Much recent research has focused on the development lead-free perovskite piezoelectrics as environmentally compatible alternatives to lead zirconate titanate (PZT). Two main categories of lead free perovskite piezoelectric ceramic systems were investigated as potential replacements to lead zirconate titanate (PZT) for actuator devices. First, solid solutions based on Li, Ta, and Sb modified (K���.���Na���.���)NbO��� (KNN) lead-free perovskite systems were created using standard solid state methods. Secondly, Bi-based materials a variety of compositions were explored for (1-x)(Bi���.���Na���.���)TiO���-xBi(Zn���.���Ti���.���)O��� (BNT-BZT) and Bi(Zn���.���Ti���.���)O������(Bi���.���K���.���)TiO������(Bi���.���Na���.���)TiO��� (BZT-BKT-BNT). It was shown that when BNT-BKT is combined with increasing concentrations of Bi(Zn[subscript 1/2]Ti[subscript 1/2])O��� (BZT), a transition from normal ferroelectric behavior to a material with large electric field induced strains was observed. The higher BZT containing compositions are characterized by large hysteretic strains (> 0.3%) with no negative strains that might indicate domain switching. This work summarizes and analyzes the fatigue behavior of the new generation of Pb-free piezoelectric materials. In piezoelectric materials, fatigue is observed as a degradation in the electromechanical properties under the application of a bipolar or unipolar cyclic electrical load. In Pb-based materials such as lead zirconate titanate (PZT), fatigue has been studied in great depth for both bulk and thin film applications. In PZT, fatigue can result from microcracking or electrode effects (especially in thin films). Ultimately, however, it is electronic and ionic point defects that are the most influential mechanism. Therefore, this work also analyzes the fatigue characteristics of bulk polycrystalline ceramics of the modified-KNN and BNT-BKT-BZT compositions developed. The defect chemistry that underpins the fatigue behavior will be examined and the results will be compared to the existing body of work on PZT. It will be demonstrated that while some Pb-free materials show severe property degradation under cyclic loading, other materials such as BNT-BKT-BZT essentially exhibit fatigue-free piezoelectric properties with chemical doping or other modifications. Based on these results, these new Pb-free materials have great potential for use in piezoelectric applications requiring a large number of drive cycles such as MEMS devices or high frequency actuators. / Graduation date: 2013

In this thesis, numerical and experimental design of a multi-frequency underwater acoustic transducer with cylindrical piezoelectric ceramic tubes is studied. In the numerical design, the acoustic, mechanical and thermal performances of the transducer are investigated by means of finite element method (FEM) in ANSYS. The design of the transducer that meets the acoustic requirements is checked in terms of the mechanical and thermal performances. After the completion of the numerical design, the transducer is manufactured and some performance tests such as impedance test, hydrostatic pressure test and full-power operation test are applied to it. Finally, the results of the numerical and experimental design are compared. As a result, the design of an underwater acoustic transducer that operates at two frequency bands centered at about 30 and 60 kHz under a hydrostatic pressure of 30 bars is accomplished. This transducer also resist to a shock loading of 500g for 1 millisecond.

The goal of this project was to develop a wind generator that utilizes the collective oscillating motion of multiple piezoelectric devices. These devices would be an alternative to rotating turbine designs for low power generation, for use in applications such as remote power generation. A series of inexpensive devices were developed that harvested energy from vortex shedding, both as independent and cooperative devices. The behavior of single devices was studied, but more interestingly, the way that multiple devices arranged together can increase power output was studied. It was shown that individual devices could harvest more energy if they were placed as specific positions relative to the vortices shed by devices upstream. Through investigating the behavior of these devices, fundamental principles of the phenomenon of vortex induced vibrations were explored. Methods were developed to measure the amplitude and frequency of these vibrations in a wind tunnel, through high speed video and correlations that were found between oscillation and power output from the piezoelectric transducers. Similarly, vortex induced vibrations were explored in an approximation of a two dimensional system in a flowing soap film.

