Relevant bibliographies by topics / Piezoelectric films

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Piezoelectric films'

Author: Grafiati
Published: 6 September 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Piezoelectric films.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Piezoelectric films"

1

Tyunina, Marina, Jan Miksovsky, Tomas Kocourek, and Alexandr Dejneka. "Hysteresis-Free Piezoresponse in Thermally Strained Ferroelectric Barium Titanate Films." Electronic Materials 2, no. 1 (January 14, 2021): 17–23. http://dx.doi.org/10.3390/electronicmat2010002.

Full text
Abstract:
Modern technology asks for thin films of sustainable piezoelectrics, whereas electro-mechanical properties of such films are poorly explored and controlled. Here, dynamic and quasi-static polarization, dielectric, and piezoelectric responses were experimentally studied in thin-film stacks of barium titanate sandwiched between electrodes and grown on top of strontium titanate substrate. Accurate piezoelectric characterization was secured by using double beam interferometric technique. All out-of-plane responses were found to be hysteresis-free. Effective piezoelectric coefficient ~50 pm/V and linear strain-voltage characteristic were achieved. The observed behavior was ascribed to field induced out-of-plane polarization, whereas spontaneous polarization is in-plane due to in-plane tensile thermal strain. Hysteresis-free linear piezoresponse was anticipated in thin films on commercial silicon substrates, enabling large thermal strain.
APA, Harvard, Vancouver, ISO, and other styles
2

Miriyala, Kumaraswamy, and Ranjith Ramadurai. "Microstructural influence on piezoresponse and leakage current behavior of Na0.5Bi0.5TiO3 Thin Films." MRS Advances 1, no. 37 (2016): 2597–602. http://dx.doi.org/10.1557/adv.2016.350.

Full text
Abstract:
AbstractSodium bismuth titanate (Na0.5Bi0.5TiO3: NBT) a lead free piezoelectric; exhibits promising features such that it could be an alternate to lead based piezoelectrics. In this work, we report the microstructural influence on piezoelectric and leakage current behavior of NBT thin films grown by pulsed laser ablation (PLD). Various microstructural features like coarse faceted grains and fine spherical grains was achieved by effective optimization of substrate temperature and oxygen partial pressures. The studies reveals that, leakage current of NBT thin films were dominated by interface limited modified Schottky emission type of conduction. The piezoelectric domain studies reveal that for NBT thin films with fine spherical grain the domain pattern was highly dominated by the morphology and in the case of coarse faceted grains the domains were relatively large and the domains were extending beyond the grain boundaries.
APA, Harvard, Vancouver, ISO, and other styles
3

Zhang Xin-Wu and Zhang Xiao-Qing. "Piezoelectric and acoustic behavior of polypropylene piezoelectret films." Acta Physica Sinica 62, no. 16 (2013): 167702. http://dx.doi.org/10.7498/aps.62.167702.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

SHIOSAKI, Tadashi. "Piezoelectric Thin Films." Journal of the Ceramic Society of Japan 99, no. 1154 (1991): 836–41. http://dx.doi.org/10.2109/jcersj.99.836.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Park, D. S., M. Hadad, L. M. Riemer, R. Ignatans, D. Spirito, V. Esposito, V. Tileli, et al. "Induced giant piezoelectricity in centrosymmetric oxides." Science 375, no. 6581 (February 11, 2022): 653–57. http://dx.doi.org/10.1126/science.abm7497.

Full text
Abstract:
Piezoelectrics are materials that linearly deform in response to an applied electric field. As a fundamental prerequisite, piezoelectric materials must have a noncentrosymmetric crystal structure. For more than a century, this has remained a major obstacle for finding piezoelectric materials. We circumvented this limitation by breaking the crystallographic symmetry and inducing large and sustainable piezoelectric effects in centrosymmetric materials by the electric field–induced rearrangement of oxygen vacancies. Our results show the generation of extraordinarily large piezoelectric responses [with piezoelectric strain coefficients ( d 33 ) of ~200,000 picometers per volt at millihertz frequencies] in cubic fluorite gadolinium-doped CeO 2− x films, which are two orders of magnitude larger than the responses observed in the presently best-known lead-based piezoelectric relaxor–ferroelectric oxide at kilohertz frequencies. These findings provide opportunities to design piezoelectric materials from environmentally friendly centrosymmetric ones.
APA, Harvard, Vancouver, ISO, and other styles
6

Maiwa, Hiroshi. "Electromechanical Properties of Ferroelectric Thin Films for Piezoelectric MEMS Applications." Advances in Science and Technology 45 (October 2006): 2422–31. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2422.

