Dissertations / Theses on the topic 'Nano-structure'
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Gangopadhyay, Subhashis. "Growth, surface structure and morphology of semiconductor nano-structures." [S.l.] : [s.n.], 2006. http://deposit.d-nb.de/cgi-bin/dokserv?idn=980582946.
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Lin, Shaohua. "Analysis of Electron Wave Scattering by Nano Grating Structure." Honors in the Major Thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/768.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucfBachelors
Engineering and Computer Science
Electrical Engineering
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Clark, Adam Hugh. "Combined scattering and spectroscopic structure determination of nano-catalysts." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10059089/.
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Several types of nano-catalysts, which includes oxides, supported mono and bimetallic catalysts have been used extensively for a range of catalytic reactions. Understanding the structure and reactivity has been a main theme to elucidate structure-function relationships. Herein, the behaviour of nano-catalysts has been studied using a range of experimental tools, with Synchrotron Radiation techniques as the major component. In addition, a range of analysis methods have been explored to determine structure using in situ and ex situ methods. Investigations into the structure of bimetallic silica supported PtZn nano-particles were conducted in situ during exposure to formic acid using X-ray absorption spectroscopy (XAS). Here it has been demonstrated that Zn is highly dispersed and bonded to the channel walls within the SBA-15 porous silica, whilst Pt forms oxide particles within the channels, in the as-synthesised form. On exposure to formic acid conversion of ZnO like species to Zn formate is observed to occur concurrent to the reduction of Pt oxide to Pt metal nano-particles. The redox characteristics of ceria supported platinum group metal (PGM) samples and ceria coated PGM metals supported on alumina have been studied in detail. XAS has been employed following the oxidation state of both the cerium and supported PGM, in addition to X-ray total scattering following the lattice structural changes, under in situ reduction-oxidation conditions. Detailed analysis has elucidated a promoted reduction of ceria upon reduction of the initial PGM oxide is observed. In the case of the inverse ceria alumina catalysts partial re-oxidation is observed upon cooling under a reducing atmosphere. Upon exposure to air, a full re-oxidation of the ceria support takes place, however only a partial oxidation (passivation), of the PGM to occur. Further reduction cycles result in ca room temperature reduction of the PGM and ceria.
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Fokin, Denis. "Nano-îlots de Pb/Si : structure et supraconductivité confinée." Paris 6, 2009. http://www.theses.fr/2009PA066421.
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Bai, Feiming. "Structure-Property Relationships of Multifeorric Materials: A Nano Perspective." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28055.
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The integration of sensors, actuators, and control systems is an ongoing process in a wide range of applications covering automotive, medical, military, and consumer electronic markets. Four major families of ceramic and metallic actuators are under development: piezoelectrics, electrostrictors, magnetostrictors, and shape-memory alloys. All of these materials undergo at least two phase transformations with coupled thermodynamic order parameters. These transformations lead to complex domain wall behaviors, which are driven by electric fields (ferroelectrics), magnetic fields (ferromagnetics), or mechanical stress (ferroelastics) as they transform from nonferroic to ferroic states, contributing to the sensing and actuating capabilities.
This research focuses on two multiferroic crystals, Pb(Mg1/3Nb2/3)O3-PbTiO3 and Fe-Ga, which are characterized by the co-existence and coupling of ferroelectric polarization and ferroelastic strain, or ferro-magnetization and ferroelastic strain. These materials break the conventional boundary between piezoelectric and electrostrictors, or magnetostrictors and shape-memory alloys. Upon applying field or in a poled condition, they yield not only a large strain but also a large strain over field ratio, which is desired and much benefits for advanced actuator and sensor applications. In this thesis, particular attention has been given to understand the structure-property relationships of these two types of materials from atomic to the nano/macro scale. X-ray and neutron diffraction were used to obtain the lattice structure and phase transformation characteristics. Piezoresponse and magnetic force microscopy were performed to establish the dependence of domain configurations on composition, thermal history and applied fields.
It has been found that polar nano regions (PNRs) make significant contributions to the enhanced electromechanical properties of PMN-x%PT crystals via assisting intermediate phase transformation. With increasing PT concentration, an evolution of PNRï PND (polar nano domains)-> micron-domains-> macro-domains was found. In addition, a domain hierarchy was observed for the compositions near a morphotropic phase boundary (MPB) on various length scales ranging from nanometer to millimeter. The existence of a domain hierarchy down to the nm scale fulfills the requirement of low domain wall energy, which is necessary for polarization rotation. Thus, upon applying an E-field along <001> direction(s) in a composition near the MPB, low symmetry phase transitions (monoclinic or orthorhombic) can easily be induced. For PMN-30%PT, a complete E-T (electric field vs temperature) diagram has been established.
As for Fe-x at.% Ga alloys, short-range Ga-pairs serve as both magnetic and magnetoelastic defects, coupling magnetic domains with bulk elastic strain, and contributing to enhanced magnetostriction. Such short-range ordering was evidenced by a clear 2theta peak broadening on neutron scattering profiles near A2-DO3 phase boundary. In addition, a strong degree of preferred [100] orientation was found in the magnetic domains of Fe-12 at.%Ga and Fe-20 at.%Ga alloys with the A2 or A2+DO3 structures, which clearly indicates a deviation from cubic symmetry; however, no domain alignment was found in Fe-25 at.%Ga with the DO3 structure. Furthermore, an increasing degree of domain fluctuations was found during magnetization rotation, which may be related to short-range Ga-pairs cluster with a large local anisotropy constant, due to a lower-symmetry structure.Ph. D.
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Ferreira, Da Silva Anailde. "Structure locale et propriétés thermodiffusives de nano-colloïdes magnétiques." Paris 6, 2013. http://www.theses.fr/2013PA066801.