A new class of micromachined devices called thin-film piezoelectric-on-substrate (TPoS) resonators is introduced, and the performance of these devices in RF and sensor applications is studied. TPoS resonators benefit from high electromechanical coupling of piezoelectric transduction mechanism and superior acoustic properties of a substrate such as single crystal silicon. Therefore, the motional impedance of these resonators are significantly smaller compared to typical capacitively-transduced counterparts while they exhibit relatively high quality factor and power handling and can be operated in air. The combination of all these features suggests TPoS resonators as a viable alternative for current acoustic devices. In this thesis, design and fabrication methods to realize dispersed-frequency lateral-extensional TPoS resonators are discussed. TPoS devices are fabricated on both silicon-on-insulator and thin-film nanocrystalline diamond substrates. The performance of these resonators in simple and low-power oscillators is measured and compared. Furthermore, a unique coupling technique for implementation of high frequency filters is introduced in which dual resonance modes of a single resonant structure are coupled. The measured results of this work show that these filters are suitable candidates for single-chip implementation of multiple-frequency narrow-band filters with high out-of-band rejection in a small footprint.

In 1880, French brothers Jacques and Pierre Curie discovered the phenomenon of piezoelectricity in naturally occurring quartz crystal, sometimes referred to as 'nature's timekeeper.' By 1959, tens of millions of devices that exploited quartz crystal's piezoelectric character were being used in the technologies of radio, telephony, and electronic timekeeping. This dissertation analyzes the rapid rise of quartz crystal technology in the United States by looking at the growth of its knowledge base as reflected primarily in patents and journal articles. The major finding of this analysis is that the rise of quartz crystal technology cannot be fully understood by looking only at individuals, institutions, and technological factors. Rather, this work posits that the concept of technological community is indispensible in explaining rapid technological growth and diffusion that would otherwise seem inexplicable. In the late 1920s, and again in the early 1940s, the knowledge base of quartz crystal technology experienced exponential growth, partly due to U.S. government patronage and enlightened regulation. However, as this study shows, quartz crystal engineers, scientists, and entrepreneurs could not have mobilized as quickly and effectively as they did unless a vibrant technological community already existed. Furthermore, the United States' ability to support such a thriving community depended in part on an early 20th century American culture that displayed an unmatched enthusiasm for democratic communications media, most especially broadcast radio and universal telephone service. Archival records, professional journal articles, government reports, manufacturer catalogs, and U.S. patents have been used to document this history of the quartz crystal technological community. This dissertation contributes to the literature on technological communities and their role in facilitating technological and ecomonic growth by showing that though such communities often form spontaneously, their growth may be nurtured and stimulated through enlightened government regulation. As such, this dissertation should be of interest to scholars in the fields of history of technology, business history, management studies, and public policy.

[pt] O presente trabalho apresenta uma modelagem da geração de ondas guiadas em estruturas laminadas compósitas através de atuadores piezoelétricos interdigitais.O estudo foi desenvolvido a partir de uma técnica que se baseia na teoria discreta de Reddy e modela os campos de deslocamento e esforços e velocidades generalizadas nas interfaces de uma estrutura laminada. O modelo desenvolvido representa trechos da estrutura em questão através de suas matrizes de impedância, relacionando os esforços e velocidades generalizadas nas interfaces de cada trecho. Após a validação do modelo através da comparação com o método dos elementos finitos, via um pacote comercial, onde foi mostrado que os campos calculados pelos dois métodos obtiveram resultados bastante aproximados nas diferentes faixas de freqüência, foi demonstrada a capacidade do modelo proposto de representar atuadores piezoelétricos interdigitais gerando modos guiados desacoplados em vigas laminadas compósitas. Foram modeladas vigas de alumínio e de ARALL e, após o cálculo das suas curvas de dispersão e dos pontos em que os seis primeiros modos são aproximadamentenão dispersivos, projetaram-se atuadores capazes de gerar de forma desacoplada alguns dos modos guiados nas vigas. A técnica proposta, que pode ser facilmente adaptada pa4ra a simulação da excitação de ondas de Lamb em placas, é capaz de modelar com precisão a rseposta em altas freqüências e pode servir como uma ferramenta valiosa para o desenvolvimento de atuadores interdigitais na monitoração em tempo real da integridade estrutural de compósitos laminados. / [en] The present work is concerned with modeling interdigital piezoeletric actuators for the excitation of guide waves in composite laminated beams. The proposed model is based on Reddys layerwise laminate theory, which relies on piece- wise constant interpolations of the displacement and eletric potential distributions along thethickness of a laminated structure. The laminated beam is also divided in pieces along its span direction, and each piece is represented by an impedance matrix that associates generalized forces with particle velocities on the interfaces of each piece, and also with the applied voltage along the electrodes of the piezoeletric element. Validation of the model was performed with the aid of a commercial Finite Element code. The model was explored to simulate the excitation of uncoupled guided wave modes incomposite laminated beams fabricated from aluminum or ARALL, which is a laminate made ofalternating layers of aluminum and arami-epoxy fiber reinforced composite. From the frequency spectrum of guided waves in the laminated beam, frequencies amd wavelengths at which the first six modes are approximately non-dispersive where determined. With this information, interdigital actuators, capable of generating uncoupled, or weakly coupled, guided modes in the beam were simulated. The proposed model, which is able to accurately reproduce responses in the high frequency/short wavelength range, could be easily adapted to simulate the extation of Lamb waves in laminated plates, and may be a valuable tool in the development of interdigital actuators for health monitoring of laminated composites.

