Dissertations / Theses on the topic 'Piezoelectric films'
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De, Poumeyrol Benjamin. "Characterization of piezoelectric paint." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273485.
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Corkovic, Silvana. "Piezoelectric thick films for microelectromechanical systems application." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/1826.
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This thesis concerns the processing and characterization of thick PZT sol-gel films for potential applications in MEMS devices. The deposition method was spin-coating. The aim was to reduce the number of coatings in the film processing by increasing the thickness of a single coating, with the restriction that the processed films must be crackfree and dense. Only by retaining the thick film dense, pore-free and crack-free one can obtain the piezoelectric properties in thick films that make the PZT thin sol-gel films attractive for the MEMS applications. Three PZT compositions, PZT 40/60, PZT 60/40 and PZT 52/48 were investigated. Each one of these PZT compositions has different crystallographic structure and thus differences in the piezoelectric properties were expected. The processing of thickness-increased sol-gel films was investigated. A combination of analysis techniques was employed. The stress development was monitored via ex-situ wafer deflection measurement after various fabrication steps. The ongoing processes in the sol-gel film were identified and correlated to certain temperature ranges and to the stress that is induced with each process in the film. It was found that crack-free films could be fabricated if a stress-controlled heating profile was applied. The PZT films were deposited on platinised silicon substrate and it was found that stress-related recrystallization was taking place in the platinum electrode which affected the total stress. After the platinum recrystallization the stress state in the bottom electrode and in the substrate was stable. Films up to 5 μm thick were obtained by repeated deposition of 200 nm thick single layers. The maximum thickness of a single coating was increased to 500 nm and a 2.5 μm film was fabricated by only 5 repeated coatings. The crystallographic orientation of all three employed PZT compositions was studied systematically on Pt/Si substrate at different thicknesses. Also, individual PZT films were deposited onto platinised sapphire substrates, or on LNO/Si substrate. It was found that the orientation of the films changes gradually with each coating. The residual stresses in all three PZT compositions were studied. A stress model for composite structures was applied for the first time in PZT films stress analysis. The results have shown that the residual stress at the room temperature is due to thermal expansion mismatch between the individual layers. Furthermore, a large orientation dependent stress variation was found in PZT 52/48 films that could be only explained if anisotropic thermal expansion in PZT were considered. The lattice parameters of all PZT compositions were determined and were in good agreement with the residual stress results. Thus, using the stress model it was possible to understand the origin of stress in PZT films. Finally, the electrical properties of the PZT films were determined. It was found that the piezoelectric, dielectric and ferroelectric properties of PZT films vary with PZT composition, film thickness and depend on the substrate type. Based on the finding it was proposed that there must be an interfacial layer that is responsible for domain wall pinning and thus reduced PZT properties in films below 5 μm thickness. In thick PZT 40/60 films enhanced piezoelectric properties were found making these PZT compositions very promising candidates for MEMS application.
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Sanchez, Mathon Gustavo. "Piezoelectric aluminum nitride thin films by PECVD." Limoges, 2009. https://aurore.unilim.fr/theses/nxfile/default/9224e391-3c48-4c10-9166-c2a2bed3c5f4/blobholder:0/2009LIMO4007.pdf.
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Des couches minces polycristallines d'AIN ont été réalisées en utilisant une technique CVD assistée par plasma micro-onde. Les paramètres, distance plasma - injecteur, température du substrat, polarisation RF du porte - substrat ont été optimisés. Il a été possible de contrôler l’orientation préférentielle <0001> ou <1010>, intéressantes pour des applications piézoélectriques. Les mécanismes de croissance qui ont conduit au développement des microstructures dans les différentes conditions ont été expliqués. La comparaison avec une technique PVD a permis d’enricher la discussion. Les performances piézoélectriques des couches obtenues ont été caractérisées par construction des dispositifs électroacoustiques d’onde de surface et d’onde de volume. Seules les couches orientées <0001> ont montré une réponse piézoélectrique et une vitesse acoustique adéquates. Une analyse exhaustive a été conduite pour expliquer les possibles raisons de ces comportementsPolycrystalline aluminum nitride thin films were produced with a microwave-plasma enhanced chemical vapor deposition technique. The plasma-injector distance, the substrate temperature and the RF bias were the main variables which allowed achieving this objective. At the time, it was possible to control the preferential orientation as <0001> or <1010>, both interesting for piezoelectric applications. The growth mechanisms that conducted to film microstructure development under different process conditions were explained, enriched by the comparison with a physical vapor deposition sputtering technique. The obtained films were characterized in their piezoelectric performance, including the construction of surface acoustic wave devices and bulk acoustic wave devices. Adequate piezoelectric response and acoustic velocities were obtained for <0001> oriented films, while <1010> oriented films did not show piezoelectric response under the configurations essayed. An extensive analysis was done in order to explain these behaviors
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DURACCIO, DONATELLA. "Piezoelectric composite films for energy harvesting devices." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2872343.
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Li, Lihua. "Piezoelectric microbeam resonators based on epitaxial Al0.3Ga0.7As films." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/3109.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Xiang, Shu. "Piezoelectric thin films and nanowires: synthesis and characterization." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41139.
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Piezoelectric materials are widely used for sensors, actuators and trasducers.
Traditionally, piezoelectric applications are dominated by multicomponent oxide
ferroelectrics such as lead zirconate titanate (PZT), which have the advantage of high piezoelectric coefficients. Recently, one-dimensional piezoelectric nanostructures such as nanowires of zinc oxide (ZnO) and gallium nitride (GaN) has gained a lot of attention due to their combined piezoelectric and semiconducting properties. The focus of this thesis is to study the processing and electric properties of such piezoelectric thin films and nanostructures for various applications.
There is an increasing interest to form thin films of multicomponent ferroelectric oxides such as PZT on three-dimensional structures for charge storage and MEMS applications. Traditional vapor phase deposition techniques of PZT offer poor conformality over threedimensional surfaces due to their reactant transport mechanisms. As an alternative, solgel synthesis may provide new process possibilities to overcome this hurdle but the film quality is usually inferior, and the yield data was usually reported for small device areas. The first part of this study is dedicated to the characterization of the electric properties and yield of PZT thin film derived from the sol-gel process. PZT thin films with good electric property and high yield over a large area have been fabricated. La doping was found to double the breakdown field due to donor doping effect. LaNiO3 thin films that can be coated on a three-dimensional surface have been synthesized by an all-nitrate based sol-gel route, and the feasibility to form a conformal coating over a three-dimensional surface by solution coating techniques has been demonstrated.
ZnO and GaN micro/nanowires are promising piezoelectric materials for energy harvesting and piezotronic device applications. The second part of this study is focused on the growth of ZnO and GaN micro/nanowires by physical vapor deposition techniques. The morphology and chemical compositions are revealed by electron microscopy. Utilizing the as-grown ZnO nanowires, single nanowire based photocell has been fabricated, and its performance was studied in terms of its response time, repeatability, excitation position and polarization dependence upon He-Cd UV-laser
illumination. The excitation position dependence was attributed to the competition of two opposite photo- and thermoelectric currents originated from the two junctions. The excitation polarization dependence was attributed to the difference in optical properties due to crystallographic anisotropy. Employing the as-grown GaN nanowires, single nanowire based strain sensor is demonstrated, and its behavior is discussed in terms of the effect of strain-induced piezopotential on the Schottky barrier height.
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Roe, Merrion Patricia. "Photosensitive and piezoelectric thin films for optical devices." Thesis, University of Southampton, 1996. https://eprints.soton.ac.uk/398885/.
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This thesis reports on the development of photosensitive and piezoelectric thin films for optical devices. The thesis is in two parts, the first concentrating on research into novel photosensitive materials for optical Bragg gratings, while Part II studies the development of piezoelectric ZnO thin films for acousto-optic devices. Bragg gratings are an important element in the development of optical communications systems. Strongly photosensitive optical waveguiding materials are required to achieve more efficient Bragg gratings in both planar and fibre waveguides. In this thesis, metal oxides are studied for photosensitivity in their pure state as RF sputtered thin films. Photosensitivity is demonstrated for the first time in RF sputtered germanium oxide and tantalum oxide thin film waveguides via Bragg diffraction. A side-polished fibre coupler, capable of monitoring both the magnitude and sign of an index change, is then used to establish large, negative and permanent index changes in tantalum oxide thin films. UV-induced changes in absorption, measured in a similar tantalum oxide film, are contrasted with the observed index change via a Kramers-Kronig analysis, while a UV-induced reduction in film reflectivity consolidates the fibre coupler result. ZnO, with a kt of 0.28, is an efficient piezoelectric material, and thin ZnO transducers permit operating frequencies of up to 3.5 GHz. In addition, ZnO transducers can be configured on curved surfaces, whose focusing properties greatly enhance device efficiency. In contrast, the operating frequency of LiNbO3 transducers is limited to approximately 0.8 GHz and curved transducers are a problem. Part II of this thesis discusses the fabrication and optimisation of ZnO transducers. Acousto-optic beam deflection by ZnO transducers on TeO2 crystals is demonstrated for the first time, and efficient in-line fibre phase modulation is achieved using a annular ZnO transducer on an optical fibre.