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Ce travail étudie l'organisation structurale et la thermodiffusion de dispersions de nanoparticules (NPs) magnétiques de ferrite obtenues par coprécipitation en milieu alcalin d'ions Fe3+ et M2+ (M2+ = Co2+, Mn2+), protégées par une couronne de maghémite. Les échantillons sont - soit directement issus de la synthèse à une fraction volumique Φ ≈ 1%, pH ≈ 2 et une force ionique I mal contrôlée, - soit à pH = 3 et I = 10-3 mol/L, tous deux fixés par stress osmotique jusqu’à Φ ≈ 30 % (puis dilution éventuelle). L’organisation spatiale des NPs, chargées positivement, est testée par diffusion de rayons X aux petits angles. L’analyse de l’intensité diffusée permet d’extraire facteurs de forme et de structure des NPs dans des situations allant depuis de faibles attractions entre NPs jusqu’à de fortes répulsions, pour lesquelles aux très fortes Φ, le colloïde devient vitreux. Le pic premier-voisin du facteur de structure, observé en phase Fluide tend alors à disparaître. La dynamique des NPs est sondée par diffusion Rayleigh forcée. Un motif périodique de température est créé dans l’échantillon fluide via l’image d’une grille par un faisceau pompe induisant par effet Soret un réseau de concentration en NPs : à la coupure de la pompe le réseau relaxe par diffusion massique des NPs. La modulation temporelle de la pompe permet de déterminer le coefficient Soret ST négatif, les NPs migrent vers les zones chaudes. Celui-ci est proportionnel à la compressibilité du système des NPs. Un modèle de type Carnahan-Starling est proposé pour décrire la dépendance en Φ de la compressibilité et de ST dans la gamme des faibles Φ, où les échantillons restent fluides, loin de la transition vitreuseThe spatial organization and the thermodiffusion of ferrite magnetic nanoparticles (NPs) in dispersion are here studied. The NPs are obtained by coprecipitation of Fe3+ and Co2+ (or Mn2+) ions in alkaline medium and protected by a maghemite shell. Colloidal samples are either directly issued from chemical synthesis at volume fraction Φ ≈ 1% and pH ≈ 2 with the ionic strength I badly controlled, or at pH Φ ≈ 3 with I = 10-3 mol/L, both being fixed by osmotic stress at Φ up to 30%. . A controlled sample dilution is then possible. Spatial organization of positively charged NPs is probed by small angle x-ray scattering. The analysis of the scattered intensity allows to extract form and structure factors of the NPs, in conditions ranging from weakly interparticle attraction to strong repulsion for which at large Φ the system becomes glassy. The first-neighbor peak of the structure factor, observed in Fluid phase, tends to disappear in glassy samples. The NPs dynamics is probed by Rayleigh forced scattering. A periodic array of temperature is created in the fluid sample via the image of a grid using a pump beam. It induces by Soret effect, an array of NPs concentration in the sample. If the pump beam is shut down, the concentration array relaxes by massic NPs diffusion. A temporal pump modulation allows to determine the Soret coefficient ST, here negative, the NPs go towards hot regions. ST is proportionnal to the compressibility of the NPs system. A description based on a Carnahan-Starling model is proposed to describe the Φ-dependence of both compressibity and Soret effect in the range of weak Φ's, where the samples remain Fluid, far from the glassy transition
Nesse trabalho, investigamos a organização estrutural e a dinâmica de dispersões de nanopartículas (NPs) magnétiques de ferrita obtidas por coprecipitação em meio alcalino de íons de Fe3+ e M2+ (M2+ = Co2+, Mn2+), protegidas por uma coroa de maguemita. As amostras são obtidas à partir da síntese com uma fração volumétrica Φ ≈ 1%, pH ≈ 2 e uma força iônica I imprecisa, ou em pH = 3 e I = 10-3 mol/L, ambos valores fixados por compressão osmótica até Φ ≈ 30 % (seguido eventualmente de uma diluição). A organização estrutural das NPs, que são carregadas positivamente, é investigada por espalhamento de raios X em baixo ângulo. A análise da intensidade espalhada permite extrair fatores de forma e de estrutura das NPs desde situações onde existem atrações pouco intensas entre NPs para situações de fortes repulsões interpartículas até mais altas concentrações nas quais o colóide se torna vítreo. O pico de primeiro vizinho do fator de estrutura, observado na fase fluida, tende a colapsar. A dinâmica das NPs é testada por espalhamento Rayleigh forçado. Um padrão periódico de temperatura é criado em amostras fluidas utilizando a imagem de uma grade formada por um feixe de luz. Este induz uma rede de concentração via efeito Soret: Quando o feixe de luz é cancelado, a rede relaxa por difusão de massa de NPs. A modulação temporal do feixe de luz permite determinar o coeficiente Soret ST negativo, as NPs migram para regiões quentes. Este é proporcional à compressibilidade do sistema de NPs. Um modelo de Carnahan-Starling é proposto para descrever a dependência com Φ da compressibilidade e de ST numa gama de valores baixos de Φ onde as amostras permanecem fluidas, longe da transição vítrea
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Alswieleh, Abdullah. "Micro- and nano-structure of polymers and molecular materials." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7164/.
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Sui, Jing. "Synthesis, characterisation and application of micro/nano structure conducting polymers." Thesis, University of Auckland, 2010. http://hdl.handle.net/2292/5843.
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Conducting polymer micro/nanostructures have recently received great attention because of their long conjugation length, high surface area and promising applications in a variety of fields. At the same time, fabrication of micro/nanostructures of conducting polymers with controlled morphology and size remains a challenge for Chemists and Materials Scientists. The focus of this thesis, therefore, is to develop novel conducting polymer micro/nanostructures with a well defined morphology and to consider their potential for applications as sensor and actuating elements. In each case, the structure, conductivity and electrochemical properties of the conducting polymer nanostructures have been characterized using FTIR, Raman, UV-vis, XPS and elemental analyses, conductivity measurements and cyclic voltammetry. Hollow nanospheres of substituted polyanilines (PANI) were fabricated chemically using ammonium persulfate as the oxidant in the presence of a polymeric acid poly(methyl vinyl ether-alt-maleic acid) (PMVEA). The effects of chemical reaction conditions, including the weight ratio of monomer to PMVEA, concentration of monomer, the molar ratio of monomer to oxidant, the reaction temperature and the type of the monomer, on the formation of hollow nanospheres were systematically studied. The weight fraction of PMVEA to monomer is particularly important for determining the size and uniform shape of the substituted PANI hollow spheres. The formation mechanism for the hollow nanospheres was studied in detail for the case of poly (o-methoxyaniline). The hollow nanospheres were used to construct a simple electrochemical oligonucleotide (ODN) sensor, where ODN probes were covalently grafted onto the residual carboxylic acid functionalities of the hollow nanospheres. Abstract II Poly(3,4-ethylenedioxythiophene) (PEDOT) hollow microspheres ranging from 0.5 to 10 μm in diameter were synthesized by chemical oxidative polymerisation of EDOT using ammonium persulfate in a catanionic surfactant solution, obtained by mixing cetyltrimethylammonium bromide (CTAB) and sodium dodecylbenzenesulfonate (SDBS). The effects of chemical reaction conditions, including the molar ratio of CTAB to SDBS, the concentration of total surfactants, the type of oxidant and magnetic stirring, on the formation of the PEDOT hollow microspheres were investigated systematically. The formation of PEDOT hollow spheres is presented as following a vesicle-templating mechanism, supported by Freeze Fracture TEM results. Moreover, the PEDOT hollow spheres showed a more effective electrocatalytic activity for the oxidation of ascorbic acid, compared to conventional PEDOT granular particles, which were also effective in lowering the ascorbic acid oxidation overpotential. By extending vesicle-template method into the electropolymerisation of polypyrrole (PPy) films with para-toluene sulfonate (pTS) as the main dopant, a novel micro ring structured surface morphology was prepared by using CTAB/SDBS vesicles as templates. Spectroscopic characterisations confirmed that the micro ring structured PPy/pTS films showed similar molecular structure and doping degree to conventional PPy/pTS films, while the incorporation of some DBS anions had a minor effect on lowering film conductivity. The actuation behaviour of micro ring structured PPy/pTS films was investigated under electrochemical stimulation. The micro ring structured PPy/pTS films showed superior actuation stability compared to conventional PPy/pTS films.
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Li, Elise Yu-Tzu. "Electronic structure and quantum conductance of molecular and nano electronics." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65270.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 129-137).
This thesis is dedicated to the application of a large-scale first-principles approach to study the electronic structure and quantum conductance of realistic nanomaterials. Three systems are studied using Landauer formalism, Green's function technique and maximally localized Wannier functions. The main focus of this thesis lies on clarifying the effect of chemical modifications on electron transport at the nanoscale, as well as on predicting and designing new type of molecular and nanoelectronic devices. In the first study, we suggest and investigate a quantum interference effect in the porphyrin family molecules. We show that the transmission through a porphyrin molecule at or near the Fermi level varies by orders of magnitude following hydrogen tautomerization. The switching behavior identified in porphyrins implies new application directions in single molecular devices and molecular-size memory elements. Moving on from single molecules to a larger scale, we study the effect of chemical functionalizations to the transport properties of carbon nanotubes. We propose several covalent functionalization schemes for carbon nanotubes which display switchable on/off conductance in metallic tubes. The switching action is achieved by reversible control of bond-cleavage chemistry in [1+2] cycloadditions, via the 8p 3 8s p 2 rehybridization it induces; this leads to remarkable changes of conductance even at very low degrees of functionalization. Several strategies for real-time control on the conductance of carbon nanotubes are then proposed. Such designer functional groups would allow for the first time direct control of the electrical properties of metallic carbon nanotubes, with extensive applications in nanoscale devices. In the last part of the thesis we address the issue of low electrical conductivity observed in carbon nanotube networks. We characterize intertube tunneling between carbon nanotube junctions with or without a covalent linker, and explore the possibility of improving intertube coupling and enhance electrical tunneling by transition metal adsorptions on CNT surfaces. The strong hybridization between transition metal d orbitals with the CNT [pi] orbitals serves as an excellent electrical bridge for a broken carbon nanotube junction. The binding and coupling between a transition metal atom and sandwiching nanotubes can be even stronger in case of nitrogendoped carbon nanotubes. Our studies suggest a more effective strategy than the current cross-linking methods used in carbon nanotube networks.
by Elise Yu-Tzu Li.
