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Sklar, Zenon. "Quantitative acoustic microscopy of coated materials." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308851.
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Kim, Han Sung. "Prediction Of Elastic Properties Of Micro- And Nano-Scale Thin Films." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211905997.
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Deva, Reddy Jayadeep. "Mechanical Properties of Silicon Carbide (SiC) Thin Films." Scholar Commons, 2007. https://scholarcommons.usf.edu/etd/210.
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There is a technological need for hard thin films with high elastic modulus. Silicon Carbide (SiC) fulfills such requirements with a variety of applications in high temperature and MEMS devices. A detailed study of SiC thin films mechanical properties was performed by means of nanoindentation. The report is on the comparative studies of the mechanical properties of epitaxially grown cubic (3C) single crystalline and polycrystalline SiC thin films on Si substrates. The thickness of both the Single and polycrystalline SiC samples were around 1-2 µm. Under indentation loads below 500 µ-Newton both films exhibit Elastic contact without plastic deformation. Based on the nanoindentation results polycrystalline SiC thin films have an elastic modulus and hardness of 422 plus or minus 16 GPa and 32.69 plus or minus 3.218 GPa respectively, while single crystalline SiC films elastic modulus and hardness of 410 plus or minus 3.18 Gpa and 30 plus or minus 2.8 Gpa respectively. Fracture toughness experiments were also carried out using the nanoindentation technique and values were measured to be 1.48 plus or minus 0.6 GPa for polycrystalline SiC and 1.58 plus or minus 0.5 GPa for single crystal SiC, respectively. These results show that both polycrystalline SiC thin films and single crystal SiC more or less have similar properties. Hence both single crystal and polycrystalline SiC thin films have the capability of becoming strong contenders for MEMS applications, as well as hard and protective coatings for cutting tools and coatings for MEMS devices.
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Schwarzer, Norbert. "Modelling of the contact mechanics of thin films using analytical linear elastic approaches." Doctoral thesis, [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11244005.
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He, Wei. "Mechanical and microstructural properties of thin metal films on compliant substrates." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2280/document.
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Le comportement mécanique de films minces métalliques déposés sur des substrats souples joue un rôle déterminant dans les performances de l'électronique flexible et des micro- systèmes électromécaniques (MEMS).Dans un premier temps, une nouvelle méthode est présentée pour caractériser le module d'élasticité de films minces submicroniques. Avec deux couches déposées de chaque côté et sur la moitié du substrat polymère, la corrélation d'image numérique (CIN) a été utilisée pour mesurer simultanément la déformation du film et du substrat in situ au cours d'un essai de traction. La différence entre les déformations mesurées sur la partie vierge et le composite permet d'extraire les propriétés élastiques de films minces de manière simple et avec grande précision. Comme attendu, la distribution des déformations est uniforme au travers de l'épaisseur du film ce qui indique une adhésion parfaite entre le film et le substrat. Dans le cas de films minces de tungstène, de chrome, de nickel et de cuivre, les valeurs de module obtenues sont proches de celles des mêmes matériaux à l'état massif.Dans un deuxième temps, une nouvelle méthode expérimentale utilisant une machine de déformation uniaxiale est présentée pour étudier l'effet Bauschinger dans des films minces métalliques déposés sur des substrats étirables. Grâce à un dispositif original, les films minces sont déposés sur des substrats prétendus et peuvent donc être déformés alternativement en tension et en compression dans un large domaine de déformations. La déformation élastique intra granulaire des films minces polycristallins et la déformation macroscopique du substrat sont mesurées in situ par diffraction des rayons X et CIN respectivement. A partir des courbes « déformation élastique – déformation macroscopique », la réponse mécanique de l'ensemble film / substrat est analysée au vu de l'histoire complète du chargement et de la microstructure (contraintes résiduelles, texture) des films minces<br>The mechanical behavior of metallic thin films deposited on soft substrates plays a crucial role in the performance of flexible electronics and MicroElectroMechanical Systems (MEMS).At first, a novel method is presented to characterize the in-plane elastic modulus of sub micrometer thin films. With two coating layers bonded symmetrically to half polyimide substrates, Digital Image Correlation (DIC) has been employed to measure time-resolved full-field strain maps of film and substrate during in situ tensile testing. The strain differences between virgin and composite parts allowed to extract the elastic properties of the thin films in a simple way with high precision. As expected, the strain distribution is uniform through the film thickness which indicates a perfect adhesion between the film and the substrate. In the case of tungsten, chromium, nickel and copper films, the values obtained are close to the bulk one.In a second step, a new experimental method using uniaxial tensile testing is presented to study Bauschinger effect in thin metallic films deposited on stretchable substrates. Thanks to our new pre-tensile setup (specific grips), the thin films were deposited on pre-stretched substrates and thus could be deformed alternately in tension and compression within a large strain domain. The elastic intra-granular strain of polycrystalline thin films and true strain of substrates are measured in situ by X-Ray Diffraction (XRD) and DIC. From lattice strain-true strain curves, the mechanical response of copper and nickel /substrate sets is analyzed in view of the complete loading history and the presence of residual stresses and crystallographic texture in thin films
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Schwarzer, Norbert. "Modelling of the contact mechanics of thin films using analytical linear elastic approaches." Doctoral thesis, N. Schwarzer: Arbitrary load distribution on a layered half space, ASME Journal of Tribology, Vol. 122, No. 4, October 2000, 672-681, ISSN 0742-4787; N. Schwarzer, F. Richter, G. Hecht: ”Elastic Field in a Coated Half Space under Hertzian pressure distribution”, J. of Surface & Coatings Technology 114 (1999) 292-304, ISSN 0257-8972; N. Schwarzer, Th. Chudoba, D. Billep, F. Richter: ”Investigation of coating substrate compounds using inclined spherical indentation”, J. of Surface & Coatings Technology 116 – 119 (1999) 244-252, ISSN 0257-8972, 2003. https://monarch.qucosa.de/id/qucosa%3A18161.