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Mohebbi, Abolfazl, and Abolfazl Mohebbi. "Optimization of polypropylene cellular films for piezoelectric applications." Doctoral thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27391.
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Cette thèse comporte deux objectifs principaux: la production en continu de films de polypropylène (PP) moussés ayant une structure cellulaire de forme oculaire, suivie par la préparation de films PP ferroélectrets par décharge corona pour des applications piézoélectriques. Dans la première partie de ce travail, une production en continu par extrusion-calandrage a été développée pour produire des films de PP moussés pour des applications piézoélectriques. Le système est basé sur un moussage physique en utilisant de l'azote supercritique (SC-N2) et le carbonate de calcium (CaCO3) comme agent de nucléation. Les paramètres de mise en œuvre (conception de vis, profil de température, agent gonflant et de nucléation ainsi que leur contenu, et la vitesse d'étirement) ont été optimisés pour obtenir une forme spécifique (oculaire) comme structure cellulaire avec une distribution uniforme de la taille des cellules. Les résultats ont montré qu'une structure cellulaire avec un plus grand rapport d'aspect (AR) des cellules possède un plus faible module de Young, ce qui est approprié pour les films cellulaires piézoélectriques. Dans la deuxième partie, des films PP ferroélectrets ont été produits. Suite à l'optimisation du procédé de décharge corona (tension de charge, distance de l'aiguille, temps de charge), les propriétés piézoélectriques des films obtenus ont été caractérisées et le coefficient piézoélectrique quasi-statique d33 a produit une valeur de 550 pC/N. Afin de mieux caractériser le comportement du film, l’analyse mécanique dynamique (DMA) a été proposée comme une méthode simple pour relier les propriétés piézoélectriques des films PP cellulaires à leur morphologie (taille, géométrie et densité des cellules). Finalement, grâce à un post-traitement basé sur la saturation du film PP moussé avec le SC-N2, une procédure en température et pression a été développée afin d’améliorer la structure cellulaire (cellules plus allongées). Ce traitement a permis d’augmenter de 45% le coefficient d33 (800 pC/N).Cette thèse comporte deux objectifs principaux: la production en continu de films de polypropylène (PP) moussés ayant une structure cellulaire de forme oculaire, suivie par la préparation de films PP ferroélectrets par décharge corona pour des applications piézoélectriques. Dans la première partie de ce travail, une production en continu par extrusion-calandrage a été développée pour produire des films de PP moussés pour des applications piézoélectriques. Le système est basé sur un moussage physique en utilisant de l'azote supercritique (SC-N2) et le carbonate de calcium (CaCO3) comme agent de nucléation. Les paramètres de mise en œuvre (conception de vis, profil de température, agent gonflant et de nucléation ainsi que leur contenu, et la vitesse d'étirement) ont été optimisés pour obtenir une forme spécifique (oculaire) comme structure cellulaire avec une distribution uniforme de la taille des cellules. Les résultats ont montré qu'une structure cellulaire avec un plus grand rapport d'aspect (AR) des cellules possède un plus faible module de Young, ce qui est approprié pour les films cellulaires piézoélectriques. Dans la deuxième partie, des films PP ferroélectrets ont été produits. Suite à l'optimisation du procédé de décharge corona (tension de charge, distance de l'aiguille, temps de charge), les propriétés piézoélectriques des films obtenus ont été caractérisées et le coefficient piézoélectrique quasi-statique d33 a produit une valeur de 550 pC/N. Afin de mieux caractériser le comportement du film, l’analyse mécanique dynamique (DMA) a été proposée comme une méthode simple pour relier les propriétés piézoélectriques des films PP cellulaires à leur morphologie (taille, géométrie et densité des cellules). Finalement, grâce à un post-traitement basé sur la saturation du film PP moussé avec le SC-N2, une procédure en température et pression a été développée afin d’améliorer la structure cellulaire (cellules plus allongées). Ce traitement a permis d’augmenter de 45% le coefficient d33 (800 pC/N).
This thesis is composed of two main objectives: the continuous production of thin foamed polypropylene (PP) films having an eye-like cellular structure, followed by the preparation of ferroelectret PP films through corona discharge for piezoelectric applications. In the first part of this work, a continuous extrusion-calendaring setup was developed to produce PP foamed films for piezoelectric applications. The setup is based on physical foaming using supercritical nitrogen (SC-N2) and calcium carbonate (CaCO3) as nucleating agent. The processing parameters (screw design, temperature profile, blowing agent and nucleating agent content, and stretching speed) were optimized to achieve a specific stretched eye-like cellular structure with a uniform cell size distribution. The results showed that a cellular structure with higher cell aspect ratio (AR) has lower Young’s modulus, which is appropriate for piezoelectric cellular films. In the second part, ferroelectret PP films were produced. After optimization of the corona discharge process (charging voltage, needle distance, charging time), the piezoelectric properties of the resulting films were characterized and the optimum quasi-static piezoelectric d33 coefficient value was 550 pC/N. To better characterize the film behavior, dynamic mechanical analysis (DMA) was proposed as a simple method to relate the piezoelectric properties of the cellular PP films to their morphology (cell size, geometry and density). Finally, through a post-processing treatment based on the saturation of the foamed PP film with SC-N2, a temperature-pressure procedure was developed to improve the cellular structure (more stretched eye-like cells). This treatment was shown to increase by 45% the d33 coefficient (800 pC/N).
This thesis is composed of two main objectives: the continuous production of thin foamed polypropylene (PP) films having an eye-like cellular structure, followed by the preparation of ferroelectret PP films through corona discharge for piezoelectric applications. In the first part of this work, a continuous extrusion-calendaring setup was developed to produce PP foamed films for piezoelectric applications. The setup is based on physical foaming using supercritical nitrogen (SC-N2) and calcium carbonate (CaCO3) as nucleating agent. The processing parameters (screw design, temperature profile, blowing agent and nucleating agent content, and stretching speed) were optimized to achieve a specific stretched eye-like cellular structure with a uniform cell size distribution. The results showed that a cellular structure with higher cell aspect ratio (AR) has lower Young’s modulus, which is appropriate for piezoelectric cellular films. In the second part, ferroelectret PP films were produced. After optimization of the corona discharge process (charging voltage, needle distance, charging time), the piezoelectric properties of the resulting films were characterized and the optimum quasi-static piezoelectric d33 coefficient value was 550 pC/N. To better characterize the film behavior, dynamic mechanical analysis (DMA) was proposed as a simple method to relate the piezoelectric properties of the cellular PP films to their morphology (cell size, geometry and density). Finally, through a post-processing treatment based on the saturation of the foamed PP film with SC-N2, a temperature-pressure procedure was developed to improve the cellular structure (more stretched eye-like cells). This treatment was shown to increase by 45% the d33 coefficient (800 pC/N).
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Yin, Shi. "Integration of epitaxial piezoelectric thin films on silicon." Thesis, Ecully, Ecole centrale de Lyon, 2013. http://www.theses.fr/2013ECDL0039/document.