Ph.D.
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Hafezi, Farzaneh. "Computational modelling of fluid-structure interaction at nano-scale boundaries." Thesis, Swansea University, 2014. https://cronfa.swan.ac.uk/Record/cronfa42753.
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With the emergence of nano-devices and nano-scale research, gaining further understanding of the evolution of drag forces exerted by molecular flows, at low Knudsen numbers (-0.1-0.5), over nano-scaled objects with 20-100 nm size is a realistic expectation. The proposed research examines the fluid-structure interaction at nano-scales from first principles. It has also critically evaluated, and if necessary modified, the assumptions made during the development of a computational model. The research has provided new insights in modelling molecular interaction with continuum as well as molecular walls and calculation procedures for predicting macroscopic properties such as velocity, pressure and drag coefficients. The proposed formulation has been compared with the state of the art formulations as published in recent journals and verified on number numerical and molecular tests as experimental and analytical results are unavailable at this scale. The effect of various geometry configurations (slit pore, inclined and stepped wall) to model the pressure driven molecular flow through confined walls is studied for number of surface roughness and driving force values given by adjusting molecular accelerations. The molecular flow over diamond, circular and square shaped cylinders confined within parallel walls has also been modelled at various input conditions. It is expected that the proposed research will have impact in developing future nanoscale applications, in the field of drug delivery, surface cleaning and protein movement, where adsorption, drag resistance or, in general, understanding of the knowledge of fluid-structure interaction at 50-100nm scale is important. Some of the future research areas resulting from this research have also been identified.
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Kandel, Shreedhar R. "Control of Shape Change of PbSe Nano Structure by Chloroalkane." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1435056285.
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SESTU, MATTEO. "The structure of nano sized poorly-crystalline iron oxy-hydroxides." Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266576.
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In this thesis the structures of three nano sized poorly-crystalline
iron oxy-hydroxides, feroxyhyte, ferrihydrite and schwertmannite, are
studied and analyzed with the aim of clarifying some dubious structural features. The widely used Rietveld re�nement and EXAFS analysis are employed in order to address the consistency of the structural models proposed for these materials, one of which, feroxyhyte,
is suggested in this thesis. Furthermore, a new computer program
exploiting the Reverse Monte Carlo algorithm and the Debye Scattering Equation is presented and used in order to analyze the elusive
structures of these iron oxy-hydroxides.
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Hu, Qiang. "Effects of nano structure on the deformation behavior of polymeric networks." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/10179.
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Zhai, Yun. "Studies on Structure and Property of Polymer-based Nano-composite Materials." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1680.
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The mixing of polymers and nanoparticles makes it possible to give advantageous macroscopic material performance by tailoring the microstructure of composites. In this thesis, five combinations of nano inclusion and polymer matrix have been investigated.
The first type of composites is titanium dioxide/ polyaniline combination. The effects of 4 different doping-acids on the microstructure, morphology, thermal stability and thermoelectric properties were discussed, showing that the sample with HCl and sulfosalicylic dual acids gave a better thermoelectric property. The second combination is titanium dioxide/polystyrene composite. Avrami equation was used to investigate the crystallization process. The best fit of the mass derivative dependence on temperature has been obtained using the double Gaussian dependence. The third combination is titanium dioxide/polyaniline/ polystyrene. In the titanium dioxide/polyaniline/ polystyrene ternary system, polystyrene provides the mechanical strength supporting the whole structure; TiO2 nanoparticles are the thermoelectric component; Polyaniline (PANI) gives the additional boost to the electrical conductivity. We also did some investigations on Polyethylene odide-TiO2 composite. The cubic anatase TiO2 with an average size of 13nm was mixed with Polyethylene-oxide using Nano Debee equipment from BEE international;
Single wall carbon nanotubes were introduced into the vinyl acetate-ethylene copolymer (VAE) to form a connecting network, using high pressure homogenizer (HPH). The processing time has been reduced to 1/60 of sonication for HPH to give better sample quality. Theoretical percolation was derived according to the excluded volume theory in the expression of the threshold as a function of aspect ratio.
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Zhang, Huayong, Jinyong Cheng, Tianduo Li, Jianmei Lu, and Yuai Hua. "Observation and Analysis of Leather Structure Based on Nano-CT - 153." Verein für Gerberei-Chemie und -Technik e. V, 2019. https://slub.qucosa.de/id/qucosa%3A34304.
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The composition, working principle and the image acquisition procedure of nano-CT were introduced. A dried piece of blue stock of chrome-tanned cattle hide was chosen for this work and a sequence of 2356
images was obtained. 3D visible digital models (5mm*3.5mm*3.5mm) of leather fiber bundle braided network (Figure 1) and the interspace between fiber bundles (Figure 2) were reconstructed. The inner
structure and composition of leather were shown accurately and intuitively in the form of 2D sectional images and 3D image. Based on the 3D model, the diameter, volume, surface area and other parameters
of the fiber bundles, the pore structure and inclusions were measured and calculated.
Take-Away:
1. 3D visible digital model of leather fiber bundle braided network was reconstructed.
2. The inner structure and composition of leather were shown accurately and intuitively in the form of 2D sectional images and 3D image.
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Yu, Boliang. "3D analysis of bone ultra structure from phase nano-CT imaging." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI016/document.
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L'objectif de cette thèse était de quantifier le réseau lacuno-canaliculaire du tissu osseux à partir d’images 3D acquises en nano CT synchrotron de phase. Ceci a nécessité d’optimiser les processus d’acquisition et de reconstruction de phase, ainsi que de développer des méthodes efficaces de traitement d'images pour la segmentation et l’analyse 3D. Dans un premier temps, nous avons étudié et évalué différents algorithmes de reconstruction de phase. Nous avons étendu la méthode de Paganin pour plusieurs distances de propagation et l’avons évaluée et comparée à d’autres méthodes, théoriquement puis sur nos données expérimentales Nous avons développé une chaine d’analyse, incluant la segmentation des images et prenant en compte les gros volumes de données à traiter. Pour la segmentation des lacunes, nous avons choisi des méthodes telles que le filtre médian, le seuillage par hystérésis et l'analyse par composantes connexes. La segmentation des canalicules repose sur une méthode de croissance de région après rehaussement des structures tubulaires. Nous avons calculé des paramètres de porosité, des descripteurs morphologiques des lacunes ainsi que des nombres de canalicules par lacune. Par ailleurs, nous avons introduit des notions de paramètres locaux calculés dans le voisinage des lacunes. Nous avons obtenu des résultats sur des images acquises à différentes tailles de voxel (120nm, 50nm, 30nm) et avons également pu étudier l’impact de la taille de voxel sur les résultats. Finalement ces méthodes ont été utilisées pour analyser un ensemble de 27 échantillons acquis à 100 nm dans le cadre du projet ANR MULTIPS. Nous avons pu réaliser une analyse statistique pour étudier les différences liées au sexe et à l'âge. Nos travaux apportent de nouvelles données quantitatives sur le tissu osseux qui devraient contribuer à la recherche sur les mécanismes de fragilité osseuse en relation avec des maladies comme l’ostéoporoseOsteoporosis is a bone fragility disease resulting in abnormalities in bone mass and density. In order to prevent osteoporotic fractures, it is important to have a better understanding of the processes involved in fracture at various scales. As the most abundant bone cells, osteocytes may act as orchestrators of bone remodeling which regulate the activities of both osteoclasts and osteoblasts. The osteocyte system is deeply embedded inside the bone matrix and also called lacuno-canalicular network (LCN). Although several imaging techniques have recently been proposed, the 3D observation and analysis of the LCN at high spatial resolution is still challenging. The aim of this work was to investigate and analyze the LCN in human cortical bone in three dimensions with an isotropic spatial resolution using magnified X-ray phase nano-CT. We performed image acquisition at different voxel sizes of 120 nm, 100 nm, 50 nm and 30 nm in the beamlines ID16A and ID16B of the European Synchrotron Radiation Facility (ESRF - European Synchrotron Radiation Facility - Grenoble). Our first study concerned phase retrieval, which is the first step of data processing and consists in solving a non-linear inverse problem. We proposed an extension of Paganin’s method suited to multi-distance acquisitions, which has been used to retrieve phase maps in our experiments. The method was compared theoretically and experimentally to the contrast transfer function (CTF) approach for homogeneous object. The analysis of the 3D reconstructed images requires first to segment the LCN, including both the segmentation of lacunae and of canaliculi. We developed a workflow based on median filter, hysteresis thresholding and morphology filters to segment lacunae. Concerning the segmentation of canaliculi, we made use of the vesselness enhancement to improve the visibility of line structures, the variational region growing to extract canaliculi and connected components analysis to remove residual noise. For the quantitative assessment of the LCN, we calculated morphological descriptors based on an automatic and efficient 3D analysis method developed in our group. For the lacunae, we calculated some parameters like the number of lacunae, the bone volume, the total volume of all lacunae, the lacunar volume density, the average lacunae volume, the average lacunae surface, the average length, width and depth of lacunae. For the canaliculi, we first computed the total volume of all the canaliculi and canalicular volume density. Moreover, we counted the number of canaliculi at different distances from the surface of each lacuna by an automatic method, which could be used to evaluate the ramification of canaliculi. We reported the statistical results obtained on the different groups and at different spatial resolutions, providing unique information about the organization of the LCN in human bone in three dimensions
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Jimenez, Alvaro. "Une biocapteur à base de résonance de plasmons de surface intégré monolithiquement avec une source d'excitation." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/8178.