Full text
Abstract:
Piezoelectric microelectromechanical systems (MEMS) employing ferrroelectric thin films have been extensively studied. In this paper, materials issues of the piezoeletric films are presented. Temperature dependence of the electrical and electromechanical properties of Pb(ZrxTi1-x)O3 (PZT, x= 0.3, 0.52, and 0.7) thin films were measured using scanning probe microscopy in the temperature range from -100°C to 150°C. The field-induced displacement increased with increase of the temperature; however, their temperature dependence was relatively small, compared with that reported on bulk PZT ceramics. Thus far, the use of PZT film has been most widely studied for MEMS applications. However, the lead toxicity associated with PZT and other lead oxide-based ferroelectrics is problematic. Therefore, properties of the lead-free thin film piezoelectrics are also described in this paper. As candidate for the lead-free piezoelectrics, Bi4-xNdxTi3O12 (BNT) and Ba(Zr0.2Ti0.8)O3 (BZT) thin films are chosen. BNT and BZT films prepared by chemical solution deposition exhibit field-induced strain corresponding to 38 pm/V and 35 pm/V, respectively.
APA, Harvard, Vancouver, ISO, and other styles
7

Yi, Juan, Yiheng Song, Shixian Zhang, Zhilong Cao, Chenjian Li, and Chuanxi Xiong. "Corona−Poled Porous Electrospun Films of Gram−Scale Y−Doped ZnO and PVDF Composites for Piezoelectric Nanogenerators." Polymers 14, no. 18 (September 19, 2022): 3912. http://dx.doi.org/10.3390/polym14183912.

Full text
Abstract:
For digging out eco−friendly and well−performed energy harvesters, piezoelectric nanogenerators are preferred owing to their effortless assembly. Corona−poling promotes output performance of either aligned or porous PVDF electrospun films and higher piezoelectric output was achieved by corona−poled porous PVDF electrospun films due to more poled electret dipoles in pores. Increasing the duration of electrospinning rendered more electret dipoles in PVDF porous electrospun films, resulting in higher piezoelectric output. Moreover, corona−poled PVDF/Y−ZnO porous electrospun films performed better than corona−poled PVDF/ZnO porous electrospun films because of the larger polar crystal face of Y−ZnO. Flexible piezoelectric polymer PVDF and high−piezoelectric Y−ZnO complement each other in electrospun films. With 15 wt% of Y−ZnO, corona−poled PVDF/Y−ZnO porous electrospun films generated maximum power density of 3.6 μW/cm2, which is 18 times that of PVDF/BiCl3 electrospun films.
APA, Harvard, Vancouver, ISO, and other styles
8

Trolier-McKinstry, Susan, Shujun Zhang, Andrew J. Bell, and Xiaoli Tan. "High-Performance Piezoelectric Crystals, Ceramics, and Films." Annual Review of Materials Research 48, no. 1 (July 2018): 191–217. http://dx.doi.org/10.1146/annurev-matsci-070616-124023.