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Les matériaux piézoélectriques, comme le titanate-zirconate de plomb Pb(ZrxTi1-x)O3 (PZT), l’oxyde de zinc ZnO, ainsi que la solution solide de Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), sont actuellement l’objet d’études de plus en plus nombreuses à cause de leurs applications innovantes dans les systèmes micro-électromécaniques (MEMS). Afin de les intégrer sur substrat de silicium, certaines précautions doivent être prises en compte concernant par exemple des couches tampon, les électrodes inférieures. Dans cette thèse, des films piézoélectriques (PZT et PMN-PT) ont été épitaxiés avec succès sous forme de monocristaux sur silicium et SOI (silicon-on-insulator) par procédé sol-gel. En effet, des études récentes ont montré que les films piézoélectriques monocristallins semblent posséder des propriétés supérieures à celles des films polycristallins, permettant ainsi une augmentation de la performance des dispositifs MEMS. Le premier objectif de cette thèse était de réaliser l'épitaxie de film monocristallin de matériaux piézoélectriques sur silicium. L'utilisation d’une couche tampon d'oxyde de gadolinium (Gd2O3) ou de titanate de strontium (SrTiO3 ou STO) déposés par la technique d’épitaxie par jets moléculaires (EJM) a été explorée en détail pour favoriser l’épitaxie du PZT et PMN-PT sur silicium. Sur le système Gd2O3/Si(111), l’étude par diffraction des rayons X (XRD) de la croissance du film PZT montre que le film est polyphasé avec la présence de la phase parasite pyrochlore non ferroélectrique. Cependant, le film PZT déposé sur le système STO/Si(001) est parfaitement épitaxié sous forme d’un film monocristallin. Afin de mesurer ses propriétés électriques, une couche de ruthenate de strontium conducteur SrRuO3 (SRO) déposée par ablation laser pulsé (PLD) a été utilisée comme l'électrode inférieure à cause de son excellente conductibilité et de sa structure cristalline pérovskite similaire à celle du PZT. Les caractérisations électriques sur des condensateurs Ru/PZT/SRO démontrent de très bonnes propriétés ferroélectriques avec présence de cycles d'hystérésis. Par ailleurs, le matériau relaxeur PMN-PT a aussi été épitaxié sur STO/Si comme l’a confirmé la diffraction des rayons X ainsi que la microscopie électronique en transmission (TEM). Ce film monocristallin est de la phase de perovskite sans présence de pyrochlore. En outre, une étude en transmission du rayonnement infrarouge au synchrotron a prouvé une transition de phase diffuse sur une large gamme de température, comme attendue dans le cas d’un relaxeur. L'autre intérêt d'avoir des films PZT monocristallins déposés sur silicium et SOI est de pouvoir utiliser les méthodes de structuration du silicium bien standardisées maintenant pour fabriquer les dispositifs MEMS. La mise au point d’un procédé de micro-structuration en salle blanche a permis de réaliser des cantilevers et des membranes afin de caractériser mécaniquement les couches piézoélectriques. Des déplacements par l'application d'une tension électrique ont ainsi pu être détectés par interférométrie. Finalement, cette caractérisation par interférométrie a été combinée avec une modélisation basée sur la méthode des éléments finis. Dans le futur, il sera nécessaire d’optimiser le procédé de microfabrication du dispositif MEMS afin d’en améliorer les performances électromécaniques. Enfin, des caractérisations au niveau du dispositif MEMS lui-même devront être développées en vue de leur utilisation dans de futures applicationsRecently, piezoelectric materials, like lead titanate zirconate Pb(ZrxTi1-x)O3 (PZT), zinc oxide ZnO, and the solid solution Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), increasingly receive intensive studies because of their innovative applications in the microelectromechanical systems (MEMS). In order to integrate them on silicon substrate, several preliminaries must be taken into considerations, e.g. buffer layer, bottom electrode. In this thesis, piezoelectric films (PZT and PMN-PT) have been successfully epitaxially grown on silicon and SOI (silicon-on-insulator) in the form of single crystal by sol-gel process. In fact, recent studies show that single crystalline films seem to possess the superior properties than that of polycrystalline films, leading to an increase of the performance of MEMS devices. The first objective of this thesis was to realize the epitaxial growth of single crystalline film of piezoelectric materials on silicon. The use of a buffer layer of gadolinium oxide(Gd2O3) or strontium titanate (SrTiO3 or STO) deposited by molecular beam epitaxy (MBE) has been studied in detail to integrate epitaxial PZT and PMN-PT films on silicon. For Gd2O3/Si(111) system, the study of X-ray diffraction (XRD) on the growth of PZT film shows that the film is polycrystalline with coexistence of the nonferroelectric parasite phase, i.e. pyrochlore phase. On the other hand, the PZT film deposited on STO/Si(001) substrate is successfully epitaxially grown in the form of single crystalline film. In order to measure the electrical properties, a layer of strontium ruthenate (SrRuO3 or SRO) deposited by pulsed laser deposition (PLD) has been employed for bottom electrode due to its excellent conductivity and perovskite crystalline structure similar to that of PZT. The electrical characterization on Ru/PZT/SRO capacitors demonstrates good ferroelectric properties with the presence of hysteresis loop. Besides, the relaxor ferroelectric PMN-PT has been also epitaxially grown on STO/Si and confirmed by XRD and transmission electrical microscopy (TEM). This single crystalline film has the perovskite phase without the appearance of pyrochlore. Moreover, the study of infrared transmission using synchrotron radiation has proven a diffused phase transition over a large range of temperature, indicating a typical relaxor ferroelectric material. The other interesting in the single crystalline PZT films deposited on silicon and SOI is to employ them in the application of MEMS devices, where the standard silicon techniques are used. The microfabrication process performed in the cleanroom has permitted to realize cantilevers and membranes in order to mechanically characterize the piezoelectric layers. Mechanical deflection under the application of an electric voltage could be detected by interferometry. Eventually, this characterization by interferometry has been studied using the modeling based on finite element method and analytic method. In the future, it will be necessary to optimize the microfabrication process of MEMS devices based on single crystalline piezoelectric films in order to ameliorate the electromechanical performance. Finally, the characterizations at MEMS device level must be developed for their utilization in the future applications
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Sullivan, Timothy Michael. "Development of a novel method for measuring the transverse piezoelectric coefficients of thin piezoelectric films." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Thesis/Summer2004/t%5Fsullivan%5F072604.pdf.
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Marques, Ana Raquel Correia Gonçalves. "Development of a piezoelectric biosensor based on PVDF films." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6575.
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Dissertação para obtenção do Grau de Mestre em
Engenharia Química e BioquímicaThe core of this work is a piezoelectric biosensor in which acoustic waves are launched in very thin PVDF polymer films to produce an oscillatory resonant device. The essence of the device consists in a polymer film system made of a piezoelectric polymer, PVDF, responsible for the film oscillation and a porous membrane, Immobilon, a special type of porous PVDF with protein binding capacity which can act as a biosensitive area. The possibility of using a film system composed only by PVDF was studied. Due to its strong hydrophobic nature, surface modification was aimed to be performed by coating a functional layer on the membrane surface, in order to improve the hydrophilicity and biocompatibility of PVDF. An immersion method was preformed and applied to porous and non-porous PVDF membranes. Three distinct coating solutions were studied, namely, polyethylene glycol (PEG), 3,4-Dihydroxy-DL-phenylalanine (DL-DOPA) and Gum Arabic solutions. Hydrophilicity improvements of the membranes were characterized by water contact angle measurements and its elemental composition was studied by elemental microanalysis. BSA protein marked with FITC fluorescein was used to perform quantitative and qualitative assays in order to study its adsorption to coated and uncoated PVDF membranes. Globally, the best results were obtained when a solution of PEG was utilized with 0.2 μm microporous membrane. The sensor response was tested with polyethylene glycol (PEG) and bovine serum albumin (BSA), using a film system composed by PVDF/0.2 μm Immobilon/PVDF, which was able to respond to the presence of both compounds in liquid medium.
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Pontes, Debora da Silva Lima [UNESP]. "Filmes finos ferroelétricos do tipo PBCT, PBST e PCST: estudo experimental e teórico." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/106648.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Perovisquita é a estrutura mais comum vista nos materiais ferroelétricos, a qual tem sido amplamente utilizado na indústria de dispositivos nas últimas décadas. Dentre essa classe de materiais o PbTiO3 é um dos materiais extensamente estudado devido a sua ampla faixa de aplicações como, por exemplo, capacitores, sensores piroelétrico e piezelétricos, memórias ferroelétricas. A substituição do Pb2+ pelos íons Ba2+/Ca2+, Ba2+/Sr2+ e Ca2+/Sr2+ no siste ma PbtiO3, a qual conduziu a formação de sistemas PBCT, PBST e PCST, produziu varias mudanças nas propriedades elétricas e estruturais desses materiais. No entanto, poucos trabalhos têm sido dedicados a esses sistemas baseado numa incorporação complexa de dois diferentes íons no sítio A, com relação a um profundo estudo teórico e experimental. A caracterização experimental por difração de raios X, espectroscopia micro-Raman e FT-IR mostram uma diminuição no grau de tetragonalidade para esses materiais. Essa alteração estrutural em função dos substituintes foi também responsável pela diminuição do grau de polarização. Nesta tese, foi aplicado também o método computacional dos primeiros princípios para estudar esta importante classe de materiais. A estrutura eletrônica, energia do banc gap, a densidade e estados (DOS) nos cristais ferroelétricos PBCT, PBST e PCST foram estudadas usando a teoria do funcional de densidade combinada com B3LYP. Os resultados teóricos foram correlacionados com os resultados experimentais para investigar e interpretar melhor a influência dos pares de íons Ba/Ca, Ba/Sr e Ca/Sr na ferroeletricidade do sistema PT. Pela análise teórica o grau de polarização bem como de tetragonalidade diminuiu no sistema PCST comparado ao PBCT e PBST, devido à presença agora de um forte caráter de ligações iônicas dentro...
