μs) is achieved, outperforming conventional ALENS based on piezoceramic actuators (∼103 μs and ∼10−1 cm V−1) and dielectric elastomer actuators (∼105 μs and ∼10−2 cm V−1). The largest output displacement of our designed ALENS is up to 53.6 μm at 4.2 kHz under 80 Vpp, and its focus is in the range of 57.44 cm to ∞. Furthermore, its performance remains unchanged after 4 × 107 vibration cycles, indicating its long-time robustness. This work sheds light on the design of advanced adaptive optical systems, where an ultrahigh focal sensitivity and a fast response are required. [ABSTRACT FROM AUTHOR]

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]

Relaxor‐PbTiO3 crystals exhibit excellent piezoelectric properties (d33 > 2000 pC N−1 and k33 > 90%) and thus attractes widespread attention in the past two decades. However, the inevitable segregation of components during the crystal growth results in relatively low‐performance consistency of Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PMN‐PT) crystals, which seriously affects their practical applications. In this work, Nd3+ as A‐site substitution is introduced to improve the uniformity of electromechanical performance of PMN‐PT crystal. The results show that the crystal exhibits a high piezoelectric coefficient of 3000 pC N−1 in rhombohedral phase with a variation of 36%. The electron probe X‐ray microanalyzer indicates that the opposite separation characteristics of Nd3+ and Ti4+ lead to improved uniformity of piezoelectric performance along the crystal boule. The giant piezoelectricity in Nd‐doped PMN‐PT is attributed to the enhanced local structural heterogeneity introduced by doping Nd. Furthermore, the Nd‐doped PMN‐PT crystal shows the rhombohedral‐tetragonal phase transition temperature in the range of 74–87 °C, which indicates that Nd‐doped PMN‐PT crystal can be a promising candidate for the design of advanced piezoelectric transducers. [ABSTRACT FROM AUTHOR]

Low driving voltage is important for miniaturization and untethered service of millirobots made of piezoelectric materials. In this research, we designed a bio-inspired bimorph-structured millirobot with a transparent relaxor ferroelectric crystal. Due to the ultrahigh piezoelectricity of the relaxor ferroelectric crystals and the optimized bimorph-based structure, the millirobot shows a maximum moving speed up to 9.22 b s−1 (body length per second) at 100 V, while the minimum driving voltage for initial movement can be as low as 3 V, which is more than two orders of magnitude smaller than that of millirobot based on dielectric elastomers. The maximum and minimum power consumptions of the millirobot are 71.6 mW and 85.9 μW, respectively. The robustness of the millirobot is reflected in its mechanical load stability carrying a 78 g mass (97.5 times of its weight) and its cryogenic tolerance. This work is believed to be beneficial to the design of various robust electromechanical devices with low driving voltage. [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]

Ferroelectric phase transitions and electromechanical properties of BaTiO3 (BT) and PbTiO3 (PT) crystals under one-dimensional shock wave compression were investigated using Landau-Ginzburg-Devonshire phenomenological approach. The results showed that the Curie temperature of both BT and PT increased with increasing pressure. Under highest shock wave compression, the orthorhombic phase was the stable state for BT, while no ferroelectric-ferroelectric phase transition was induced for PT. At room temperature, the electromechanical parameters for PT and BT were found to decrease with increasing one-dimensional compression, except for the dielectric susceptibility [variant_greek_epsilon]22 and piezoelectric coefficient e24 of tetragonal BT. The variations of dielectric and piezoelectric parameters were analyzed according to the elastic Gibbs free-energy. [ABSTRACT FROM AUTHOR]

Keywords: Nd-dopants; piezoelectric transducers; piezoelectricity; relaxor ferroelectric crystals EN Nd-dopants piezoelectric transducers piezoelectricity relaxor ferroelectric crystals 1 1 1 06/21/22 20220617 NES 220617 B Piezoelectric Transducers b In article number 2201719, Fei Li, Zhuo Xu, and co-workers, by using A-site rare earth dopants, greatly enhance the piezoelectricity of PMN-PT crystals and offset the variations of properties along the crystal growth direction induced by the segregation of B-site cations. The Nd-doped PMN-PT crystals could be a promising candidate for underwater acoustic transducer applications in future. Nd-dopants, piezoelectric transducers, piezoelectricity, relaxor ferroelectric crystals. [Extracted from the article]

• 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]

Abstract: Relaxor ferroelectric-based Pb(Mg1/3Nb2/3)O3–32PbTiO3 (PMN–32PT) single crystal growth and thermal analysis were reported. The as-grown PMN–32PT crystal was determined by XRD to be a single phase with rhombohedral structure at room temperature. The Curie temperature was in the range of 137–146°C with ferroelectric rhombohedral to tetrahedral phase transition temperature of 92–118°C. The piezoelectric coefficients were about 2000pC/N with longitude electromechanical coupling factors about 0.93. DSC/TGA analysis of the as-grown PMN–32PT crystal indicated that the melting point of PMN–32PT was 1302.1°C in sealed condition while reduced to 1282.9°C in open system due to the evaporation of PbO and the transformation into pyrochlore phases. [Copyright &y& Elsevier]

The relaxor-based ferroelectric single crystals Pb(In1/2Nb1/2)O3- Pb(Mg1/3Nb2/3)O3-PbTiO3 were grown successfully using the vertical Bridgman technique. The crystals were spontaneously nucleated and induced to grow by the seed respectively, with diameter of Ø25-40 mm and length of 80-170 mm. The [001]-oriented wafers of as-grown crystals showed the excellent electrical characterizations (ε∼5500, tanδ∼1.35%, d33 ∼1900pC/N, k33∼0.9). Both the higher rhombohedral-tetragonal phase transition temperature (Tr/t ∼100-120°C) and Curie temperature (Tc ∼170-200°C) enlarged the operating temperature range of the devices. The crystals had the stable time dependence of piezoelectric properties. Therefore, the successful growth and high performance made the crystal be a promising candidate for the ultrasonic applications. [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]

A Pb(In 1/2 Nb 1/2)O 3 –Pb(Mg 1/3 Nb 2/3)O 3 –PbTiO 3 relaxor ferroelectric single crystal with a 5" diameter and 145 mm length was grown by the modified Bridgman method. The composition distribution of the crystal boule was investigated. The result showed that the PbTiO 3 contents increased along the growth direction, which means that compositional segregation existed, and the effective segregation coefficient was simulated to be 0.84, which is close to that of 3" single crystal. The horizontal composition distribution in the crystal demonstrated that the solid-melt interface of the 5" single crystal was serious convex during crystal growth and was caused by the nonuniform radial thermal field of the large melt. The dielectric, piezoelectric, ferroelectric properties and domain structures were measured to investigate the effect of the composition change along the crystal growth direction. Based on the domain structure and electrical performance, the crystal boule was divided into rhombohedral, morphotropic phase boundary and tetragonal regions. It was found that the optimal piezoelectric coefficient d 33 of the 5" single crystal was more than 2000 pC/N. This work provided positive information for large sized single crystal growth of a relaxor ferroelectric single crystal. • The 5'' diameter by 145 mm long of PIN-PMN-PT crystal along [110] direction was grown by the modified Bridgeman method. • The compositions of single crystal samples along the crystal growth direction and horizontal direction were measured for compositional segregation and horizontal component distribution effect of 5 inches single crystal growth. • The dielectric, piezoelectric and ferroelectric properties of [001] C samples along the crystal growth direction were investigated. Considering the performance of all samples, the crystal in the rhombohedral phase near MPB are suitable for engineering applications. [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]