L’étude présentée est le fruit d’une collaboration entre le groupe de recherche de l'Electrodynamique du INP-ENSEEIHT (Toulouse), LAPLACE Laboratoire de Recherche et l'École Polytechnique de Gdańsk, le Département Génie Electrique et Automatique. L’objectif de cet projet est la conception d’un moteur piézoélectrique multicellulaire composé de plusieurs stators de moteurs à rotation de mode (3 au minimum) permettant de garantir des fréquences de résonance élevées ainsi qu’une répartition des efforts de frottement plus favorables. Le dimensionnement du moteur s’appuiera sur un cahier des charges du domaine de l’automobile, en visant une structure la plus simple possible à mettre en oeuvre. Outre un travail important concernant la conception, il faudra procéder à sa caractérisation après la réalisation du prototype. La dernière étape concernera la définition des stratégies d’alimentation et de commande d’une telle structure qui posera inévitablement le problème de l’autoadaptativité des cellules résonantes à une même fréquence de résonance. Le moteur multicellular (MPM) proposé sera une combinaison du moteur à onde progressive annulaire (Shinsei) et moteur à rotation de mode. Il combine les avantages des deux moteurs par une combinaison de trois cellules élémentaires de moteurs à rotation de mode. La combinaison de ces deux concepts, accroît le nombre de surface de contact. Les dimensions préliminaires et les paramètres de la MPM prototype ont été vérifiés en utilisant son modèle développé analytique (géométrique) et méthodes numériques (MÉF). Le modèle analytique de la MPM a été développé sur la base de circuit équivalent de la Langevin actuateur. La model analytique a été fait dans Matlab. Les principaux paramètres calculés sont: fréquence de résonance 26.2 kHz, couple bloque 0.4 Nm et la vitesse 40 tr/mn. En utilisant le modèle MÉF les fréquences de résonance et les valeurs du stress de la MPM prototype ont été déterminés. . Des simulations ont été effectuées pour sélectionner la fréquence de résonance et la forme pour concevoir le contre mass. Les fréquences de résonances résultantes sont 25.6 kHz et simulations du stress moins de 9 N/mm2. Comparaison des résultats fréquence de résonance calcule à modèle analytique (26.2 kHz) et le modèle FEM (25.6 kHz) du une prototype MPM, il convient de noter, que de modèle analytique est fortement modèle précis. Enfin, la réalisation des pièces par imprimante 3D a été décidée (contre-mass et carter) et les matériaux: aluminium et nylatron. Les autres parties ont été réalisés sur une machine à commande numérique à l'aide de l'acier. Les mesures de la MPM prototype ont été effectuées. L'étape suivante a consisté à tester le moteur et vérifier la fréquence de résonance, et la mesure de déplacement, résonances fréquences résultantes sont 22 kHz et déplacement 1.1 μm sur rotor/stator point du contact. Finalement, les paramètres mécaniques ont été mesurés. Les meilleurs paramètres mécaniques ont été obtenus sur dSpace support de laboratoire: vitesse - 46-48 tr/mn, et le couple bloqué – 0.4 Nm. Les résultats sont satisfaisants et donnent un bon point de départ pour les futurs travaux. / The research works in the frame of the dissertation have been carried out with the cooperation between the University INP - ENSEEIHT - LAPLACE (Laboratory on Plasma and Conversion of Energy), Toulouse, France, and the Gdańsk University of Technology, Faculty of Electrical and Control Engineering, Research Unit Power Electronics and Electrical Machines, Gdańsk, Poland. The main scope of the dissertation was following: development a novel concept, implementation and analysis of the multicell piezoelectric motor (MPM) for the control of the car seat position. The new concept of the MPM is based on a combined topology using the working principles of the traveling wave motor/actuator (known as the Shinsei motor), and the electromechanical structure of the rotating-mode motor/actuator. The electromechanical structure of each rotating-mode motor has been considered as an independent one – referred to as a "single cell". The application of the novel MPM for the control of the car seat position will reduce the number of gears due to its direct coupling with the driving/movement shaft of the seat positioning system. The achieved effects of a such integrated structure will be following: a higher efficiency, a lower noise of performance, a low cost of manufacturing, and in general a lower pollution of the environment. The preliminary dimensions and parameters of the prototype MPM have been verified using its developed analytical (geometrical) model and numerical methods (FEM). The prototype MPM has been manufactured. Finally, the laboratory measurements of the MPM prototype has been carried out.

