Thèses : « Film structurel »

1

Boutet, de Monvel Violaine. « Du feedback vidéo à l'IA générative : sur la récursivité dans les arts et médias ». Electronic Thesis or Diss., Paris 3, 2025. http://www.theses.fr/2025PA030009.

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Cette thèse érige, sous le prisme du feedback, un pont entre l’art vidéo pionnier des années 1960 à 1980 et les pratiques en lien avec l’IA générative, que les avancées phénoménales de l’apprentissage profond ont précipitées depuis le milieu des années 2010. La rétroaction renvoie en cybernétique à l’autorégulation par la boucle de systèmes naturels et technologiques. Appliqué à des dispositifs analogiques, numériques ou hybrides en circuit fermé, ce processus automatisé qualifie aussi les effets contingents qui en résultent à l'écran. La première partie revient sur l’influence colossale que la théorie de l’information et la notion de bruit ont exercé sur la genèse du genre vidéo depuis l’avènement du médium, en 1965. Elle se concentre sur le paradigme narcissique (Rosalind Krauss, 1976) qui en a renseigné les canons jusqu’à la fin des années 1970, en analysant la place centrale occupée par la perception humaine et son extension prothétique télévisuelle. La seconde partie s’attache à l’exploration concurrente de ladite vision des machines, en dialogue avec les outils (Steina et Woody Vasulka, 1976). À partir du retournement technocratique de l’esthétique alors inhérent au traitement d’images en temps réel, une transition est opérée de la synthèse audiovisuelle à ses pendants cinématiques, puis artificiels. La troisième partie se penche sur la création en prise avec des modèles d’IA générative développés depuis l’introduction des GANs, en 2014. Interrogeant la redistribution de l’agentivité en réseau, elle considère ultimement la généalogie récursive des arts et médias, ainsi que les conditions d’une culture algorithmique sensible entre signal et données
This thesis raises, through the prism of feedback, a bridge between pioneer video art from the 1960s to the 1980s and the practices associated with generative AI, which the phenomenal advances in deep learning have precipitated since the mid-2010s. Retroaction in cybernetics refers to the self-regulation by the loop of natural and technological systems. Applied to closed-circuit analog, digital or hybrid setups, this automated process also qualifies the contingent effects that result from it on screen. The first section looks back at the colossal influence that information theory and the notion of noise have had on the genesis of the video genre since the advent of the medium, in 1965. It revolves around the narcissistic paradigm (Rosalind Krauss, 1976) that essentialized its canons until the late 1970s, by analyzing the central place occupied by human perception and its televisual prosthetic extension. The second section focuses on the concurrent exploration of so-called machine vision, in dialogue with the tools (Steina and Woody Vasulka, 1976). Building upon the technocratic reversal of aesthetics then inherent to real-time image processing, a transition is made from audiovisual synthesis to its cinematic, and artificial counterparts. The third section contemplates creation with generative AI models developed since the introduction of GANs, in 2014. Questioning the redistribution of agency in networks, it ultimately considers the recursive genealogy of the arts and media, as well as the conditions for a sensitive algorithmic culture between signal and data

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2

Garg, Akhilesh. « Organic Self-Assembled Films for Nonlinear Optics : Film Structure, Composition and Kinetics of Film Formation ». Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28872.

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Organic materials exhibiting second-order non-linear optical (NLO) properties are a key to the development of advanced electro-optic (EO) modulators used in fiber-optic communications system. This work addresses the fabrication and characterization of organic materials with NLO properties using a self-assembly approach by alternately dipping a charged substrate into positively and negatively charged polymers to build up layer-by-layer (LbL) films. The effect of solution pH on the formation of LbL films fabricated using the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly{1-[p-(3–-carboxy-4–-hydroxyphenylazo)benzenesulfonamido]-1,2-ethandiyl} (PCBS) was studied using a quartz crystal microbalance with dissipation (QCM-D) monitoring, ellipsometry, absorbance, and second harmonic generation (SHG) measurements. PCBS has an azo-benzene chromophore side group that, when sufficiently oriented, results in measurable SHG. Films of PAH/PCBS fabricated at neutral pH where both PAH and PCBS are highly charged led to thin bilayers, ~1 nm, with a 1:1 molar ratio of PCBS:PAH. This molar ratio was found to be important for long-range polar ordering of PCBS in these films. Increasing the rate of convection was found to reduce the time required for complete adsorption of the polyion. This can have a significant impact on fabrication of films with high bilayer numbers. A variation of the above technique, which involves adsorbing one of the constituents electrostatically and another covalently, was studied using PAH and a reactive dye, Procion Brown (PB), which has a significantly higher hyperpolarizability than PCBS. It was found that a high pH, ~10.5, was important for achieving covalent attachment of the PB to the underlying PAH films. This resulted in much higher SHG intensities compared to when PB was deposited pH at 8.5-9.5 where the attachment of PB was due to a combination of electrostatic and covalent interactions. QCM-D results for PAH/PB films revealed the presence of a high percentage of unreacted amine groups in the underlying PAH film. A rate constant value for PB attachment step to the underlying PAH was also calculated. To enhance the SHG intensity of these films, silver nanoprisms were synthesized and deposited onto films using physisorption. An enhancement in the SHG intensity was observed for both PAH/PCBS and PAH/PB films.
Ph. D.

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3

Schiefer, Stefan. « Crystal structure of fiber structured pentacene thin films ». Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-75797.

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4

Hatton, Hilary J. « Magnetic and structural studies of nanoscale multilayer and granular alloy systems of Ag and FeCo ». Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286916.

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5

Lee, Jae-kyun. « Structure-property correlation of polyimide thin films and line structures / ». Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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6

Parihar, U., N. Padha, J. R. Ray, M. S. Desai, C. J. Panchal, P. K. Mehta, Ірина Володимирівна Чешко et al. « Effect of Film Thickness and Annealing on the Structural and Optical Properties of CuInAlSe2 Thin Films ». Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35321.

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CuIn1 – xAlxSe2 (CIAS) thin films were grown using flash evaporation method by varying the film thickness from 500 nm to 700 nm. Prepared CIAS thin films were annealed at 573 K for one hour in vacuum. The influence of film’s thickness and the annealing temperature were characterized by the X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive analysis of X-ray (EDAX), Optical transmission measurements, and Hall Effect measurement. As the film thickness increases the crystallinity improves and due to that the optical absorption also improves. The further improvement for different thicknesses of CIAS thin films were observed by annealing. The thicker (700 nm) and annealed CIAS thin film shows the crystallite size of 24.3 nm, energy band gap of 1.19 eV, and resistivity of about 9  102 Ω cm. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35321

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7

Morris, Anthony Kevin. « It's all a plot : an examination of the usefulness of the popularly accepted structural paradigm in the practice of writing of a feature film script ». Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/16632/1/Anthony_Morris_Thesis.pdf.

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This study took the widely-accepted, ‘industry standard’ Structural Paradigm of feature film plotting, and ‘road tested’ it, assessing its value as a tool in the process of actually writing a feature film script. The methodology employed was to write a feature film script (titled THE ARM THAT DOES THE HARM) and look to apply the Paradigm to the writing process. Journals recording the process were kept and peer assessment undertaken. The data from these sources was then analysed and conclusions drawn. The reason for and value of this study are that, while this Paradigm is widely espoused by screenwriting gurus, taught as part of film courses and applied as a tool of script assessment and review, there is very little documented evidence of its actual value to the practice of writing a script. My findings revealed that, though a useful reference point throughout, the Paradigm is most valuable during the early stages of story structuring and again, most particularly, when editing later drafts. An important outcome of this study was that it identified the Paradigm as a valuable tool, not a rule that must be adhered to, a series of points a narrative must be seen to ‘hit’ in order for it to be considered to have been told correctly. Further, this study demonstrated in practice how this tool can be applied. This study suggests that trying to force an evolving story into the confines of the Paradigm can inhibit the story from developing ‘organically’ from its characters. Rather, the Paradigm should be applied as a tool for helping shape stories that first and foremost should be character-driven.

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8

Morris, Anthony Kevin. « It's all a plot : an examination of the usefulness of the popularly accepted structural paradigm in the practice of writing of a feature film script ». Queensland University of Technology, 2008. http://eprints.qut.edu.au/16632/.

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This study took the widely-accepted, ‘industry standard’ Structural Paradigm of feature film plotting, and ‘road tested’ it, assessing its value as a tool in the process of actually writing a feature film script. The methodology employed was to write a feature film script (titled THE ARM THAT DOES THE HARM) and look to apply the Paradigm to the writing process. Journals recording the process were kept and peer assessment undertaken. The data from these sources was then analysed and conclusions drawn. The reason for and value of this study are that, while this Paradigm is widely espoused by screenwriting gurus, taught as part of film courses and applied as a tool of script assessment and review, there is very little documented evidence of its actual value to the practice of writing a script. My findings revealed that, though a useful reference point throughout, the Paradigm is most valuable during the early stages of story structuring and again, most particularly, when editing later drafts. An important outcome of this study was that it identified the Paradigm as a valuable tool, not a rule that must be adhered to, a series of points a narrative must be seen to ‘hit’ in order for it to be considered to have been told correctly. Further, this study demonstrated in practice how this tool can be applied. This study suggests that trying to force an evolving story into the confines of the Paradigm can inhibit the story from developing ‘organically’ from its characters. Rather, the Paradigm should be applied as a tool for helping shape stories that first and foremost should be character-driven.

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9

Reddy, K. Siva Sankara. « Electrical Properties Of Diamond Like Carbon Films In Metal-Carbon-Silicon (MCS) Structure ». Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/192.

