Kohlenstoffnanoröhren als eigenständige Modifikation des Kohlenstoffs sind zylindrische, aus mehreren Lagen Kohlenstoff aufgebaute Röhren, die über einen Hohlraum im Inneren verfügen. Bereits kurze Zeit nach ihrer Entdeckung, kam die Idee auf, Substanzen in diesen Hohlraum zu füllen. Durch den Einbau von Katalysatormaterial während der Synthese, ist bereits eine Vielzahl von Elementen als Füllmaterial zugänglich. Um jedoch nicht auf Elemente limitiert zu sein, die als Katalysator für die CNT-Synthese dienen, ist es möglich eine postsynthetische Füllung durchzuführen. Hier werden ungefüllte CNT geöffnet und anschließend, unter Ausnutzung der Kapillarkräfte, gefüllt. In der vorliegenden Arbeit wurden zunächst verschiedene Methoden zur Füllung untersucht. Neben lösemittelbasierten Methoden wurde mit Salzschmelzen, durch Gasphasentransport und durch Füllung mit einer kovalenten Präkursorverbindung gefüllt. Da metallische Partikel das Ziel waren, folgte im Anschluss an die Füllung mit Salzen, Salzlösungen, oder anderen Präkursoren jeweils eine Reduktion mit Wasserstoffgas bei erhöhten Temperaturen. Die Ergebnisse der Füllung wurden umfassend mittels Elektronenmikroskopie untersucht. Füllungsgrade wurden mittels Thermogravimetrie bestimmt. So konnten für zahlreiche Elemente eine geeignete Methode zur Füllung mit metallischen Partikeln entwickelt werden. Im Falle der Füllung mit Zinn konnte zudem gezeigt werden, dass ein Zusammenhang zwischen der Dauer der Füllreaktion und dem Anteil an drahtartigen Nanostrukturen in den CNT, sowie ein Zusammenhang zwischen der eingesetzten Lösungskonzentration und dem Füllungsgrad besteht. Im weiteren Verlauf der Arbeit wurde die Synthese von intermetallischen Partikeln in CNT untersucht. Hierbei dienten die Systeme Nickel-Zinn und Cobalt-Zinn, die als vielversprechende Materialien im Einsatz als Anodenmaterial in Lithium-Ionen-Akkumulatoren diskutiert werden, als Modellsysteme. Zunächst wurde gezeigt, dass es nicht möglich ist, aus einem Gemisch des Zinnsalzes und des jeweiligen anderen Salzes erfolgreich intermetallische Partikel herzustellen. Mittels Pulverröntgendiffraktometrie (XRD) und energiedispersiver Röntgenspektroskopie (EDX) konnte gezeigt werden, dass lediglich Zinnpartikel in den CNT vorhanden waren. Schließlich konnte mit dem Verfahren der sequentiellen Füllung eine erfolgreiche Synthese intermetallischer Nanostrukturen bewerkstelligt werden. Hierbei wird die CNT zuerst mit einer Lösung von Zinnchlorid gefüllt und schließlich reduziert. Anschließend erfolgt eine weitere Füllung mit einem Nickel- bzw. Cobaltsalz und einer nachfolgenden Reduktion. Während dieser zweiten Reduktion erfolgt die Bildung der intermetallischen Nanostrukturen in den CNT. Mittels XRD konnte gezeigt werden, dass tatsächlich intermetallische Strukturen in der Probe enthalten sind und dass man zudem durch das Verhältnis der beiden eingesetzten Elemente (Zinn zu Nickel bzw. Cobalt) Einfluss auf die vorherrschende intermetallische Verbindung nehmen kann. Durch EDX-Linienscans und Elementkarten, die am Transmissionselektronenmikroskop angefertigt wurden, konnte nachgewiesen werden, dass einzelne, in den CNT befindliche Partikel, tatsächlich aus den beiden Elementen Zinn und Nickel bzw. Cobalt bestehen und somit intermetallisch sind. Ein erster Test des erhaltenen Materials aus CNT und intermetallischen Nickel-ZinnVerbindungen als Anodenmaterial konnte bereits durchgeführt werden. Die gemessene Kapazität lag bereits im Bereich von Graphit, welches üblicherweise als Anodenmaterial verwendet wird, könnte jedoch durch Erhöhung des Anteils der intermetallischen Verbindung noch weiter gesteigert werden.