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Le champ biomédical n’a pas échappé à l’évolution de la technologie, elle cherche aussi à intégrer plusieurs fonctions dans un espace restreint. Un des points forts du développement est la massification de points de service, afin d'obtenir un diagnostic rapide des maladies. Le diagnostique aux premières étapes de son évolution permettra réduire considérablement les coûts associés aux traitements des patients. Le présent document exprimera une alternative à l'évolution de la technologie des biocapteurs qui sont basés sur le phénomène optique appelé résonance par plasmons de surface.
Ce projet de recherche vise l’étude de l’intégration monolithique des deux tiers des composants principaux qui conforment normalement à ce type de biocapteurs optiques. Tandis que d'autres projets de recherche ont centré leurs travaux sur l’intégration de la surface de réaction et le détecteur, notre travail a pris en compte l’intégration de la source de lumière et la surface de réaction biologique. Deux types de sources ont été employés au moment de faire la conception, l’étude de matériaux, la fabrication et la caractérisation de la performance de notre dispositif. La première source a employé des puits quantiques à l’intérieur d’une gaufre de GaAs qui nécessitait un pompage optique pour son fonctionnement. La deuxième source a eu une gaufre commerciale employée pour la fabrication des diodes d’émission lumineuse verticale, qui a dû être excitée par un courant électrique.
On a découvert que les deux types de sources sont complémentaires. La source avec des puits quantiques a démontré une amélioration de la performance en comparaison à notre système commercial de référence. La deuxième source a démontré la faisabilité d’intégration monolithique en permettant se rapprocher à la fabrication d’un prototype commercial. La porte reste donc ouverte pour la poursuite du développement de cette technologie en cherchant un nouveau système employant ces deux sources, mais usant de meilleures caractéristiques.
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Hua, Weijie. "Structure and spectroscopy of bio- and nano-materials from first-principles simulations." Doctoral thesis, KTH, Teoretisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31944.
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This thesis is devoted to first-principles simulations of bio- and nano-materials,focusing on various soft x-ray spectra, ground-state energies and structures of isolated largemolecules, bulk materials, and small molecules in ambient solutions. K-edge near-edge x-ray absorption fine structure (NEXAFS) spectra, x-ray emission spectra, andresonant inelastic x-ray scattering spectra of DNA duplexes have been studied by means oftheoretical calculations at the density functional theory level. By comparing a sequence of DNAduplexes with increasing length, we have found that the stacking effect of base pairs has verysmall influence on all kinds of spectra, and suggested that the spectra of a general DNA can bewell reproduced by linear combinations of composed base pairs weighted by their ratio. The NEXAFS spectra study has been extended to other realistic systems. We have used cluster modelswith increasing sizes to represent the infinite crystals of nucleobases and nucleosides, infinitegraphene sheet, as well as a short peptide in water solution. And the equivalent core holeapproximation has been extensively adopted, which provides an efficient access to these largesystems. We have investigated the influence of external perturbations on the nitrogen NEXAFSspectra of guanine, cytosine, and guanosine crystals, and clarified early discrepancies betweenexperimental and calculated spectra. The effects of size, stacking, edge, and defects to theabsorption spectra of graphene have been systematically analyzed, and the debate on theinterpretation of the new feature has been resolved. We have illustrated the influence of watersolvent to a blocked alanine molecule by using the snapshots generated from molecular dynamics. Multi-scale computational study on four short peptides in a self-assembled cage is presented. It isshown that the conformation of a peptide within the cage does not corresponds to its lowest-energyconformation in vacuum, due to the Zn-O bond formed between the peptide and the cage, and theconfinement effect of the cage. Special emphasis has been paid on a linear-scaling method, the generalized energy basedfragmentation energy (GEBF) approach. We have derived the GEBF energy equation at the Hartree-Focklevel with the Born approximation of the electrostatic potential. Numerical calculations for amodel system have explained the accuracy of the GEBF equation and provides a starting point forfurther refinements. We have also presented an automatic and efficient implementation of the GEBFapproach which is applicable for general large molecules.QC 20110404
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Bousige, Colin. "Structure et dynamique de systèmes unidimensionnels modèles : les nano-peapods de carbone." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00771820.
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Ce travail de thèse est consacré à l'étude sur une large gamme de températures d'un système unidimensionnel modèle, les nano-peapods de carbone. Ces composés sont constitués de fullerènes (C60, dans notre cas) insérés dans des nanotubes de carbone monofeuillets. Les diamètres des fullerènes et des tubes étant concordant, les fullerènes s'arrangent selon un réseau 1D.Dans le premier chapitre de ce manuscrit, nous décrivons la synthèse des peapods de carbone. Dans les deux chapitres suivants, nous décrivons les différents modèles et méthodes expérimentales qui nous permettent de déterminer l'évolution de la structure moyenne des chaînes de fullerènes, ainsi que la dynamique de rotation et de translation des molécules.Dans les trois derniers chapitres, nous décrivons l'évolution de la structure et de la dynamique des chaînes sur trois gammes de températures, que nous appelons hautes (500-1100 K), basses (0-200 K), et intermédiaires (200-500 K). Les résultats expérimentaux concernant deux types d'échantillons, les peapods monomères et les peapods polymères (dans lesquels les degrés de liberté de rotation sont restreints) sont confrontés à des modèles analytiques. Nous mettons en évidence trois comportements différents des chaînes dans ces trois gammes de température.
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Yan, Xiaodong. "Controllable fabrication of zinc oxide functional nano-/micro-structure in aqueous solution." Thesis, University of Auckland, 2010. http://hdl.handle.net/2292/5930.