Grâce à son faible coût, sa grande résolution et son absence d’effet ionisant, l’imagerie ultrasonore haute fréquence est devenue une technique usuelle pour les applications médicales telles que l’imagerie de l’œil, de la peau ou du petit animal. Cette méthode repose sur la capacité de matériaux piézoélectriques à créer des ondes acoustiques hautes fréquences dans les tissus à explorer. Les dispositifs qui opèrent ces conversions électromécaniques sont appelés transducteurs ultrasonores et doivent délivrer des fréquences de résonance de plus de 20 MHz, nécessitant l’intégration des films piézoélectriques ayant une épaisseur de quelques dizaines de micromètres. La fabrication de tels matériaux pour les transducteurs mono- et multi-éléments est toujours difficile suivant les procédés choisis. Dans ce manuscrit, le procédé de dépôt par électrophorèse a été étudié. Il permet le dépôt de films épais sur de nombreux substrats de formes complexes en vue de la fabrication de transducteurs hautes fréquences. Dans cette thèse, il est clairement montré que l’électrophorèse est un procédé simple prometteur et performant pour préparer des films épais homogènes sans défaut avec des propriétés fonctionnelles élevées pour la réalisation de transducteurs hautes fréquences (40 MHz). / Thanks to its relatively low cost, high resolution and absence of ionizing radiations, high frequency ultrasonic imaging is becoming a popular technique for medical applications such as eyes, skin or small animal. It relies on the ability of piezoelectric materials to generate high frequency ultrasonic waves in the scanned media. Ultrasonic transducers are used to perform these electromechanical conversions and operated at resonant frequencies over 20 MHz. For this, piezoelectric layers of few tens of micrometers thick are required. Such thicknesses for single element transducers, and even more for multi-element transducers, is difficult to deliver due to limitations of current fabrication process. In the present dissertation we addressed the electrophoretic deposition (EPD) technique that enables deposition of piezoelectric thick films on various complex-shaped substrates. A procedure to prepare high frequency transducers by EPD was developed. In the dissertation it was demonstrated that EPD is a promising process to prepare homogeneous thick-film structures without significant defects. The procedure allowed obtaining high electromechanical performance transducers using a simple and low cost process.

Os termo eletretos piezelétricos de teflon FEP apresentam-se como elementos que podem competir em preço e funcionalidade com os transdutores atuais. Quando carregados impulsivamente, as folhas de teflon FEP retêm cargas elétricas superficiais por um período longo, superior a 500 anos. Excitados mecanicamente, resultam em um alto nível de sinal elétrico e, excitados eletricamente, retornam a energia em deformação mecânica. O processo de fabricação projetado envolve a produção de um transdutor piezelétrico com uma densidade superficial de carga uniforme, através da formação de vacúolos gasosos formados sobre a superfície do filme polimérico. Os altos índices piezelétricos dos transdutores fabricados são confirmados por um sistema de medição estático, também projetado e desenvolvido neste trabalho, onde o coeficiente piezelétrico é medido de maneira direta. / The thermo-formed electrets of teflon FEP films are shown as elements that can be competitive either in price and functionality matters, as per the transducers being used nowadays. Once charged by an impulse voltage, the teflon FEP sheets keep the superficial electric charges for long periods, up to 500 years. Mechanically excited, they result in a high electric signal and, once electrically excited, return in a mechanical deformation. The projected manufactory process includes the production of a piezoelectric transducers with uniformly charged superficial density, though the formation of gaseous vacuoles over the polymeric film surface. The high piezoelectric levels of the manufactured transducers are confirmed by a static measurement system, also projected and developed in this same work, where the piezoelectric coefficient is measured by a direct way.