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During recent years, new types of materials have been discovered with unique properties. One family of such materials are two-dimensional materials, which include graphene and MXene. These materials are stronger, more flexible, and have higher conductivity than other materials. As such they are highly interesting for new applications, e.g. specialized in vivo drug delivery systems, hydrogen storage, or as replacements of common materials in e.g. batteries, bulletproof clothing, and sensors. The list of potential applications is long for these new materials. As these materials are almost entirely made up of surfaces, their properties are strongly influenced by interaction between their surfaces, as well as with molecules or adatoms attached to the surfaces (surface groups). This interaction can change the materials and their properties, and it is therefore imperative to understand the underlying mechanisms. Surface groups on two-dimensional materials can be studied by Transmission Electron Microscopy (TEM), where high energy electrons are transmitted through a sample and the resulting image is recorded. However, the high energy needed to get enough resolution to observe single atoms damages the sample and limits the type of materials which can be analyzed. Lowering the electron energy decreases the damage, but the image resolution at such conditions is severely limited by inherent imperfections (aberrations) in the TEM. During the last years, new TEM models have been developed which employ a low acceleration voltage together with aberration correction, enabling imaging at the atomic scale without damaging the samples. These aberration-corrected TEMs are important tools in understanding the structure and chemistry of two-dimensional materials. In this thesis the two-dimensional materials graphene and Ti3C2Tx MXene have been investigated by low-voltage, aberration-corrected (scanning) TEM. High temperature annealing of graphene covered by residues from the synthesis is studied, as well as the structure and surface groups on single and double Ti3C2Tx MXene. These results are important contributions to the understanding of this class of materials and how their properties can be controlled.

Self-assembly of colloidal microparticles is one of the strategies for making characteristic patterns. These versatile self-assemblies provide a route to elevate the efficiency of an electronic device. Silsesquioxane particles with various functionalities were synthesized by a modified Stöber condensation method. This thesis describes the synthesis of benzylchloride silsesquioxanes, benzylchloride-amine silsesquioxanes and amine-functionalized silsesquioxane particles with multi-fluorescent tags. The size and morphology of the particles were controlled by varying the concentration of base and anhydrous ethanol (solvent). The size distribution of particles was controlled by adjusting the molar ratios of organotrialkoxy silane, base, and ethanol concentrations. Through selective post-functionalization with fused arenes of anthracene and rhodamine, multifluorescent particles were obtained. Morphologies and optical properties of particles were characterized by TEM, SEM, fluorescence optical microscopy, and absorption and fluorescence spectroscopies. The composition of silsesquioxanes was confirmed by FTIR, thermogravimetric analysis, and elemental analysis. A versatile technique was developed for the self-assembly of particles on different polymer substrates by changing the colloidal suspension concentration and the polymer substrate.

Cubic boron nitride (cBN) thin films offer attractive mechanical and electrical properties. The synthesis of cBN films have been deposited using both physical and chemical vapor deposition methods, which generate internal residual, stresses that result in delamination of the film from substrates. Boron nitride films were deposited using electron beam evaporation without bias voltage and nitrogen bombardment (to reduce stresses) were characterize using FTIR, XRD, SEM, EDS, TEM, and AFM techniques. In addition, a pin-on-disk tribological test was used to measure coefficient of friction. Results indicated that samples deposited at 400°C contained higher cubic phase of BN compared to those films deposited at room temperature. A BN film containing cubic phase deposited at 400°C for 2 hours showed 0.1 friction coefficient.

