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Showing 1 to 20 of 20 for “"HAADF"”.
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Avances y limitaciones de la técnica de microscopia electrónica de transmisión-barrido con detección de electrones a alto ángulo para el análisis de nuevos nanomateriales con aplicaciones en eficiencia energética.
… Tesis es analizar las limitaciones de la técnica HAADF-STEM en equipos de aberración corregida para el estudio de los materiales avanzados antes presentados. Respecto a los materiales semiconductores cuaternarios, la complejidad adicional que surge en el análisis de su composición a partir de la …
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Quantitative High-angle Annular Dark Field Scanning Transmission To Electron Microscopy For Materials Science
… structures. High-angle annular dark field (HAADF) STEM imaging using atomic number (Z) contrast has proven capable of resolving atomic structures with better than 2 A lateral resolution. In this work, the HAADF STEM imaging mode is used in combination with multislice simulations. This …
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Nanoscale characterization of InSb/InAs novel functional semiconductor nanostructures for LEDs / Caracterización a nanoescala de nanoestructuras funcionales novedosas de InSb/InAs para LEDs
… column resolved high angle annular dark field (HAADF) – scanning transmission electron microscopy (STEM) characterization technique has been considered, where Sb compositions are realized through HAADF-STEM atomic column intensities. In order to interpret the Sb composition through HAADF-STEM …
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Gold-containing bimetallicnanoparticles
… combined with high angle annular dark field (HAADF) imaging, energy dispersive X-ray elemental mapping using a silicon drift detector (SDD), tomography, and electron energy loss spectroscopy (EELS). Sizes and shapes of the Cu-Au, Pd-Au, and Pt-Au nanoparticles are studied by TEM. Morphological …
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Electron microscopy characterisation of size-selected Pd clusters and industrial Pd catalysts
… field scanning transmission electron microscopy (HAADF-STEM) technique. The driving force of this work is to establish reliable and efficient methods for the structural characterisation of nanostructures. The characterisation of nanostructures is essential to our fundamental understanding of …
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Structure and Dynamics in Ligand-Protected and Supported Metal Nanoparticles
… field scanning transmission electron microscopy (HAADF-STEM) measurements characterize metal clusters and nanoparticles on the basis of the number of metal atoms they contain. Ligand-protected 13-atom gold clusters serve as a model system to illustrate the capabilities of a correlated use of these …
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Shear-band structure in metallic glasses
… field scanning transmission electron microscopy (HAADF-STEM). It was found that those properties sensitively depend on the position along the shear band, offering a more complex view of shear-band structure than the commonly considered simple nano-scale planar defect. Next, the origin of the …
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Atomic structure and defects of III-V compound semiconductor strained-layer-superlattices for infrared detection
… In a STEM with a high angle annular dark field (HAADF) detector, the recorded real space image can be readily interpreted based on the peak intensities and peak positions as the intensity scales with the atomic density and atomic numbers to a good approximation. In particular, a probe forming …
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Preparation and characterization of bimetallic core-shell nanoparticles
… were characterised using UV-vis spectroscopy, HAADF imaging, AFM imaging and with cyclic voltammetry. The citrate-stabilised gold nanoparticle seeds provided a better starting material for the bimetallic core-shell nanoparticles, however this route had problems with aggregation and morphology. …
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X-RAY CHARACTERIZATION OF PLATINUM GROUP METAL CATALYSTS
… from both XRD and XAS. With aberration-corrected HAADF, particles ranging from sub-nm-size down to clusters of a few atoms and isolated single-atoms can be routinely imaged. A challenge to the interpretation of these images is the characterization of mixed atomic species, in this case, palladium …
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ECO-FRIENDLY HYDROXYAPATITE-BASED MATERIALS AS METAL ADSORBENTS: OPTIMIZATION OF SURFACE PROPERTIES FOR WATER AND WASTEWATER REMEDIATION
… XPS, 119Sn Mӧssbauer spectroscopy, TEM, and HAADF-STEM/EDS provided insights into tin speciation, structural composition, and morphological features, revealing structural differences between the materials. Sn/HAP was found to be crystalline, indicating that Sn surface deposition did not alter …
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Effects Of Bond Coat Surface Preparation On Thermal Cycling Lifetime And Failure Characteristics Of Thermal Barrier Coatings
… equipped with high angle annular dark field (HAADF) and X-ray energy dispersive spectroscopy (XEDS). TBC specimens for TEM/STEM analysis were prepared by focused ion beam (FIB) in-situ lift-out (INLO) technique. Superior thermal cycling lifetime was observed for TBCs with as-sprayed bond coats …
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Structure Sensitivity of Alkanes Hydrogenolysis and Alkynes Hydrogenation on Supported Ir Catalysts
… The characterization results including HAADF-STEM and volumetric CO chemisorption show the difference of Ir nuclearity in the subnanometer regime and nanoparticles (~1.4 nm), while XPS and DRIFTS indicate the difference of electronic properties from metal-support interaction on the two …
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Effect of ceria and zirconia on nanoparticulate rhodium catalysts
… situ by BET surface area measurement, TEM, STEM HAADF, EDX, XPS, and XAFS.<br/>The combination of Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), Mass Spectrometry (MS) and Energy Dispersive X-ray Absorption Fine Structure (EDE) techniques in a synchronous, time-resolved …
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Probing nano-scale atomic and electronic structures of iron-based superconductors
… (STEM) using a high angle annular dark field (HAADF) detector. By investigating energy loss near edge structure (ELNES) of the Fe-L2,3 edge recorded in electron energy loss spectroscopy (EELS) spectra, especially the L3/L2 white-line intensity ratio, we show the d-state occupancy of the Fe …
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Evolution Of Lamellar Structures In Al-ag Alloys
In the present study, the formation and the evolution of lamellar structures in different Al-Ag alloys were investigated by transmission electron microscopy (TEM). Plates of the hexagonal [gamma] phase form semi-coherently on the {111} planes of the face centered cubic lattice of the alloy after …
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Gold And Silver Alloy Nanoparticles: Synthesis, Characterization And Atomic Structure
… with high angle annular dark field imaging (HAADF-STEM), high energy X-ray based atomic pair distribution function (PDF) analysis and small angle X-ray scattering (SAXS). Composition determination of large nanocrystals is challenging due to the lack of available techniques to quantify the …
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Síntesis de nanoestruturas metálicas de oro y plata a partir de precursores organometálicos: Propiedades plasmónicas y catalíticas
… of the core-shell morphology through HAADF-STEM and EDX techniques. In the same way as in the former chapters we have studied the formation of the new nanostructures by the use of UV-Vis absorption spectroscopy, transmission electron microscopy and nuclear magnetic resonance, what has …
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Characterization of type-II GaSb quantum rings in GaAs solar cells
… of GaSb/GaAs nanostructures is analyzed by HAADF-STEM. The results show the presence of welldeveloped GaSb QRs in both p-doped and n-doped heterostructures. However, in the undoped sample grown under the same conditions such well-developed QRs have not been observed. It is found that …
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Strengthening of metastable beta titanium alloys
Using current technology, it is now possible to probe material at atomic length scales, increasing our fundamental understanding of material behavior and properties. Metastable $\beta$ titanium alloys are a subset of titanium alloys with huge potential for the aerospace sector. However, they …