In this thesis, photocrosslinked ferrocene-based methacrylate polymers for thin-film cathodes in lithium batteries have been synthesized. Patterned thin-film electrodes of the ferrocene-based methacrylate polymers are fabricated by photocrosslinking. The structure and composition of the photocrosslinkable polymers are characterized by infrared spectra, nuclear magnetic resonances, and gel permeation chromatography. The result of quartz crystal microbalance shows that the crosslinked polymers prevent the polymers from dissolving into organic electrolytes. The cyclic voltammogram shows the photocrosslinked ferrocene-based methacrylate polymers have a redox couple. The energy capacity of the polymer for lithium batteries is about 40-50 mAh g-1 at a discharge rate of 10 C. The results show that the photocrosslinked ferrocene-based methacrylate polymers also improve the batteries.

Enhancing the effective peel resistance of plastically deforming adhesive joints through laser-based surface micro-machining Edwin Hernandez Diaz Inspired by adhesion examples commonly found in nature, we reached out to examine the effect of different kinds of heterogeneous surface properties that may replicate this behavior and the mechanisms at work. In order to do this, we used pulsed laser ablation on copper substrates (CuZn40) aiming to increase adhesion for bonding. A Yb-fiber laser was used for surface preparation of the substrates, which were probed with a Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). Heterogeneous surface properties were devised through the use of simplified laser micromachined patterns which may induce sequential events of crack arrest propagation, thereby having a leveraging effect on dissipation. The me- chanical performance of copper/epoxy joints with homogeneous and heterogeneous laser micromachined interfaces was then analyzed using the T-peel test. Fractured surfaces were analyzed using SEM to resolve the mechanism of failure and adhesive penetration within induced surface asperities from the treatment. Results confirm positive modifications of the surface morphology and chemistry from laser ablation that enable mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy, bond toughness, and effective peel force were appreciated with respect to sanded substrates as control samples.

No description available.

No description available.

Subarctic and alpine areas are sensitive to climatic change when they lie at the margin of permafrost occurrence. Patterned ground in such areas is generated from an interplay among different mechanisms such as temperature, hydrology, soil texture, snow cower and vegetation. The aim of this study is to describe the connection between patterned ground characteristics and altitude and to evaluate the impact different variables have on the appearance of patterned ground. To understand these interactions is a discussion of self-organization processes, threshold effects and feedback mechanisms essential.  In this investigation, characteristics of patterned ground are examined along an elevation gradient in the Abisko area in Northern Sweden. The study is limited to formations that are categorized into non-sorted circles on flat ground. To detect significant correlations between the characteristics of patterned ground and altitude nine places between 400 and 1400 m above sea level with at least 100 m difference in altitudes were investigated. These sites were categorized into six ridges and three sinks to evaluate the importance of topography. Non-sorted circles have less dwarf shrub, more moss-lichen cover and more cryptogam crust than surrounding ground. Outside the formations the amount of dwarf shrub decreases and the moss-lichen cover increases above 1000 m above sea level. At the highest altitude also a cryptogam crust is occurring around non sorted circles. Significant correlations exist between declining ground temperature and altitude, declining distance between non-sorted circles and altitude, and less dwarf shrub vegetation on non-sorted circles and altitude. These relationships are expected and can be connected to cryoturbation and abiotic stress. Shorter distance between formations can be linked to increased abiotic stress and less coverage soil stabilizing dwarf shrub vegetation. Formations are larger in sinks than ridges and surrounded by less dwarf shrub and more moss-lichen vegetation. This difference can be explained by longer snow duration, humid soil conditions and prolonged freezing processes in ground. Non-sorted circles on an east aspect slope ridge at about 900 meters altitude is characterized by low soil temperatures, high soil moisture, low height and low coverage plants. Around these formations is a well-developed ground cover consisting primarily of dwarf shrub vegetation. These observations are a sign of positive interaction resulting in strong self-generating soil movements that have exceeded a threshold when breaking through vegetation cover. Low soil temperature and high moisture at the time of measurement might be explained by existing ice-front and free water convection. These patterned ground characteristics can be linked to permafrost, the inflow of water from higher leeward slopes and thin snow cower.

En microélectronique, certains dispositifs (MEMS) nécessitent une couche de protection appelée encapsulation pour assurer un fonctionnement optimal. Ce procédé met en jeu une couche structurée de polymère BCB (benzocyclobutène). Celle-ci est en contact avec unsubstrat de silicium d’un côté et une couche de nickel de l’autre. Une compréhension du comportement de ces interfaces et primordiale. L’objectif de cette thèse est la caractérisation de l’énergie d’adhérence des interfaces discontinues Ni/BCB et BCB/Si. Deux essaismécaniques (test de flexion 4-points et insertion de lame) ont été mis en œuvre. Les modèles analytiques mis au point dans le cas d’une interface continue ont servi à l’exploitation de ces essais mais ont aussi montré leur limite. La structuration de l’interface induit des effets géométriques et des effets d’échelle qui ne sont pas bien pris en compte par les modèles classiques. Pour pallier à cette difficulté, un modèle analytique modifié est proposé pour le test d’insertion de lame, ainsi que des calculs de simulation numérique. Ils mettent en avant l’influence des paramètres de la structuration : taille des motifs, espacement. / In microelectronics, some devices (MEMS) need to be encapsulated by a protective layer for optimal performances. This technique involves a patterned layer made of BCB polymer (benzocyclobutene). This layer is between a nickel film and a silicon substrate. A good understanding of those two interfaces is of first importance. The aim of this thesis is the mechanical characterization of the fracture energy of the Ni/BCB and BCB/Si patterned interfaces. Two mechanical tests (the 4-points bending test and the wedge test) have been selected in that purpose. Analytical models are well established to analyze those tests but for continuous interfaces. With patterned ones, those models are limited and do not take into account all the size effects and the geometrical effects induced by the patterning. A modified analytical model is proposed for the wedge test in order to overcome these limitations. Numerical studies are also carried out to complement the study. Patterning effects such as the size of the patterns and the space between them are enhanced.

Gas source molecular beam epitaxy (GSMBE) has been used to grow InGaAs/lnP epitaxial layers in selected areas defined by SiO2-masked InP substrates, with the goal of obtaining controlled in-plane variations in the bandgap of the InGaAs wells. The ability to alter the bandgap of the semiconductor spatially over the surface in one growth procedure is desirable for integrating laser, waveguide and detector devices. To form the masked substrates, stripes (ranging in width from 2 pm to 50 pm) were opened up in SiO2 by standard photolithography. The crystal growths were carried out at various substrate temperatures (ranging from 460 °C to 510 °C) and arsenic fluxes (V/lll ratios ranging from 1.2 to 3.4). The properties of the epitaxial layers were investigated by using such analytical techniques as photoluminescence, electroluminescence and transmission electron microscopy (TEM). Photoluminescence measurements performed on waveguide stripes of decreasing width reveal an increasing red-shift of the e1-hh1 transition in InGaAs wells. The maximum red-shift occurred when growing at a high substrate temperature and a low arsenic flux. For example, a decrease in slit width from 50 pm to 10 pm resulted in a 25 meV shift of the photoluminescence peak. From cross-sectional TEM measurements, the wavelength shift observed can be attributed primarily to an increase in thickness of the InGaAs well, due to incorporation of additional indium and gallium migrating from the material on the masked regions. The interfaces in the centre of the stripe region are defect free; however, stacking faults and thickness variations are evident 1-2 pm from the edges. These results are confirmed by scanning photoluminescence, in which the maximum intensity occurs at the centre of the stripe and decreases to zero at the edges. Mapping of the peak wavelength across the stripe reveals a diffusion profile, with the edges being additionally red shifted by 10 nm. Reactive ion etching of the edge and the polycrystalline material results in a much improved spectral photoluminescence scan, in both increased intensity of the bandgap peak and elimination of lower energy peaks assumed to be correlated with edge effects. Finally, a stripe contact light emitting device, with a single 50 A quantum well InGaAs/lnP structure, was fabricated and electrically pumped. The device exhibited spectral peak wavelength shifts between narrow stripes (10 pm) and wide stripes (50 pm) of 22 nm, similar to the value observed by photoluminescence studies. / Thesis / Master of Engineering (ME)