Perovskites are the most commonly seen ferroelectrics, which have been widely used in the industry of devices in the last few decades. In addition, Lead titanate (PbTiO3) is an extensively studied material wich a wide range of application, for intance as capacitors, piezoeletric and pyroelectric sensors and ferroelectric memories. The substitution of Pb2+ ions Ba2+/Ca2+, Ba2+/Sr2+ e Ca2+/Sr2+ ions in the PbTiO3 system, which leads to the formation of the PBCT, PBST e PCST systems, induces several change in the electric and structural properties of these materials. However, PBCT, PBST and PCST systems based on the complex incorporation of two different ions at site A have not been thoroughly investigated and the literature contains few reports concerning their experimental and theoretical study of these materials. The characterization with X-ray diffraction, Raman spectroscopy and spectroscopy techniques on the infrared region of these samples showed a decrease of the tetragonality degree. These structural modifications were also responsible by the decrease in the polarization degree of these samples. In this thesis, we also have applied first-principles computational methods to the study this important class of materials. The electronic structure, energy band structure, and density of states (DOS) in ferroelectric crystal PBCT and PCST are studied by using density functional theory (DFT) combined with the B3LYP. The theoretical results were correlated with experimentals results to investigate and interpret better the influence of pairs of ions Ba/Ca, Ba/Sr and Ca/Sr on the ferroelectricity of the system PT. By theoretical analysis the degree of polarization as well as ferroelectricity in the PCST decreased compared with the systems PBCT and PBST, due to the presence of strong ionic character in this crystal... (Complete abstract click electronic access below)
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Sriram, Sharath, and sharath sriram@gmail com. "Deposition, Characterisation, and Piezoelectric Response Estimation of Strontium-doped Lead Zirconate Titanate Thin Films." RMIT University. Electrical and Computer Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090507.144751.
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Lead zirconate titanate (PZT), in the form of both bulk and thin films, is used in most piezoelectric applications due to its high piezoelectric response coefficients. Strontium-doped lead zirconate titanate (PSZT) has shown improved piezoelectric response characteristics in bulk form. This work investigates the deposition and characterisation of PSZT in the form of thin films, and reports on results from the estimation of the piezoelectric response of these thin films using two new techniques. The influence of RF magnetron sputter deposition parameters on the composition and orientation of PSZT thin films has been studied. Investigation of the consequence of varying the oxygen partial pressure during deposition on thin film stoichiometry, the influence of the choice of metal-coated silicon substrates on thin film orientation, and the effect of post-deposition cooling rate have been used to identify optimal deposition conditions. The existence of a modified unit cell resulting from these deposition parameters has been verified, and the resulting lattice parameters were estimated. Extensive materials characterisation (using microscopy, diffraction, and spectroscopy) of the PSZT thin films deposited on gold and platinum coated silicon substrates is reported. The limited techniques available for quantitative estimation of d33 for piezoelectric thin films initiated an investigation into alternative possibilities, as a consequence of which two new techniques for piezoelectric coefficient estimation, under the inverse piezoelectric effect, have been developed. One technique capitalises on the measurement accuracy of the nanoindenter in following thin film displacement, while the other uses a standard atomic force microscope in contact imaging mode to estimate d33. The development, scope, and limitations of both techniques are discussed. The techniques developed have been used to estimate the piezoelectric response of PSZT thin films. Depending on the thin film deposition parameters and the analysis frequency, values of piezoelectric response higher than any measured for thin films on silicon have been estimated. PSZT thin films deposited on gold-coated silicon at low deposition temperatures resulted in d33 values up to 892 pm/V. The study of the piezoelectric response in the millihertz frequency regime resulted in colossal values (ranging in tens of thousands of pm/V) for PSZT thin films deposited at high temperatures on platinum-coated silicon. This was hypothesised to be a result of enhanced ferroelastic domain switching. This hypothesis was verified by reducing the clamping on domains by synthesising island-structured PSZT films and obtaining an increased piezoelectric response.
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Luo, Hongyu Shih Wei-Heng Shih Wan Y. "Colloidal processing of PMN-PT thick films for piezoelectric sensor applications /." Philadelphia, Pa. : Drexel University, 2005. http://dspace.library.drexel.edu/handle/1860/500.
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Chen, Lang. "Effects of electric field on piezoelectric responses of ferroelectric thin films." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2182.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Material Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Ouyang, Jun. "Orientation dependence of the piezoelectric properties of epitaxial ferroelectric thin films." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2699.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Material Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Deng, Ken Kan. "Piezoelectric MEMS disk resonator and filter based on epitaxial Al0.3Ga0.7As Films." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4157.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Dalakoti, Abhishek. "Optimization of PZT based thin films and piezoelectric micromachined ultrasonic transducers (pMUTs)." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Fall2005/a%5Fdalakoti%5F083105.pdf.
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Pontes, Debora da Silva Lima. "Filmes finos ferroelétricos do tipo PBCT, PBST e PCST : estudo experimental e teórico /." Bauru : [s.n.], 2012. http://hdl.handle.net/11449/106648.
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Orientador: Elson Longo da SilvaBanca: Alberthmeiry Teixeira de Figueiredo
Banca: Alejandra Hortencia Miranda Gonzáles
Banca: Marcia Tsuyama Escote
Banca: Maria Fernanda do Carmo Gurgel
O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caracter institucional e integra as atividades de pesquisa em materiais de diversos campi
Resumo: Perovisquita é a estrutura mais comum vista nos materiais ferroelétricos, a qual tem sido amplamente utilizado na indústria de dispositivos nas últimas décadas. Dentre essa classe de materiais o PbTiO3 é um dos materiais extensamente estudado devido a sua ampla faixa de aplicações como, por exemplo, capacitores, sensores piroelétrico e piezelétricos, memórias ferroelétricas. A substituição do Pb2+ pelos íons Ba2+/Ca2+, Ba2+/Sr2+ e Ca2+/Sr2+ no siste ma PbtiO3, a qual conduziu a formação de sistemas PBCT, PBST e PCST, produziu varias mudanças nas propriedades elétricas e estruturais desses materiais. No entanto, poucos trabalhos têm sido dedicados a esses sistemas baseado numa incorporação complexa de dois diferentes íons no sítio A, com relação a um profundo estudo teórico e experimental. A caracterização experimental por difração de raios X, espectroscopia micro-Raman e FT-IR mostram uma diminuição no grau de tetragonalidade para esses materiais. Essa alteração estrutural em função dos substituintes foi também responsável pela diminuição do grau de polarização. Nesta tese, foi aplicado também o método computacional dos primeiros princípios para estudar esta importante classe de materiais. A estrutura eletrônica, energia do banc gap, a densidade e estados (DOS) nos cristais ferroelétricos PBCT, PBST e PCST foram estudadas usando a teoria do funcional de densidade combinada com B3LYP. Os resultados teóricos foram correlacionados com os resultados experimentais para investigar e interpretar melhor a influência dos pares de íons Ba/Ca, Ba/Sr e Ca/Sr na ferroeletricidade do sistema PT. Pela análise teórica o grau de polarização bem como de tetragonalidade diminuiu no sistema PCST comparado ao PBCT e PBST, devido à presença agora de um forte caráter de ligações iônicas dentro... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Perovskites are the most commonly seen ferroelectrics, which have been widely used in the industry of devices in the last few decades. In addition, Lead titanate (PbTiO3) is an extensively studied material wich a wide range of application, for intance as capacitors, piezoeletric and pyroelectric sensors and ferroelectric memories. The substitution of Pb2+ ions Ba2+/Ca2+, Ba2+/Sr2+ e Ca2+/Sr2+ ions in the PbTiO3 system, which leads to the formation of the PBCT, PBST e PCST systems, induces several change in the electric and structural properties of these materials. However, PBCT, PBST and PCST systems based on the complex incorporation of two different ions at site A have not been thoroughly investigated and the literature contains few reports concerning their experimental and theoretical study of these materials. The characterization with X-ray diffraction, Raman spectroscopy and spectroscopy techniques on the infrared region of these samples showed a decrease of the tetragonality degree. These structural modifications were also responsible by the decrease in the polarization degree of these samples. In this thesis, we also have applied first-principles computational methods to the study this important class of materials. The electronic structure, energy band structure, and density of states (DOS) in ferroelectric crystal PBCT and PCST are studied by using density functional theory (DFT) combined with the B3LYP. The theoretical results were correlated with experimentals results to investigate and interpret better the influence of pairs of ions Ba/Ca, Ba/Sr and Ca/Sr on the ferroelectricity of the system PT. By theoretical analysis the degree of polarization as well as ferroelectricity in the PCST decreased compared with the systems PBCT and PBST, due to the presence of strong ionic character in this crystal... (Complete abstract click electronic access below)
Doutor
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Willis, Jim. "Dependence of piezoelectric response in gallium nitride films on silicon substrate type." Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175274577.