Full text
Abstract:
Piezoelectric materials convert between electrical and mechanical energies such that an applied stress induces a polarization and an applied electric field induces a strain. This review describes the fundamental mechanisms governing the piezoelectric response in high-performance piezoelectric single crystals, ceramics, and thin films. While there are a number of useful piezoelectric small molecules and polymers, the article focuses on inorganic materials displaying the piezoelectric effect. Piezoelectricity is first defined, and the mechanisms that contribute are discussed in terms of the key crystal structures for materials with large piezoelectric coefficients. Exemplar systems are then discussed and compared for the cases of single crystals, bulk ceramics, and thin films.
APA, Harvard, Vancouver, ISO, and other styles
9

Lavine, Marc S. "Piezoelectric bioorganic thin films." Science 373, no. 6552 (July 15, 2021): 291.15–293. http://dx.doi.org/10.1126/science.373.6552.291-o.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Nakagawa, Yasuhiko, and Yasuo Gomi. "New piezoelectric Ta2O5thin films." Applied Physics Letters 46, no. 2 (January 15, 1985): 139–40. http://dx.doi.org/10.1063/1.95712.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Piezoelectric films"

1

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.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Corkovic, Silvana. "Piezoelectric thick films for microelectromechanical systems application." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/1826.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
3

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.

Full text
Abstract:
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 comportements
Polycrystalline 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
APA, Harvard, Vancouver, ISO, and other styles
4

DURACCIO, DONATELLA. "Piezoelectric composite films for energy harvesting devices." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2872343.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

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.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
6

Xiang, Shu. "Piezoelectric thin films and nanowires: synthesis and characterization." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41139.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
7

Roe, Merrion Patricia. "Photosensitive and piezoelectric thin films for optical devices." Thesis, University of Southampton, 1996. https://eprints.soton.ac.uk/398885/.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
8

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.

Full text
Abstract:
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).
APA, Harvard, Vancouver, ISO, and other styles
9

Yin, Shi. "Integration of epitaxial piezoelectric thin films on silicon." Thesis, Ecully, Ecole centrale de Lyon, 2013. http://www.theses.fr/2013ECDL0039/document.

Full text
Abstract:
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 applications
Recently, 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
APA, Harvard, Vancouver, ISO, and other styles
10

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.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Piezoelectric films"

1

Defaÿ, Emmanuel. Integration of Ferroelectric and Piezoelectric Thin Films. Hoboken, NJ, USA: John Wiley & Sons, Inc, 2011. http://dx.doi.org/10.1002/9781118616635.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

European, Workshop on Piezoelectric Materials (4th 2004 Montpellier France). 4th European Workshop on Piezoelectric Materials: Montpellier, France, 21-23 July, 2004. Les Ulis, France: EDP Sciences, 2005.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Bruce, Tuttle, American Ceramic Society Meeting, and Advanced Dielectric, Piezoelectric and Ferroelectric Thin Films Symposium (2004 : Indianapolis, Ind.), eds. Advanced dielectric, piezoelectric and ferroelectric thin films: Proceedings of the 106th Annual Meeting of the American Ceramic Society : Indianapolis, Indiana, USA (2004). Westerville, Ohio: American Ceramic Society, 2005.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Lang, Sydney B. Frontiers of ferroelectricity: A special issue of the Journal of materials science. New York: Springer, 2007.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

McGinn, Christine. Thin film piezoelectric elements for active devices. [New York, N.Y.?]: [publisher not identified], 2022.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Güthner, Peter. Untersuchung der lokalen piezoelektrischen Eigenschaften dünner ferroelektrischer Polymerfilme. Konstanz: Hartung-Gorre, 1992.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

IEEE International Symposium on Applications of Ferroelectrics (10th 1996 East Brunswick, N.J.). ISAF '96: Proceedings of the Tenth IEEE International Symposium on Applications of Ferroelectrics, East Brunswick, NJ, U.S.A., August 18-21, 1996. Edited by Kulwicki Bernard M, Amin Ahmed, Safari Ahmad, Institute of Electrical and Electronics Engineers., and IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society. [New York, N.Y.]: Institute of Electrical and Electronics Engineers, 1996.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

IEEE International Symposium on Applications of Ferroelectrics (9th 1994 University Park, Pa.). ISAF '94: Proceedings of the Ninth IEEE International Symposium on Applications of Ferroelectrics, Penn State Scanticon Conference Center, the Pennsylvania State University, University Park, Pennsylvania, USA, August 7-August 10, 1994. Edited by Pandey R. K, Liu Michael, Safari Ahmad, Institute of Electrical and Electronics Engineers., and IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society. [New York, N.Y.]: Institute of Electrical and Electronics Engineers, 1994.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

