Search results for "TRANSMISSION ELECTRON"
showing 10 items of 426 documents
Automated diffraction tomography combined with electron precession: a new tool forab initionanostructure analysis
2009
AbstractThree-dimensional electron diffraction data was collected with our recently developed module for automated diffraction tomography and used to solve inorganic as well as organic crystal structuresab initio. The diffraction data, which covers nearly the full relevant reciprocal space, was collected in the standard nano electron diffraction mode as well as in combination with the precession technique and was subsequently processed with a newly developed automated diffraction analysis and processing software package. Non-precessed data turned out to be sufficient forab initiostructure solution by direct methods for simple crystal structures only, while precessed data allowed structure s…
Towards metal chalcogenide nanowire-based colour-sensitive photodetectors
2018
Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2016/6 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. Authors are grateful to Reinis Ignatans for XRD measurements.
Growth and characterization of self-assembled Cd1−xMgxO (0 ≤ x ≤ 1) nanoparticles on r-sapphire substrates
2014
In this work, the growth of isolated Cd1−xMgxO nanoparticles on r-sapphire substrates is extended to the entire range of Mg content (0 ≤ x ≤ 1) using the spray pyrolysis method. The sizes of the Cd1−xMgxO nanoparticles were in the ranges 4–6 nm and 15–30 nm (with a nanoparticle density of 1010 cm−2). The composition of the nanoparticles was determined using transmission electron microscopy energy dispersive X-ray analysis (TEM-EDAX), while the compound formation was confirmed using X-ray photoelectron spectroscopy. A systematic decrease in the a lattice parameter of Cd1−xMgxO on increasing the Mg content substantiated the successful incorporation of Mg2+ ions into the cubic CdO lattice. Sin…
Three‐Component Self‐Assembly Changes its Course: A Leap from Simple Polymers to 3D Networks of Spherical Host–Guest Assemblies
2021
Angewandte Chemie / International edition 60(21), 12132 - 12142 (2021). doi:10.1002/anie.202103178
Mechanical and structural characterizations of gamma- and alpha-alumina nanofibers
2015
Abstract We investigate the applicability of alumina nanofibers as a potential reinforcement material in ceramic matrix compounds by comparing the mechanical properties of individual nanofibers before and after annealing at 1400 °C. Mechanical testing is performed inside a scanning electron microscope (SEM), which enables observation in real time of the deformation and fracture of the fibers under loading, thereby providing a close-up inspection of the freshly fractured area in vacuum. Improvement of both the Young's modulus and the breaking strength for annealed nanofibers is demonstrated. Mechanical testing is supplemented with the structural characterization of the fibers before and afte…
A multi-technique, micrometer- to atomic-scale description of a synthetic analogue of chukanovite, Fe-2(CO3)(OH)(2)
2014
International audience; A synthetic analogue of chukanovite Fe-2(CO3)(OH)(2) is formed during experimental work on iron-clay interactions simulating the cooling of containers in radioactive waste repositories. Despite its small size and the mixture with other minerals it is undoubtedly identified by X-Ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. For the first time, the structural characterisation of a synthetic chukanovite is carried out thanks to the combination of Automated Diffraction Tomography and Precession Electron Diffraction. Refinement results and comparison with literature data show that the structure…
Zinc Chalcogenide Seed-Mediated Synthesis of CdSe Nanocrystals: Nails, Chesses and Tetrahedrons
2015
Systematically shape-controlled synthesis of colloidal semiconductor nanocrystals (NCs) has attracted increasing attention recently for both fundamental and technological interest. The study on the synthesis of colloidal CdSe NCs has given rise to well-developed methods for producing diverse shapes such as rods, wires, cubs and discs. In the current study, we demonstrate the shape evolution of CdSe NCs by using a seed-mediated approach by control reaction temperature and injection methods. The synthesis utilizes small (2.0–3.0 nm) zinc chalcogenide NCs with zincblende structure as seeds for subsequent growth, which results in distinct shapes of nail-shaped, tetrahedron-shaped, chess piece-s…
3D Electron Diffraction: The Nanocrystallography Revolution
2019
Crystallography of nanocrystalline materials has witnessed a true revolution in the past 10 years, thanks to the introduction of protocols for 3D acquisition and analysis of electron diffraction data. This method provides single-crystal data of structure solution and refinement quality, allowing the atomic structure determination of those materials that remained hitherto unknown because of their limited crystallinity. Several experimental protocols exist, which share the common idea of sampling a sequence of diffraction patterns while the crystal is tilted around a noncrystallographic axis, namely, the goniometer axis of the transmission electron microscope sample stage. This Outlook review…
Uniaxial Alignment of Polycyclic Aromatic Hydrocarbons by Solution Processing
2005
The self-organization of two polycyclic aromatic hydrocarbons with different aromatic core sizes, dodecylphenyl-substituted hexa-peri- hexabenzocoronene and an extended disk consisting of 96 carbon atoms 6-fold-alkyl-substituted, on the surface from solution has been investigated. Highly ordered surface layers of both materials could be obtained by the zone-casting technique, despite an apparently low self-organization in drop-cast films. The zone-cast films revealed high macroscopic uniaxial orientation of the columns with a molecular edge-on arrangement on the glass support as confirmed by polarized optical microscopy, UV-vis measurements in polarized light, high-resolution transmission e…
Ferroelectric Domain Walls in BaTiO3: Fingerprints in XRPD Diagrams and Quantitative HRTEM Image Analysis
1997
The structure of ferroelectric domain walls in BaTiO3 has been investigated through two complementary approaches, a global one by the fine analysis of X-ray diffraction patterns, the other essentially local via a quantitative image analysis method developed and applied to High Resolution Transmission Electron Microscopy images. These two original approaches converge towards a clear description of 90○ walls which are shown to be a 4–6 nm wide region where the crystallographic discontinuity is accommodated by irregular atomic displacements. The results given here demonstrate that the usual structural theoretical description of walls commonly accepted for energy calculations are far too simpli…