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Nanostructures of ZnO show intriguing chemical, electrical, and physical properties and are promising for a broad range of applications in catalysis, electronics and photonics. Cost-effective techniques that can be used to prepare structures with controllable compositional, structural, and functional properties are fundamental to the utilization of ZnO in small scale devices with enhanced performance. Although many methods have been developed to fabricate ZnO nanostructures, systematic research on functional materials development based on ZnO is still needed as this fascinating material probably has the richest family of low-dimensional nanostructures. The research reported in this thesis aims to develop ZnO-based nanostructural materials using a facile and low-temperature aqueous solution growth approach, to analyze their compositional, mechanical, structural, and functional properties using advanced characterization techniques, to get a better understanding of the mechanisms behind nanostructure growth, and to explore their potentials in catalytic, optical, and electronic applications. In the first part of this thesis, low-dimensional ZnO nano-/micro-rods with tailored structural property (growth direction, aspect ratio, and surface distribution density) were grown on glass substrates in aqueous solutions containing zinc salt and hexamethylenetetramine at temperatures generally lower than 95oC. The substrates were pre-deposited with a thin layer of ZnO seeds using a magnetron sputter. The potential influences of growth conditions, typically including concentration, pH, type of zinc salt, solution temperature, reaction duration, and inorganic or organic additive, have been subjected to systematic investigation. This led to an improved understanding of the chemical reactions and nucleation/growth processes involved in the morphological evolution of ZnO-based hierarchical nanostructures. The second part of the thesis, ZnO nano-/micro-rod arrays with controllable distribution density have been successfully synthesized by adjusting the initial pH of the weak acidic growth solution. ZnO arrays with a large inter-rod space provide a good opportunity for characterizing the property of an individual rod. In this research, mechanical property tests have been successfully peformed directly on a single rod without the need of any complicated sample preparation. The electronic properties of these aligned ZnO nanorod arrays have also been explored by studying the I-V characteristics of both heterojuction and homojuction p-n devices. In next two chapters, complex ZnO structures, including nanotubes and three-dimensional ball-shaped clusters have been presented and disscussed, respectively. The morphology and microstructure of these structures were characterized by scanning electron microscopy, transmission electron microscopy, and in-situ cathodoluminescence. The corresponding growth mechanisms were proposed based on the analysis of the characterization results. Chapter 7 describes that aligned ZnO nano-rod arrays were further used as templates to prepare a novel composite nanostructure. By coating these ZnO nanorods with TiO2 nanowires using magnetron sputtering technique, a ZnO/TiO2 core-brush structure has been successfully achieved. Their morphology and microstructure have been investigated using scanning electron microscopy, transmission electron microscopy, powder X-ray diffractometer, energy-dispersive X-ray spectroscopy and X-ray Photoelectron Spectroscopy. This composite nanostructure shows a significantly enhanced photocatalytic activity in decomposition of a typical organic dye under UV and sunlight irradiation. This new structure has many other interesting properties and may have great potential in other optoelectronic applications. In the last part of this thesis, conclutions and future works are addressed according to the synthesis, characterization and application results.
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Puttick, Simon. "Probing the nano-structure of ionic liquids using the nuclear overhauser effect." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581983.
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A methodology utilising the distance dependence of the rotating frame Overhauser effect (ROE) has been developed to investigate the existence of nano-structured domains in ionic liquids. A partition coefficient termed the domain preference integral ratio (DPIR) has been created to offer a simple perspective by which the preferential solubility of probe molecules in ionic liquids can be assessed. A model system, consisting of the first five oligomers of methyl methacrylate (MMA) has been designed to investigate the source of an 'ionic liquid effect' observed in the free radical polymerisation (FRP) of MMA conducted in ionic liquids. Investigation by rotating frame Overhauser effect spectroscopy (ROESY) and calculation of the DPIR has been used to probe the solvation environment of the model system. Furthermore, calculation of the DPIR for the reversible addition fragmentation chain transfer (RAFT) control agent cyanobenzoyl dithiobenzoate (CB DB) has led to a series of predictions of the outcome of the RAFT controlled FRP of MMA in ionic liquids. The reaction kinetics of the RAFT controlled reactions have been monitored to investigate the success of the methodology to predict the outcome of a reaction based upon the observed solvation environment of one of the reactant molecules.
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Duplock, Elizabeth. "First principles study of structure-property relationships in nano-structured carbon materials." Thesis, University of Kent, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429796.
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Chang, Tieh-Ming, and 張鐵明. "FDTD simulation of nano imaging with silver nano rod structure." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/68127858152127808964.
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碩士國立臺灣大學
物理研究所
94
Silver nanorods have an excellent localization of the transmitted wave; especially the localized spot has a space below the bottom of the nanorods. In this dissertation, the near field distribution of silver nanorods is investigated. The numerical method knows as finite difference time domain (FDTD) is introduced into near field optics. The effects of various radius, lengths, gaps and separations of silver nanorod array are investigated. Results of the calculation provide a direct theoretical basis for the relation between the localization of surface Plasmon and the enhance of near field. The near field distribution of nano hexagonal rod, and the parallel nanorod array are studies systematically using our FDTD method. It is found that the image is highly dependent on the spacing and radius of nanorods. Results of single nanorod show similar near field distribution to an electrical dipole. Due to the boundary condition at the interface, the polarized incident wave enhance the field at boundary of the nanorod. The influence of nanorods on contrast is studied with FDTD method as well. Silver nanorods have an excellent effect on localizing the transmitted wave, especially, the enhancements below the bottom of the nanorods. In this dissertation, a systematic apparoach to studying the near-field distributions, from a single nanorod to an array of nanorods, is carried out. The three-dimensional finite difference time domain (3D FDTD) which is a well known and powerful numerical method is used to simulate the interactions of the optical waves with the silver nanorods. The near-field distribution of a single nanorod is similar to an electrical dipole. The effects of radius variation, lengths of nanorods, gaps and spacings in the silver nanorod array are investigated. It is found that the image formed from the transmitted wave is highly dependent on the spacing and radius of nanorods. According to the relation between the localization of surface plasmon and the enhancement of near field, the optimal criteria can be obtained in constructing optical nanolithographic sturcutures.
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Lin, Dong-Yih, and 林東毅. "NanoCapsules:The Nano-Structure Possessing Controllable permeability." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/93560817592408105888.
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碩士國立成功大學
化學系碩博士班
93
The synthesis of nano-capsules by utilizing CuAu hollow nano-spheres was described in this study. Nano-capsules are the complex materials, with the core adopted of CuAu hollow nano-spheres and the shell made of net-like polymer with an engineered outermost layer. The net-like polymer plays an important role in this study, because it can provide the tunable permeability to CuAu hollow. The unique ability of the developed nanocapsules was further discussed by using several kinds of dye molecules and DNA as fillers. The multifunctional nano-capsules, capable of controlling incubation and release, were demonstrated. And the investigations of incubation and release have been characterized by fluorescence spectrophotometer and fluorescence microscope. The results confirmed that the nano-capsules indeed possessed encapsulating and releasing properties, and can be applied in various kinds of substances.
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Liao, Jhe-Yi, and 廖哲頤. "Fabrication and Discussion on Nano-Metal Structure." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/26234325211097917959.
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碩士國立中山大學
光電工程學系研究所
100
Abstract Negative index structures could be implemented through surface Plasmon polariton waves generated by nanostructures. We are interested in PMMA grating structure on curved metal surface. In order to fabricate this kind of samples, a series process parameters have been tested and also the lift-off process has been developed. Our results show superlens effect under optical microscope(OM). The sub-wavelength grating image is reconstructed in the non-grating region where the PMMA dielectric layer is not uniform. Surface Plasmon(SPP) waves generated in the grating region propagate to the non-grating region and are scattered out through the non-uniform PMMA layer. The grating information is not resolvable under OM but clear in the reconstructed region. It shows that SPP waves can show super resolution and a simple batch process should be developed in the future.
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SHENG-CHIEH, CHANG, and 張勝傑. "Study for nano-structure of II-VI Semiconductor." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/37156253411605999607.
