Relaxor-PbTiO3 (PT) based ferroelectric crystals with the perovskite structure have been investigated over the last few decades due to their ultrahigh piezoelectric coefficients (d33 > 1500 pC/N) and electromechanical coupling factors (k33 > 90%), far outperforming state-of-the-art ferroelectric polycrystalline Pb(Zr,Ti)O3 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 and acoustic tweezers, 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.

中文翻译：

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用于电声换能器的弛豫-PbTiO3铁电晶体的优点和挑战——综述

具有钙钛矿结构的弛豫-PbTiO3 (PT) 基铁电晶体由于其超高压压电系数 (d33 > 1500 pC/N) 和机电耦合系数 (k33 > 90%) 远胜于状态，在过去的几十年里得到了研究。最先进的铁电多晶 Pb(Zr,Ti)O3 陶瓷，处于先进电声应用的最前沿。在这篇综述中，从压电材料的角度介绍了弛豫-PT晶体在各种电声器件中的性能优点。机会不仅来自超高特性，特别是耦合和压电系数，还来自新颖的振动模式和晶体学/域工程。针对各种应用，包括医用超声换能器、水下换能器、声学传感器和镊子，建立了具有不同成分和相的晶体的品质因数 (FOM)。对于每种器件应用，我们对弛豫-PT 铁电晶体的最新发展进行了调查，并与最先进的多晶压电晶体进行了比较，重点是其强大的各向异性特征和晶体学独特性，包括工程域-属性关系。本综述首先介绍电声换能器和压电材料的历史。然后讨论了高性能弛豫-PT 单晶的开发，重点关注其在换能器应用中的独特性。在第三部分中，评估了用于各种超声应用的各种压电材料 FOM，包括诊断超声、治疗超声、水下声学和无源传感器、触觉传感器和声学镊子，以全面了解材料在超声条件下的行为。运营条件。然后建立结构-性能-性能关系。最后，总结了弛豫-PT 晶体的影响和挑战，以指导下一代电声换能器弛豫-PT 晶体开发中正在进行和未来的研究。