Orientador: Lisandro Pavie Cardoso / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-07T10:55:28Z (GMT). No. of bitstreams: 1 Menezes_AlanSilvade_M.pdf: 6146664 bytes, checksum: 0379ab9f914d1e2c189aba25560a6217 (MD5) Previous issue date: 2006 / Resumo: Neste trabalho, o método baseado na variação nas posições angulares dos picos secundários em uma varredura Renninger da difração múltipla de raios-X usando radiação síncrotron foi utilizado para a determinação dos coeficientes piezelétricos da -histidina. HCl. H2O. A grande sensibilidade da técnica a pequenas deformações na célula unitária dos cristais analisados permite esta determinação, desde que o campo elétrico seja aplicado nas direções específicas escolhidas nas amostras. Foram determinados os parâmetros de rede da -histidina.HCl. H2O pura e dopada com Ni 2+, com boa precisão, a partir da escolha adequada dos picos secundários nas varreduras Renninger, e, também determinou-se o coeficiente d14 para a amostra dopada. Destes resultados foi observada uma contração do volume da célula unitária (0,04%) do cristal dopado em relação ao puro, resultado também obtido através do refinamento das amostras em forma de pó com o método de Rietveld. O efeito do Ni 2+ na rede da -histidina.HCl. H2O foi evidenciado na comparação entre as varreduras Renninger para os dois cristais, puro e dopado, através de mudanças na intensidade, posição angular e assimetria dos picos secundários, principalmente no pico correspondente ao caso de quatro-feixes (604)(404) simultâneos para a reflexão primária (10 0 0), que praticamente desapareceu no cristal dopado, indicando possivelmente uma mudança de fase nas reflexões deste pico secundário. Observamos ainda, a mudança no hábito de crescimento e na coloração do cristal quando dopado com Ni 2+ , e a clara diminuição na taxa de crescimento da face [1 0 0]. Por fim, a difração múltipla de raios-X usando a radiação síncrotron permitiu a determinação, pela primeira vez, de todos os coeficientes piezelétricos do cristal de -histidina.HCl. H2O: [ d14] = 295(9) pC/N; [ d25] = 41(5) pC/N; [ d36] = 230(20) pC/N, assim como do coeficiente [ d14] = 93(5) pC/N para o cristal dopado com Ni 2+ / Abstract: In this work, the method based on the variation in the secondary peak angular positions of the Renninger scanning of the X-ray multiple diffraction using synchrotron radiation was used in the determination of -histidine.HCl. H2O piezoelectric coefficients. The high sensitivity of this technique to subtle distortions in the analyzed crystal unit cells allows this determination since the electric field be applied towards the previously chosen specific directions in the samples. Pure and Ni 2+ -histidine. HCl. H2O lattice parameters were measured with good precision from the adequate choice of Renninger scanning secondary peaks as well as, the d14 piezoelectric coefficient of the doped sample. From these results a contraction of the doped unit cell volume (0.04%) regarding the pure one was obtained, which is in agreement with that contraction obtained from the refinement of powder samples using the Rietveld method. The effect of Ni 2+ in the -histidine. HCl. H2O lattice was evidenced in the comparison between the Renninger scanning for both pure and doped crystals through the intensity, angular position and asymmetry of the secondary peaks, mainly the one corresponding to the (604)(404) four-beam simultaneous case for (10 0 0 ) primary reflection, that has practically disappeared for the doped crystal scanning. It indicates a possible change in the phase of the secondary peak reflections. It was also observed a change in the growth habit and color of the crystal when doped as well as a clear decrease in the [100] face growth ratio. At last, the x-ray multiple diffraction using synchrotron radiation allowed, for he firs ime, the determination of all piezoelectric coefficients for the -histidine. HCl. H2O crystal: [ d14] = 295(9) pC/N; [d25] = 41(5) pC/N; [d3]? = 230(20) pC/N, and the [d14] = 93(5) pC/N for the Ni 2+ doped crystal coefficient / Mestrado / Estrutura de Liquidos e Solidos ; Cristalografia / Mestre em Física