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碩士淡江大學
物理學系
89
In this paper , we study the best growth condition of Zn1-xCdxSe/ZnCd multi-quantum well by the Hot-Wall Epitaxial system. First we study the optimal washing condition for the substrate , the grow the ZnSe films by fix the growth temperature , at different substrate temperature , Use the microscopy , X-Ray diffraction , and Photoluminescence(PL) to analyse the quality of films , we obtain the best substrate temperature. Next by fix the substrate temperature , we grow the film and change the growth temperature , then analyse the quality of films , we obtain the best growth temperature. To study the influence of annealing on the film , first we fix the annealing time at 3 min on different annealing temperature , and use PL to determine the best annealing temperature . Then we fix annealing temperature on different annealing time to the sample , and use PL to get the best annealing time . After the study of annealing , we add a step of annealing in epitaxial processes . We use these growth condition to growth Zn1-xCdxSe/ZnCd multi-quantum well , and use X-Ray diffraction , PL to analyse the quality of sample , use these condition , we can make the better quantum well sample .
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Hau, CHAN-Yan, and 陳彥豪. "Studies on the Structure/properties of nano-Polypyrrole." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/20947070969536907166.
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碩士國立臺灣科技大學
高分子工程系
91
Abstract Polypyrroles doped with two dopants were prepared by chemical polymerization in aqueous solutions of pyrrole monomer. The solutions contained di(2-ethylhexyl) sulfosuccinate (DEHS) as a dopant, Tetra -n-butylammonium Hexafluorophsphate (PF6) as a codopant, and amm- onium persulfate (APS) as an oxidant. The PPY composite 【polypyrrole- di(2-ethylhexyl) sulfosuccinate(PPY-DEHS) codoped with Hexafluorop- hsphate (PF6) －PPY-DEHS- PF6】were soluble in DMSO, m-cresol, NMP etc. The maximum electrical conductivity of room temperature for PPY-DEHS- BF4 is 92 S/cm, is greatly higher than of polypyrrole doped with DEHS And compare structure and properties with PPY-DEHS and PPY-DEHS- PF6 by FTIR、UV-Vis、TGA、DSC、X-Ray。
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Hsiao, Yu-Lung, and 蕭育隆. "Plasmonic Lens structure with variant spacing nano-slits." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/dp9r6h.
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碩士國立宜蘭大學
電子工程學系碩士班
105
Following the arrival of the nanoscale age, optical components have been miniaturized to nanoscopic scales. Nanoscale lenses are plasmonic lenses that are primarily made of metal. The surface plasmon effect, produced by plasma between metals and a dielectric surface, improves the focal points of lenses. In this study, a novel method to create plasmonic lenses by changing the space between slits is proposed. To validate this method, the finite difference time domain function in computer software was used for simulations and testing. First, due to the lack of a formula for the spacing between slits, we consulted structures developed in other studies. Multiple experiments were conducted to compare focal point locations and intensities; the currently best results are described in this study. The emphasis of the experiment was the focal point. The wavelengths used were in the red band of the visible spectrum. For visible wavelengths, silver is the most common material used in simulations. Therefore, silver was used in the preliminary experiments. Subsequently, other metals were tested using software simulations to design the structure. In order to perform tests and comparison, two parameters were changed: the width and lengths of the slits were fixed, and the spacing between slits was variable. To simplify calculations, the slits were placed in a linear arrangement, so that the point with the highest focus of light were compared. Sampled values were used to compare two different lenses and confirm that the proposed method can be used to create plasmonic lenses.
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Yu-Feng, Chen, and 陳玉豐. "Study for Nano Structure of II-VI Semiconductor." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/95340351929199578953.
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碩士淡江大學
物理學系碩士班
95
This thesis is devoted to study the properties of Ⅱ-Ⅵ semiconductor Nano structure. We attempt to develop different nano structures based on GaAs substrate with CdSe/CdSSe/ZnSe, including: quantum ring, nano hole, quantum wire, different size quantum dot on the same substrate , and various ways to grow quantum dot. First we rinse the substrate in order to cause flutes and fillisters, grow quantum ring and quantum wire based on the properties of surrounding and assembling of quantum dot and then try to grow them with different materials and ways. For example, we grow quantum ring with its quality of covering, study its properties of growing ; find out the nano hole, and study the relationships between depth and width of nano hole and the ways of growing and heat treatment and then find out the causes of nano hole growing and then control its size and finally grow nano hole with different materials and ways. Furthermore, we attempt to grow quantum sticks with extremely tiny sizes based from substrates with different ways of heat treatment in order to understand its physical properties and causes. At the same time, we attempt to grow quantum dot with better qualities, with gradation models, and then control the height, density and the rate of height and width.
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Wang, Pei-Ting, and 王姵婷. "Gold-BSA nano composite structure analysis and application." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/30323656495179683072.
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碩士國立臺灣師範大學
化學系
103
To assay any possible influences of denaturation on the structure and biochemical functions of proteins, we synthesized artificial cells from AuCl4- and bovine serum albumin (BSA). Results showed that the resulting particles (denoted Au@BSA) were spherical in shape, with a gold core surrounded by a 20-nm BSA layer. When the Au@BSA was exposed to 1 M sodium hydroxide solutions, the interaction force between the cell’s wall and the probe of the atomic force microscope (AFM) increased with time, and the conductivity of the surface of the cell increased as well. After five minutes, both tended to their maximum values. The Au@BSA particles showed similar denaturation symptoms as immersed in 1 M hydrochloric acid. The Au@BSA particles also showed responses to oxidants like and NaClO and hydrogen peroxide. As exposed to NaClO, the BSA layer was badly corroded, and the core became fragile. Despite this, the sensitivty to H2O2 rendered Au@BSA functioning as a fluorescent H2O2 probe and even as a probe for glucose if horseradish peroxidase (HRP) and glucose oxidase (GOx) were incorporated. Besides, the Au@BSA particles also showed potential in the fabricating nanocircuitry. Au@BSA-based filed-effect transistor was thus developed, which could be useful for the detection of biologically important substances. Key words:Gold Nanoparticle, Artificial Cell, Atomic Force Microscopy, Denaturation, Force Curve
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Liao, Wei Chien, and 廖偉倩. "Micro-cone Structure Fabrication by Nano 3D Lithography." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/94736410376514536970.
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碩士國立清華大學
奈米工程與微系統研究所
104
Micro-cone structures have been widely utilized in different area, for example, microneedle for drug delivering, tip of atomic force microscopy (AFM), microelectrode for academic research, light guide plate of display, etc. These structures are manufactured by common microfabrication technologies usually with complex processes and have some instruct limits in fabricating various shapes and achieving high quality tips such as etching, standard photo lithography process, LIGA process etc. In contrast, a promising method called Nano 3D lithography (N3L) integrated with TPP and dosage accumulation is versatile and feasible to implement arbitrary structures. This thesis proposes to fabricate widely-used micro-cone structures through N3L system with 780nm, 532nm laser and precise optical elements. In the fabrication system, structure was formed by a focused laser with three-axis stage movement, and the voxel size can be adjusted by laser power and the magnification of objective.
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Jagannathan, Sudhakar. "Process, structure, property relationships of electrospun nano fibers." 2003. http://etd.utk.edu/2003/Jagannathan,Sudhakar.pdf.
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Thesis (M.S.)--University of Tennessee, Knoxville, 2003.Title from title page screen (viewed Mar. 17, 2004). Thesis advisor: Kevin M. Kit. Document formatted into pages (xiv, 127 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 119-123).
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方天青. "The Development of 3D Nano-Structure Exposure System." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/65458718914362159029.
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Lin, Bo-Chen, and 林柏辰. "Nano- Mechanical Properties and Structure of Co60Fe20B20 Thin Films." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7fh349.