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Amorphous carbon film with Diamond like properties is the subject of intense interest in the past one and half decade. The unusual properties of these diamond like carbon films arise from the preponderance of SP3 tetrahedral bonding of carbon in the film. Depending on the processing technique and the processing conditions used, the structure of the films can range from amorphous carbon to large grain polycrystalline diamond. These deposited amorphous carbon films, which are smooth, may find their use in optoelectronics, in dielectric films and in microelectronics. These films are found to be chemically inhomogeneous(containing SP3 hybridized carbon in a matrix of SP2 hybridized non-graphitic carbon). There is a possibility of using these films as substrates in microelectronics, provided the deposited films are structurally smooth, are chemically homogeneous and are dopable with both types of impurities. A host of other advantages of using diamond like carbon as a substrate material in microelectronics made it a topic of interest to many investigators. This prompted the author to take up investigations on diamond like carbon films from the point of examining the electrical properties of these films and on the possibility of conceiving devices based on these films. This investigation dealt with, sputter deposition of diamond like carbon films and their electrical characteristics in MCS device structures. In this, emphasis is given to the importance of processing parameters involved and the effect of each parameter on the electrical and structural properties of the film. Various substrate treatments were done prior to sputtering and found that the DLC nature of the film exists in all the films but differ from one another in electrical resistivity, in nucleation density and in their adherence to the substrate. Films deposited on substrates treated with low vapour pressure oil resulted in compressive strain in the film and lead to very poor adhesion. The nucleation density increased when the substrates are pretreated with ultrasonic agitation in hard SiC grit. The substrate temperature had a direct impact on the resistivity of the film: resistivity decreases with increase in substrate temperature. The constituents of the plasma modified the structural properties of the film, e.g. the Hydrogen content in the plasma has resulted in increasing the SP3 hybridization content of the film, by acting as SP2- SP2 network terminator. Ultra violet light focused onto the substrate, in general, enhanced the deposition rate. Inclusion of Nitrogen in the plasma substantially increased the conductivity of the material and this is used in doping of the DLC film. The carbon films deposited on silicon are used for electrical characterisation. Deposition of metal electrode on the carbon film lead to the basic (MCS) device structure. The I vs.V characteristics of the MCS structure resemble those of junction diodes. From the I vs.V characteristics at different temperatures, it has been found that the reverse current goes through a maximum, drops back to certain level and once again increases with gradual increase in temperature. This behaviour of the structure with A1 as well as Ag as top electrode materials is explained by the heterojunction formed at the C-pSi interface. The initial increase in the reverse current is dominated by the drift of minority carriers across the depletion width at the reverse biased junction. With increase in temperature, the depletion width reduces to a minimum above a certain temperature, where the diffusion of carriers controls the current across the device. From the constructed energy-band diagram of heterojunction, it is shown that the change in the transport phenomena from drift of minority carriers to diffusion of majority carriers at the junction, introduces a barrier at the critical temperature; This is responsible for the drop in current at the critical temperature. This explains the anomaly of drop in reverse current with increase in temperature. The C vs. v characteristics showed a bell shaped behaviour indicating the presence of two junctions connected back to back. This confirms the type of contact formed at the metal-carbon interface and the type of conductivity of the film, concluding that A1 makes a Schottky contact where as Ag makes an ohmic contact and the deposited film behaves like n-type material. The C vs. V behaviour with temperature is explained by the two types of contacts in the case of Al-GpSi, i.e. Schottky contact at Al-C; and heterojunction at C-pSi interface. These C vs. V and I vs.V changes with temperature are in tune with each other and the model proposed takes care of all the characteristics observed. In case of Ag-GpSi, C vs. V with temperature shows junction like behaviour at elevated temperatures and are explained by the presence of the interface at C-pSi. It has been observed that in some of the carbon films, when an electric field of the order of l06 V/cm is applied, the reflectance of the Aluminium metal dot is increased by 5 times, coupled with a 50 to 100 times increase in the associated capacitance of the MCS structure. The increase in reflectance is explained by considering the film to be inhomogeneous with a matrix of varying dielectric constants (SP3 hybridized carbon in a medium of SP2 bonded carbon). The transformed film, is homogeneous and enhances the reflectance of the Aluminium dot. This is termed as "homogeneity induced smoothness." The transformation of inhomogeneous material to homogeneous material is further confirmed by the Raman spectroscopy, in which the broad peak is converted to a sharp peak changing the FWHM from 93 cm-1 to 4 cm-1 ; denoting the structural order in the film. To the best of our knowledge, this is the first investigation reporting the crystalline nature of the DLC, with structural order and the corresponding FWHM of the Raman peak as low as 4 cm-1. The preparational conditions of the film to get this transformation and the influence of various process parameters are examined. Devices based on Metal-Carbon-Oxide- Silicon (MCOS) structure are realized by thermally grown oxide/sputter deposited oxide on silicon, prior to carbon deposition. These structures showed voltage controlled negative resistance(VCNR) characteristics. The applied voltage and its distribution across the reverse biased junction and across the oxide gives rise to a negative resistance region. With the number of V vs. I characteristics measured, it is observed that the negative resistance region also shifts. This is attributed to the trapped charges in the carbon changing the distribution of applied voltage. This is explained by modifying the energy-band diagram. A concept of the accumalated charges at the oxide barrier filling up the higher energy states in the carbon and silicon, to become hot carriers is used. As long a. more voltage is dropped across the oxide, these hot carriers can surmount the barrier at the reverse biased junction. The flow of these carriers is cut off when the additional voltage is dropped across the reverse biased junction leading to a drop in the current. A further increase in the applied voltage nominally increases the current due to increase in the leakage current. A new hybrid (electrical/optical) read only memory (ROM) element is conceived and the way in which the information can be written and read is discussed. A two terminal negative resistance device using MCOS structure is fabricated and tested for its VCNR property. An analog memory device is proposed using the MCOS structure as gate in an FET. The work reported in this thesis has been divided into nine chapters. The introductory remarks on the importance of the area of research and about the work reported in this thesis are given in chapter one. Chapter two deals with some of the basic concepts related to understand the reported work. In chapter three the research work done by other investigators covering different aspects of this work is reported and some of their investigations are reviewed. Chapter four dealt with the various preparative techniques to deposit films, their structural characterisation, and the experimental work carried out to electrically characterize these films. Chapter five presents the I vs.V & C vs. V analysis and a model to qualitatively explain them. In chapter six field induced transformation phenomena of some of these films and its impact on the reflectance of the metal dot is dealt. Chapter seven consists of the MCOS device structure, its I vs.V characteristics and a model to explain the behaviour. Chapter eight presents the application part of same of the phenomena observed in conceiving a new hybrid ROM element and a two terminal negative resistance device. The concluding ninth chapter itemizes the important results of the work and suggestions to carry forward this work which can open up new vistas in the diamond like carbon film based technology and its applications in microelectronics.

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10

Reddy, K. Siva Sankara. « Electrical Properties Of Diamond Like Carbon Films In Metal-Carbon-Silicon (MCS) Structure ». Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/192.