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In this work the author presents simulation procedures (mathematical models) with the aim to help determining and analysing the mechanical properties of coating-substrate-systems and finding an optimal coating structure which should protect the compound from inelastic deformation under a given range of load conditions. Such procedures may be used as a tool to minimise the search field for experimental work. For this purpose one would need a mathematical model which allows one to calculate the complete elastic field with all its displacement and stress components within a multilayer film on a substrate under given mechanical loading and intrinsic stress conditions.
Due to copyright restrictions the author is not allowed to publish the Part II of his habilitation thesis at this place. It concerns the references in meta data.<br>In der Arbeit werden mathematische Modelle zur Berechnung der mechanischen Eigenschaften geschichtet aufgebauter Materialien unter unterschiedlichsten Lastbedingungen (Kontakt- und intrinsische Beanspruchung) vorgestellt und diskutiert.
Auf Grund von Schutzrechtsbestimmungen ist eine Veröffentlichung der in der Habilitation angegebenen Literatur im Teil II an dieser Stelle nicht möglich. Der interessierte Leser wird gebeten die Arbeiten in den entsprechenden Journalen einzusehen. Dies betrifft die in den Metadaten angegebenen Veröffentlichungen des Autors.
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Ashrafi, Behnam. "Theoretical and experimental investigations of the elastic properties of carbon nanotube-reinforced polymer thin films." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21910.
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Nanocomposites are a promising new class of materials for the mechanical components of microstructures such as microactuators and microresonators. This work presents a combination of theoretical and experimental investigations of the utility of carbon nanotube-reinforced composites for designing microstructures. In the theoretical part of this research, the effects of nanotube aspect ratio, dispersion, alignment, and volume fraction on the elastic modulus and longitudinal wave velocity are analyzed by recourse to the Mori-Tanaka theory. The calculated bounds on Young's modulus and wave velocity capture the trend of the experimental results reported in the literature. Polymer-matrix nanocomposites reinforced with aligned, dispersed single-walled carbon nanotubes are identified as excellent candidates for small structures with properties rivaling those of metallic- and ceramic-structures used in the current generation of microelectromechanical systems (MEMS). The experimental part of this research focuses on the manufacture and characterization of carbon nanotube-reinforced polymer thin films. A novel nanoindenter-based bending test is developed for characterizing the elastic properties of nanocomposite thin films. This technique is first numerically verified using finite element methods. Polymer thin films with known mechanical properties are then utilized to validate the technique experimentally. Next, epoxy-matrix and vinyl ester epoxy-matrix nanocomposite films (ranging from 50 to 70 μm in thickness) reinforced with low concentrations (<1% by weight) of single-walled carbon nanotubes are successfully manufactured and characterized. Finally, using carbon nanotube sheets (buckypaper), polymer-matrix nanocomposite films with high volume fractions of carbon nanotubes (30-40%) are manufactured by using two different techniques: vacuum infiltration and hot press. This relatively high content of carbon nanotubes results in a three- to four-fold increase in the elasti<br>Les nano-composites sont une nouvelle classe de matériaux prometteurs pour les composants mécaniques de microstructures telles que les micro-actuateurs et micro-résonateurs. Ce travail présente une combinaison d'études théoriques et expérimentales sur l'utilité de composites renforcés par des nanotubes de carbone pour la conception de microstructures. Dans la partie théorique de cette recherche, les effets du rapport de forme, de la dispersion, de l'alignement et de la fraction volumique des nanotubes sur le module élastique et la vitesse d'onde longitudinale ont été analysés en utilisant la théorie de Mori-Tanaka. Les limites calculées du module d'Young et de la vitesse d'onde capturent la tendance des résultats expérimentaux rapportés dans la littérature. Les nano-composites à matrice polymère renforcée avec des SWNT alignés et dispersés ont été identifiés comme d'excellents candidats pour de petites structures dont les propriétés rivalisent avec les structures métalliques ou céramiques utilisées dans la présente génération de systèmes micro-électro-mécaniques (MEMS). La partie expérimentale de cette recherche focalise sur la fabrication et la caractérisation de films polymères minces renforcés avec des nanotubes de carbone. Du aux difficultés rencontrées avec les techniques traditionnelles pour la caractérisation du module élastique de films polymère minces, une nouvelle technique, un test en flexion par nano-indentation, a été développée avec succès. La technique a été d'abord vérifiée numériquement par la 00 méthode d'éléments finis. Puis des films polymère minces avec des propriétés connues ont été utilisés pour vérifier cette technique expérimentalement. Par la suite, des films minces (épaisseur variant de 50 à 70 μm) de nano-composite à matrice époxy et vinyle-ester renforcées avec de faibles concentrations de SWNT (1% par masse) ont été fabriqués et caractérisés avec succès
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Chima-Okereke, Chibisi. "The elastic properties of PZT thin films on Pt/SiOâ‚‚/Si substrate measured by nanoindentation." Thesis, Queen Mary, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424915.