Dans l'industrie nucléaire, les composants en alliages de zirconium (Zr) sont utilisés comme éléments de structure dans les assemblages combustibles. La fabrication de ces éléments, leur utilisation en Réacteur à Eau Pressurisée (REP) et leur stockage avant retraitement induisent, entre autres, des sollicitations thermo-mécaniques complexes. Ce travail, grâce à une approche expérimentale multi-échelles, propose de mieux préciser les mécanismes de déformation qui sont à considérer. Pour cela, nous avons mené, sur des échantillons prélevés sur des composants en alliage de Zr destinés à être utilisés en REP, des essais mécaniques (fluage, traction, relaxation) et, d'autre part, des caractérisations microstructurales. Des essais de fluage multiaxial ont ainsi permis de mettre en évidence une anisotropie de comportement, dont l'origine physique a été montrée au moyen d'analyses en diffraction des électrons rétrodiffusés (EBSD) et d'observations en Microscopie Electronique en Transmission (MET). Par une démarche similaire, nous avons aussi identifié la nature des mécanismes accommodant la déformation à l'échelle du grain et à celle du polycristal. Ainsi, les incompatibilités de déformation intergranulaires et les cinétiques d'écoulement viscoplastiques identifiées expérimentalement s'expliquent par l'intervention de processus de traînage d'espèces en solutions par les dislocations, ainsi que l'activation locale de vieillissement dynamique. Enfin, nous avons esquissé des pistes pour l'utilisation de ces résultats dans des modélisations numériques. / In the nuclear industry, zirconium (Zr) based alloys are used as core structural materials in Pressurized Water Reactors (PWRs). The manufacturing of those components, and their environment during or after their use in PWRs induce complex thermo-mechanical loadings. This work, through a multi-scale experimental approach, proposes to focus on the deformation mechanisms that occur during those loadings. Using samples taken from Zr alloy components, we carried out different mechanicals tests (creep tests, tensile tests, relaxation tests) and microstructural characterizations. Results of multiaxial creep tests were correlated to Transmission Electron Microscope (TEM) observations and Electron BackScattered Diffraction (EBSD) analyses. Therefore, the macroscopic creep anisotropy was related to the physical mechanisms observed at the dislocation scale and during mesoscopic measurements. Our conclusions also show that the viscoplastic properties obtained experimentally match a control of dislocation mobility by solute species dragging processes. Further, the intergranular strain incompatibilities that we observed could be explained by local activations of dynamic strain ageing mechanisms. Finally, we used our results to suggest improvements on physically-based modelling techniques.

Electron tomography allows visualization of objects in a form of reconstructed 3D virtual volumes with resolution power of electron microscopy. The thesis is focused primarily on biological applications of electron tomography applied on tilt series images acquired in transmission electron microscope at room temperature. Specifically, the interaction of tick-borne encephalitis virus with neural cells and 3D ultrastructure of the central electron-dense part of the flagellum 9 + 1 (Caryophyllaeides fennica) were investigated. Finally, electron tomography was combined and correlated with atomic force microscopy to allow repetitive examination of ultrathin sections on electron microscopy grids.

Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) and SrCo0.48Fe0.12Ti0.4O3-delta (SCFT) were synthesised by co-precipitation. BSCF was pressed and sintered at 1100℃ for 10 hours to pellets (relative density: 93%) from which X-ray diffraction (XRD) revealed single Pm-3m phase (a=3.9782 A). Scanning electron microscopy (SEM) revealed clear equiaxed grains (grain size 33 ± 16 micro metre). The pellets were decomposed in 7 ± 1 % CO2/N2 at 800℃ for 1 to 30 minutes. XRD confirmed secondary phases: R-3mH phase (a=b=5.1397 A, c=9.4847 A) and Fm-3m phase (a=4.2490 A). Electron backscattered diffraction (EBSD) ascribed R-3mH and Fm-3m phases to the surface and part of the cross-section precipitates, respectively as revealed by SEM. Energy dispersive X-ray spectroscopy (EDX) revealed the compositions of R-3mH and Fm-3m phases to be Ba0.65±0.03Sr0.35±0.03CO3 (BSC) and CoO, respectively. Transmission electron microscopy (TEM) and EDX revealed the structure (15R, R3m and R-3mH) and composition (Ba0.20Sr0.10Co0.59Fe0.10Ox) of lamellar precipitates in cross-section, suggesting Ba and Sr diffuse from the lamellae to BSC. A unique orientation relation (BSCF {111} // BSC {0001}) was uncovered by EBSD. TEM revealed high symmetry contact planes of lamellae and BSCF, suggesting nucleation energy governs decomposition. Fresh BSCF pellets were decomposed in N2 at 800℃. Fm-3m and P63/mmc phases were confirmed by XRD and lamellae were observed by SEM, followed by decomposition in 7±1 % N2/CO2 at 800℃. XRD revealed higher weight % of BSC and CoO. SEM revealed BSC preferring lamellae, hence hexagonal phases accelerated BSC formation. BSCF pellets were dip coated in SCFT propan-2-ol suspension (3:10), followed by sintering at 1165℃ for 10 hours. XRD revealed a Pm-3m phase (a=3.885 A) and SEM revealed a grain size of 65 ± 9 micro metre and open porosity of 1.6 ± 1 %. They were annealed in 7 ± 1 % CO2/N2 at 800℃. XRD revealed no secondary phases, suggesting enhanced stability. However, oxygen permeability was reduced (1.2 ml/cm2 to 0.8 ml/cm2) because the coating composition changed to Ba0.20Sr0.27Co0.40Fe0.10Ti0.04Ox; this was revealed by EDX.

Graphene and other two-dimensional materials can be stacked together to form vander Waals heterostructures: synthetic crystals composed of different atomically thin layers with a bespoke electronic band structure. Structural characterisation of vander Waals heterostructures is difficult using conventional methods as the properties are almost entirely defined by the nature of the buried interfaces between dissimilar crystals. These methods also fall short of resolving the atomic structure of buried defects in van der Waals materials such as graphite. This work demonstrates the refinement and successful application of ion beam specimen preparation to produce cross sectional slices through these unique crystals so that they can be characterised by high resolution scanning transmission electron microscopy (STEM). Cross sectional specimen were prepared using in situ lift-out in a focused ion beam (FIB) dual-beam instrument. The fine polishing steps were optimised to prevent damage to the core of the specimen. High resolution STEM imaging of twin defects in graphene, hexagonal boron ni-tride and MoSe2 revealed that the boundaries are not atomically sharp but extended across many atoms. Advanced processing and analysis of these images uncovered fundamental mechanics which govern their geometry. This technique was further applied to complex transition metal dichalcogenide heterostructures to quantitatively determine the properties of buried interfaces between atomically thin crystals.

Iron oxides, have been widely studied as promising anode materials in lithium-ion batteries (LIBs) for their high capacity (≈ 1000 mA h g-1 for Fe2O3 and Fe3O4,), non-toxicity, and low cost. In this work, β-FeOOH has been evaluated within a LIB half-cell showing an excellent capacity of ≈ 1500 mA h g-1 , superior to Fe2O3 or Fe3O4. Reaction mechanism has been proposed with the assistance of X-ray photoelectron spectroscopy (XPS). Various magnetic properties have been suggested for β-FeOOH such as superparamagnetism, antiferromagnetism and complex magnetism, for which, size of the material is believed to play a critical role. Here, we present a size-controlled synthesis of β-FeOOH nanorods. Co-existing superparamagnetism and antiferromagnetism have been revealed in β-FeOOH by using a Physical Property Measurement System (PPMS). Compared with the high price of lithium in LIBs, sodium-ion batteries (SIBs) have attracted increasing attentions for lower cost. Recent studies have reported Na0.44MnO2 to be a promising candidate for cathode material of SIBs. This thesis has approached a novel solid-state synthesis of Na0.44MnO2 whiskers and a nano-scaled open cell for in situ TEM study. Preliminary results show the first-stage fabrication of the cell on a biasing protochip.