Comparative Study of the Effective Properties of 0-3 and Gyroid Triply Periodic Minimal Surface Cement-Piezocomposites

In the present numerical simulation work, effective elastic and piezoelectric properties are calculated and a comparative study is conducted on a cement matrix-based piezocomposite with 0-3 and gyroid triply periodic minimal surface (TPMS) inclusions. The present study compares the effective properties of different piezoelectric materials having two different types of connectivity of the inclusions namely, 0-3 inclusions where the inclusions are physically separated from each other and are embedded within the matrix and the second one is TPMS inclusions having interpenetrating phase type connectivity. Effective properties are calculated for four different materials at five different volume fractions namely, 10%, 15%, 20%, 25%, and 30% volume fractions of inclusion by volume. In terms of effective properties and direct piezoelectric effect, TPMS piezocomposite is found to perform better compared to 0-3 piezocomposite. Lead-free piezoelectric material 0.5Ba(Ca_0.8Zr_0.2)O₃ - 0.5(Ba_0.7Ca_0.3)TiO₃ demonstrates better performance compared to all other material inclusions studied. The present study attempts to highlight improved piezoelectric effective properties of lead-free material-based piezocomposites with TPMS inclusions.

Cold Sintering of PZT 2-2 Composites for High Frequency Ultrasound Transducer Arrays

Medical ultrasound and other devices that require transducer arrays are difficult to manufacture, particularly for high frequency devices (>30 MHz). To enable focusing and beam steering, it is necessary to reduce the center-to-center element spacing to half of the acoustic wavelength. Conventional methodologies prevent co-sintering ceramic–polymer composites due to the low decomposition temperatures of the polymer. Moreover, for ultrasound transducer arrays exceeding 30 MHz, methods such as dice-and-fill cannot provide the dimensional tolerances required. Other techniques in which the ceramic is formed in the green state often fail to retain the required dimensions without distortion on firing the ceramic. This paper explores the use of the cold sintering process to produce dense lead zirconate titanate (PZT) ceramics for application in high frequency transducer arrays. PZT–polymer 2-2 composites were fabricated by cold sintering tape cast PZT with Pb nitrate as a sintering aid and ZnO as the sacrificial layer. PZT beams of 35 μm width with ~5.4 μm kerfs were produced by this technique. The ZnO sacrificial layer was also found to serve as a liquid phase sintering aid that led to grain growth in adjacent PZT. This composite produced resonance frequencies of >17 MHz.

Overview of Ultrasound Detection Technologies for Photoacoustic Imaging

Ultrasound detection is one of the major components of photoacoustic imaging systems. Advancement in ultrasound transducer technology has a significant impact on the translation of photoacoustic imaging to the clinic. Here, we present an overview on various ultrasound transducer technologies including conventional piezoelectric and micromachined transducers, as well as optical ultrasound detection technology. We explain the core components of each technology, their working principle, and describe their manufacturing process. We then quantitatively compare their performance when they are used in the receive mode of a photoacoustic imaging system.

Investigating the Pre-Damaged PZT Sensors under Impact Traction

Ships are usually under vibration, impact, and other kinds of static and dynamic loads. These loads arise from water flow across the hull or surfaces, the propeller cavitation, and so on. For optimal design purposes and reliable performance, experimental measurements are necessary. These sensors are often used under or near the water, working conditions that improve the risk of sensor damage. This paper aims at investigating, by the use of finite elements, the behavior of damaged piezoelectric sensors under traction and impact loads. The numerical method was calibrated using results available in the literature regarding piezoelectric and elastic plates with a central crack. After calibration, the simulation was used on two types of Lead-Zirconium-Titanium oxide (PZT) sandwich panel structures reinforced by aluminum skins. The results proved that the damage size and impact energy are important factors affecting the response of piezoelectric sensors; therefore, special attention might be considered when using these sensors for marine applications.

Advantages and Challenges of Relaxor-PbTiO3 Ferroelectric Crystals for Electroacoustic Transducers- A Review

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.

Superior piezoelectric composite films: taking advantage of carbon nanomaterials

Piezoelectric composites comprising an active phase of ferroelectric ceramic and a polymer matrix have recently found numerous sensory applications. However, it remains a major challenge to further improve their electromechanical response for advanced applications such as precision control and monitoring systems. We here investigated the incorporation of graphene platelets (GnPs) and multi-walled carbon nanotubes (MWNTs), each with various weight fractions, into PZT (lead zirconate titanate)/epoxy composites to produce three-phase nanocomposites. The nanocomposite films show markedly improved piezoelectric coefficients and electromechanical responses (50%) besides an enhancement of ~200% in stiffness. The carbon nanomaterials strengthened the impact of electric field on the PZT particles by appropriately raising the electrical conductivity of the epoxy. GnPs have been proved to be far more promising in improving the poling behavior and dynamic response than MWNTs. The superior dynamic sensitivity of GnP-reinforced composite may be caused by the GnPs' high load transfer efficiency arising from their two-dimensional geometry and good compatibility with the matrix. The reduced acoustic impedance mismatch resulting from the improved thermal conductance may also contribute to the higher sensitivity of GnP-reinforced composite. This research pointed out the potential of employing GnPs to develop highly sensitive piezoelectric composites for sensing applications.

Piezoelectric composites for sensor and actuator applications

In the last 25 years, piezoelectric ceramic-polymer composites have been conceptualized, prototyped, fabricated, and implemented in an array of applications encompassing medical imaging and military missions, among others. A detailed snapshot of the materials used, and a detailed account of the major innovative methods developed in making various piezoelectric ceramic-polymer composites are presented. The salient aspects of processing of such composites are summarized, and structure-processing-property relations are described using connectivity as the unifying central concept. Computer-aided design (CAD)-based fabrication methods, which result in composites whose structural complexity surpass that of composites obtained with traditional methods, are described to introduce the reader to novel concepts in processing of piezocomposites. A brief survey of some recent advances made in modeling of (0-3), (1-3), and (2-2) composites also is provided.

Samarium and manganese-doped lead titanate ceramic fiber/epoxy 1-3 composite for high-frequency transducer application

Samarium- (Sm) and manganese- (Mn) doped lead titanate ceramic fibers with a diameter of 35 microm were prepared using a sol-gel method. The X-ray diffraction pattern shows that the fibers have a pure perovskite structure. The 1-3 composite disks with a thickness of 31-41 microm and with ceramic volume fraction of approximately 0.68 have been prepared using the samarium and manganese doped lead titanate (PSmT) fibers. The resonance characteristics of the poled composite disks were measured. A focused transducer was fabricated using a concave 1-3 composite disk with nonuniform thickness in order to enhance its bandwidth. The insertion loss (IL), pulse-echo response and frequency spectrum of the composite transducer were measured. The center frequency of the transducer was approximately 31 MHz with a -3 dB bandwidth of approximately 123% and a low IL of 29.3 dB.