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Bock, Florian. "Active learning of interatomic potentials to investigate thermodynamic and elastic properties of Ti0.5Al0.5N at elevated temperature." Thesis, Linköpings universitet, Teoretisk Fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176587.
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With the immense increase in the computational power available for the material science community in recent years, a range of new discoveries were made possible. Accurate investigations of large scale atomic systems, however, still come with an extremely high computational demand. While the recent development of Graphics Processing Unit (GPU) accelerated supercomputing might offer a solution to some extent, most well known electronic structure codes have yet to be fully ported to utilize this new power. With a soaring demand for new and better materials from both science and industry, a more efficient approach for the investigation of material properties needs to be implemented. The use of Machine Learning (ML) to obtain Interatomic Potentials (IP) which far outperform the classical potentials has increased greatly in recent years. With successful implementation of ML methods utilizing neural networks or Gaussian basis functions, the accuracy of ab-initio methods can be achieved at the demand of simulations with empirical potentials. Most ML approaches, however, require high accuracy data sets to be trained sufficiently. If no such data is available for the system of interest, the immense cost of creating a viable data set from scratch can quickly negate the benefit of using ML. In this diploma project, the elastic and thermodynamic properties of the Ti0.5Al0.5N random alloy at elevated temperature are therefore investigated using an Active Learning (AL) approach with the Machine Learning Interatomic Potentials (MLIP) package. The obtained material properties are found to be in good agreement with results from computationally demanding ab-initio studies of Ti0.5Al0.5N, at a mere fraction of the demand. The AL approach requires no high accuracy data sets or previous knowledge about the system, as the model is initially trained on low accuracy data which is removed from the training set (TS) at a later stage. This allows for an iterative process of improving and expanding the data set used to train the IP, without the need for large amounts of data.
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Hostert, Carolin [Verfasser]. "Towards designing elastic and magnetic properties of Co-based thin film metallic glasses / Carolin Hildegard Hostert." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1026067758/34.
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ZANONI, RAYMOND. "BRILLOUIN SPECTROSCOPY OF LANGMUIR-BLODGETT FILMS (THIN FILMS, ELASTIC CONSTANTS)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183852.
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The goal of this dissertation has been to develop techniques in order to use Brillouin spectroscopy as a tool for studying the elastic properties of thin films on a scale of ≃100 Å. In order to develop that capability we have built a tandem multi-pass Fabry-Perot interferometer, and that interferometer was used to study the elastic properties of Langmuir-Blodgett films. These films were chosen because they can be deposited one molecular layer at a time. As a result of these investigations we have measured the density and elastic constants of the Langmuir-Blodgett film cadmium arachidate. Samples of cadmium arachidate were prepared on molybdenum and BK-7 glass substrates. Data were accumulated for a range of thicknesses and for different scattering geometries. These data will be used to argue that guided acoustic waves were observed in a highly anisotropic film. The observed guided acoustic waves will be identified as a Rayleigh wave and a tight band of Sezawa modes. No Love modes were detected in these experiments; however, evidence for reorientational modes typical of anisotropic liquids was detected. The dispersion of the Rayleigh wave as a function of thickness together with thick film scattering data were used to estimate the elastic constants in cadmium arachidate. In particular the shear elastic constant c₄₄ was found to be a small value: c₄₄ < 4.0x10⁸ N/m². The remaining elastic constants were estimated, assuming hexagonal film symmetry, to be c₆₆ < 4.5x10⁹ N/m², C₁₁ ≃ 1.1x10¹⁰ N/m², c₃₃ ≃ 2.1x10¹⁰ N/m², c₁₃ ≃ 1.0x10¹⁰ N/m², and c₁₂ > 3.x10¹⁰ N/m². It is interesting to note that the acoustical behavior of cadmium arachidate is quite similar to the smectic phase liquid crystals (c₄₄ = 0).
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Leroy, Samuel. "Les forces de surface dynamiques pour l'investigation mécanique des surfaces molles." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00610528.