IEEE International Symposium on Applications of Ferroelectrics (13th 2002 Nara-shi, Japan). ISAF 2002: Proceedings of the 13th IEEE International Symposium on Applications of Ferroelectrics : Nara, Japan, May 28-June 1, 2002. Edited by White Grady, Tsurumi Takaaki, and IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society. Piscataway, NJ: Institute of Electrical and Electronics Engineers, Ultrasonics, Ferroelectrics, and Frequency Control Society, 2002.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

IEEE International Symposium on Applications of Ferroelectrics (11th 1998 Montreux, Switzerland). ISAF 1998: Proceedings of the Eleventh IEEE International Symposium on Applications of Ferroelectrics, Montreux, Switzerland, August 24-27, 1998. Edited by Colla Enrico, Damjanovic Dragon, Setter N. 1949-, IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society., and Institute of Electrical and Electronics Engineers. Piscataway, NJ: Institute of Electrical and Electronics Engineers, 1998.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Piezoelectric films"

1

Cain, Markys G., and Mark Stewart. "Piezoelectric Resonance." In Characterisation of Ferroelectric Bulk Materials and Thin Films, 15–35. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-1-4020-9311-1_2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Seminara, Lucia, Maurizio Valle, Marco Capurro, Paolo Cirillo, and Giorgio Cannata. "Piezoelectric Polymer Films for Tactile Sensors." In Lecture Notes in Electrical Engineering, 169–73. Boston, MA: Springer US, 2011. http://dx.doi.org/10.1007/978-1-4614-0935-9_29.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Mironov, Aleksey, Pavel Doronkin, Aleksejs Safonovs, and Vitalijs Kuzmickis. "Piezoelectric Films Application for Vibration Diagnostics." In Lecture Notes in Networks and Systems, 201–12. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-26655-3_18.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Xu, Baomin, David White, James Zesch, Alexandra Rodkin, Steve Buhler, John Fitch, and Karl Littau. "Thick Piezoelectric Films from Laser Transfer Process." In Ceramic Transactions Series, 245–58. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118408186.ch23.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Huang, Zhaorong, and Glenn Leighton. "Interferometry for Piezoelectric Materials and Thin Films." In Characterisation of Ferroelectric Bulk Materials and Thin Films, 87–113. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-1-4020-9311-1_5.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Cain, Markys G., and Mark Stewart. "Standards for Piezoelectric and Ferroelectric Ceramics." In Characterisation of Ferroelectric Bulk Materials and Thin Films, 267–75. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-1-4020-9311-1_12.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Stewart, Mark, and Markys G. Cain. "Direct Piezoelectric Measurement: The Berlincourt Method." In Characterisation of Ferroelectric Bulk Materials and Thin Films, 37–64. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-1-4020-9311-1_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Sayer, M., D. A. Barrow, R. Noteboom, E. M. Griswold, and Z. Wu. "Piezoelectric and Ferroelectric Devices: Potential and Issues." In Science and Technology of Electroceramic Thin Films, 399–412. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-017-2950-5_29.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Verardi, P. "Piezoelectric Thin Films for High Frequency Electroacoustic Devices." In Piezoelectric Materials: Advances in Science, Technology and Applications, 285–92. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4094-2_28.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Küppers, H., T. Leuerer, U. Schnakenberg, W. Mokwa, M. Hoffmann, T. Schneller, U. Böttger, and R. Waser. "PZT thin films for piezoelectric micro-actuator applications." In Transducers ’01 Eurosensors XV, 990–93. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59497-7_234.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Piezoelectric films"

1

Al Ahmad, Mahmoud, Abdulellah Shaman, and Mousa Hussein. "Displacement Extraction of Piezoelectric Films." In 2018 IEEE 5th International Conference on Engineering Technologies and Applied Sciences (ICETAS). IEEE, 2018. http://dx.doi.org/10.1109/icetas.2018.8629185.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Hatch, Theodore, John Styrvoky, Jared Barton, Hualiang Zhang, Gayatri Mehta, and Sandra Boetcher. "Small-Scale Power Generation and Storage Using Piezoelectric Films." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64649.

