Ferroelectric materials are the best dielectric and piezoelectric materials known today. Since the discovery of barium titanate in the 1940s, lead zirconate titanate ceramics in the 1950s and relaxor-PT single crystals (such as lead magnesium niobate-lead titanate and lead zinc niobate-lead titanate) in the 1980s and 1990s, perovskite ferroelectric materials have been the dominating piezoelectric materials for electromechanical devices, and are widely used in sensors, actuators and ultrasonic transducers. Energy losses (or energy dissipation) in ferroelectrics are one of the most critical issues for high power devices, such as therapeutic ultrasonic transducers, large displacement actuators, SONAR projectors, and high frequency medical imaging transducers. The losses of ferroelectric materials have three distinct types, i.e., elastic, piezoelectric and dielectric losses. People have been investigating the mechanisms of these losses and are trying hard to control and minimize them so as to reduce performance degradation in electromechanical devices. There are impressive progresses made in the past several decades on this topic, but some confusions still exist. Therefore, a systematic review to define related concepts and clear up confusions is urgently in need. With this objective in mind, we provide here a comprehensive review on the energy losses in ferroelectrics, including related mechanisms, characterization techniques and collections of published data on many ferroelectric materials to provide a useful resource for interested scientists and engineers to design electromechanical devices and to gain a global perspective on the complex physical phenomena involved. More importantly, based on the analysis of available information, we proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses. For multi-domain ferroelectric single crystals and ceramics, intrinsic and extrinsic energy loss mechanisms are discussed in terms of compositions, crystal structures, temperature, domain configurations, domain sizes and grain boundaries. The intrinsic and extrinsic contributions to the total energy dissipation are quantified. In domain engineered ferroelectric single crystals and ceramics, polarization rotations, domain wall motions and mechanical wave scatterings at grain boundaries are believed to control the mechanical quality factors of piezoelectric resonators. We show that a thorough understanding on the kinetic processes is critical in analyzing energy loss behavior and other time-dependent properties in ferroelectric materials. At the end of the review, existing challenges in the study and control of losses in ferroelectric materials are analyzed, and future perspective in resolving these issues is discussed.

中文翻译：

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铁电材料的损失。

铁电材料是当今已知的最好的介电和压电材料。自20世纪40年代钛酸钡、20世纪50年代锆钛酸铅陶瓷以及20世纪80年代和90年代弛豫-PT单晶（如铌镁酸铅-钛酸铅和铌锌酸铅-钛酸铅）的发现以来，钙钛矿铁电材料一直是机电器件中占主导地位的压电材料，广泛应用于传感器、执行器和超声波换能器。铁电体中的能量损失（或能量耗散）是高功率设备最关键的问题之一，例如治疗超声换能器、大位移执行器、声纳投影仪和高频医学成像换能器。铁电材料的损耗具有三种不同的类型，即弹性损耗、压电损耗和介电损耗。人们一直在研究这些损耗的机制，并努力控制和最小化它们，以减少机电设备的性能下降。过去几十年来，这一主题取得了令人瞩目的进展，但仍然存在一些困惑。因此，迫切需要对相关概念进行系统梳理，厘清相关概念，澄清混乱。考虑到这一目标，我们在这里对铁电体的能量损失进行了全面的回顾，包括相关机制、表征技术和许多铁电材料的已发表数据集，为感兴趣的科学家和工程师设计机电器件和获得对所涉及的复杂物理现象的全球视角。更重要的是，基于对现有信息的分析，我们提出了一个通用的理论模型来描述弹性、介电、压电和机械损耗之间的内在关系。对于多畴铁电单晶和陶瓷，从成分、晶体结构、温度、畴结构、畴尺寸和晶界方面讨论了内在和外在能量损失机制。量化了总能量耗散的内在和外在贡献。在域工程铁电单晶和陶瓷中，极化旋转、域壁运动和晶界处的机械波散射被认为控制压电谐振器的机械品质因数。我们表明，对动力学过程的透彻理解对于分析铁电材料的能量损失行为和其他随时间变化的特性至关重要。在综述的最后，分析了铁电材料研究和控制损耗中现有的挑战，并讨论了解决这些问题的未来前景。