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Ce travail étudie comment la mesure des forces hydrodynamiques exercées par un liquide confiné entre une sphère et une surface d'intérêt permet de sonder à distance et sans contact les propriétés mécaniques de cette surface. Nous présentons tout d'abord le principe de cette technique originale de sonde fluide et la machine à forces de surface dynamique que nous utilisons pour mettre en oeuvre ces expériences de nano-rhéologie. Puis nous nous intéressons à deux applications que nous avons plus particulièrement étudiées. D'une part, l'étude des propriétés de friction des bicouches lipidiques. Nous mettons en évidence une très faible friction mesurée sur certaines bicouches fluides et son potentiel rôle pour la bio-lubrification. D'autre part l'étude des propriétés élastiques de couche mince d'élastomère. Nous développons pour cela une théorie de l'élasto-hydrodynamique à géométrie sphère-plan en mode dynamique et présentons des résultats expérimentaux en très bon accord. Nous sommes capables de mesurer le module d'Young de films mince de PDMS d'épaisseur allant jusqu'à 600~nm. Enfin, nous présentons les développements instrumentaux réalisés pour optimiser les performances de la machine à forces de surfaces comme sonde fluide.
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Warnicke, Peter. "Tailored Properties of Ferromagnetic Thin Films." Doctoral thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9403.
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Magnetic thin films and patterned nanostructures have been studied with respect to their magnetic properties using SQUID-magnetometry, magnetic force microscopy, electrical measurements, and micromagnetic calculations. Properties of vortex domain walls, trapped in Permalloy nanowires with artificial constrictions, were investigated experimentally and by numerical calculations. In particular, the geometrical extent and strength of the pinning potential were evaluated. In these wires, long-range vortex domain wall displacement induced by spin polarized alternating currents was obtained numerically at reduced threshold current densities as compared with the direct current case. Due to the asymmetry of the energy potential, the long-range displacement direction is determined by the vortex chirality. Strained FeCo/Pt superlattices with strong perpendicular anisotropy were investigated experimentally. The strain was controlled by varying the thickness of each alternating layer with monolayer precision and was found to have a dominating effect on the total anisotropy. Epitaxial films of the diluted magnetic semiconductor (Ga,Mn)As were studied with focus on how the ferromagnetic transition temperature could be controlled by post-growth annealing. The ferromagnetic transition temperature was enhanced by approximately 85% for a Mn-doping concentration of 6% under certain conditions. A method to manipulate micrometer sized magnetic particles on patterned arrays of elliptical Permalloy microstructures was studied. Controlled motion and separation of the magnetic particles were obtained using applied rotating magnetic fields. The domain structure of the elliptical elements was studied numerically.
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Ren, Yitao. "Waveguide properties of thin polymer films." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4563/.
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Some basic concepts and principles of optical dielectric slab waveguiding and experimental methodology involving characterisation of waveguide films are introduced, Results from the characterisation of thin polymeric waveguide films and measurements of refractive indices of the films are presented. The birefringence of some polymer films is analysed and discussed. The photostabilities of several dopants (DEMI, Ultra-DEMI, Dicyclohexyl-DEMI, Mor2, Morpip and DCM) are investigated in a polymer matrix (PMMA), and their measured photostabilities are presented. These organic chromophores change their properties in the course of photodegradation. Degradation experiments are carried out by exposing the doped waveguide films to light in air, vacuum and nitrogen environments. The degradation mechanisms of these chromophores are discussed. It is found that the degradation of the DEMI, Ultra-DEMI, Dicyclohexyl-DEMI and DCM are due to photooxidation, their photostabilities are much higher in vacuum than in air. The Mor2 and Morpip degrade by direct photodecomposition, their photostabilities are in the same order when exposed to light in their main absorption bands. The oxygen free environment (e.g. vacuum) is essential to increase their photostabilities. A beam branching effect in DCM doped waveguide film is observed. Stacked multi-layer waveguides are investigated as possible humidity sensors. Symmetric structure (PMMA/P-4VP/PMMA/P-4VP/PMMA) (P4VP-I) and unsymmetric structure (Si02/P-4VP/Zeonex/P-4VP/Air) (P4VP-II) are studied. Special procedures and process have been developed to fabricate multi-layer waveguide structures in experiments. It is found that both structures have good reversibilities and show reasonable stabilities. 30 ppm concentrations of water vapour can be detected by the P4VP-II structure. The experimental results show that the overall response of P4VP-II structure exhibits good linearity with increase of the concentration of water vapour. The structures can not only measure the phase shift of interference, but also can measure the direction of fringe movement. The sensitivity of the structure can be further improved by using different combinations of polymers in the structure.
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Critchley, Susan Marie. "Electronic properties of phthalocyanine thin films." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315067.
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Kumar, Atul. "Diffraction stress analysis of thin films; investigating elastic grain interaction." Stuttgart Max-Planck-Inst. für Metallforschung, 2005. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-24805.
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Rycroft, Ian M. "Electric, magnetic and optical properties of thin films, ultra thin films and multilayers." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318142.
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Babkair, S. S. "Multilayer ferromagnetic thin films." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234564.
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Choi, Jaehwan. "Statistical approach to the elastic property extraction and planar elastic response of polycrystalline thin-films." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092851082.
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Thesis (Ph. D.)--Ohio State University, 2004.<br>Title from first page of PDF file. Document formatted into pages; contains xvi, 156 p.; also includes graphics (some col.). Includes bibliographical references (p. 150-156). Available online via OhioLINK's ETD Center
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Atherton, Timothy James. "Frustration phenomena due to elastic anisotropy in thin liquid crystal films." Thesis, University of Exeter, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436421.