Full text
Abstract:
Piezoelectric materials have many applications including sensors, actuators, and motors. However, the ability of piezoelectric films to generate electricity from wind power has only recently been advanced. Piezoelectric films harvest wind energy by means of a layer of polyvinylidene fluoride (PVDF) that upon deformation generates an internal electrical voltage across two silver-ink electrodes. These films are allowed to freely flap in an airflow to cause deformation and thus electricity generation. A single small film (4.14 cm (1.63 in) × 1.63 cm (0.64 in) × 0.15 cm (0.06 in)) is tested at various wind speeds. The output of the film may be enhanced with the addition of a bluff body (in this case, a cylinder) upstream from the film. The vortex shedding from the cylinder produces a wake that can enhance the vibrations of the piezoelectric device, which in turn optimize voltage and/or power output. Voltage and power output is recorded across varying load resistances. The method of storing useful energy from the piezoelectric films is also of particular interest. Preliminary experiments using a LTC3588-1 energy harvester to various configurations of supercapacitors and Li-ion batteries are conducted. The LTC3588-1 is comprised of an efficient rectifier with a buck converter to allow the chip to efficiently charge the super capacitor while only requiring a small input to begin charging.
APA, Harvard, Vancouver, ISO, and other styles
3

Liu, Tianning, Margeaux Wallace, Susan Trolier-McKinstry, and Thomas N. Jackson. "Piezoelectric thin films on polyimide substrates for flexible piezoelectric devices." In 2017 75th Device Research Conference (DRC). IEEE, 2017. http://dx.doi.org/10.1109/drc.2017.7999459.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Wang, J. J., J. M. Hsieh, R. W. Tsai, and Y. C. Su. "Piezoelectric PDMS films for power MEMS." In TRANSDUCERS 2011 - 2011 16th International Solid-State Sensors, Actuators and Microsystems Conference. IEEE, 2011. http://dx.doi.org/10.1109/transducers.2011.5969868.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Hrovat, Marko, Darko Belavic, Hana Ursic, Jena Cilensek, Silvo Drnov, Janez Holc, Marina Santo Zarnik, and Marija Kosec. "Piezoelectric thick films on LTCC substrates." In 2010 33rd International Spring Seminar on Electronics Technology (ISSE). IEEE, 2010. http://dx.doi.org/10.1109/isse.2010.5547259.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Zhang, X., X. Wang, G. Cao, D. Pan, and Z. Xia. "Piezoelectric polytetrafluoroethylene films with void structure." In 2009 IEEE 9th International Conference on the Properties and Applications of Dielectric Materials (ICPADM). IEEE, 2009. http://dx.doi.org/10.1109/icpadm.2009.5252280.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Gurin, Sergey A., Ekaterina A. Pecherskaya, Kseniya Yu Spitsyna, Andrey V. Fimin, Dmitriy V. Artamonov, and Anastasiya E. Shepeleva. "Thin Piezoelectric Films for Micromechanical Systems." In 2020 Moscow Workshop on Electronic and Networking Technologies (MWENT). IEEE, 2020. http://dx.doi.org/10.1109/mwent47943.2020.9067450.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Polla, Dennis L., P. J. Schiller, and L. F. Francis. "Microelectromechanical systems using piezoelectric thin films." In SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, edited by Massood Tabib-Azar, Dennis L. Polla, and Ka-Kha Wong. SPIE, 1994. http://dx.doi.org/10.1117/12.190900.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Krupanidhi, Saluru B., and Apurba Laha. "Integrated piezoelectric thin films for microactuators." In Smart Materials, Structures, and Systems, edited by S. Mohan, B. Dattaguru, and S. Gopalakrishnan. SPIE, 2003. http://dx.doi.org/10.1117/12.514850.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Trolier-McKinstry, Susan. "Piezoelectric films for MEMS applications (Conference Presentation)." In Active and Passive Smart Structures and Integrated Systems XIII, edited by Alper Erturk. SPIE, 2019. http://dx.doi.org/10.1117/12.2507279.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Piezoelectric films"