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碩士國立雲林科技大學
材料科技研究所
105
This investigation examines the nano-indentation property and structure of CoFeB thin films, which were sputtered onto Si(100) substrates to thicknesses of 1000 Å to 5000 Å under the following conditions; (a) as-deposited films were maintained at room temperature (RT); (b) films underwent post-annealing treatment at 150 ◦C for 1 h; (c) films underwent post-annealing treatment at 250 ◦C for 1 h, and (d) films underwent post-annealing treatment at 350 ◦C for 1 h. The XRD results revealed that the CoFeB films that underwent post-annealing treatment at 250 ◦C and 350 ◦C had body-centered cubic (BCC) CoFeB (110) structure whereas those that underwent post-annealing treatment at 150 ◦C and the as-deposited films at RT were amorphous. Films that underwent post-annealing treatment at a higher temperature and thicker CoFeB films exhibited a stronger CoFeB (110) crystallization. The nano-indention results revealed that the hardness (H) and Young’s modulus (E) of CoFeB thin films depend on mean grain size. The high values of nano-mechanical properties of as-deposited and thinner films arise from grain refinement, consistent with the Hall-Petch effect. The grain size was negatively related to hardness and Young's modulus. The nano-mechanical properties of CoFeB thin films that were underwent post-annealing at higher a temperature are worse than those that underwent post-annealing at a lower temperature as well those of the as-deposited films. Keywords: Nano-indentation, Hall-Petch effect, Young’s modulus, Hardness
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Chang, Chen-Fu, and 張振福. "Characterization of Bulk Copper Alloys with Nano/Amorphous Structure." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/86785723623967030365.
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碩士國立臺灣海洋大學
材料工程研究所
95
Abstract In this study, copper-based alloy rods in Cu-Zr-Al ternary system with high glass-forming ability were prepared by the copper mold casting method. Be, Sc and Ag were added to replace parts of Cu and Al, respectively. The alloy rods were mainly amorphous/nanocrystalline structure with diameters up to 3 mm. The fraction of amorphous structure was increased by the addition of Cu-Be and Al-Sc alloys. According to the compression test, the maximum of the compressive fracture stress was 1700 MPa due to the strain-hardening by the interaction of dendrites and shear-bands. With the addition of Ag, The alloy rods transferred into a brittle cleavage fracture mode. The electrochemical behavior of the alloy rods was studied. The corrosion resistance of the alloy rods in 1N H2SO4 and 1N NaOH solutions was better than that in 3.5 wt% NaCl solution because of the formation of the passive film. However, for the alloy rods in 3.5 wt% NaCl solution, the corrosion resistance of their amorphous/nanocrystalline states was superoir to that of their fully crystalline states.
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Su, Yu-Lun, and 蘇郁倫. "Silicon based nano-structure field emission light emitting device." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/75876755704016265611.
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碩士國立臺灣大學
電子工程學研究所
92
Abstract In this thesis, we develop the silicon based metal nano-pillar structure and silicon dry etching nano-pillar structure. Then use the phosphor and vacuum system to make the main field emission display(FED) device. In my experience the silicon wafer is coated a metal thin film and spin coated the nano-particle. Then I add voltage on the device to produce the nano-pillar structure on the thin metal film over the silicon. This method is quick and the process is easy. I also measured its conditions to understand the factor of the forming of the nano-pillar. Spin coating the nano-particle on the silicon wafer is another method. I use the dry etching method to make the nano-pillar structure on silicon wafer. The condition is easy to control and it has uniform dry etching surface. Then I put the completed nano-device and the ITO glass coated by phosphor together, then put them into the vacuum system, I add the voltage to emit the electrons. We find that the uniform of nano-particle will effect the nano-pillar structure and the phenomenon of field emission. At last I find the disadvantages of the field emission device and find the improvements. I use the photo mask lithography process to protect the nano-pillar structure, and measure the spectrum of the device. We find the field emission efficiency and the conditions of voltage and current, etc. I also bring up some improvements to overcome the problems.
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陳盈君. "Effect of Nano-scaled Magnetic Structure on Thermal Conductivity." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/50816199348044350384.
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Chi, Kai-Yuan, and 紀凱原. "Fabrication of Nano-Array Structure by Using Nanoimprint Lithography." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/28961015871711653478.
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碩士國立臺灣大學
物理研究所
95
Before long, it could come true that nanoimprint lithography will replace photolithography in semiconductor manufacture and nano technology. After Stephen Y. Chou, related technologies proposed by C. G. Wilson and G. M. Whiteside make it more possible. One reason is that nanoimprint can save much more cost and time waste in manufacture. More important one is the breakthrough about the diffraction of light. Although nanoimprint is highly developed, the fabrication under low pressure and the mechanics must be investigated. The researched object of this article is the nanostructure with high aspect ratio. In the first, we will introduce hard mask manufacture. In the method, SiO2 is used as a sacrificial layer to make deeper etch length. The most important part of nanoimpirnt is the leaf off process. Because the mold contains more surface area than the substrate, the adhesion force is asymmetric on both sides. It usually results to fracture or incomplete leaf off. Then we will show how to minimize the adhesion force between mold and polymer by coating an SAM layer. Thereafter, we will compare the results of PS and PMMA under different pressure, imprint time and temperature and find out the best parameters. At last, we will measure the force curve by AFM. The reasons why the mechanics of micro behavior and macro one are different will be discussed in the conclusion.
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Kao, Ming-Hsuan, and 高名璿. "Optimal Surface Nano Structure in Crystalline Silicon Solar Cells." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/89127942643988468447.
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碩士元智大學
光電工程研究所
99
Ｗe successfully form self-assemble ,close-packed and monolayer polystyrene nanospheres on the surface of silicon wafers, by employing simpley and cost-effectively spin-coating method. These nanospheres are used as sacrificial etching masks for reactive ion etching (RIE) process to fabricate different profile nano-arrays characterized as broadband antireflective and effective carrier collection structures for enhancing light harvesting of crystalline Si-based solar cells. Conventional antireflection layers were usually fabricated by depositing a single or multiple layers with restricted thickness and material selection on the silicon solar cells. However, the conventional method exhibited several drawbacks : 1. The stack of layers serve narrow-band antireflective properties. 2. Thermal mismatch and instability of the thin-film stacks have been the major obstacles to achieve broadband antireflection coatings. 3. Selection of materials with proper dielectric constants is difficult. According to the previous studies, the surface nano-arrays were reported to exhibit better broadband antireflective characteristics than the multiple antireflective layers, it opens up exciting opportunities for photovoltaic devices to further improve performance. In this project, we intend to demonstrate a high performance, large area Si solar cells by integrateing the antireflective nanostructure, We utilized rigorous coupled wave analysis (RCWA) method to calculate the reflectance of the nanostructured solar cells and desire to further optimize the light harvesting of the cells. In addition, implementation of the nanostructure will be conducted on silicon-based solar cells to reduce the broadband reflectance. After the RIE process, the samples with trapezoid structure were treated by dipping in HF:HNO3:H2O (2:48:50) solution to remove the damaged layer. This step is called defect removal etching (DRE). Not only the reflectance were reduced but also the lifetime was increased after DRE process. The data of lifetime and reflectance were input to APSYS simulator to calculate the short circuit current, open circuit voltage, and power conversion effeciency. The effeciency of trapezoid structures with DRE treatment achieve 15.51%, which shows an 16.53% compared to flat Si solar cells. We believe the trapezoid structures with DRE treatment are excellent anti-reflectance structures, which are promising candidates to realize the low-cost, high-efficiency solar cells.
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Chen, Kuei-Bai, and 陳奎百. "Nano-Structure Enhanced Organic Light Emitting Materials and Devices." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/69313460674782550942.
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Wang, Sih Han, and 王思涵. "Magnetic Behavior Analysis of Magnetic Composite Nano/Micro Structure." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/09708299442991158342.
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Chi, Kai-Yuan. "Fabrication of Nano-Array Structure by Using Nanoimprint Lithography." 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1407200721080100.
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Chen, Liang-Yi. "Photoluminescence Spectrum and Raman Spectroscopy of GaN Nano-structure." 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-0508200820410000.
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Che, Cheng Keng, and 鄭耕哲. "Electrochromic Property Study of Nano-Composite Prussian Blue Structure." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/14822402196627799851.