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Allen, R. A. "Structure and properties of azobenzene thin films." Thesis, Lancaster University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379750.
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Javed, Athar. "Magnetic properties of Fe-Ga thin films." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531234.
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李瑞如 and Sui-yu Li. "Mechanical properties of Tial-based thin films." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224787.
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Wallace, Roger James. "The optical properties of YBCO thin films." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388097.
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Smith, V. C. "Chlorine sensing properties of thin porphyrin films." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264752.
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Nasser, G. Y. "The electrical properties of thin carbon films." Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370126.
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Li, Sui-yu. "Mechanical properties of Tial-based thin films /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B23273264.
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Choi, Jae Hyeok. "Nanomechanical properties of hydrated organic thin films." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42984.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2007.<br>Includes bibliographical references (leaves 167-171).<br>Hydrated organic thin films are biological or synthetic molecularly thin coatings which impart a particular functionality to an underlying substrate and which have discrete water molecules associated with them. Such films exist in biology (e.g. cell membrane lipid bilayers) and have a broad array of potential engineering applications (e.g. biological implant and sensor surfaces, marine antifouling paints etc.). This doctoral thesis focuses on two important classes of hydrated organic thin films that were prepared and studied in vitro. The first model system was an oligo(ethylene oxide)-based self-assembling monolayer (OEO-SAM) which is a synthetic material that is known to exhibit exceptional resistance to nonspecific protein adsorption and, hence, it is a viable candidate for producing implant surfaces with improved biocompatibility. The second model system was the biologically relevant phosphorylcholine(PC)-supported lipid layer which mimics the structure of the cell membrane. The objective of this doctoral thesis was to quantify the functional form of the net surface interaction (force versus separation distance, F(D)), as well as the contact mechanical properties (e.g. elasticity, plasticity, fracture) of these two model systems under different solution conditions, in order to formulate a hypothesis for the molecular origins of the dominant interactions and furthermore, to gain a mechanistic understanding of their in vivo function and performance. For the OEO-SAMs, F(D) was found to exhibit the maximum monotonic repulsive functional form for intermediate surface packing densities (-70%) on loading (approach) and negligible adhesion (Fadhesion<0.3nN) on unloading (retract). Both were attributed to an electrostatic component arising from a dipole induced effective surface charge, as well as a nm-thick hydrated water layer.<br>(cont.) For the PC lipid layers, the effect of length scale on the yield threshold force, Fy, was studied by varying the probe tip end radius, Rtip, used for the surface force measurements. Fy decreased by 20x (Force/Radius) as Rtip increased from 30 nm to 80 nm, presumably due to the fact that the contact area possessed an increased density of molecular-level defects, thereby causing stress concentrations and a reduction in mechanical stability of the layer.<br>by Jae Hyeok Choi.<br>Ph.D.
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Kusano, Yukihiro. "Production and properties of CN thin films." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624452.
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Běhounek, Tomáš. "Imaging Reflectometry Measuring Thin Films Optical Properties." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-233857.
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V této práci je prezentována inovativní metoda zvaná \textit{Zobrazovací Reflektometrie}, která je založena na principu spektroskopické reflektometrie a je určena pro vyhodnocování optických vlastností tenkých vrstev .\ Spektrum odrazivosti je získáno z map intenzit zaznamenaných CCD kamerou. Každý záznam odpovídá předem nastavené vlnové délce a spektrum odrazivosti může být určeno ve zvoleném bodu nebo ve vybrané oblasti.\ Teoretický model odrazivosti se fituje na naměřená data pomocí Levenberg~-~Marquardtova algoritmu, jehož výsledky jsou optické vlastnosti vrstvy, jejich přesnost, a určení spolehlivosti dosažených výsledků pomocí analýzy citlivosti změn počátečních nastavení optimalizačního algoritmu.
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Jenderka, Marcus. "Growth and Properties of Na2IrO3 Thin Films." Master's thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-201974.
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The layered honeycomb lattice iridate Na2IrO3 is a novel candidate material for either a topological insulator or spin liquid. These states of matter are one possible starting point for the future realization of scalable quantum computation, but may also find application in magnetic memory or low-power electronic devices. This thesis reports on the pulsed laser deposition of high-quality heteroepitaxial (001)-oriented Na2IrO3 thin films with well-defined in-plane epitaxial relationship on 5-by-5 and 10-by-10 square millimeter single-crystalline sapphire, YAlO3 and zinc oxide substrates. Three-dimensional Mott variable range hopping is the dominant conduction mechanism between 40 and 300 K. Moreover, a signature of the proposed topological insulator phase is found in magnetoresistance by observation of the weak antilocalization effect that is associated with topological surafce states. Compared to single crystals, a smaller, 200-meV optical gap
in Na2IrO3 thin films is found by Fourier-transform infrared transmission spectroscopy.
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Farmer, David John. "Elastic measurements in ultra-thin polymer structures." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33073/.