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Zai, Marvin Ho-Ming. "Chemical synthesis of lead zirconate titanate thin films for a piezoelectric actuator." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367760.
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Tillman, Mark. "Effect of constrained sintering on the piezoelectric properties of PZT thick films." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7321.
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This thesis concerns the processing of thick lead zirconate titanate (PZT) films integrated with rigid substrates. The aim was to better understand the evolution of the microstructure, stress, and electrical properties of the films under constrained sintering conditions. This is an important process to understand because of the degrading effects that constrained sintering has on PZT films, which are employed vastly in commercial applications. It is hypothesised that the better understandings can lead to the development of PZT films that exhibit superior dielectric and piezoelectric properties than those in current production. The shrinkage of PZT films was examined in order to better understand the ways in which the rigidity of the substrate affects densification during sintering. This was done by processing isolated regions of PZT film on silicon substrates. These were sintered using a halogen bulb which exhibited a spot at a temperature of 725°C and with a ramp rate of less than 10 seconds. In this way the sintered regions could be ‘frozen’ mid sintering. The shrinkage of the films was determined at various sintering times. It was found that film shrinkage had finished within 2 minutes of sintering. The evolution of the constrained films during sintering was then examined as a function of the microstructure, stress and electrical property development. It was found that the grain sizes and electrical properties increased within 2 minutes of sintering. However, at longer sintering times there was a degradation of the films. Furthermore, tensile stresses developed during sintering which had degrading effects. This work was expanded upon by motioning the PZT films in a single line scan through the sintering spot to sinter larger areas of the film in one motion. This resulted in a high control over the sintering times, which was vital as the highest electrical properties were found at short sintering times. Next it was examined if the electrical properties could be further increased by applying a compressive stress. It was found that the dielectric properties increased as a result of increased domain wall vibrations. However, there was a decrease in domain reorientation during poling as a result of the effect of the compressive stress, thus the piezoelectric properties reduced. The evolution of PZT films under constrained sintering was better understood as a result of these studies, and led to the development of a sintering method in which the dielectric and piezoelectric properties were increased.
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Kabulski, Adam. "Aluminum nitride thin films and structures for piezoelectric microelectromechanical systems (PMEMS) applications." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5952.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vi, 70 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 67-70).
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Almusallam, Ahmed. "Screen-printed low temperature piezoelectric thick films for energy harvesting on fabrics." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/419487/.
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This thesis details the improvement in the dielectric, piezoelectric and mechanical (such as flexibility) properties of screen-printed flexible low-temperature PZT-polymer composite films on woven-fabrics. These improvements have been achieved by optimising the composite formulation and the post processing procedures. The polymeric binders were evaluated to find the optimum PZT-binder composite. The optimum PZT-binder composite with weight ratio 2.57:1 (denoted ECS-PolyPZT 6a) provided a relative dielectric constant of 146 and a d33 value of 22.8 pC/N at initial poling conditions measured on alumina. The PZT phase was a mixture of PZT particle sizes 2 and 0.8 μm with weight ratio of 4:1. Applying optimum poling conditions improved the d33 values to 36, 40 and 70 pC/N when the material screen-printed on alumina, Kapton and Polyester-cotton. The difference in the d33 coefficients on the different substrates is due to the clamping effect and in each case the free-standing d33fs value was calculated to be 80 pC/N. Applying cold isostatic pressing (CIP) at 250 MPa for 2 minutes improved the d33 values to 76.6 pC/N on Polyester-cotton. Adding 0.2% silver-nano particles by weight to the material improved the d33 to 76 pC/N on Polyester-cotton with no CIP. Combining these two measures yields a d33 value of 83 pC/N. The final optimised d33fs was 98 pC/N compared with the original value of 49 pC/N. When evaluating these films for use in energy harvesting applications, it was found that when applying compressive and tensile forces, the output mainly depends on the compliance of the substrate. The optimum PZT-binder composite printed on 1 × 1 cm2 woven-fabric Kermel, which has a higher compliance than Polyester-cotton and Cotton fabrics, provided output energy of 0.2 and 0.018 μJ/cycle when connected to a 30 and 1 MΩ resistive load in compression and tension, respectively. However, when applying a bending force to the sample, the output voltage increases with reducing compliance and increasing thicknesses of the substrate. Cotton substrates with lower compliances and higher thickness gave the highest energy output of 0.192 μJ per bending cycle into 70 MΩ when applying a bending curvature of 5 mm radius. Therefore, careful selection of the substrates is important to maximise the performance in sensing or energy harvesting application.
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LAURENTI, MARCO. "Synthesis and characterization of piezoelectric thin films as functional materials for sensing." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2591162.
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This thesis reports about the sputter deposition and characterization of ZnO nanomaterials both in the form of dense and sponge-like thin films. It is shown that high-quality ZnO thin films can be successfully grown on both hard and flexible conductive substrates, with the final aim of proving that their piezoelectric and electrical properties can be successfully exploited in the fabrication of piezoelectric-based nanosensors and nanoactuators. To further state the versatility of ZnO thin films, both spin coated and sputtered dense ZnO thin films were used as seed layers for promoting the growth of well-aligned ZnO nanowires. A strong relationship between the kind of seed layer, i.e., sputtered or spin-coated, and the final NWs morphology, surface chemistry and thus wettability was noticed. In particular NWs grown on sputtered seed layers showed a superhydrophobic behavior, ideal for self-cleaning, anti-fogging or microfluidic devices. In contrast, on spin coated seed layers, highly hydrophilic NWs were obtained, being suitable for further surface functionalization with enhanced adsorption properties towards biological agents or dye for imaging, diagnostic, optical or photovoltaic applications. Finally, the sponge-like morphology is further exploited for the synthesis and characterization of Mn- and Sb- doped, sponge-like ZnO films. The presence of Mn dopant resulted in a high resistance contribution. On the contrary, typical ferroelectric switching phenomena were observed in the Sb-doped ZnO films, showing the presence of hysteretical polarization loops.
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Li, Huidong Shih Wei-Heng Shih Wan Y. "Sodium potassium niobate-based lead-free piezoelectric ceramics: bulk and freestanding thick films /." Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2799.
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Farrell, Richard. "High temperature studies of thin film aluminum nitride and piezoelectric characterization of mesa structures." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10299.
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Thesis (M.S.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains vi, 74 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 68-71).
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Yalamanchili, Hyma. "Dynamic bandgap tuning of solid thin film photonic crystal structures." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/10976.
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Thesis (M.S.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains viii, 95 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 89-95).
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Kang, Chiwon Kim Dong Joo. "Structural and electrical characterization of highly oriented (KxNax)NbO3 (KNN) thin films by chemical solution deposition." Auburn, Ala, 2009. http://hdl.handle.net/10415/1604.
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Piekarski, Brett Harold. "Lead zirconate titanate thin films for piezoelectric actuation and sensing of mems resonators." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/3195.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Shepley, Philippa Mary. "Effect of piezoelectric strain on the magnetic properties of Pt/Co thin films." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11758/.
