This work, part of a two-volume set, applies the material developed in the Volume One to various boundary value problems (reflection and refraction at plane surfaces, composite media, waveguides and resonators). The text also covers topics such as perturbation and variational methods.

Acoustic Fields and Waves in Solids

The piezoelectric effect in ferroelectric single crystals and ceramics is investigated considering intrinsic (lattice), and extrinsic (originating mainly from displacement of domain walls) contributions. The focus of the study of intrinsic properties is on piezoelectric anisotropy, which was examined using the Landau-Ginsburg-Devonshire phenomenological theory. It is shown that the enhanced piezoelectric response along nonpolar directions, observed in many perovskite systems, is a consequence of the flattening of the Gibbs free energy profile. This flattening is common for temperature-, composition-, and external field-induced enhancement of the piezoelectric properties along nonpolar axes. A brief review of recent advances in understanding the origins of the piezoelectric nonlinearity, hysteresis, and frequency dispersion is also given.

Contributions to the Piezoelectric Effect in Ferroelectric Single Crystals and Ceramics

Keywords: hysteresis ; ferroelectric ; piezoelectric Reference LC-CHAPTER-2006-001 Record created on 2006-08-03, modified on 2017-05-10

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Hysteresis in Piezoelectric and Ferroelectric Materials

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.

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Losses in ferroelectric materials

The importance of using the most pertinent mathematical description of the mass load versus frequency relation for quartz crystal thin‐film thickness monitors is reviewed. The different usable crystal load ranges of the so‐called frequency‐ and period‐measurement techniques in comparison with the Z‐Match technique are calculated for most of the commonly used deposition materials. A new thin‐film thickness monitoring procedure is described, which takes the influence of the acoustic film properties on the mass load versus frequency slope into consideration without need for the explicit knowledge of the acoustic impedance ratio z of the deposited film and the quartz crystal. It is shown how the effective z value in the composite resonator built by the quartz crystal and the deposited foreign layer can be derived from a measurement of a quasiharmonic overtone resonance frequency in addition to the commonly practiced exclusive measurement of the fundamental resonance frequency. The presently established relati...

R. Holland

Papers

Representation of Dielectric, Elastic, and Piezoelectric Losses by Complex Coefficients