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This thesis contains details of a series of experiments performed to investigate the acoustic and elastic properties of ultra-thin polymer structures. Three main investigations were conducted. The first involved studying quantised vibrations in ultra-thin (∼100 nm) polystyrene films on silicon substrates. These films were vibrated via the picosecond acoustic technique, an optical pump-probe method. Quantised, harmonic vibrations were observed in the films with frequencies of the order of 10 GHz. The polymer films were then loaded by evaporating small thicknesses (2.5 - 30 nm) of gold. The frequencies of loaded areas were observed relative to the unloaded films. This frequency shift is described via a theory that considers the elastic wave equation in the structure with appropriate boundary conditions. Excellent agreement between experiment and theory is achieved, suggesting the potential for using these films as ultra-sensitive mass sensors. The second experimental chapter deals with experiments performed on polymer Bragg reflectors. These multilayer structures were again investigated via the picosecond technique. The reflected intensity of the probe laser beam was observed to be modulated by the strain pulse as it travelled through the structure. These results were compared to theoretically generated signals and this comparison suggests that, in the polymer structures considered here, the modulation can be described almost exclusively by the photo-elastic effect. Although the modulation is small it opens up the possibility of using similar structures in combinations with micro-cavities to act as high frequency optical components. The final experimental chapter details attempts to develop a new metrology for elastic properties in ultra-thin polymer films floated on a water surface. The films were cut into annuli and placed on a Langmuir-Blodgett trough before surfactant was placed around the outside. By moving the barriers of the trough, a surface pressure difference between the inside and outside of the annulus could be controlled and a wrinkling pattern induced around the annulus. A system for imaging and counting the wrinkles as a function of the surface pressure difference was developed and a theory that attempts to describe this is detailed. While the experimental technique is successful in producing highly controlled, reproducible wrinkles, the theoretical analysis currently overestimates the Young's modulus of the films. The reasons for this as well as avenues for further work are considered. The results of these three investigations all demonstrate the rich physics accessible in ultra-thin polymer films. Furthermore, it points to their potential to b e a key material as devices are more commonly manufactured at the nano-scale.
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Ng, Hoi-pang. "Mechanical and electrical properties of nickel-aluminium thin films /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21852315.
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Gump, Jared Clinton. "Elastic properties of germanium selenium glasses and metastable cobalt films /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486462067840445.
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Zhao, Jie-hua. "Thermomechanical properties and phase transition of thin and ultra-thin films /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Andrade, Silva Ignacio Javier. "Wrinkling and folding induced pattern formation in elastic thin sheets." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEN065.
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Cette thèse explore deux mécanismes de formation de motifs dans des feuilles minces élastiques : la formation de rides et des plis. La première partie de la thèse aborde le rôle des conditions aux limites dans l’analyse des instabilités de rides dans des films minces tendus. Les instabilités de rides ont été largement étudiés dans des géométries simples, où la direction des rides est connue à priori. Par exemple, le problème de Lamé, consistant en une feuille annulaire radialement étirée, a servi de modèle pour le formation de rides en traction dans des géométries axiales. Nous étudions les effets de la modification des conditions de charge et de la géométrie. Premièrement, nous considérons une feuille annulaire étirée vers l’intérieur dont le bord extérieur est fixé et comparons l’analyse du motif ridé avec le cas du problème de Lamé. Deuxièmement, nous étudions le problème élastique d’une feuille élastique infinie perforée d’un trou elliptique et soumise à une tension différentielle uniforme entre son bord extérieur et intérieur. Nous calculons le champ de contraintes dans l’état pré-déformé et leurs composantes principales et directions correspondantes. Nous obtenons un diagramme de phase montrant les différents états de contrainte de la membrane et discutons des résultats possibles au-delà de l’instabilité de flambement. La deuxième partie de la thèse aborde la forme à l’équilibre des motifs d’origami non rigide à sommet unique dans des feuilles élastiques. La conception de métamatériaux mécaniques inspirés de l’origami est généralement axée sur la cinématique d’assemblages de plaques planaires rigides reliées par des charnières (origami rigide). Lorsque les panneaux sont flexibles (origami non rigide), de nouveaux comportements apparaissent, tels que le cas des cônes pliables (f-cones), des feuilles circulaires décorées de plis radiaux. Ces structures sont toujours bistables, en ce sens qu’elles peuvent passer d’une configuration métastable à une autre. Nous avons proposé un modèle général de f-cones composés de feuilles inextensibles qui démontre la nature bistable de ces systèmes. De plus, le modèle est capable de prédire les formes d’équilibre pour toutes les déflexions en fonction des angles de plis et leur réponse. En outre, nous avons testé la validité de l’hypothèse d’inextensibilité au moyen d’une étude numérique d’éléments finis, dans laquelle les plis sont modélisés sous forme de tranches continues de la plaque qui se plient en raison d’un gradient de dilatation thermique<br>This thesis explores two mechanisms for pattern formation in elastic thin sheets : wrinkling and folding. The first part of the thesis discusses the role of boundary conditions in the analysis of