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The effect of strain from piezoelectric transducers on the perpendicular magnetic anisotropy (PMA), magnetic domain wall energy and domain wall creep motion of Pt/Co thin films has been investigated. Thin films of Pt/Co/X, where X is Pt, Ir/Pt or Ir, were deposited by sputtering onto thin glass substrates, which were bonded to piezoelectric transducers. Applying a voltage of up to 150 V to the transducers caused tensile out-of-plane strain in the Pt/Co/X thin films for the case of biaxial transducers, and a uniaxial in-plane tensile strain in the case of uniaxial transducers. Measurements of magnetic anisotropy showed that tensile out-of-plane strain lowered the PMA of Pt/Co/Pt, while uniaxial in-plane strain induced an in-plane magnetic anisotropy. To understand the effect of strain on the magnetic domain walls in Pt/Co/X thin films, the Dzyaloshinskii-Moriya interaction (DMI) field was measured. The DMI field varied between Pt/Co/X films, from close to zero in some Pt/Co/Pt films, indicating domain walls with a Bloch structure, to values large enough to give domain walls a strong Néel component. The DMI field did not change significantly under tensile out-of-plane strain, meaning changes in the domain wall energy were due only to the change in PMA. Magnetic hysteresis loops of Pt/Co/X thin films showed that the coercive field was reduced by the change in PMA under strain. The magnetisation reversal was investigated further by measurements of the velocity of magnetic domain walls in the creep regime. The domain wall velocity increased by between 10 and 90 % under tensile out-of-plane strain. No measurable changes were seen in the pinning energy of the films, showing that while the height of the barrier to magnetisation reversal is reduced, the anisotropy energy landscape is not distorted significantly. The highest changes in domain wall velocity were seen in the Pt/Co/Pt films with very low DMI fields, from which it is concluded that the creep velocity of Bloch domain walls is more sensitive to strain than that of walls with a Néel component.
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Schweizer, Thomas Martin. "Electrical characterization and investigation of the piezoresistive effect of PEDOT:PSS thin films." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04172005-231324/unrestricted/schweizer%5Fthomas%5Fm%5F200505%5Fmast.pdf.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005.Kippelen, Bernard, Committee Member ; Brand, Oliver, Committee Chair ; Allen, Mark G., Committee Member. Includes bibliographical references.
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Hobbs, William Bradford. "Piezoelectric energy harvesting: vortex induced vibrations in plants, soap films, and arrays of cylinders." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33811.
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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.
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Riosbaas, Miranda Tiffany. "Phase Change Activation and Characterization of Spray-Deposited Poly(vinylidene) Fluoride Piezoelectric Thin Films." Thesis, University of California, Davis, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1585118.
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Structural safety and integrity continues to be an issue of utmost concern in our world today. Existing infrastructures in civil, commercial, and military applications are beginning to see issues associated with age and environmental conditions. In addition, new materials are being put to service that are not yet fully characterized and understood when it comes to long term behavior. In order to assess the structural health of both old and new materials, it is necessary to implement a technique for monitoring wear and tear. Current methods that are being used today typically depend on visual inspection techniques or handheld instruments. These methods are not always ideal for large structures as they become very tedious leading to a substantial amount of both time and money spent. More recently, composite materials have been introduced into applications that can benefit from high strength-to-weight ratio materials. However, the use of more complex materials (such as composites) leads to a high demand of structural health monitoring techniques, since the damage is often internal and not visible to the naked eye. The work performed in this thesis examines the methods that can be used for phase change activation and characterization of sprayable poly(vinylidene) fluoride (PVDF) thin films in order to exploit their piezoelectric characteristics for sensing applications. PVDF is widely accepted to exist in four phases: alpha, beta, gamma, and delta. Alpha phase PVDF is produced directly from the melt and exhibits no piezoelectric properties. The activation or transition from α phase to some combination of beta and/or gamma phase PVDF leads to a polarizable piezoelectric thin film to be used in sensing applications. The work herein presents the methods used to activate phase change in PVDF, such as mechanical stretching, annealing, and chemical composition, to be able to implement PVDF as an impact detection sensor. The results and analysis provided in this thesis will present the possibilities of spray-deposited PVDF thin films in both small-scale and large-scale sensing applications that can be applied to both simple and complex geometries.
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Starschich, Sergej [Verfasser]. "Ferroelectric, Pyroelectric and Piezoelectric Effects of Hafnia and Zirconia Based Thin Films / Sergej Starschich." München : Verlag Dr. Hut, 2017. http://d-nb.info/1149579447/34.
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Hsieh, Peter Y. (Peter Yaw-ming) 1975. "DC magnetron reactive sputtering of low stress AlN piezoelectric thin films for MEMS application." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9736.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.Includes bibliographical references (p. 59-60).
Microelectromechanical systems (MEMS) often incorporate piezoelectric thin films to actuate and detect motion of mechanical structures. Aluminum nitride is advantageous for MEMS use because it can be deposited at low temperatures, is easily patterned using conventional photolithographic techniques, and is compatible with CMOS contaminant requirements for silicon IC foundries. In this work, AIN thin films were deposited on silicon for use in a MEMS ultrasonic resonator. The resonator is configured as a gravimetric chemical sensor. A rotatable central composite designed experiment was performed to optimize film properties affecting device performance: film crystallinity, stress, and uniformity. Film property response characterization was conducted with x-ray diffractometry, spectroscopic ellipsometry, and surface profilometry. Optimization of film deposition parameters improved AIN film properties in the MEMS sensors. Film property characterization using response surface methodology indicated microstructural changes due to sputtered particle bombardment of the growing film surface. Surface morphology of the sputtered AIN films was assessed using tapping mode atomic force microscopy and scanning electron microscopy. Energetic particle bombardment of the growing film surface helped to yield dense crystalline films with zone T microstructure. Thermalization of the impinging particle flux resulted in voided films with zone 1 microstructure with inferior film properties. Correlation between film crystallinity and oxygen content was explored with x-ray photoelectron spectrometry. Changes in film microstructure and composition are correlated with variations in deposition parameters. Adatom mobility during film growth appears to play an important role in determining final film properties.
by Peter Y. Hsieh.
S.M.
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Martinez, Julia Vivian. "Fabrication, materials, and characterization for efficient MEMS power generation." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Thesis/Summer2004/j%5Fmartinez%5F072604.pdf.
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Harnagea, Catalin. "Local piezoelectric response and domain structures in ferroelectric thin films investigated by voltage modulated force microscopy." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963578456.
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Lorenzo, Robert. "Piezoelectric properties of metalorganic chemical vapor deposition-grown gallium nitride films under an applied electric field." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1173985036.
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Moreira, Milena de Albuquerque 1977. "Synthesis of thin piezoelectric ALN films in view of sensors and telecom applications = Síntese de filmes finos de ALN piezoelétrico para aplicações em sensores e dispositivos de alta frequência." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260817.