Solid oxide fuel cells (SOFCs) represent a next generation energy source with high energy conversion efficiency, low pollutant emission, good flexibility with a wide variety of fuels, and excellent modularity suitable for distributed power generation. As an electrochemical energy conversion device, SOFC’s performance and reliability depend sensitively on the catalytic activity and stability of the electrode materials. To date, however, the development of electrode materials and microstructures is still based largely on trial-and-error methods because of inadequate understanding of the mechanisms of the electrode processes. Identifying key descriptors/properties of electrode materials or functional heterogeneous interfaces, especially under in situ conditions, may provide guidance to the design of electrode materials and microstructures. This thesis aims to gain insight into the electrochemical and catalytic processes occurring on the electrode surfaces using unique characterization tools with superior sensitivity, high spatial resolution, and excellent surface specificity applicable under in situ/operando conditions. Carbon deposition on nickel-based anodes is investigated with in situ Raman spectroscopy and SERS. Analysis shows a rapid nucleation of carbon deposition upon exposure to small amount of propane. Such nucleation process is sensitive to the presence of surface coating (e.g., GDC) and the concentration of steam. In particular, operando analysis of the Ni-YSZ boundary indicates special function of the interface for coking initiation and reformation. The coking-resistant catalysts (BaO, BZY, and BZCYYb) are systematically studied using in situ Raman spectroscopy, SERS, and EFM. In particular, time-resolved Raman analysis of the surface functional groups (-OH, -CO3, and adsorbed carbon) upon exposure to different gas atmospheres provides insight into the mechanisms related to carbon removal. The morphology and distribution of early stage carbon deposition are investigated with EFM, and the impact of BaO surface modification is evaluated. The surface species formed as a result of sulfur poisoning on nickel-based anode are examined with SERS. To identify the key factors responsible for sulfur tolerance, model cells with welldefined electrode-electrolyte interfaces are systematically studied. The Ni-BZCYYb interface exhibits superior sulfur tolerance. The oxygen reduction kinetics on LSCF, a typical cathode material of SOFC, is studied using model cells with patterned electrodes. The polarization behaviors of these micro- electrodes, as probed using a micro-probe impedance spectroscopy system, were correlated with the systematically varied geometries of the electrodes to identify the dominant paths for oxygen reduction under different electrode configurations. Effects of different catalyst modifications are also evaluated to gain insight into the mechanisms that enhance oxygen reduction activity. The causes of performance degradation of LSCF cathodes over long term operation are investigated using SERS. Spectral features are correlated with the formation of surface contamination upon the exposure to air containing Cr vapor, H2O, and CO2. Degradation in cathode performance occurs under normal operating conditions due to the poisoning effect of Cr from the interconnect between cells and the high operating temperature. The surface-modified LSCF cathode resists surface reactions with Cr vapor that impairs electrode performance, suggesting promising ways to mitigate performance degradation.

Patterned resistive sheets (PRS) are resistive sheets with periodic patterns which provide further advantages to the functionality of the microbolometer. This study examines the potential of both single- and double-layer designs to achieve spectral selectivity in both broadband and narrowband absorption in the microbolometer's application. First, important design parameters, including rules and processes, are established. These include descriptions of sheet resistance, air gap, material refractive index, thicknesses of dielectric and bolometric layers, mirror, pattern shape and size, and unit cell period. Moreover, interactions among these elements are examined. Second, single-layer designs using dipole and slot PRS are introduced as initial designs for the reduced thermal mass design. Applying holes without changing spectral selectivity are investigated for narrowband application. Moreover, the method to tune the change of spectral selectivity is introduced. Third, newly stacked two-color design is suggested. The out-of-band transmission and reflection characteristics of the dipole and slot PRS are investigated to increase the absorption of each layer. Additionally, different pattern shapes, such as the circular patch and square patch, are investigated for easier fabrication. / text

Recognition and classification of patterned ground polygons from remote sensing data Abstract The main objective of this thesis has been to prove the possibility of using object based image analysis classification for identification of the ice-wedge polygons and to find general method for their classification. The thesis contains a comparison of the object based and pixel based classification of the subject. The three classification rulesets for OBIA were developed on three test sites on Mars captured by HiRISE sensor. As a result, the general classification approach is suggested. The manually collected datasets, which are common in geomorphological research, were used as the reference sample. The OBIA classification provided better results in all three cases, whereas the pixel classification was valid in only one case. Another objective has been the automatization of the process of gaining information about morphometric characteristics of the ice-wedge polygons and the subsequent classification of the polygons. Within the scope of the process were developed methods for creating polygonal network and specified parameters of those methods. Several toolboxes for the ArcGIS software were prepared and they are part of the results of the thesis. Keywords: patterned ground, ice-wedge polygons, remote sensing,...