1

Polcawich, Ronald G. A Piezoelectric MEMS Microphone Based on Lead Zirconate Titanate (PZT) Thin Films. Fort Belvoir, VA: Defense Technical Information Center, November 2004. http://dx.doi.org/10.21236/ada429041.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Farrell, R., V. R. Pagan, A. Kabulski, Sridhar Kuchibhatl, J. Harman, K. R. Kasarla, L. E. Rodak, P. Famouri, J. Peter Hensel, and D. Korakakis. High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films. Office of Scientific and Technical Information (OSTI), May 2008. http://dx.doi.org/10.2172/1015474.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Johnson, Raegan Lynn. Characterization of piesoelectric ZnO thin films and the fabrication of piezoelectric micro-cantilevers. Office of Scientific and Technical Information (OSTI), January 2005. http://dx.doi.org/10.2172/850081.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Dudley, Michael. Synchrotron White Beam X-Ray Topography Characterization of LGX and SXGS Bulk Single Crystals, Thin Films and Piezoelectric Devices. Fort Belvoir, VA: Defense Technical Information Center, April 2007. http://dx.doi.org/10.21236/ada470957.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Trolier-McKinstry, Susan, and Thomas R. Shrout. Crystal Growth and Thin Film Deposition of High Performance Piezoelectrics. Fort Belvoir, VA: Defense Technical Information Center, January 2001. http://dx.doi.org/10.21236/ada428818.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Jones, Gary D., Roger Alan Assink, Tim Richard Dargaville, Pavel Mikhail Chaplya, Roger Lee Clough, Julie M. Elliott, Jeffrey W. Martin, Daniel Michael Mowery, and Mathew Christopher Celina. Characterization, performance and optimization of PVDF as a piezoelectric film for advanced space mirror concepts. Office of Scientific and Technical Information (OSTI), November 2005. http://dx.doi.org/10.2172/876343.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Galili, Naftali, Roger P. Rohrbach, Itzhak Shmulevich, Yoram Fuchs, and Giora Zauberman. Non-Destructive Quality Sensing of High-Value Agricultural Commodities Through Response Analysis. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7570549.bard.