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Orientador: Ioshiaki DoiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Os requisitos do mercado consumidor de dispositivos de alta frequência têm sido cada vez mais exigentes nas últimas décadas. Assim, é necessária uma melhoria contínua no desempenho dos dispositivos a fim de atender a estes requisitos. Numa visão macro, alterações no desenho dos dispositivos podem resultar em melhoria de desempenho. Em uma visão micro, as propriedades físicas dos materiais que compõem os dispositivos têm uma forte influência no desempenho final dos mesmos. No caso de dispositivos de alta frequência baseados em materiais piezoelétricos, uma forma natural de melhorar o seu desempenho é através da melhoria das propriedades da camada piezoelétrica. O material piezoelétrico estudado neste trabalho é o Nitreto de Alumínio (AlN), o qual destaca-se entre outros materiais piezoelétricos devido à sua combinação única de propriedades. Esta tese apresenta o resultado de estudos experimentais na síntese de filmes finos de AlN tendo em vista aplicações em altas frequências, microeletrônica e sensores. O principal objetivo desta tese é a melhoria nas propriedades funcionais do AlN para melhor atender aos requisitos das aplicações em questão. Isto é obtido através do controle cuidadoso da estrutura, textura cristalográfica e composição do filme. As propriedades piezoelétricas dos filmes de AlN foram melhoradas através da dopagem dos filmes com Sc. Amostras com diferentes concentrações de Sc foram fabricadas e analisadas, e o valor do coeficiente de acoplamento eletromagnético (kt2) foi duplicado ao adicionar 15 % de Sc aos filmes de AlN. O aumento no valor de kt2 é desejável uma vez que pode diminuir as restrições no projeto de dispositivos de alta frequência. Neste trabalho é proposta também uma nova configuração experimental com o objetivo de obter um melhor controle na deposição de filmes de AlN inclinados no eixo-c. Filmes com uniformidade em espessura e inclinação foram obtidos ao utilizar-se a referida configuração experimental. Filmes com tais características são aplicáveis em sensores baseados em dispositivos eletroacústicos operando em meio líquido/viscoso. Foram também realizados estudos com o objetivo de obter filmes de AlN orientados no eixo-c e depositados diretamente sobre substratos de Si e a temperaturas reduzidas. A técnica de deposição utilizada foi HiPIMS e os resultados indicam melhorias significativas na textura dos filmes quando comparados com o processo de deposição convencional por corrente-direta pulsada
Abstract: The requirements of the consumer market on high frequency devices have been more and more demanding over the last decades. Thus, a continuing enhancement of the devices¿ performance is required in order to meet these demands. In a macro view, changing the design of the device can result in an improvement of its performance. In a micro view, the physical properties of the device materials have a strong influence on its final performance. In the case of high frequency devices based on piezoelectric materials, a natural way to improve their performance is through the improvement of the properties of the piezoelectric layer. The piezoelectric material studied in this work is AlN, which is an outstanding material among other piezoelectric materials due to its unique combination of material properties. This thesis presents results from experimental studies on the synthesis of AlN thin films in view of telecom, microelectronic and sensor applications. The main objective of the thesis is to custom design the functional properties of AlN to best suit these for the specific application in mind. This is achieved through careful control of the crystallographic structure and texture as well as film composition. The piezoelectric properties of AlN films were enhanced by doping with Sc. Films with different Sc concentrations were fabricated and analyzed, and the coupling coefficient (kt2) was enhanced a factor of two by adding 15 % of Sc to the AlN films. The enhancement of kt2 is of interest since it can contribute to a more relaxed design of high frequency devices. Further, in order to obtain better deposition control of c-axis tilted AlN films, a new experimental setup were proposed. When this novel setup was used, films with well-defined thicknesses and tilt uniformity were achieved. Films with such characteristics are very favorable to use in sensors based on electroacoustic devices operating in viscous media. Studies were also performed in order to obtain c-axis oriented AlN films deposited directly on Si substrates at reduced temperatures. The deposition technique used was HiPIMS, and the results indicated significant improvements in the film texture when comparing to the conventional Pulsed DC deposition process
Doutorado
Eletrônica, Microeletrônica e Optoeletrônica
Doutora em Engenharia Elétrica
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Yoon, Sang Hoon Kim Dong Joo. "Growth and characterization of ZNO and PZT films for micromachined acoustic wave devices." Auburn, Ala, 2009. http://hdl.handle.net/10415/1719.
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Lusiola, Tony. "Synthesis and processing of KNN powders and thick films for MEMS devices." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7846.
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Pb-free piezoelectric materials have grown in importance through increased environmental concern related to the presence of Pb and the subsequent legislation that has arisen including directives such as Waste Electrical and Electronic Equipment (WEEE) and the Restriction of Hazardous Substances Directive (RoHS). While much progress has been made on producing Pb-free bulk materials, the need to integrate these next generation Pb-free piezoelectric materials with substrates to form functional micro devices has received less attention and raises a number of challenges. With respect to the high temperature mixed oxide synthesis method, a simple, cost effective and robust low temperature molten hydroxide synthesis (MHS) method derived from the molten salt synthesis (MSS) method, has been developed to produce K0.5Na0.5NbO3 (KNN) small grain powders and is a method that lends itself easily to industrial scale up. A powder/sol gel composite ink film forming technique has been used to produce KNN thick films on silicon substrates. Characterisation of the produced films has shown the films to exhibit piezoelectric coefficients for un-doped material in the region of 30pC/N. The work will report on the Na ion favouring mechanism of the MSS and the related mechanism of the MHS. The work will also report on the dielectric and piezoelectric characteristics of initial KNN thick films produced and an investigation into use of dopants and process modification to improve the KNN thick film’s characteristics.
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Chaban, Nicolas. "Ingénierie des contraintes de films minces d'oxydes de LaNiO3 : les substrats piézoélectriques." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00721808.
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Ce travail est né de l'idée d'associer l'ingénierie des matériaux sous forme de couches minces, domaine qui motive depuis de nombreuses années les chercheurs du LMGP, à des substrats piézoélectriques à fort coefficients de déformation. Les matériaux piézoélectriques peuvent convertir une énergie électrique en une énergie mécanique (de déformation) et vice-versa. Il est alors aisé d'imaginer qu'une couche mince synthétisée à la surface d'un substrat piézoélectrique profitera de la déformation de ce dernier quand il est soumit à un champ électrique. Le substrat mis en jeu est le PMN-PT, composé qui présente de forts coefficients de déformation. Dans cette étude le film synthétisé et mis en œuvre est le LaNiO3. Il cristallise dans une structure pérovskite ABO3. Cette structure présente l'avantage de permettre une grande variété de distorsions structurales et peut accueillir un grand nombre d'éléments chimiques.
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Starschich, Sergej [Verfasser], Rainer [Akademischer Betreuer] Waser, and Michael [Akademischer Betreuer] Heuken. "Ferroelectric, Pyroelectric and Piezoelectric Effects of Hafnia and Zirconia Based Thin Films / Sergej Starschich ; Rainer Waser, Michael Heuken." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1162503297/34.
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Akitegetse, Cléophace. "Approche numérique et expérimentale pour l'amélioration d'une méthode de mesure de la force d'adhérence de la glace par l'utilisation de films piezoélectriques /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2007. http://theses.uqac.ca.
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Thèse (M.Eng.) -- Université du Québec à Chicoutimi, 2007.La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ingénierie. CaQQUQ Bibliogr.: f. 133-137. Document électronique également accessible en format PDF. CaQQUQ
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Dauchy, Florent. "Stress analysis, dielectric, piezoelectric, and ferroelectric properties of PZT thick films. Fabrication of a 50MHz Tm-pMUT annular array." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/2464.
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PZT films up to 35 μm thick were fabricated, using a composite sol gel route combining a PZT powder and a PZT sol. The maximum temperature for the process was 710°C. A demonstration of single layer and multilayer structures was given to show the flexibility of this technology. With Stoney’s Equation, studies of the in-situ film stress development as a function of the film thickness and density was effectuated. It helped to understand that the internal forces increase considerably with the film thickness and density. This study yields to set up experimental conditions in which a crack free surface finish of a 28μm thick film revealed the adaptability of the spin coating technique to fabricate thick films. The wet etching technology revealed the possibility of a great adaptability to pattern and shape innovative devices such as bars 10 μm wide of 21μm PZT thick film. The results open the way to a wide range of new industrial application requiring small features and/or multilayer PZT thick film with embedded electrodes. The single element and annular array devices have been shown to resonate at approximately 60MHz in air and 50 MHz in water. Three types of the composite thick film – 2C+4S, 2C+5S and 2C+6S – were used to fabricate the Tm-pMUT devices. In each case the most effective poling was obtained by maintaining the poling field of 8.4V/μm during cooling from the poling temperature (200ºC) to ‘freeze’ poled domains in place. This ‘freezing’ was required to prevent the tensile stresses within the film from reorienting the domains at high temperatures when the poling field is removed. Increasing values of thickness mode coupling coefficient (kt) were observed with increasing levels of sol infiltration (decreasing density). Such behaviour is thought to be due to non linear effects on the piezoelectric coefficient (e33) at high levels of porosity. For very dense thick film material a kt of 0.47 was observed which is comparable to that observed for the bulk material.
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WANG, ZHI-MING, and 王志明. "The studies of piezoelectric polyvinylidene fluoride films." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/09820725991647926390.
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Gomes, Isabel Alexandra Domingues Tarroso. "Manganite thin films deposited on piezoelectric substrates." Doctoral thesis, 2013. http://hdl.handle.net/1822/27324.