tensional wrinkling of thin films. Wrinkling phenomena have been widely studied in simple geometries, where the direction of wrinkles is known a priori. For instance, the Lamé problem, consisting of a radially stretched annular sheet, has served as a prototypical model for theoretical and experimental studies in axial geometries. We study the effect of changing the loading conditions and geometry of the Lamé problem. First, we consider an inwardly stretched annular sheet whose outer edge is clamped and compare the analysis of the wrinkled pattern with the Lamé case. Second, we study the elastic problem of an infinite elastic sheet perforated by an elliptic hole and subjected to a uniform differential tension between its outer and inner edges. We compute the stress field in the pre-buckled state and their corresponding principal components and directions. We obtain a phase diagram showing different stress states of the membrane and discuss the possible outcomes beyond the buckling instability.The second part of the thesis discusses the equilibrium shape of nonrigid single-vertex origami patterns in elastic sheets. The designing of origami-inspired mechanical meta- materials usually focuses on the kinematics of assemblies of rigid flat plates connected by hinges (rigid origami). When the panels are allowed to bend (nonrigid origami), novel behaviors emerge, such as the case of foldable cones (f-cones), circular sheets decorated by radial creases. These structures are generically bistable, in the sense that they can snap-through from one metastable configuration to another. We propose a model for f-cones made of inextensible sheets that demonstrates the bistable nature of these systems. Moreover, the model is able to predict the equilibrium shapes for any deflections as a function of the folding angles and crease mechanics. Furthermore, we test the validity of the inextensible hypothesis by means of an FEA study, where the creases are modeled as continuous slices of the plate that fold due to a nonuniform thermal field
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Akaoglu, Baris. "Optical Properties Of Silicon Based Amorphous Thin Films." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605492/index.pdf.
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Silicon based hydrogenated amorphous semiconducting (intrinsic and n/p doped a-Si:H and a-Si1-xCx:H) thin films have been deposited by plasma enhanced chemical vapor deposition (PECVD) system. In order to analyze the optical response of these amorphous films, intrinsic optical absorption mechanisms have resumed and spectral variations of absorption coefficient &<br>#61537<br>(E) are derived. The exponential variation of absorption coefficient for energies below the band edge is discussed in the frame of randomly distributed square well like potential fluctuations of localized states. Urbach constant EU and the slope B are deduced as disorder parameters. Both intensity sensitive transmittance and reflectance, and amplitude/phase sensitive ellipsometric techniques for multilayer thin films are theoretically and practically treated. Various methodologies are developed for the determination of thickness, refractive index and absorption coefficient of the films. A reflectance unit is adapted to the spectrometer and all the measuring instruments are computerized and relevant software packets have been developed. IR spectroscopy has been used for determination of mainly hydrogen concentrations and bonding properties. Establishing the production-characterization-improved growth conditions cycle successfully, the following results are obtained: (a) determination of lateral inhomogeneity of films along the radial direction of the plasma reactor, (b) determination of vertical inhomogeneity due to both substrate and air ambient, (c) perfect adjustment of refractive index and band gap of a-Si1-xCx:H films by changing carbon content of the films, (d) effect of plasma power density on both growth and carbon content.
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Backholm, Jonas. "Electrochromic Properties of Iridium Oxide Based Thin Films." Doctoral thesis, Uppsala universitet, Fasta tillståndets fysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8505.
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Electrochromic iridium oxide (IrOx) and iridium-tantalum oxide (IrTaOx) thin films were prepared by reactive magnetron sputtering. Composition, density, and structure were determined using Rutherford backscattering spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. The electronic density of states (DOS) and the solid phase chemical diffusion coefficient (D) were determined for hydrogen in IrOx and IrTaOx by potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). The complex refractive indices were determined for colored and bleached IrOx and IrTaOx by inverting transmission and reflectance, measured using spectrophotometry in the 300-2500 nm wavelength range. A very porous structure, with a stoichiometry of IrO2.2, was found for IrOx. It contained ~4 nm sized grains. The IrTaOx had a denser structure built up by ~4 nm sized grains. The composition of IrTaOx was found to vary on a nanometer scale, with an average composition of IrTa1.4O5.6. It was found that DOS can be measured using PITT and EIS in the presence of spontaneous side reactions, even for systems influenced by non-negligible charge transfer kinetics and Ohmic drops. It was found that the measured DOS is 30-50% of the theoretically calculated DOS and that D is in the 10-10 – 10-11 cm2/s range for both materials. The hydrogen diffusion mechanism was described by an anomalous diffusion model, possibly indicating percolation or diffusion paths described by a fractal network. The refractive indices were found to be ~1.3 and ~2 for IrOx and IrTaOx, respectively, and independent of coloration state, whereas the extinction coefficients were found to modulate by ~30% for IrOx and ~50% for IrTaOx, making IrTaOx more favorable for electrochromic applications. A modulation peak was found at ~660 nm for both IrOx and IrTaOx associated with the removal of intraband transitions within the Ir t2g band.
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Petersson, Anna. "IR optical properties in thin films of diamond." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160592.