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Amorphous carbon film with Diamond like properties is the subject of intense interest in the past one and half decade. The unusual properties of these diamond like carbon films arise from the preponderance of SP3 tetrahedral bonding of carbon in the film. Depending on the processing technique and the processing conditions used, the structure of the films can range from amorphous carbon to large grain polycrystalline diamond. These deposited amorphous carbon films, which are smooth, may find their use in optoelectronics, in dielectric films and in microelectronics. These films are found to be chemically inhomogeneous(containing SP3 hybridized carbon in a matrix of SP2 hybridized non-graphitic carbon). There is a possibility of using these films as substrates in microelectronics, provided the deposited films are structurally smooth, are chemically homogeneous and are dopable with both types of impurities. A host of other advantages of using diamond like carbon as a substrate material in microelectronics made it a topic of interest to many investigators. This prompted the author to take up investigations on diamond like carbon films from the point of examining the electrical properties of these films and on the possibility of conceiving devices based on these films. This investigation dealt with, sputter deposition of diamond like carbon films and their electrical characteristics in MCS device structures. In this, emphasis is given to the importance of processing parameters involved and the effect of each parameter on the electrical and structural properties of the film. Various substrate treatments were done prior to sputtering and found that the DLC nature of the film exists in all the films but differ from one another in electrical resistivity, in nucleation density and in their adherence to the substrate. Films deposited on substrates treated with low vapour pressure oil resulted in compressive strain in the film and lead to very poor adhesion. The nucleation density increased when the substrates are pretreated with ultrasonic agitation in hard SiC grit. The substrate temperature had a direct impact on the resistivity of the film: resistivity decreases with increase in substrate temperature. The constituents of the plasma modified the structural properties of the film, e.g. the Hydrogen content in the plasma has resulted in increasing the SP3 hybridization content of the film, by acting as SP2- SP2 network terminator. Ultra violet light focused onto the substrate, in general, enhanced the deposition rate. Inclusion of Nitrogen in the plasma substantially increased the conductivity of the material and this is used in doping of the DLC film. The carbon films deposited on silicon are used for electrical characterisation. Deposition of metal electrode on the carbon film lead to the basic (MCS) device structure. The I vs.V characteristics of the MCS structure resemble those of junction diodes. From the I vs.V characteristics at different temperatures, it has been found that the reverse current goes through a maximum, drops back to certain level and once again increases with gradual increase in temperature. This behaviour of the structure with A1 as well as Ag as top electrode materials is explained by the heterojunction formed at the C-pSi interface. The initial increase in the reverse current is dominated by the drift of minority carriers across the depletion width at the reverse biased junction. With increase in temperature, the depletion width reduces to a minimum above a certain temperature, where the diffusion of carriers controls the current across the device. From the constructed energy-band diagram of heterojunction, it is shown that the change in the transport phenomena from drift of minority carriers to diffusion of majority carriers at the junction, introduces a barrier at the critical temperature; This is responsible for the drop in current at the critical temperature. This explains the anomaly of drop in reverse current with increase in temperature. The C vs. v characteristics showed a bell shaped behaviour indicating the presence of two junctions connected back to back. This confirms the type of contact formed at the metal-carbon interface and the type of conductivity of the film, concluding that A1 makes a Schottky contact where as Ag makes an ohmic contact and the deposited film behaves like n-type material. The C vs. V behaviour with temperature is explained by the two types of contacts in the case of Al-GpSi, i.e. Schottky contact at Al-C; and heterojunction at C-pSi interface. These C vs. V and I vs.V changes with temperature are in tune with each other and the model proposed takes care of all the characteristics observed. In case of Ag-GpSi, C vs. V with temperature shows junction like behaviour at elevated temperatures and are explained by the presence of the interface at C-pSi. It has been observed that in some of the carbon films, when an electric field of the order of l06 V/cm is applied, the reflectance of the Aluminium metal dot is increased by 5 times, coupled with a 50 to 100 times increase in the associated capacitance of the MCS structure. The increase in reflectance is explained by considering the film to be inhomogeneous with a matrix of varying dielectric constants (SP3 hybridized carbon in a medium of SP2 bonded carbon). The transformed film, is homogeneous and enhances the reflectance of the Aluminium dot. This is termed as "homogeneity induced smoothness." The transformation of inhomogeneous material to homogeneous material is further confirmed by the Raman spectroscopy, in which the broad peak is converted to a sharp peak changing the FWHM from 93 cm-1 to 4 cm-1 ; denoting the structural order in the film. To the best of our knowledge, this is the first investigation reporting the crystalline nature of the DLC, with structural order and the corresponding FWHM of the Raman peak as low as 4 cm-1. The preparational conditions of the film to get this transformation and the influence of various process parameters are examined. Devices based on Metal-Carbon-Oxide- Silicon (MCOS) structure are realized by thermally grown oxide/sputter deposited oxide on silicon, prior to carbon deposition. These structures showed voltage controlled negative resistance(VCNR) characteristics. The applied voltage and its distribution across the reverse biased junction and across the oxide gives rise to a negative resistance region. With the number of V vs. I characteristics measured, it is observed that the negative resistance region also shifts. This is attributed to the trapped charges in the carbon changing the distribution of applied voltage. This is explained by modifying the energy-band diagram. A concept of the accumalated charges at the oxide barrier filling up the higher energy states in the carbon and silicon, to become hot carriers is used. As long a. more voltage is dropped across the oxide, these hot carriers can surmount the barrier at the reverse biased junction. The flow of these carriers is cut off when the additional voltage is dropped across the reverse biased junction leading to a drop in the current. A further increase in the applied voltage nominally increases the current due to increase in the leakage current. A new hybrid (electrical/optical) read only memory (ROM) element is conceived and the way in which the information can be written and read is discussed. A two terminal negative resistance device using MCOS structure is fabricated and tested for its VCNR property. An analog memory device is proposed using the MCOS structure as gate in an FET. The work reported in this thesis has been divided into nine chapters. The introductory remarks on the importance of the area of research and about the work reported in this thesis are given in chapter one. Chapter two deals with some of the basic concepts related to understand the reported work. In chapter three the research work done by other investigators covering different aspects of this work is reported and some of their investigations are reviewed. Chapter four dealt with the various preparative techniques to deposit films, their structural characterisation, and the experimental work carried out to electrically characterize these films. Chapter five presents the I vs.V & C vs. V analysis and a model to qualitatively explain them. In chapter six field induced transformation phenomena of some of these films and its impact on the reflectance of the metal dot is dealt. Chapter seven consists of the MCOS device structure, its I vs.V characteristics and a model to explain the behaviour. Chapter eight presents the application part of same of the phenomena observed in conceiving a new hybrid ROM element and a two terminal negative resistance device. The concluding ninth chapter itemizes the important results of the work and suggestions to carry forward this work which can open up new vistas in the diamond like carbon film based technology and its applications in microelectronics.

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11

Öhrman, Olov. « Structured MFI film catalysts and adsorbents ». Doctoral thesis, Luleå, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16949.

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A method originally developed at the division of Chemical Technology, Luleå University of Technology was tailored for the preparation of well-defined ZSM-5 films and zoned MFI films on supports suitable for catalysis and adsorption applications. Films were grown on monoliths, ceramic foams, alumina beads, soda glass beads and quartz glass. The supports were seeded with silicalite-1 crystals and hydrothermally treated in a single or several steps. The materials were evaluated by scanning electron microscopy, x-ray diffraction, N2 and NO2 sorption, x-ray photoelectron spectroscopy, ICP-AES, p-xylene isomerization and cracking of 1,3,5-tri-isopropylbenzene. The thickness of the continuous films could be controlled from 110 nm to 9 µm. Zoned MFI films were prepared from precursor ZSM-5 films by overgrowth with silicalite-1. A multi-step synthesis protocol was used to prevent excessive bulk crystallization. Ultrasound treatment was beneficial for removal of loosely attached crystals on top of the zeolite films. Defects such as cracks and open grain boundaries were observed by SEM and in concert, mesopores were observed by N2 sorption. Model parameters were fitted to experimental data from catalytic test reactions and these parameters indicated that thicker films contained more defects, probably in the form of open grain boundaries and cracks (mesopores) as observed by SEM and N2 sorption. Films supported on quartz were more catalytically active than films on alumina and soda glass. This was attributed to partial poisoning of the acid sites in the films on the latter two substrates, probably due to solid-state ion exchange of impurities such as alkali metals from the alumina and soda glass support to the film. As expected, thicker films possessed higher diffusion resistance than thin films. Surprisingly, a higher external activity was observed after zoning. This was attributed to formation of mesopores, migration of aluminum from the precursor ZSM-5 film to the external surface, and increased surface roughness upon zoning. ZSM-5 films supported on monoliths were successfully tested for NO2 sorption. As expected, the adsorption capacity per g zeolite was independent of film thickness. Formation of NO was observed as a result of NO2 adsorption on strong sites. Thicker films resulted in higher diffusion resistance as expected. The present work has resulted in substantial and valuable new fundamental understanding of the performance of thin molecular sieve film catalysts and adsorbents. These findings may facilitate development of novel materials for industrial applications.
Godkänd; 2005; 20061004 (ysko)

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Öhrman, Olov G. W. « Structured MFI film catalysts and adsorbents / ». Luleå : Luleå University of Technology, 2005. http://epubl.luth.se/1402-1544/2005/07.

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13

Young, Joseph Y. J. 1968. « Squeeze-film damping for MEMS structures ». Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/34334.

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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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15

Wolf, Arne. « Film structure of vertical annular flow ». Thesis, Imperial College London, 1995. http://hdl.handle.net/10044/1/8178.

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Romer, Stephen. « The decline of the British film industry : an analysis of market structure, the firm and product competition ». Thesis, Brunel University, 1993. http://bura.brunel.ac.uk/handle/2438/6301.

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Tungchaiwattana, Somjit. « A study of particle structure and film formation mechanism on the mechanical properties of synthetic rubber films ». Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/a-study-of-particle-structure-and-film-formation-mechanism-on-the-mechanical-properties-of-synthetic-rubber-films(3014e013-bc99-4fbf-8282-5d13ed4251b3).html.

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This thesis investigated a new group of poly(Bd)/poly(Bd-co-MAA) core-shell particles that were ionically crosslinked and cast as nanostructured ionomer films from aqueous dispersions. The new group of poly(Bd)/poly(Bd-co-MAA) core-shell particles were studied for structure-property relationships and morphology. The covalent crosslinking content in the core and the shell were varied at constant ionic crosslinking. Stress-strain data showed control of the nanostructured films. The chain transfer agent used during the preparation of the nanoparticles core-shells was shown to independently tune the mechanical properties of the films.

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Dobiášová, Andrea. « Strukturní a transportní vlastnosti semi-IPN hydrogelů na bázi polyvinylalkoholu ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449409.

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The aim of master thesis was to study structural and transport properties of PVA films modified with method of semi-IPN with suitable polyectrolytes and plasticizers. The first important step was optimalization of PVA films preparation, when time of heating was set at 90 °C for 1 hour. Drying was set at 50 °C for 24 hours. Molecular weight of PVA was chosen 85–124 kDa in concentration 10 wt.%. For preparation of PVA-based semi-IPN thin films polyelectrolytes (polyglutamic acid, DEAE-dextran hydrochloride) and plasticizer (glycerol) were selected. Basic characterization of prepared materials was performed with FTIR, TGA, SEM and specific surface analysis. The difference between modified PVA films was in the chargé of individual functional groups carried by used polyelectrolytes. Surfaces of all the PVA films were smooth without visible defects. Transport properties were characterized with the method of horizontal diffusion cell with methylen blue used as a probe. Diffusion coefficients of methylen blue through PVA films were determined. It was found, that the fastest pass was throw PVA film without additives. The slowest diffusion was observed through PVA/DEAE-dextran film, because of the same charge of the film with a probe. PVA/PGA reacted with methylen blue to form a complex. Plasticizer effect on the diffusion was only minor; it caused a slight decrease of diffusion coefficient. These films were easier to handle.

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Chacouche, Khaled. « Structures minces férromagnétiques et férroélectriques ». Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1053/document.

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Cette thèse traite avec des équations aux dérivées partielles provenant de la physique mathématique. En particulier, à partir de modèles 3D ferromagnétisme et ferroélectricité, nous obtenons des modèles 1D et 2D par l'intermédiaire de processus asymptotiques basés sur des méthodes de réduction de dimension. Le modèle 3D ferromagnétisme a été proposé par W.F. Brown depuis lesannées 40. Il est également possible d'utiliser un modèle dynamique, décrivant l'aimantation au cours du temps, en utilisant un système introduit par L.D. Landau et E.M. Lifschitz en 1935. Pour le modèle ferroélectrique, nous nous référons aux papiers de P. Chandra et P.B. Littlewood, W. Zhang et K. Bhattacharya et au livre de T. Mitsui, I. Taksuzaki et E. Nakamura.Ma thèse est constituée de trois parties :Au début, je considère l'énergie micromagnétique avec des coefficients dégénératifs dans un fil mince. Après avoir montrer l'existence de minimiseurs du problème, j'identifie l'énergie limite lorsque la section du fil tend vers zéro.Dans la deuxième partie, j'étudie le comportement asymptotique des solutions dépendant du temps des problèmes micromagnétique dans une multi-structure constituée de la jonction de deux fils minces. En supposant que les volumes des deux fils tendent vers zéro avec la même vitesse. On obtient un problème limite couplé par une condition de jonction. Le problème limite reste non-convexe, mais devient complètement local.Dans le dernier chapitre, à partir d’un modèle variationnel 3D non convexe et non-local pour la polarisation électrique dans un matériau ferroélectrique, et à l'aide d'un processus asymptotique basé sur la réduction de dimension, j'analyse des phénomènes de jonction pour deux films minces ferroélectriques joints orthogonaux. Selon la façon dont la réduction se passe, on obtienttrois modèles différents de dimension 2. On remarque qu’un effet de mémoire du processus de réduction apparaît, ce dernier dépend de la compétition entre les épaisseurs des deux films: Le paramètre de guidage est la limite du rapport des épaisseurs des deux films
This thesis deals with partial differential equations coming from mathematical physics. Particularly, starting from 3D models for ferromagnetism and ferroelectricity, we derive 1D and 2D models via asymptotic processes based on dimensional reduction methods. The 3D model for ferromagnetism was proposed by W.F. Brown in the 40s and it is based on a system introduced by L.D. Landau and E.M. Lifschitz in 1935. About the ferroelectric model, we refer tothe papers of P. Chandra and P.B. Littlewood, W. Zhang and K. Bhattacharya and to the book of T. Mitsui, I. Taksuzaki, and E. Nakamura.This thesis based on three works:At the beginning, we consider micromagnetic energy, with some degenerating coefficients, in a thin wire. After showing the existence of minimizers, we identify the limit energy as the section of the wire vanishes.In the second part, we study the asymptotic behavior of the solutions of a time dependent micromagnetic problem in a multi-structure consisting of two joined thin wires. We assume that the volumes of the two wires vanish with same rate. We obtain two 1D limit problems coupled by a junction condition on the magnetization. The limit problem remains non-convex, but now it becomes completely local.In the last chapter, starting from a non-convex and nonlocal 3D variational model for the electric polarization in a ferroelectric material, and using an asymptotic process based on dimensional reduction, we analyze junction phenomena for two orthogonal joined ferroelectric thin films. We obtain three different 2D-variational models for joined thin films, depending on how the reduction happens. We note that, a memory effect of the reduction process appears, and it depends on the competition of the relative thickness of the two films: The guide parameter is the limit of the ratio between these two small thickness

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Auvray, Loïc. « Mise en évidence de structures bicontinues et aléatoires dans les microémulsions de Winsor à film interfacial souple : relations structure-courbure du film-basses tensions interfaciales ». Paris 11, 1985. http://www.theses.fr/1985PA112060.

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Nous étudions par diffusion centrale des rayons X et des neutrons la structure des microémulsions de Winsor qui contiennent des proportions comparables d'eau et d'huile et sont associées à des tensions interfaciales très petites. Nous obtenons quatre résultats expérimentaux essentiels : i) les microémulsions de Winsor sont des systèmes colloïdaux dispersés. Un film interfacial de tensioactif, mis en évidence par les comportements asymptotiques de l'intensité diffusée, sépare l'eau et l'huile à l'échelle microscopique. Ii) la structure de ces microémulsions est aléatoire. Le rayon de courbure moyen du film est proportionnel au produit des fractions volumiques d'eau et d'huile et inversement proportionnel à la concentration du tensioactif, comme le prévoient les théories de microémulsions aléatoires proposées par Talmon-Prager et de Gennes-Levinson-Jouffroy. Iii) ces microémulsions sont bicontinues : la courbure moyenne du film déduite d'expériences de variations des contrastes varie continument avec la fraction volumique d'huile et s'annule quand la microémulsion contient autant d'eau que d'huile. Iv) les corrélations à grande échelle de l'eau (ou de l'huile) sont de type volume exclus. Ces corrélations s'interprètent bien par l'existence de volumes élémentaires corrélés d'eau et d'huile dans la microémulsion, dont la taille est bien définie et est fixée par la rigidité du film. Nous relions théoriquement la structure de l'interface microémulsioneau (ou huile) en excès et les variations des tensions interfaciales avec la salinité à des effets de courbure spontanée du film interfacial
We have studied by small angle scattering of X-rays and neutrons the structure of concentrated Winsor micro emulsions, which contain comparable proportions of oil and water and are associated to very law interfacial tensions. We have obtained four essential experimental results: i) the Winsor micro emulsions are colloidal dispersed systems. A surfactant interfacial film, evidenced by the asymptotic behaviors of the scattered intensity, separates oils from water at microscopic scales. Ii) The structure of these micro emulsions is random. The film mean radius of curvature is proportional to the product of the oil and water volume fraction and inversely proportional to the surfactant concentration, as predicted the theories of random micro emulsions proposed by Talmon-Prager and de GennesJouffroy-Levinson. Iii) These micro emulsions are bicontinuous: the film average mean curvature, deduced from contrast variations experiments, varies continuously with the oil volume fraction and vanishes when the micro emulsion contains as much ail as water. Iv) The water (or oil) correlations at large scale are excluded volume like correlations. They are well interpreted by the existence in the micro emulsion of elementary correlated volumes of oil and water, whose size is well defined and fixed by the film stiffness. We theoretically relate the structure of the interface between a micro emulsion and an oil (or water) phase in excess and the variations of the interfacial tensions with salinity to the effects of the surfactant interfacial film spontaneous curvature

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Nasta, Dominique. « Code structures and transgressive strategies in film ». Doctoral thesis, Universite Libre de Bruxelles, 1989. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213226.

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Tian, Zhengrong. « Multilayer microwave structures using thick-film technology ». Thesis, Middlesex University, 2002. http://eprints.mdx.ac.uk/6385/.

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Multilayer techniques, in conjunction with thick-film technology have been applied to the design and fabrication of several multilayer microwave structures to achieve the low cost and high performance goals set by modern microwave circuits and systems. To provide accurate material parameters for the design of multilayer thick-film components, a novel slit cavity resonator method has been developed that enables the relative permittivity and loss tangent of dielectric samples to be measured easily, and with high accuracy. A particular feature of this method is that it can be used to measure thick-film samples that are normally only available in relatively thin layers in a two-layer format. Rigorous electromagnetic analysis on a slit cavity has been performed that accounts for the effect of the fringing fields and the radiation from the slits. The method has been verified through measurement on several thick-film materials over X-band. Both the analytical methods and the fabrication techniques for multilayer microwave microstrip structures are presented. Several multilayer thick-film microstrip line test structures have been designed and characterised, and these provide a basic database for the design of multilayer microstrip components. A new design procedure for the multilayer end-coupled filter has been developed that enables the designer to arrive at the physical dimensions of the multilayer structure based on the filter specification. This design technique is effective as it combines the accuracy of electromagnetic (EM) analysis and the efficiency of circuit simulation. The multilayer gap, which is the most critical element of multilayer end-coupled filters, has been characterised using EM analysis and the data is incorporated into a circuit simulator. Measured and simulated results are presented that verify the new design technique. A 40% bandwidth has been achieved experimentally, which shows a very significant improvement over conventional single layer structures, where the bandwidth achievable is normally less than 5%. Novel, octave band DC blocks have been designed, fabricated and tested using a new multilayer format. The tight coupling required between the coupled lines in this component was realized by overlapping these lines in a multilayer structure. Very good agreement was obtained between measured and simulated data. The multilayer approach was also applied to the design of coupled line bandpass filters where a measured 80% bandwidth was achieved. For the first time, the properties of multilayer coupled lines using a range of different thick-film dielectrics are examined using their coupled-mode parameters. Design curves for multilayer coupled lines are obtained, that provide important information on the design of multilayer directional couplers. A practical design strategy for multilayer directional couplers is developed, which overcomes the problem of excessive computation that is normally associated with the electromagnetic optimization of multilayer circuit designs. The methodology has been verified through the design and measurement of wide bandwidth 2dB and 3dB directional couplers that were fabricated using multilayer, thick-film technology. New techniques for the design and fabrication of multilayer microwave thick-film components have thus been established, both theoretically and through practical circuit fabrication and measurement.

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Eggleston, James Michael. « Optical spectroscopy of thin film semiconductor structures ». Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4769/.

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This thesis consists of a study of several thin film semiconductor structures of practical technological use either presently or in the near future. The first system studied is an ultra thin film single crystal gallium arsenide layer. The absorption spectra of these layers are measured and transitions at both the F- point and L-point of the Brillouin Zone are observed, the latter are not normally measurable in thicker layers. The observed shift in the F-point absorption edge is attributed to contributions from the Franz-Keldysh Effect and the Moss-Burstein Effect. The temperature dependence of the L-point energy gap is measured and compared with previous data. The next system investigated is an n-type porous silicon layer coated with p-type polyaniline. Both photoluminescence and electroluminescence spectra and the electrical characteristics have been measured for this system. The interface between the two layers is found to be a rectifying junction consistent with a potential barrier formed at the interface. In forward bias, it is possible to generate electroluminescence in the visible and near infra red regions. The final structure studied is a thin film cadmium sulphide-cadmium telluride solar cell structure. The cells are found to have a low efficiency of around 1% as grown, but a process of treatment with cadmium chloride and annealing in air improves this by a factor of approximately ten. Photoluminescence measurements on the back surface of the cadmium telluride revealed three major emission bands at 1.59 eV, 1.55 eV and 1.45 eV. By varying temperature and incident laser power, attempts at assigning the bands to specific impurity centres in the cadmium telluride is made Using a novel bevelling etch technique to prepare samples, depth dependent measurement of the photoluminescence is possible. This reveals that the major changes associated with the improvement in efficiencies occurs at the interface between the CdS and the CdTe.

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Craib, Glenn R. G. « Thin film structural determination and surface analysis ». Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320771.

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A combined approach to the use of surface analysis techniques and X-ray diffraction has been introduced. In particular the development of the microstructure of UHV evaporated thin metallic films has been investigated with a view to clarifying influences on microstructure (particularly texture). This study has shown the wide range of experimental parameters which affect the final film structure, such as temperature, oblique incidence and substrate roughness. An automated energy dispersive X-ray diffractometer has been developed for the study of thin film texture. The required corrections for loss of intensity due to sample positioning have been developed and verified. Pole figures have been collected for erbium and nickel thin films (thickness 200-1200 nm) grown on molybdenum or glass substrates. Results for the erbium films show a substantial effect on the texture of the film, contributed by the temperature of the substrate during deposition. The texture varies from mixed fiber at low temperature, to a strong single fiber orientation at around 663 K, to mixed fiber at higher temperatures. The strong orientation at 663 K has been shown to vary from either (002) to (101) depending on as yet unknown experimental conditions. The effect of substrate roughness appears to be only in the degree of orientation and it does not affect the overall nature of the texture of the film. The texture of the nickel films shows a form of "granular epitaxy" at substrate temperatures above 300 K. The presence of tensile stress within one of these nickel thin film samples has been determined and is interpreted to give support to a proposed mode of granular epitaxy.

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Aschenbeck, Jens. « Novel amorphous silicon thin film transistor structures ». Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620172.

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Macé, Michel. « Modelisation de structures amorties par film viscoelastique ». Paris 6, 1991. http://www.theses.fr/1991PA066563.

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Les films viscoelastiques sont de plus en plus utilises dans le domaine des constructions navales militaires afin de repondre aux objectifs de discretion acoustique visant a reduire les niveaux vibratoires de certaines structures. Dans cette etude, nous proposons une methode pour dimensionner de telles structures comportant un film amortissant, a savoir une theorie de plaque et une theorie de coque composites, valables en statique et en dynamique, et qui tiennent compte des proprietes geometriques et materielles de ce film. Ces theories font egalement l'objet de validations numeriques et experimentales

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Tucker, Nigel Paul. « Magnetic structure of Gd thin-film surfaces ». Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364156.

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Ranade, Aditya Prakash. « Structure Property Relationships in Various Layered Polymeric Systems ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1157753371.

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Roos, Andreas. « Growth and characterization of advanced layered thin film structures : Amorphous SmCo thin film alloys ». Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177674.

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This report describes the growth and characterization of thin amorphous samarium-cobalt alloy films. The samarium-cobalt alloy was grown by DC magnetron sputtering in the presence of an external magnetic field parallel to the thin film. The external magnetic field induces a uniaxial in-plane magnetic anisotropy in the samarium-cobalt alloy. The thin films were characterized with x-ray scattering, and the magnetic anisotropy was characterized with the magneto optic Kerr effect. The measurements showed a uniaxial in-plane magnetic anisotropy in the samarium-cobalt alloy films. It is not clear how amorphous the samples really are, but there are indications of crystalline and amorphous areas in the alloys.

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Ma, Lok Wang Materials Science &amp Engineering Faculty of Science UNSW. « Deformation mechanisms in TiN-based thin film structures ». Awarded by:University of New South Wales. School of Materials Science and Engineering, 2005. http://handle.unsw.edu.au/1959.4/22065.

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The deformation mechanisms and contact response of TiN-based thin films deposited onto a soft substrate using a physical vapour deposition (PVD) technique is still an area of both technological importance and considerable discussion. These coatings are commonly applied to various kinds of steel cutting tools, creating surfaces with enhanced tribological properties. However, no extensive systematic study of the deformation mechanisms in these thin film systems has been performed to date. In the present study, the effect of the coating microstructure, indenter geometry, coating thickness and substrate hardness on the deformation mechanisms in both TiN and TiAlN coatings of varying thickness deposited onto ductile steel substrates has been investigated using a combination of nanoindentation and microstructural analysis, including focused ion beam (FIB) milling and transmission electron microscopy (TEM). Different modes of cracking, such as columnar and transverse cracking, as well as shear steps at the coating/substrate interface, were observed. The microstructure of the TiN coatings was found to be very important in controlling their modes of deformation. Thicker coatings were seen to contain more equiaxed grains, so less columnar shearing occurred and inclined cracks were found to be a more dominant fracture type in the thicker coating. Also, it was found that soft substrates absorbed most of the energy from indentation by plastic deformation. It was found that both the TiN and TiAlN/TiN dual-layer coatings exhibited broadly similar mechanisms of deformation. The epitaxial interface between the TiAlN and TiN in the dual-layer coating did not appear to affect the deformation behaviour. As a further investigation of the overall deformation behaviour for the coating/substrate systems studied, a DualBeam FIB was used to generate three dimensional images of the indented regions which provided additional information on the crack morphology. For the first time, a systematic study of the deformation behaviour of TiN and TiAlN coatings upon indentation has been carried out. FIB milling was demonstrated to be a highly appropriate technique for characterization of the deformation behaviour of these coatings, allowing detailed, high resolution microstructural investigations to be performed in both two and three dimensions.

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Lusk, David Stuart. « Omnidirectional reflectors based on thin film multilayer structures ». Thesis, University of the West of Scotland, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404650.

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Kelf, Timothy Andrew. « Light-matter interactions on nano-structured metallic film ». Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/373815/.

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This thesis describes a study into the optical properties of nano-structured metallic films. Structures are produced by electrochemically depositing metal through a self-assembled template of polymer micro-spheres. This versatile technique allows nano-structured surface made from almost any metal to be produced quickly and cheaply. Geometries ranging from array of shallow dishes, to sharp metallic spikes and encapsulated spherical cavities can all be produced on the same sample. This thesis presents an in-depth study into the properties delocalised and localised surface plasmon polaritons. These plasmons can be tuned in energy by controlling the sample geometry and angle of the incident light. The coupling between these two types of plasmon is also investigated and theories are put forward to understand the observed results. These findings could prove useful in the design of plasmon guiding and computing devices. With an understanding into the plasmonic properties of the metallic nanostructures, research is undertaken to explore how the associate local electric field couples to molecules adsorbed onto a samples surface. A strong correlation between surface plasmons and enhanced Raman scattering is found, leading the observation of the beaming of the Raman scattered light. The nano-structured substrates are also shown to have excellent reproducibility as well as enhancement of the Raman signals, leading to applications such as high sensitivity molecular sensors. Finally, the interaction between organic semiconductor molecules and surface plasmons is explored. A strong interaction between the different states is found and plasmon enhanced fluorescence is also observed. These studies open the way for greater control over the exciton states, which have potential for the use in novel laser systems.

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Blanchet, Aaron R. (Aaron Robert) 1974. « Microelectromechanical (MEMS) structures for thin film property measurement ». Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9735.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1998.
Includes bibliographical references (leaf 87).
Microelectromechanical systems (MEMS) are becoming the bases for an important industry with potential applications in numerous fields. The current study explores the use of MEMS-based, electrically-actuated structures to determine thin film mechanical properties, including intrinsic stresses of deposited metal films. An overview of the importance of thin film stress measurement and the advantages of this particular MEMS-based technique provides motivation for this study. A new analysis of the mechanics in bilayer beams is presented, and is used to relate changes in electrical measurements to the intrinsic stress of films deposited on micromachined beams. Proof-of-principle studies using evaporatively deposited silver films were carried out, and showed agreement in stresses measured using different MEMS-based devices, but the same beam analysis. Stress was measured through experiments using electrical "pull-in" of beams and results are compared both to curvature studies using MEMS-based cantilevers and to standard wafer-based, scanning-laser curvature analysis. Thermal cycling was performed on all the devices, yielding data suggesting different rates of thin film stress relaxation for the films deposited on MEMS-based devices and a film on an oxidized Si wafer. Differences in stress relaxation rates are attributed to the different interfaces involved. These studies point to future work which will lead to optimized MEMS-based devices to be used for high-sensitivity, in-situ, thin film stress measurements.
by Aaron R. Blanchet.
S.M.

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Donchev, Evgeniy. « Thin-film diode structures for advanced energy applications ». Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/25297.

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Presented within this thesis is the work towards studies on thin-film diode structures for use in advanced energy applications. The main energy application pursued within this study is the solar rectenna device, considered to be next-generation in energy harvesting due to promises of efficiencies beyond the Shokley-Queisser limit for solar cells. A RECTifying antENNA (RECTENNA) is a device consisting of an antenna, with dimensions scaled to the wavelength of the electromagnetic wave to be absorbed, and the resulting signal rectified by a diode of sufficient cut-off frequency to efficiently operate at the desired harvesting frequency. In studying the rectenna device and its efficiency limits, diode performance requirements have been outlined that are used to identify suitable structures to be used in future prototype manufacturing of energy relevant devices, for example solar rectenna, rectenna for microwave power transmission, antenna-coupled diode photodetectors, hot-electron devices, etc. Silicon based Schottky barrier and Metal-(native oxide)Insulator-Metal diodes have been, for the first time, systematically studied by using conventional manufacturing techniques to produce optimised devices. The result being n-type Si Schottky barrier diodes with various top metals (Ag, Al, Au, Nb, Cr, Mo, Ni and Ti) displaying low ideality factors close to unity (exception made from Al), good low-bias rectification properties, low leakage currents and optimised barrier heights. By analysing and comparing the performance metrics for these diodes, it was established that Cr, Ti, Mo and Ni have the potential to be used as passive devices for energy applications, with Cr displaying the highest cut-off frequency at 39.6 GHz, whereas Mo and Ni having desirable properties that also make them suitable as active components. Native oxide Metal-Insulator-Metal diodes based on Al, Cr, Nb and Ti, and their native oxide derivatives topped with a selection of metals of different workfunctions (Ag, Al, Au, Nb, Cr, Mo, Ni and Ti) all displayed asymmetric current-voltage characteristics. By comparing the rectification properties of all structures, it was established that higher electron affinity insulators (Nb2O5 and TiO2) have better performance metrics than the lower electron affinity insulators (Al2O3 and Cr2O3), with the Nb based structures outperforming the Ti based devices. Three figure of merits were used to characterise the MIM diodes, with the Nb/Nb2O5/Ag device displaying the highest at 35.6 asymmetry, 4.0 nonlinearity and 7.9/V responsivity, making it suitable for lower end energy applications such as IR or Optical sensing. An initial study into Metal-Insulator-Insulator-Metal diodes with insulators grown by reflection high energy electron diffraction assisted pulsed laser deposition has shown a proof of concept for the improved performance of double-insulator over single-insulator tunnel diodes, and identified factors that need to be controlled when considering this novel approach to study the double-insulator devices.

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Guillon, Jean-Pierre Charles François. « Tear film structure of the contact lens wearer ». Thesis, City University London, 1987. http://openaccess.city.ac.uk/7955/.

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New techniques are proven in this thesis which allow the visual examination of the tear film on the cornea and on different types of contact lenses. The techniques are as follows: 1. A high magnification technique of photography using the biomicroscope and crossed polarised light, allows the measurement of tear film layer thicknesses and on the surface of rigid contact lenses and 'in vivo receding contact angle'. 2. A low magnification technique of photography allows the recording and the analysis of the superficial layers of the tear film over a wide area of the eye and contact lens surface. 3. A clinical instrument has been designed for the routine clinical observation of the tear film. It permits the visual measurement of the tear film break-up time (BUT) without the use of fluorescein. 4. A unique technique of in-vivo photography of the mucous coverage of the corneal epithelial surface and contact lens surfaces is presented. Such techniques improve the understanding of surface wettability problems. As a result of this work the appearance of the normal lipid layer of the pre-ocular tear film has been classified into seven grades within a thickness range of 0.02μm to 0.58μm. As we well as the normal, two examples of abnormal lipid layers are described. The manner by which Meibomian gland secretion occurs and performs its role in the tear film is illustrated and analysed. Forced gland secretion by pressure induced localised lipid thickness increase. Eyelid closure was seen to compress the lipid film and instillation of saline broke up the lipid film. It can be seen that the pre-soft lens tear film usually possesses a thin superficial lipid layer and an aqueous phase of limited dimensions. On the other hand the pre-PMMA rigid contact lens tear film rarely possesses a visible superficial lipid layer and its aqueous layer measured 1.5μm on average. The addition of the 'wetting' solution acts on the thickness of the aqueous phase which increases to 2.5μm and supports a minimal lipid layer. The use of contact lens materials of better wettability permits the formation of films of increased thickness (up to 5.5μm) with a visible superficial lipid layer which was seen to stabilise the film and retard its drying. The main differences in mucous coverage are described as follows. At the level of the basal layer of the tear film the mucous coverage takes a continuous undulated form on the corneal epithelium but a discontinuous sporadic distribution on soft lenses decreasing to sporadic occurrence on rigid lenses. Finally, because of the acquisition of the quantitative results, new infra-structures of the pre-lens tear film for soft and rigid lenses are proposed.

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Almurshedi, Ahmed. « Alternative plate deformation phenomenon for squeeze film levitation ». Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/17120.

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This thesis deals with a theoretical and an experimental exploration of squeeze film levitation (SFL) of light objects. The investigations aimed to find the important design parameters controlling this levitation mechanism and also to suggest an alternative way to implement SFL. The study, through computer modelling and experimental validation, focused on Poisson's contraction effect for generating SFL. A finite element model (ANSYS) was verified by experimental testing of five different plate designs. Each plate was subjected to a uniaxial plain stress by an arrangement of two hard piezoelectric actuators (PZT) bonded to the bottom of the plate and driven with DC or AC voltages. It was observed that pulsation of a dimple or crest shaped elastic deformation along the longitudinal axis in the central area of the plate was created because of Poisson's contraction. This Poisson's effect generated the squeeze-film between the plate and the levitated object. The separation distance between a floating lightweight object and the plate was analysed using computational fluid dynamics (ANSYS CFX) through creation of a modelling model for the air-film entrapped between the two interacting surfaces - a typical three-dimensional fluid-solid interaction system (FSI). Additionally, the levitation distance has been experimentally measured by a Laser Sensor. A satisfactory agreement has been found between model predictions and experimental results. Two levitation systems, one based on a horn transducer (Langevin type) and the other one in the form of a plain rectangular plate made of Aluminium and firmly fastened at both ends with a surface-mounted piezoelectric actuator, were compared in this thesis. Both devices were based on SFL mechanism. Evidently, the performances of both designs were greatly influenced by the design structure and in particular by the driving plate characteristics such as plate size and geometry as well as the driving boundary conditions. To this end, physical experiments were carried out and it was found that the device utilising horn-type transducer yields better levitation performance. Ultimately, the research explained the confusion between three approaches to non-contact levitation through literature review and also pointed out some essential parameters like piezoelectric actuators location, material of the driving structure, coupled-field between the actuators and the driving structure and the fluid-solid interface that was existed between the excited plate and the levitated object.

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37

Gryn, Iryna. « Auto-assemblage de défauts structurels et de nano-objets dans des films cristaux liquides ». Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066710.

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Un intérêt scientifique croissant dans les cristaux liquides (LC) est née de leur capacité à guider l'assemblage des colloïdes1,2 et des nanoparticules (NPs)3-8 en configurations spatiales bien définies. Dans cette thèse, nous avons étudié les LC smectiques A (SmA) qui produisent 1D et 2D modèles de défauts de taille nanométrique9 avec sub-micrométrique périodicité et sont capables d'assembler des NP dans des structures ordonnées par défaut/NP interactions. La thèse a été axé sur deux tâches principales: l'élaboration d'une méthode fiable pour motifs de défaut de la création avec la symétrie et la périodicité prédéfinie qui peut être réglé par des champs électriques appliqués; assemblage NPs de nature différente, la taille et la forme en structures ordonnées dans accordable LC tableaux de défauts. Dans ce mémoire, nous avons montré que les modèles de défauts 1D et 2D peuvent être créés soit par variation de l'épaisseur du film à cristaux liquides en l'absence de champ électrique externe, ou en appliquant le champ à une épaisseur donnée. La morphologie de motif est déterminée par l'épaisseur de la région confinée, où le directeur de LC de rotation perpendiculaire à l'orientation parallèle à des substrats. Dans les cellules hybrides SmA/NP NPs anisométriques alignent le long de la directrice en l'absence de défauts, mais alignent parallèle à la ligne des défauts10 dans le noyau de défaut. Un champ électrique appliqué à la ligne normale de défaut de contestation de l'interaction des particules anisotropes défaut et peut conduire à une orientation perpendiculaire, en fonction du type et de la taille des particules. Ajout sphériques NPs d'or à SmA LCs conduit à la déstabilisation des domaines de défauts linéaires, la stabilisation de bandes striées et empêche l'agrégation même pour une grande concentration de NPs d'or dans les cellules hybrides
An increasing scientific interest in liquid crystals (LCs) has arisen from their ability to guide the assembly of colloids and nanoparticles (NPs) into well-defined spatial patterns. In this thesis we have studied the smectic A (SmA) LCs which produce 1D and 2D patterns of nanometer size defects with sub-micrometer periodicity and are capable to assemble NPs into ordered structures via defect/NP interactions. The dissertation was focused on two main tasks: developing a reliable method for creation defect patterns with predefined symmetry and periodicity which can be tuned by applied electric fields; assembling NPs of different nature, size and shape into ordered structures within tunable LC defect arrays. In this thesis we have shown that 1D and 2D defect patterns can be created either by varying the LC film thickness in the absence of external electric field, or by applying the field at a given thickness. The pattern morphology is determined by the thickness of the confined region, where the LC director rotates from normal to parallel to the substrates orientation. In SmA/NPs hybrid cells anisometric NPs align along the director in the absence of defects but align parallel to line defects within the defect core. An electric field applied normal to the defect line challenges the anisotropic particle-defect interaction and may lead to perpendicular orientation, depending on the particle type and size. Adding spherical gold NPs (GNPs) to SmA LCs leads to destabilization of linear defect domains, stabilization of striated stripes and prevents aggregation even for a large concentration of GNPs in hybrid cells

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38

McDaid, Liam. « Electrical characterisation of silicon-on-insulator structures ». Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385320.

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39

Wong, Kok Hou Centre for Advanced Macromolecular Design Faculty of Engineering UNSW. « Honeycomb structured porous film from amphiphilic block copolymers for biomedical applications ». Awarded by:University of New South Wales. Centre for Advanced Macromolecular Design, 2008. http://handle.unsw.edu.au/1959.4/41493.

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In recent times, it was divulged that highly ordered honeycomb structured porous films from a variety of polymers could be fabricated by breath figures (water droplets) templating technique. In contrast to existing macroporous fabrication techniques, this technique is simple, more versatile and very cost effective. Amphiphilic block copolymers composed of a hydrophobic and a hydrophilic block were employed in this research to examine the process of porous film formation and the outcome of films generated using breath figure technique. A customized film casting system, established according to the casting parameters affecting the outcome of films was used to generate honeycomb structured porous films for the studies. The casting method best suited to generate highly ordered honeycomb structured porous films and the procedures to manipulate the size of the pores in films generated from amphiphilic block copolymers were also investigated and identified. Analyses into the formation process of the honeycomb structured porous films revealed that the airflow casting method where the cast of polymer solution was supplied with a flow of moist air was the most suitable method to generate highly ordered honeycomb structured porous films from amphiphilic block copolymers. Variations to the casting conditions of the airflow casting method such as the rate of moist airflow could only provide limited alterations to the size of pores on films generated. However, changes to the chemical system of the casting solution such as the concentration and the molecular weight of polymers in the polymer solvent was more prominent in manipulating the size of pores in the generated films. On the other hand, any extreme variations to either the physical conditions or the chemical system could devastate the hexagonal arrangement of pores in these films. In the synthesis of amphiphilic block copolymers in this research, RAFT polymerization technique was used to generate the hydrophobic polymer block followed by the subsequent chain extension polymerization of the hydrophilic polymer block. The polymerization 'process, especially the hydrophilic chain extension polymerization, was investigated in details. It was established that there were significant dependence on the composition of the initial polymer block used, particularly the molecular weight and the type of chain transfer (RAFT) end group in the hydrophobic polymer chain. Incompatible RAFT end group and high polymer molecular weights of the initial block usually lead to slower rate of subsequent chain extension coupled with increased terminations. These copolymers generated were usually bimodal in molecular weight distributions and broad in polydispersity indexes. Honeycomb structured porous films generated from one of these amphiphilic block copolymers were assessed as scaffoldings for cell culture to regenerate cells. In particular, the effects of cellular attachments and proliferations on the honeycomb porous structures were investigated. The assessment of these honeycomb structured porous films indicated that not only were these films not cytotoxic but they also enhanced the quantity of cellular proliferation (2.7x) when used as cell culture substrate compared to standard non-porous polystyrene cell culture surfaces. Finally, this research had shown a simple way to generate a new class of highly ordered porous material that could be customized individually for a wide range of applications. The synthesis of amphiphilic block copolymers to generate these films could be achieved by RAFT polymerization with a board selection of polymers choices according to applications. A porous cell substrate such as honeycomb structured porous films could enhance cellular growth when used as a cell culture substrate.

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40

Werrett, M. R. « The structure-function relationships in laminated barrier films ». Thesis, De Montfort University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376563.

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41

Botiz, Ioan. « Processes of Ordered Structure Formation in Polypeptide Thin Film Solutions ». Mulhouse, 2007. https://www.learning-center.uha.fr/opac/resource/processes-of-ordered-structure-formation-in-polypeptide-thin-film-solutions/BUS4012009.

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La transformation de films solides minces de PS-PBLG en solutions, via l'exposition à la vapeur de solvant, nous a permis de nucléer et de croître dans de telles solutions de structures 3D ellipsoïdales ordonnées contenant des millions de molécules. Ces structures étaient orientées de manière aléatoire mais réparties de façon homogène sur la surface du film et possédaient une forme anisotrope que nous avons attribuée à une croissance asymétrique dans les directions latérales. Les expériences présentées dans ce travail ont prouvé que la taille des structures ellipsoïdales (limitée en raison de la diminution de la sursaturation) augmentait avec la diminution de la concentration de polymère dans la solution de film. Par conséquent, l'ordre des polypeptides dans une solution de film à deux concentrations de polymère consécutives conduit à une distribution bimodale des structures ellipsoïdales sur la surface du film. La réalisation d'expériences dans différentes conditions environnementales nous a permis de conclure que la solubilité du polymère pouvait être influencée par la variation de l'humidité de la phase gazeuse environnante. L'augmentation de l'humidité de la phase gazeuse environnante a conduit à une diminution de la valeur de la solubilité du polymère et à une augmentation de la tension interfaciale entre les structures ordonnées et la solution. Nous avons proposé que la complexation de PBLG par l'eau, via des interactions de liaison hydrogène, conduit à un "nouveau" polymère qui provoque la formation de structures ordonnées solides également à de faibles concentrations de polymère. Nous avons testé cette hypothèse en utilisant également de l'eau et d'autres non-solvants protiques comme le méthanol ou l'acide trifluoroacétique. À la fin, nous avons montré que le processus de formation de la structure ordonnée était réversible à la variation de l'humidité ou de la pression de vapeur d'un non-solvant protique dans la phase gazeuse environnante
Transforming thin solid films of PS-PBLG into solutions, via exposure to solvent vapor, allowed us to nucleate and grow in such solutions ordered ellipsoidal 3D structures containing millions of molecules. These structures were randomly oriented but homogeneously distributed on the film surface and possessed an anisotropic shape which we attributed to asymmetric growth in lateral directions. The experiments presented in this work proved that the size of ellipsoidal structures (limited due to decrease of supersaturation) was found to be increasing with the decrease of polymer concentration in film solution. Consequently, the ordering of polypeptides in a film solution at two consecutive polymer concentrations led to a bimodal distribution of ellipsoidal structures on the film surface. Performing experiments under different environmental conditions allowed us to conclude that polymer solubility could be influenced via surrounding gas-phase humidity variation. Increasing the humidity of the surrounding gas-phase led to a decrease of the value of polymer solubility and to an increase of interfacial tension between the ordered structures and the solution. We proposed that complexation of PBLG by water, via hydrogen bonding interactions, led to a "new" polymer which causes the formation of solid ordered structures also at low polymer concentrations. We tested this hypothesis by using besides water also other protic nonsolvents like methanol or trifluoroacetic acid. At the end, we have shown that the process of ordered structure formation was reversible upon varying humidity or vapor pressure of a protic non-solvent in the surrounding gas-phase

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42

Abeygunasekera, Anne Dinali. « Novel thick film multilayer structures incorporating interconnects and antennas ». Thesis, University of Surrey, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492976.

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The theme of this work has been multilayer microwave circuits, and. has focused on two aspects, namely multilayer interconnects and multilayer antennas. The report provides a detailed analysis of unwanted coupling in multilayer interconnections. New data are presented on the effects of coupling between conductors in highly integrated, multilayer circuits working at frequencies up to 100 GHz.

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43

Borge, Amruta. « GIANT MAGNETO-IMPEDANCE EFFECT IN THIN FILM LAYERED STRUCTURES ». Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3166.

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Recently, the giant magneto impedance (GMI) effect has been studied extensively because of its potential applications in sensor elements. The focus of this thesis work is to explore different compositions and processing conditions for CoSiB and NiFe thin films to obtain the soft magnetic properties and to evaluate their potential use in GMI sensor applications. Prior to this study, an MH Looper was constructed, which was extremely important and provided the basic magnetic characterization of the many ferromagnetic thin films deposited during this work. The CoSiB films were co-sputter deposited in an ultra high vacuum chamber. Films with different relative compositions of Co, Si and B were deposited by varying respective target powers. Different substrate bias conditions were also studied. Also, NiFe films were studied by varying relative composition by variation of target powers and also by variation deposition pressure. The effect of annealing was also studied. The magnetic and electrical characterization of these films was done using the MH Looper, Quad-pro four-point probe resistivity measurement, and Low Frequency Impedance analyzer HP4192A. Finally, CoSiB films with soft magnetic properties were obtained with optimized set of deposition parameters. A sample for GMI measurement was prepared, consisting of a multilayer thin film structure: CoSiB 200nm/ Cu 400nm / CoSiB 200nm. A serpentine pattern was generated on this film by photolithography technique. After obtaining the pattern, GMI studies were performed using LF impedance analyzer. This instrument was capable of providing the drive frequency in the range of 5Hz to 13MHz, but the impedance mis-match of the test fixture limited useful measurements to 9MHz. The highest GMI ratio observed was 6.2% at a 21 Oe longitudinal magnetic bias field at an 8MHz drive frequency. Transverse permeability measurements were performed by the use of two magnetic field axes of the MH Looper. The permeability behavior of the device reflects the impedance behavior with the external field. Permeability measurements were also performed on NiFe GMI Device with NiFe 600nm/ Cu 1200nm / NiFe 600nm sandwich structure. This sample was not successfully patterned and hence the impedance measurements could not be performed. Correlation of the magnetic properties of the structures was studied with the impedance responses.
M.S.E.E.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering

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McAneney, J. « Characteristics of thin and ultrathin film ferroelectric capacitor structures ». Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432670.

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45

Coe-Sullivan, Seth (Seth Alexander). « Hybrid organic/quantum dot thin film structures and devices ». Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33935.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (p. 157-169).
Organic light emitting diodes have undergone rapid advancement over the course of the past decade. Similarly, quantum dot synthesis has progressed to the point that room temperature highly efficient photoluminescence can be realized. It is the purpose of this work to utilize the beneficial properties of these two material sets in a robust light emitting device. New deposition techniques are necessary to the realization of this goal, enabling QD organic hybrids to be created in a quick and reliable manner compatible with known device fabrication methods. With these techniques, quantum dot light emitting devices are fabricated, measured, and analyzed. The devices are of high efficiency and color saturation, and provide us with a test bed for understanding the interactions between inorganic QDs and organic thin films.
by Seth Coe-Sullivan.
Ph.D.

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46

Collins, Simon Andrew. « Sensors for structural control applications using piezoelectric polymer film ». Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13613.

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47

Dayan, Dror. « The manifestations of political power structures in documentary film ». Thesis, Bournemouth University, 2018. http://eprints.bournemouth.ac.uk/31565/.

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The aim of this practice-led research is to explore the ways in which the political and social power structures between filmmaker and protagonist are manifested in the aesthetics and cinematic means of documentary film. Through a synthesis of filmmaking practice and “hidden knowledge” with critical theories from the fields of cultural studies and political philosophy the research devise methodological approaches to the critical analysis of documentary films in light of the political and material conditions of their emergence. By exploring filmmaking practice, both through the practical aspects of the research as well as through experiences made and reported by filmmakers, and placing those in the context of wider theories pertaining to issues of power structures and representation, it sheds light on the different aspects which must be considered when approaching the analysis of a documentary film for its ideological and political content. The work also asserts that in order to fully understand and analyse a documentary film, a wider range of factors must be considered, most prominently the material conditions of the filmmaking process. Those include the financing and commissioning of the film, the conditions of its production as well as its distribution and reception. Drawing on methodologies of dialectical materialism in cultural studies, the research approaches the studied films as well as the practical experiences in a holistic fashion, contextulaising them in historical, political and cultural processes instead of viewing them as isolated texts divorced from social context.

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Mogonye, Jon-Erik. « Stable Nanocrystalline Au Film Structures for Sliding Electrical Contacts ». Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849672/.

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Hard gold thin films and coatings are widely used in electronics as an effective material to reduce the friction and wear of relatively less expensive electrically conductive materials while simultaneously seeking to provide oxidation resistance and stable sliding electrical contact resistance (ECR). The main focus of this dissertation was to synthesize nanocrystalline Au films with grain structures capable of remaining stable during thermal exposure and under sliding electrical contact stress and the passing of electrical current. Here we have utilized a physical vapor deposition (PVD) technique, electron beam evaporation, to synthesize Au films modified by ion implantation and codeposited ZnO hardened Au nanocomposites. Simultaneous friction and ECR experiments of low fluence (< 1x10^17 cm^-2) He and Ar ion implanted Au films showed reduction in friction coefficients from ~1.5 to ~0.5 and specific wear rates from ~4x10^-3 to ~6x10^-5 mm^3/N·m versus as-deposited Au films without significant change in sliding ECR (~16 mΩ). Subsurface microstructural changes of He implanted films due to tribological stress were analyzed via site-specific cross-sectional transmission electron microscopy (TEM) and revealed the formation of nanocrystalline grains for low energy (22.5 keV) implantation conditions as well as the growth and redistribution of cavities. Nanoindentation hardness results revealed an increase from 0.84 GPa for as-deposited Au to ~1.77 GPa for Au uniformly implanted with 1 at% He. These strength increases are correlated with an Orowan hardening mechanism that increases proportionally to (He concentration)1/3. Au-ZnO nanocomposite films in the oxide dilute regime (< 5 vol% ZnO) were investigated for low temperature aging stability in friction and ECR. Annealing at 250 °C for 24 hours Au-(2 vol%)ZnO retained a friction coefficient comparable to commercial Ni hardened Au of ~ 0.3 and sliding ECR values of ~35 mΩ. Nanoindentation hardness increases of these films (~2.6 GPa for 5 vol% ZnO) are correlated to microstructure via high resolution TEM and scanning electron microscope cross-sections to both Hall-Petch and Orowan strengthening mechanisms. Also presented is a correlation between electrical resistivity and grain size in the oxide dilute range based on the Mayadas-Shatzkes (M-S) electron scattering model. Using the M-S model in combination with a model describing solute drag stabilized grain growth kinetics we present a new technique to probe grain boundary mobility and thermal stability from in-situ electrical resistivity measurements during annealing experiments.

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49

Gryn, Iryna. « Auto-assemblage de défauts structurels et de nano-objets dans des films cristaux liquides ». Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066710.

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Un intérêt scientifique croissant dans les cristaux liquides (LC) est née de leur capacité à guider l'assemblage des colloïdes1,2 et des nanoparticules (NPs)3-8 en configurations spatiales bien définies. Dans cette thèse, nous avons étudié les LC smectiques A (SmA) qui produisent 1D et 2D modèles de défauts de taille nanométrique9 avec sub-micrométrique périodicité et sont capables d'assembler des NP dans des structures ordonnées par défaut/NP interactions. La thèse a été axé sur deux tâches principales: l'élaboration d'une méthode fiable pour motifs de défaut de la création avec la symétrie et la périodicité prédéfinie qui peut être réglé par des champs électriques appliqués; assemblage NPs de nature différente, la taille et la forme en structures ordonnées dans accordable LC tableaux de défauts. Dans ce mémoire, nous avons montré que les modèles de défauts 1D et 2D peuvent être créés soit par variation de l'épaisseur du film à cristaux liquides en l'absence de champ électrique externe, ou en appliquant le champ à une épaisseur donnée. La morphologie de motif est déterminée par l'épaisseur de la région confinée, où le directeur de LC de rotation perpendiculaire à l'orientation parallèle à des substrats. Dans les cellules hybrides SmA/NP NPs anisométriques alignent le long de la directrice en l'absence de défauts, mais alignent parallèle à la ligne des défauts10 dans le noyau de défaut. Un champ électrique appliqué à la ligne normale de défaut de contestation de l'interaction des particules anisotropes défaut et peut conduire à une orientation perpendiculaire, en fonction du type et de la taille des particules. Ajout sphériques NPs d'or à SmA LCs conduit à la déstabilisation des domaines de défauts linéaires, la stabilisation de bandes striées et empêche l'agrégation même pour une grande concentration de NPs d'or dans les cellules hybrides
An increasing scientific interest in liquid crystals (LCs) has arisen from their ability to guide the assembly of colloids and nanoparticles (NPs) into well-defined spatial patterns. In this thesis we have studied the smectic A (SmA) LCs which produce 1D and 2D patterns of nanometer size defects with sub-micrometer periodicity and are capable to assemble NPs into ordered structures via defect/NP interactions. The dissertation was focused on two main tasks: developing a reliable method for creation defect patterns with predefined symmetry and periodicity which can be tuned by applied electric fields; assembling NPs of different nature, size and shape into ordered structures within tunable LC defect arrays. In this thesis we have shown that 1D and 2D defect patterns can be created either by varying the LC film thickness in the absence of external electric field, or by applying the field at a given thickness. The pattern morphology is determined by the thickness of the confined region, where the LC director rotates from normal to parallel to the substrates orientation. In SmA/NPs hybrid cells anisometric NPs align along the director in the absence of defects but align parallel to line defects within the defect core. An electric field applied normal to the defect line challenges the anisotropic particle-defect interaction and may lead to perpendicular orientation, depending on the particle type and size. Adding spherical gold NPs (GNPs) to SmA LCs leads to destabilization of linear defect domains, stabilization of striated stripes and prevents aggregation even for a large concentration of GNPs in hybrid cells

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50

Milton, A. J. « Structural properties of polyaniline films ». Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5548/.

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This thesis describes the experimental investigations of the structural properties of the conductive polymer, poly aniline. These studies have been performed on free-standing film samples, solution cast using the solvent N- methyl-2-pyrrolidinone (NMP). Such specimens have enabled a wealth of detailed information about polyaniline to be derived. The polymer itself was synthesised in the emeraldine base form using a chemical route optimised at Durham. The product was then assessed for its chemical structure and molecular weight using (^13)c NMR, elemental analysis and gel permeation chromatography. The process of fabricating the polymer into free-standing films is discussed and assessed. It has been shown that such films may be oriented by the application of uniaxial stress at elevated temperatures and this procedure has been described and analysed in detail. This stretching process aligns the polymer chains on a molecular level and hence produces changes in the physical properties of films. In particular, upon doping to the conducting emeraldine salt form by protonation in aqueous HCl, stretch oriented films display a remarkable increase in conductivity (parallel to the stretch direction) over their unstretched, doped counterparts. Various thermal analysis techniques, including dynamic mechanical thermal analysis, dielectric thermal analysis, thermomechanical analysis and infrared spectroscopy have been used to probe the physical properties of polyaniline films. Using these techniques a number of important thermal transitions have been observed and furthermore the stretch alignment process has been rationalised. Infrared orientational analysis has revealed detailed information about the molecular orientation produced during macroscopic stretching of a film. The type and degree of chain orientation has been analysed as well as the geometrical structure of a single chain. X-ray diffraction has probed the crystalline fraction of polyaniline films. Various aspects concerning the crystalline fraction of film samples has been derived along with an orientational analysis which has been contrasted with the infrared results. An even greater amount of structural information has been revealed by neutron diffraction and this technique has enabled a detailed examination of the structure of the crystalline phases of polyaniline to be made.

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