Full text
Abstract:
The objectives of this project were to develop nondestructive methods for detection of internal properties and firmness of fruits and vegetables. One method was based on a soft piezoelectric film transducer developed in the Technion, for analysis of fruit response to low-energy excitation. The second method was a dot-matrix piezoelectric transducer of North Carolina State University, developed for contact-pressure analysis of fruit during impact. Two research teams, one in Israel and the other in North Carolina, coordinated their research effort according to the specific objectives of the project, to develop and apply the two complementary methods for quality control of agricultural commodities. In Israel: An improved firmness testing system was developed and tested with tropical fruits. The new system included an instrumented fruit-bed of three flexible piezoelectric sensors and miniature electromagnetic hammers, which served as fruit support and low-energy excitation device, respectively. Resonant frequencies were detected for determination of firmness index. Two new acoustic parameters were developed for evaluation of fruit firmness and maturity: a dumping-ratio and a centeroid of the frequency response. Experiments were performed with avocado and mango fruits. The internal damping ratio, which may indicate fruit ripeness, increased monotonically with time, while resonant frequencies and firmness indices decreased with time. Fruit samples were tested daily by destructive penetration test. A fairy high correlation was found in tropical fruits between the penetration force and the new acoustic parameters; a lower correlation was found between this parameter and the conventional firmness index. Improved table-top firmness testing units, Firmalon, with data-logging system and on-line data analysis capacity have been built. The new device was used for the full-scale experiments in the next two years, ahead of the original program and BARD timetable. Close cooperation was initiated with local industry for development of both off-line and on-line sorting and quality control of more agricultural commodities. Firmalon units were produced and operated in major packaging houses in Israel, Belgium and Washington State, on mango and avocado, apples, pears, tomatoes, melons and some other fruits, to gain field experience with the new method. The accumulated experimental data from all these activities is still analyzed, to improve firmness sorting criteria and shelf-life predicting curves for the different fruits. The test program in commercial CA storage facilities in Washington State included seven apple varieties: Fuji, Braeburn, Gala, Granny Smith, Jonagold, Red Delicious, Golden Delicious, and D'Anjou pear variety. FI master-curves could be developed for the Braeburn, Gala, Granny Smith and Jonagold apples. These fruits showed a steady ripening process during the test period. Yet, more work should be conducted to reduce scattering of the data and to determine the confidence limits of the method. Nearly constant FI in Red Delicious and the fluctuations of FI in the Fuji apples should be re-examined. Three sets of experiment were performed with Flandria tomatoes. Despite the complex structure of the tomatoes, the acoustic method could be used for firmness evaluation and to follow the ripening evolution with time. Close agreement was achieved between the auction expert evaluation and that of the nondestructive acoustic test, where firmness index of 4.0 and more indicated grade-A tomatoes. More work is performed to refine the sorting algorithm and to develop a general ripening scale for automatic grading of tomatoes for the fresh fruit market. Galia melons were tested in Israel, in simulated export conditions. It was concluded that the Firmalon is capable of detecting the ripening of melons nondestructively, and sorted out the defective fruits from the export shipment. The cooperation with local industry resulted in development of automatic on-line prototype of the acoustic sensor, that may be incorporated with the export quality control system for melons. More interesting is the development of the remote firmness sensing method for sealed CA cool-rooms, where most of the full-year fruit yield in stored for off-season consumption. Hundreds of ripening monitor systems have been installed in major fruit storage facilities, and being evaluated now by the consumers. If successful, the new method may cause a major change in long-term fruit storage technology. More uses of the acoustic test method have been considered, for monitoring fruit maturity and harvest time, testing fruit samples or each individual fruit when entering the storage facilities, packaging house and auction, and in the supermarket. This approach may result in a full line of equipment for nondestructive quality control of fruits and vegetables, from the orchard or the greenhouse, through the entire sorting, grading and storage process, up to the consumer table. The developed technology offers a tool to determine the maturity of the fruits nondestructively by monitoring their acoustic response to mechanical impulse on the tree. A special device was built and preliminary tested in mango fruit. More development is needed to develop a portable, hand operated sensing method for this purpose. In North Carolina: Analysis method based on an Auto-Regressive (AR) model was developed for detecting the first resonance of fruit from their response to mechanical impulse. The algorithm included a routine that detects the first resonant frequency from as many sensors as possible. Experiments on Red Delicious apples were performed and their firmness was determined. The AR method allowed the detection of the first resonance. The method could be fast enough to be utilized in a real time sorting machine. Yet, further study is needed to look for improvement of the search algorithm of the methods. An impact contact-pressure measurement system and Neural Network (NN) identification method were developed to investigate the relationships between surface pressure distributions on selected fruits and their respective internal textural qualities. A piezoelectric dot-matrix pressure transducer was developed for the purpose of acquiring time-sampled pressure profiles during impact. The acquired data was transferred into a personal computer and accurate visualization of animated data were presented. Preliminary test with 10 apples has been performed. Measurement were made by the contact-pressure transducer in two different positions. Complementary measurements were made on the same apples by using the Firmalon and Magness Taylor (MT) testers. Three-layer neural network was designed. 2/3 of the contact-pressure data were used as training input data and corresponding MT data as training target data. The remaining data were used as NN checking data. Six samples randomly chosen from the ten measured samples and their corresponding Firmalon values were used as the NN training and target data, respectively. The remaining four samples' data were input to the NN. The NN results consistent with the Firmness Tester values. So, if more training data would be obtained, the output should be more accurate. In addition, the Firmness Tester values do not consistent with MT firmness tester values. The NN method developed in this study appears to be a useful tool to emulate the MT Firmness test results without destroying the apple samples. To get more accurate estimation of MT firmness a much larger training data set is required. When the larger sensitive area of the pressure sensor being developed in this project becomes available, the entire contact 'shape' will provide additional information and the neural network results would be more accurate. It has been shown that the impact information can be utilized in the determination of internal quality factors of fruit. Until now,
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Piezoelectric films' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography