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Atomic force microscopy (AFM) is a young and widely used method of ima- ging surface, nanostructures, biological and other sensitive objects using sharp tip on a flexible cantilever scanning the sample surface. When operating in air it reaches resolution of about several nanometers. The resolution is mainly depen- dent on the used tip. The thesis deals with modification of old tips by carbon nanotubes (CNT) in scanning electron microscope (SEM) using techniques inclu- ding focused ion beam (FIB) and gas injection system (GIS). Several procedures of CNT sample preparation and attaching the CNT on tip are presented. The functionality of modified tips was checked in AFM using the calibration sample consisting of well-defined nanostructures. 1

El espermatozoide humano es uno de los tipos celulares más diferenciados, capaz de moverse con autonomía al salir del cuerpo masculino donde se produce y lograr su objetivo en el sistema reproductor femenino. Se forma a partir de un complejo y ordenado proceso de división y diferenciación celular. Para conseguir este proceso, debe reestructurar sus orgánulos internos, dividir su carga genética a la mitad, condensar su ADN para facilitar la motilidad y evitar daños irreparables, y reducir su volumen. Además, debe madurar su membrana para alcanzar el objetivo de fecundar el ovocito femenino. Desde el descubrimiento del espermatozoide, muchas publicaciones han mostrado la estructura morfológica que define a esta célula. Sin embargo, en el núcleo del espermatozoide, existe una estructura que ha suscitado mucha controversia hasta nuestros días, y que se les llama ‘vacuolas’. Estas estructuras fueron documentadas en un informe escrito por Theodor Eimer hace más de un siglo (Eimer 1874). Antiguos trabajos realizados en primates llevados a cabo por Bedford (Bedford 1967) y Zamboni (Zamboni y col. 1971) mediante microscopía electrónica reportaron que las vacuolas nucleares son estructuras específicas de la cabeza del espermatozoide humano. Estas vacuolas estaban presentes tanto en el espermatozoide maduro como en espermátidas tempranas (Holstein y Roosen-Runge, 1981; Johannisson 1987; Auger y Dadoune, 1993). Por lo que se ha sugerido que esta formación vacuolar ocurre de manera natural durante el proceso de condensación del núcleo espermático (Tanaka y col. 2012). Sin embargo, muchos años después del descubrimiento de las vacuolas, sigue sin estar clara su naturaleza, origen y función. En esta tesis doctoral, hemos estudiado las vacuolas nucleares del espermatozoide humano mediante técnicas ultraestructurales e inmuno-citoquímicas. Además, hemos analizado las mismas muestras espermáticas en fresco y seleccionándolas mediante swim-up con medios capacitantes. A partir de las micrografías obtenidas con estas técnicas, hemos analizado morfológica y morfométricamente las vacuolas. Con ello demostramos que las vacuolas son, en realidad, invaginaciones de la envoltura nuclear y su contenido procede del citoplasma. Estas estructuras no varían después de seleccionar los espermatozoides mediante su motilidad con medio capacitante. En el último apartado, mostramos la utilización de una técnica ultraestructural y de análisis de imagen para recrear un diseño 3D de la cabeza del espermatozoide y de las vacuolas. En esta tomografía en 3D corroboramos los resultados demostrados. Por ello, debido a todos los datos publicados en esta tesis doctoral, proponemos cambiar la terminología de estas ‘vacuolas’ por ‘invaginaciones nucleares’. Asimismo, es necesaria una revisión en la clasificación de estas invaginaciones como parámetro negativo de calidad espermática.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19730号 / 工博第4185号 / 新制||工||1645(附属図書館) / 32766 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 江口 浩一, 教授 安部 武志, 教授 陰山 洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The goal of this work is to develop a model to predict the microstructure of Li-ion batteries, specifically focusing on the cathode component of the batteries. This kind of model has the potential to assist researchers and battery manufacturers who are trying to optimize the capacity, cycle life, and safety of batteries. Two dynamic particle packing (DPP) microstructure models were developed in this work. The first is the DPP1 model, which simulates the final or dried electrode structure by moving spherical particles under periodic boundaries using Newton's laws of motion. The experience derived from developing DPP1 model was beneficial in making the final model, called DPP2. DPP2 is an improved version of DPP1 that includes solvent effects and is used to simulate the slurry-coating, drying, and calendering processes. Two type of properties were used to validate the DPP1 and DPP2 models in this work, although not every property was used with the DPP1 model. First are the structural properties, which include volume fraction, and electronic and ionic conductivities. Experimental structural properties were determined by analyzing 2D cross sectional images of the battery cathodes. These images were taken through focused ion beam (FIB) planarization and scanning electron microscopy (SEM). The second category are the mechanical properties, which include film elasticity and slurry viscosity. These properties were measured through experiments executed by our group. The DPP2 model was divided into two submodels : active-free and active-composite. The 2D cross sectional images of the simulated structure of the models have a similar particle arrangements as the experimental structures. The submodels show reasonable agreement with the experimental values for liquid and solid mass density, shrink ratio, and elasticity. For the viscosity, both models show shear-thinning behavior, which is a characteristic of slurries. The volume fractions of the simulated structures of the active-free and active-composite models have better agreement with the experimental values, which is also reflected in the 2D cross sectional images of the structure.

Vanadium dioxide (VO_2) is a material of particular interest due to its exhibited metal to insulator phase transition at 68°C that is accompanied by an abrupt and significant change in its electronic and optical properties. Since this material can exhibit a reversible drop in resistivity of up to five orders of magnitude and a reversible drop in infrared optical transmission of up to 80%, this material holds promise in several technological applications. Solid phase crystallization of VO_2 thin films was obtained by a post-deposition annealing process of a VO_{x,x approx 2} amorphous film sputtered on an amorphous silicon dioxide (SiO_2) layer. Scanning electron microscopy (SEM) and electron-backscattered diffraction (EBSD) were utilized to study the morphology of the solid phase crystallization that resulted from this post-deposition annealing process. The annealing parameters ranged in temperature from 300°C up to 1000°C and in time from 5 minutes up to 12 hours. Depending on the annealing parameters, EBSD showed that this process yielded polycrystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated single-crystal particles. In addition to these films on SiO_2, other VO_2 thin films were deposited onto a-, c-, and r-cuts of sapphire and on TiO_2(001) heated single-crystal substrates by pulsed-laser deposition (PLD). The temperature of the substrates was kept at ~500°C during deposition. EBSD maps and orientation imaging microscopy were used to study the epitaxy and orientation of the VO_2 grains deposited on the single crystal substrates, as well as on the amorphous SiO_2 layer. The EBSD/OIM results showed that: 1) For all the sapphire substrates analyzed, there is a predominant family of crystallographic relationships wherein the rutile VO_2{001} planes tend to lie parallel to the sapphire's {10-10} and the rutile VO_2{100} planes lie parallel to the sapphire's {1-210} and {0001}. Furthermore, while this family of relationships accounts for the majority of the VO_2 grains observed, due to the sapphire substrate's geometry there were variations within these rules that changed the orientation of VO_2 grains with respect to the substrate's normal direction. 2) For the TiO_2, a substrate with a lower lattice mismatch, we observe the expected relationship where the rutile VO_2 [100], [110], and [001] crystal directions lie parallel to the TiO_2 substrate's [100], [110], and [001] crystal directions respectively. 3) For the amorphous SiO_2 layer, all VO_2 crystals that were measurable (those that grew to the thickness of the deposited film) had a preferred orientation with the the rutile VO_2[001] crystal direction tending to lie parallel to the plane of the specimen. The use of transmission electron microscopy (TEM) is presented as a tool for further characterization studies of this material and its applications. In this work TEM diffraction patterns taken from cross-sections of particles of the a- and r-cut sapphire substrates not only solidified the predominant family mentioned, but also helped lift the ambiguity present in the rutile VO_2{100} axes. Finally, a focused-ion beam technique for preparation of cross-sectional TEM samples of metallic thin films deposited on polymer substrates is demonstrated.

The goal of this work is to further understand the relationships between porous electrode microstructure and mass transport properties. This understanding allows us to predict and improve cell performance from fundamental principles. The investigated battery systems are the widely used rechargeable Li-ion battery and the non-rechargeable alkaline battery. This work includes three main contributions in the battery field listed below. Direct Measurement of Effective Electronic Transport in Porous Li-ion Electrodes. An accurate assessment of the electronic conductivity of electrodes is necessary for understanding and optimizing battery performance. The bulk electronic conductivity of porous LiCoO2-based cathodes was measured as a function of porosity, pressure, carbon fraction, and the presence of an electrolyte. The measurements were performed by delamination of thin-film electrodes from their aluminum current collectors and by use of a four-line probe. Imaging and Correlating Microstructure To Conductivity. Transport properties of porous electrodes are strongly related to microstructure. An experimental 3D microstructure is needed not only for computation of direct transport properties, but also for a detailed electrode microstructure characterization. This work utilized X-ray tomography and focused ion beam (FIB)/scanning electron microscopy (SEM) to obtain the 3D structures of alkaline battery cathodes. FIB/SEM has the advantage of detecting carbon additives; thus, it was the main tomography tool employed. Additionally, protocols and techniques for acquiring, processing and segmenting series of FIB/SEM images were developed as part of this work. FIB/SEM images were also used to correlate electrodes' microstructure to their respective conductivities for both Li-ion and alkaline batteries. Electrode Microstructure Metrics and the 3D Stochastic Grid Model. A detailed characterization of microstructure was conducted in this work, including characterization of the volume fraction, nearest neighbor probability, domain size distribution, shape factor, and Fourier transform coefficient. These metrics are compared between 2D FIB/SEM, 3D FIB/SEM and X-ray structures. Among those metrics, the first three metrics are used as a basis for SG model parameterization. The 3D stochastic grid (SG) model is based on Monte Carlo techniques, in which a small set of fundamental inter-domain parameters are used to generate structures. This allows us to predict electrode microstructure and its effects on both electronic and ionic properties.

<p>  </p> <p>Transition to a sustainable power grid entails the use of all net-zero carbon emission technology that is currently available. Liquid metal-cooled fast nuclear reactors (LMFRs) are technologies capable of competitively providing power while attaining sustainability and reliability. Uranium-zirconium metallic alloys have been proposed as LMFRs fuels based on the performance of the fuel in experimental scale reactors, achieving up to 20 at.% burn-up. The following phenomena affects the irradiation performance of U-Zr fuels: constituent redistribution, swelling, fuel-cladding mechanical interaction (FCMI), and fuel-cladding chemical interaction (FCCI). Further understanding of these phenomena, and development of predictive models requires data collection of variables such as composition, morphology of the redistribution regions, porosity distribution, porosity morphology, fission gas release, and the relation between local composition and porosity evolution. </p> <p>To achieve this, focused ion beam-scanning electron microscopy (FIB-SEM) serial sectioning was applied to specimens from the different compositional regions developed during constituent redistribution of a U-10 wt.% Zr fuel neutron irradiated to 5.7 at.% burn-up. High-resolution backscattered electron (BSE) micrographs, and energy dispersive spectroscopy (EDS) spectra were obtained for several sections of each specimen. Each section was analyzed to identify the microstructural and compositional evolution in the specimen volume. Three-dimensional porosity and phase volume distribution was obtained using image processing and three-dimensional object classification. The study revealed local segregation of phases within each of the regions, porosity distribution dependency on temperature and local composition, preferential porosity nucleation sites, porosity evolution trends, interconnectivity, possible sinks/nucleation sites for porosity and precipitates, as well as possible mechanisms for fission gas release.</p>

<p> Monolithic uranium molybdenum alloys (U-Mo) are considered a candidate for converting high-performance research and test reactors from high-enriched uranium to low enrichment alternatives. The metallic fuel is capable of conversion due to the high U loading and favorable radiation performance. During irradiation, the fuel undergoes a three-part swelling behavior, with an initial linear swelling rate followed by an increase in the swelling rate represented by an increase in the nucleation of fission-gas bubbles, and ending with stabilization at the highest fission densities. Understanding the high burnup regime is critical to extending the life of the reactor and creating accurate fuel performance models. To accurately inform swelling models, it is necessary to experimentally characterize the pore evolution as a function of burnup and the influence of diffusion barrier-fuel interaction on the morphology. Therefore, a systematic approach was conducted to experimentally characterize the influence of irradiation and fuel-diffusion barrier interaction on the pore morphology and then empirically model the porosity evolution. Initially, three separate locations in a monolithic U-Mo fuel plate with burnups ranging from 8.9-9.4x1021 fissions/cm3 were investigated using scanning electron micrography (SEM) to characterize the morphological porosity dependence on fission density. To investigate the impact of the Zr-fuel interface on the pore morphology, two specimens were imaged using synchrotron microcomputed tomography (Sr-µCT) from a U-Mo monolithic miniplate irradiated to 9.8x1021 fissions/cm3, one at the diffusion barrier and one in the bulk fuel. Synchrotron microcomputed tomography allows for the characterization of the influence of fuel-Zr diffusion barrier interaction on the pore morphology in three dimensions; however, due to the novelty of this technique applied to nuclear fuels the results were verified with SEM serial sectioning. The multimodal comparison between the Sr-µCT and SEM serial sectioning allows for a direct assessment of the capabilities of each technique for nuclear fuel applications. Due to the complex microstructure and imaging challenges in analyzing these samples, several model-based image processing and characterization tools were developed to aid in the analysis. An empirical model for porosity evolution in high-burnup U-Mo was developed and accurately modeled the porosity behavior. The experimental results from the current work and the empirical model developed can be used to inform mechanistic modeling efforts in the community. </p>

Transmission Electron Microscopy (TEM) is a reliable tool for chemical and structural studies of nanostructured systems. The shape, size and volumes of nanoparticles on surfaces play an important role in surface chemistry. As nanostructured surfaces become increasingly important for catalysis, protective coatings, optical properties, detection of specific molecules, and many other applications, different techniques of TEM can be used to characterize the properties of nanoparticles on surfaces to provide a path for predictability and control of these systems. This dissertation aims to provide fundamental understanding of the surface chemistry of Electroless Metallization onto Polymeric Surfaces (EMPS) through characterization with TEM. The research focuses on a single EMPS system: deposition of Ag onto the cross-linked epoxide "SU8", where Au nanoparticles act as nucleation sites for the growth of Ag nanoparticles on the polymer surface. TEM cross sections were analyzed to investigate the morphology of the Au nanoparticles and to determine the thicknesses of the Ag nanoparticles and of the Ag layers. A method for the direct measurement of the volume and thickness of nanomaterials has been developed in the project using High-Angle Annular Dark-Field (HAADF) Scanning Transmission Electron Microscopy (STEM). The morphology of Au and Ag NPs has been studied to provide reliable statistics for 3-D characterization. Deposition rates have been obtained as a function of metallization conditions by measuring the composition and thickness of the metal for EMPS. In the present work a calibration method was used to quantify the sensitivity of the HAADF detector. For thin samples a linear relationship of the HAADF signal with the thickness of a material is found. Cross-sections of multilayered samples provided by Triquint Semiconductors, FL, were analyzed as calibration standards with known composition in a TECNAI F30 transmission electron microscope to study the dependence of the HAADF detector signal on sample thickness and temperature. Dynamical diffraction processes play an important role in electron scattering for larger sample thicknesses. The HAADF detector intensity is not linearly dependent on sample thicknesses for thick samples. This phenomenon involves several excitation processes including Thermal Diffuse Scattering (TDS) which depends on temperature-dependent absorption coefficients. Multislice simulations have been carried out by Python programming using the scattering parameters (2) available in the literature. These simulations were compared with experimental results. Wedge-shaped Focused Ion Beam (FIB) samples were prepared for quantitative HAADF-STEM intensity measurements for several samples and compared with these simulations. The discrepancies between the simulated and experimental results were explained and new sets of absorptive parameters were calculated which correctly account for the HAADF-STEM contrasts. A database of several pure elements is compiled to illustrate the absorption coefficients and fractions of scattered electrons per nanometer of the sample. In addition, the wedge-shaped FIB samples were used for studying the HAADF-STEM contrasts at an interface of a high- and a low-density material. The use of thick samples reveals an increased signal at the interfaces of high- and low-density materials. This effect can be explained by the transfer of scattered electrons from the high density material across the interface into the less-absorbing low-density material. A ballistic scattering model is proposed here for the HAADF-STEM contrasts at interfaces of thick materials using Python. The simulated HAADF-STEM signal is compared with experimental data to showcase the above phenomenon. A detailed understanding of the atomic number contrast in thick samples is developed based on the combination of experimental quantitative HAADF-STEM and simulated scattering. This approach is used to describe the observed features for Ag deposition on SU8 polymers.