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Tese de doutoramento Programa Doutoral em Física (MAP-FIS)O interesse crescente em conseguir controlar a magnetização de materiais magnéticos através de campos eléctricos, para aplicações em spintrónica, levou ao desenvolvimento de compósitos magnetoeléctricos com diversas geometrias e composiçoes. Entre estas estruturas compósitas encontram-se os lmes nos de manganites com magnetorresistência colossal depositados sobre substratos piezoeléctricos. Estas estruturas permitem, por um lado, tirar partido do facto de as manganites com magnetorresistência colossal serem particularmente sensíveis aos efeitos de deformação e, por outro, da possibilidade de controlar de maneira reversível a deformação imposta aos lmes e, consequentemente, a sua magnetização, por meio da utilização de substratos piezoeléctricos. Neste trabalho, lmes nos da manganite ferromagnética e metálica La0:67Sr0:33MnO3 (LSMO), com alta largura de banda, e da manganite com ordenamento de carga e baixa largura de banda Pr0:50Ca0:50MnO3 (PCMO) foram depositados em substratos cristalinos piezoeléctricos de LiNbO3 e 0.68Pb(Mg1=3Nb2=3)O3 0.32PbTiO3 (PMN-PT). Foi feita uma caracterização detalhada das suas propriedades estruturais, magnéticas e de transporte eléctrico. Os lmes de LSMO depositados sobre LiNbO3 eram fortemente orientados, com uma direcção preferencial de crescimento (111) pseudocúbica. Veri cou-se, nos lmes, uma transição paramagnética-ferromagnética, com temperaturas de Curie entre 265 K e 360 K, e resistividades eléctricas de baixa temperatura na gama 0:15 0 4:5 .cm. Nestas amostras veri cou-se que a temperatura de deposição afectou as propriedades dos lmes produzidos, no sentido em que um aumento da temperatura de deposição de 600 C para 690 C aumentou a temperatura de Curie de 265 K para 330 K e originou um comportamento metálico. O comportamento da magnetorresistência variou com o aumento da temperatura de deposição, tendo-se observado a supressão da acentuada magnetorresistência de baixo campo. Esta tinha um valor aproximado de -15%, e tinha surgido no lme depositado a 600 C devido ao efeito túnel através das fronteiras de grão, que é dependente do spin. Isto foi também observado nas medidas de magnetorresistência anisotrópica. Nos lmes nos de LSMO sobre substratos ferroeléctricos de PMN-PT do tipo relaxor , foi observado um crescimento com orientação pseudocúbica (001). Foram também observados pequenos incrementos na magnetização abaixo da temperatura de Curie TC = 340 K. Veri cou-se uma correlação entre estas variações na magnetização dos lmes e variações na constante dieléctrica dos substratos, o que sugere um acoplamento magnetoeléctrico. A resistência eléctrica dos lmes foi medida em função do campo eléctrico aplicado ao substrato, o que mais uma vez mostrou um acoplamento através da deformação piezoeléctrica. A maior taxa de variação da resistência obtida foi de 10 /V. Este valor foi medido na zona de baixo campo eléctrico, i.e., onde a deformação é reversível. Os lmes nos de PCMO depositados sobre LiNbO3, orientados segundo c, possuíam também uma orientação (111) pseudocúbica. O seu parâmetro de rede variou sistematicamente com a sua espessura. A fase com ordenamento de carga foi estabilizada nestes lmes e a temperatura TCO a qual ela ocorreu encontrava-se na gama 210 TCO 240 K. Para além disso, TCO aumentou com o decréscimo da espessura dos lmes, devido a deformação epitaxial induzida pelo seu crescimento. A magnetorresistência do PCMO depositado num substrato de LiNbO3 orientado segundo c foi medida numa unidade de campos magnéticos pulsados. Foi observada uma transição de uma fase metálica com cargas desordenadas, para uma fase isoladora com ordenamento de carga. Esta transição ocorreu a um campo crítico H c = 2:3 T a temperatura de 200 K, numa medida efectuada em campo magnético decrescente. Finalmente, os lmes nos de PCMO depositados em PMN-PT eram orientados, com uma orientação preferencial de crescimento (001) pseudocúbica. Foi observado o controlo piezoeléctrico da resistência eléctrica. A taxa de variação da resistência eléctrica dos lmes foi de 11 /V na região reversível da curva de deformação em função do campo eléctrico aplicado.
The growing interest in controlling the magnetization by electric elds for spintronics applications has led to the development of magnetoelectric composites with diverse geometries and compositions. Among these composite structures are colossal magnetoresistive manganite thin lms deposited on piezoelectric substrates. Colossal magnetoresistive manganites, on the one hand, are particularly sensitive to the e ects of strain, making them good candidates for incorporation in magnetoelectric composites. On the other hand, piezoelectric substrates allow for a reversible control of the strain applied to the lms, and therefore of the magnetization. In this work, high-bandwidth ferromagnetic metallic manganite La0:67Sr0:33MnO3 (LSMO) and low-bandwidth charge-ordered Pr0:50Ca0:50MnO3 (PCMO) were deposited on LiNbO3 and 0.68Pb(Mg1=3Nb2=3)O3 0.32PbTiO3 (PMN-PT) single crystal piezoelectric substrates. A detailed characterization of the structural, magnetic and transport properties of the produced samples has been performed. The LSMO thin lms on LiNbO3 were highly oriented, with a pseudocubic (111) preferred growth direction. The lms were ferromagnetic with Curie temperatures between 265 K and 360 K and low temperature resistivity values in the range 0:15 0 4:5 .cm. In these samples the deposition temperature was seen to a ect the properties of the deposited lms, in the sense that an increase in the deposition temperature from 600 C to 690 C strongly enhances the ferromagnetic Curie temperature from 265 K to 330 K and increases metallic conduction. The magnetoresistance behaviour is also modi ed as the deposition temperature is increased, with the suppression of the low eld magnetoresistance due to spin polarized tunnelling across grain boundaries. This is con rmed by the measurements of anisotropic magnetoresistance. In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical In the LSMO thin lms deposited on the relaxor ferroelectric PMN PT a pseudocubic (001)-oriented growth was observed. Slight increases in the magnetization, below the Curie temperature TC = 340 K, were observed in the lms. These variations were found to correlate with variations in the dielectric constant of the substrate, suggesting a magnetoelectric coupling. The electrical resistance of the lms was measured as a function of the electric eld applied to the substrate, once again showing a coupling via piezoelectric strain. The resistance varied up to 10 /V in the low electric eld region, i.e., where the strain is reversible. The PCMO thin lms deposited on z-cut LiNbO3 were also pseudocubic (111)-oriented. Their pseudocubic lattice parameter varied systematically with lm thickness. The charge-ordered phase was stabilized in the lms and the temperature TCO at which it occurs was in the range 210 TCO 240 K. Moreover, TCO increased with decreasing lm thickness due to thickness-induced strain in the lms. The magnetoresistance of a PCMO lm on z-cut LiNbO3 was measured with pulsed magnetic elds. The critical magnetic eld at which the crossover from the charge-disordered, metallic phase to the charge-ordered phase was measured in decreasing eld, and the obtained value was H c = 2:3T at 200 K, much smaller than in previous studies of lms on SrTiO3 or LaAlO3. If this corresponds to a lower value for the charge ordering melting eld, it can make the PCMO thin lms on LiNbO3 more suitable for applications. Finally, the thin lms of PCMO deposited on PMN-PT were oriented, with a preferred pseudocubic (001) growth direction. A piezoelectric control of the electrical resistance of the lms was observed. The variation of the electrical resistance with the applied electric eld was around 11 /V in the reversible region of the strainelectric eld curve.
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Lin, Chih-Wei, and 林志緯. "Study on Fabrication and Properties of Piezoelectric Films." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/szy2x9.
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Lai, Jen-Hui, and 賴仁暉. "Study of Piezoelectric Thin Films bySol-Gel Process." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/43759238933719518732.
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碩士大葉大學
機械工程研究所碩士班
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This dissertation will focus on the method of Sol-Gel by using the serial solution of Diol to process another solution of piezoelectric films. Moreover, in this dissertation some issues like the characteristics regarding piezoelectricity are discussed: P-E curve of piezoelectric films, dielectric constant , coercive field , remnant polarization , piezoelectric coefficient and , fatigue test. As for PZT piezoelectric films’ thickness, we have already deepened its thickness up to 1.45µm by applying spin-coater spirally to avoid rupturing. According to my experiment result, it is possible to manufacture static and fine piezoelectric films. Plus, when gauging out the remnant polarization value is 26.8 , while coercive field value is 2.82 , I also learn that due to the dropping of temperature and deepening of piezoelectric films’ thickness, the remnant polarization value of piezoelectric films would have a excellent representation. As for fatigue test, I do the measuring with the value of 105, 107, and 109 respectively. Among them, only the experiment with the value of 109 does great changes－the phenomenon of fatigue occurs－after a long time testing. The other values like 105, 107 have little alteration in this research.