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博士國立清華大學
工程與系統科學系
95
A prussian blue (PB) film possesses special photoelectric properties, and therefore it can be used in dyeing industry, thin-film battery, biosensor, electrocatalytic film, electrochromic material and so on. PB electrochromic devices (ECDs) have energy saving concept, high contrast ratio, bi-stable and many other advantages. Consequently, PB ECDs fulfill the bill of energy crisis and portable display, which are the most popular issues in nowadays. Traditional EC films were thin film structures. EC materials need electrons from conductive substrate and ions from electrolyte to redox. However, the thin film structures disadvantage the electron transmission and ion diffusion and lead to slow response time and poor durability. Recently, nano-technology brings researchers new thoughts and developments, and it makes EC technology has a substantial improvement. The thesis proposes a novel PB EC structure. We use randomly conductive nano-particles as a conductive porous template and then the PB film is electro-deposited on them. This structure has high porosity; therefore, the electrolytes can easily permeate into the whole structure to increase the reaction area and redox speed. The structure also has a concept of nano-composite material, which can strengthen the whole structure to prolong the durability. We call this novel structure as a nano-composite PB (NPB) and expect that it can bring a breakthrough of EC technology.
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Liu, Ching-Wen, and 劉景文. "Micro and Nano hybrid structure applied in optical films." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/00035319725545843789.
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碩士國立清華大學
動力機械工程學系
99
In this research, a micro and nano hybrid structure was realized by using simple micro and nano processing methods. Micro-structures generated by using exposure, development and etching processing; nano-sturctures were generated by using AAO processing. Two different nano-structures were fabricated using this process, 50 nm nano-pores by using oxalic acid as electrolyte and 100 nm nano-pores by using phosphoric acid as electrolyte. Furthermore, for oxalic acid, second anodization was required to obtain nano-pores, also for both oxalic acid and phosphoric acid second anodization was used to obtain more ordered nano-pores. The fabricated structures were used as molds in a nano-imprint lithography process where the structures were successfully transferred to a transparent polymer film. This transparent film can be applied to optical films such as the diffuser in a back lighting module. The imprinted samples were tested for transmittance and compared with a “blank” sample, which has no nano-structures. Obvious increment in transmittance can be observed compared with the “blank” sample.
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Chen, Chung-Min, and 陳仲民. "Manufacturing and wettability of dual - dimension micro/nano - structure." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/31992680139829618485.
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碩士淡江大學
機械與機電工程學系碩士班
100
The present study has been proposed three manufacturing methodology to fabricate the hydrophobic ripple structure , and measured the contact angle between a distilled water and these ripple structure which droplets vertically on hydrophobic ripple structure using by the contact angle analysis system : (1) used the micro-electroforming and particle-nickel technology to fabricate the roughen ripple structure with 4.0μm in wavelength can be obtained average contact angle approximately 130 degree ; (2) adhered the nonionic surfactant on the peaks of the ripple structure with 4.0μm in wavelength can be obtained an average contact angle approximately 140 degree (3) used the replicating method to copy the PDMS ripple structure with 2.0μm in wavelength from a PDMS ripple structure has same wavelength and a gold film sputtered on the ripple structure can be obtained average contact angle approximately 154 degree。
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Chang, Tzu-Han, and 張茲翰. "Plasmonic properties of metal/dielectric grating hybrid nano-structure." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/16489916544271045920.
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碩士國立臺灣大學
應用物理所
100
Plasmonics metallic nanostructures can confine and manipulate light down to nanoscale, and give promising scenarios for nanophotonic applications. In this thesis, we have designed and fabricated a new hybrid nanostructure, dielectric-embedded metallic grating, via large patterning nanoimprimt lithog- raphy technique. The plasmonics properties of Fabry-Perot resonance in such device are investigated both experimentally and theoretically. The anticross- ing behavior due to the strong coupling between the surface plasmon polari- tons and Fabry-Perot resonace is observed and explained qualitatively quite well. Our newly designed geometry possesses high electric field enhance- ment, high quality factors and great sensitivity, which will open up a new potential in applications such as integrated plasmonic circuits, bio sensing, atom-trap, etc.
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Kuo, Chun-Yueh, and 郭峻岳. "Nano-Scale Structure with Lithography Process by Wavelength 365nm." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/9svhs6.
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碩士國立臺灣師範大學
光電科技研究所
105
Fin-type transistor has well gate control capability. This study will investigate photo lithography process to reach the nanometer scale fin/wall by wavelength 365nm without E-beam writer. We will design the dummy layout to protect and avoid damage the Fin. In order to further reduce Fin width, the thermal oxidation process is used to comsumpt Si and obtains the nano-scale line width. The nano Fin/wall is successfull demonstrated with Fin width 8nm in this thesis.
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Tseng, Kuo-Tung, and 曾國棟. "Laser 3D printing technology for micro / nano composite structure." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/bkvmm8.
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碩士中原大學
機械工程研究所
106
This thesis proposed a method to create molds with hierarchical micro/nano structures to enable the imprinting of conductive polymer polyaniline (PANI) for use as an electrode.The microstructure of mold was made by 3D printing. Computer-aided software (AutoCAD) was used to draw square column structures with micrometer size, and self-made 3D printer was used to fabricate micro-columns. Then the laser interference lithography was employed to build nanostructure on the surface of the micro-columns to form hierarchical micro/nano structures. Polydimethylsiloxane (PDMS) was used as a soft mold to duplicate the pattern of the previous hard mold. At last, PANI solution was poured into PDMS mold, then heat up to fabricate PANI solidified film applied in the supercapacitor. Using field emission scanning electron microscope (FE-SEM) confirmed that the surface structure of the film identification. On a three-electrode electrochemical cell, experiments were performed to characterize the electrochemical properties of plane PANI and PANI with microstructure and hierarchical microstructure, respectively. Cyclic voltammetric (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) measurements were then conducted using 1M H2SO4 as an electrolytic solution. Experimental results demonstrated that its specific capacity was 487 F/g, which is higher approximately 60% compared with PANI plane film. Increasing the surface area of PANI through the inclusion of hierarchical structures enhanced oxidation/reduction reactions, leading to a higher average specific capacitance.
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Fan, Jun-Hao, and 范俊豪. "Application of ZnO Nano-Rod and Nano-Film Bilayer Structure on Flexible Dye-Sensitized Solar Cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/r9j6xv.
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碩士國立虎尾科技大學
電子工程系碩士班
101
In this study, the ZnO working electrode was prepared on ITO/PEN substrates by hydrothermal method and doctor-blade method in dye sensitized solar cell; the ZnO nano-rod was fabricated by hydrothermal method, and the ZnO nano-film was prepared by doctor blade method. The main purpose of the ZnO nano-rod is to collect photogenerated electrons and reduce the charge recombination, while the polydisperse ZnO nano-film is used as a light-scattering layer not only to improve the adsorption of the dye molecules, but also to enhance the absorption of the illumination light. The ZnO (nano rods/nano-film) bilayer structure was used as the working electrode of dye sensitized solar cell. In the SEM analysis, when the nano-film with thickness of 35 μm, the cell efficiency will achieve 2.61% in DSSC. It was found that the the nano-film with thickness of 30 μm, and the the nano-rod with length of 4.5 μm, the best cell efficiency will achieve 3.05% for the ZnO bilayer structure DSSC. In addition, the incident photon-to-current conversion efficiency (IPCE) from 44.6% increases to 53.4%. Electrochemical impedance spectroscopy (EIS) shows that the working electrode with thickness of 35 μm has the smallest RK, so there is the best efficiency for DSSC. In addition, the electrode life time in the bilayer structure electrode is larger than in the nano-film electrode. Thus, ZnO nano-rod and nano-film bilayer structure DSSC have superior electron transport property than ZnO nano-film DSSC. Keywords: ZnO ; nano-rod ; nano-film ; dye-sensitized solar cell