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In the past decades new interest in diamond and possible applications of diamond has emerged. In this master thesis, optical properties of thin films of diamond were investigated for the possible use as an Internal Reflection Element (IRE) in Attenuated Total Reflection Fourier Infra Red (ATR-FTIR) spectroscopy. First a theoretical study of optical properties was made using Fresnel’s equations. Secondly the ray-tracing software TracePro was tested as a possible tool for further investigations of optical properties in advanced geometries. Finally, experimental measurements were made to compare the simulated result with measured data. Results obtained with TracePro were consistent with the theoretically expected results as to dependence of layer thickness, polarization and wavelength, and TracePro was therefore a possible tool for the investigation of optical properties in thin films. Although no extra information was given from TracePro for this specific geometry, TracePro can be a valuable tool in the investigation of more advanced geometries. The experimental measurements showed the importance of a well-defined layer thickness and also showed a stronger dependence of the underlying coating materials than expected from simulations. Further investigations need to be made to fully understand the dependence of the underlying coating materials SiO2 and Si3N4, particularly regarding different polarization states.
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Siyambalapitiya, Chamila S. "Growth and physical properties of magnetite thin films." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001676.
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Gerber, Peter. "Electrical and electromechanical properties of ferroelectric thin films /." Aachen : Shaker, 2007. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016147900&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Al-Dhhan, Z. T. "Dielectric properties of thin films based on CeO2̲." Thesis, Brunel University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380605.
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Vernon-Parry, Karen Dorothy. "The microstructure and properties of superconducting thin films." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280799.
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Murphy, Thomas Patrick. "Electrochromic properties of tin-nickel oxide thin films." Thesis, Oxford Brookes University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284756.
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Page, Kristopher. "Photocatalytic thin films : their characterisation and antimicrobial properties." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/17547/.
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This thesis is concerned with the synthesis and characterisation of TiO2 based photocatalyst thin films and the assessment of their antimicrobial properties. When exposed to light of wavelength less than 380 nm TiO2 films can demonstrate self-cleaning and self-disinfecting properties. This is due to photocatalytic processes occurring on the film surface resulting in film superhydrophilicity and reactive oxygen species (ROS) production. These ROS and radicals readily oxidise organic pollutants and microbes adherent to the material surface. Consequently, TiO2 thin films are of great research interest as self-cleaning, antimicrobial coatings. TiO2 and doped TiO2 materials were prepared by a simple sol-gel route from titanium n-butoxide as the principle precursor material. Film deposition was carried out using a dip-coating technique, with substrates withdrawn from the precursor sol at a fixed speed. Deposited films were calcined to produce crystalline thin films, with excellent adherence to the substrate (glass slides). Films were characterised using a number of analytical techniques including UV-visible spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and EXAFS/XANES. Photocatalysis and film hydrophilicity were investigated using established methods. Stearic acid photodegradation, monitored by FT-IR was used to assess film photocatalysis, by monitoring the peak areas of the C-H stretching region. Relative film hydrophilicities were determined by measuring the contact angle of a sessile droplet of water. Antimicrobial properties of the films were assessed with typical examples of Gram- positive and Gram-negative organisms. Staphylococcus aureus (NCTC 6571) and Escherichia coli (NCTC 10418) were selected. Films demonstrated microbicidal activity against both organisms under 365nm UV illumination, and under illumination by a typical hospital lamp (28W 2-D fluorescent). Microbial adhesion to various substrates was also examined, using a dip-blot method. Films produced in this study demonstrate excellent potential as durable surface coatings with significant antimicrobial activity against microbes of clinical importance.
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Abu, Bakar Mizarina. "Microwave properties of high temperature superconducting thin films." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289384.
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One of the most exciting studies of contemporary physics is that of high temperature superconductor (HTS). Since its discovery, a large body of experimental and theoretical work by various groups has attempted to achieve a common understanding of this phenomenon. One of the main driving forces for applications centres on the possibility of new and improved microwave devices based on HTS materials, mainly due to the large reduction in the surface resistance that HTS has to offer. However, various problems need to be addressed before the use of HTS materials can be justified, for example fundamental issues such as the nonlinearity of these materials with respect to microwave power, which form the basis of this work. Microwave measurements were conducted on four magnetron sputtered and three laser ablated, Icm2 YBCO thin films, grown on LaAI03 and MgO substrates, respectively, employing the dielectric (rutile) resonator and coplanar resonator techniques. The low power response of the films was initially analysed, looking for clues to the underlying pairing mechanisms in these films. Power dependence and microwave intennodulation distortion (lMD) measurements were conducted between 12 K to 60 K to investigate the nonlinear response of the films, both in zero and finite dc (10 mT) fields. The effect of patterning on the microwave response of the films was also studied. From these measurements, it was observed that the microwave losses of these films are extrinsic in nature, probably a consequence of weak links/defects, and the results also show that films fabricated from the same technique can have significantly varying quality.
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Alani, Ahmed. "Preparation and properties of ceramic superconducting thin films." Thesis, Liverpool John Moores University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261443.
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Hilou, H. W. "Electrical properties of R.F. sputtered thin oxide films." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355425.
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Rauf, Ijaz Ahmad. "Structure and properties of indium oxide thin films." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358371.
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Deva, Reddy Jayadeep. "Mechanical properties of Silicon Carbide (SiC) thin films." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002615.
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