scholarly journals Automated electron diffraction tomography – development and applications

2019 ◽  
Vol 75 (4) ◽  
pp. 463-474 ◽  
Author(s):  
Ute Kolb ◽  
Yaşar Krysiak ◽  
Sergi Plana-Ruiz
Keyword(s):  
Electron Diffraction ◽  
Structure Analysis ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Electron Diffraction Data ◽  
Diffraction Tomography ◽  
Established Method ◽  
General Applicability ◽  
Transmission Electron ◽  
Electron Microscopes

Electron diffraction tomography (EDT) has gained increasing interest, starting with the development of automated electron diffraction tomography (ADT) which enables the collection of three-dimensional electron diffraction data from nano-sized crystals suitable for ab initio structure analysis. A basic description of the ADT method, nowadays recognized as a reliable and established method, as well as its special features and general applicability to different transmission electron microscopes is provided. In addition, the usability of ADT for crystal structure analysis of single nano-sized crystals with and without special crystallographic features, such as twinning, modulations and disorder is demonstrated.

Structural insights intoM2O–Al2O3–WO3(M= Na, K) system by electron diffraction tomography

2015 ◽  
Vol 71 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Iryna Andrusenko ◽  
Yaşar Krysiak ◽  
Enrico Mugnaioli ◽  
Tatiana E. Gorelik ◽  
Diana Nihtianova ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Three Dimensional ◽  
Large Cell ◽  
Systematic Investigation ◽  
Electron Diffraction Data ◽  
Diffraction Tomography ◽  
Structure Investigation ◽  
X Ray ◽  
Cell Parameters ◽  
Wide Range

TheM2O–Al2O3–WO3(M= alkaline metals) system has attracted the attention of the scientific community because some of its members showed potential applications as single crystalline media for tunable solid-state lasers. These materials behave as promising laser host materials due to their high and continuous transparency in the wide range of the near-IR region. A systematic investigation of these phases is nonetheless hampered because it is impossible to produce large crystals and only in a few cases a pure synthetic product can be achieved. Despite substantial advances in X-ray powder diffraction methods, structure investigation on nanoscale is still challenging, especially when the sample is polycrystalline and the structures are affected by pseudo-symmetry. Electron diffraction has the advantage of collecting data from single nanoscopic crystals, but it is frequently limited by incompleteness and dynamical effects. Automated diffraction tomography (ADT) recently emerged as an alternative approach able to collect more complete three-dimensional electron diffraction data and at the same time to significantly reduce dynamical scattering. ADT data have been shown to be suitable forabinitiostructure solution of phases with large cell parameters, and for detecting pseudo-symmetry that was undetected in X-ray powder data. In this work we present the structure investigation of two hitherto undetermined compounds, K5Al(W3O11)2and NaAl(WO4)2, by a combination of electron diffraction tomography and precession electron diffraction. We also stress how electron diffraction tomography can be used to obtain direct information about symmetry and pseudo-symmetry for nanocrystalline phases, even when available only in polyphasic mixtures.

scholarly journals A Convergence of Beauty and Utility

2014 ◽  
Vol 70 (a1) ◽  
pp. C41-C41
Author(s):  
John Steeds
Keyword(s):  
Electron Diffraction ◽  
Three Dimensional ◽  
Good Control ◽  
Critical Parameters ◽  
Specimen Thickness ◽  
Meaningful Information ◽  
Local Environments ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Convergent Beam

The effective routine achievement of useful convergent beam electron diffraction (CBED) patterns was frustrated for many years until transmission electron microscopes (TEMs) were developed that overcame the practical difficulties. Because specimen thickness and orientation are two critical parameters in electron diffraction and are not under good control because of the difficulty of producing thin enough regions it was necessary to have TEMs capable of forming small focussed probes of less than 100nm diameter in local environments where the hydrocarbon level was sufficiently low to reduce carbon contamination to a reasonable level. Once these problems were overcome the importance of three-dimensional diffraction became apparent but to exploit this property it was necessary to develop TEMs with a large angular range in the diffraction plane. With appropriately designed instruments very beautiful CBED patterns could be obtained from crystalline samples and a variety of experimental techniques were exploited to extract meaningful information from them.

scholarly journals Ab-initio crystal structure analysis and refinement approaches of oligo p-benzamides based on electron diffraction data

2012 ◽  
Vol 68 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Tatiana E. Gorelik ◽  
Jacco van de Streek ◽  
Andreas F. M. Kilbinger ◽  
Gunther Brunklaus ◽  
Ute Kolb
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Electron Diffraction ◽  
Ab Initio ◽  
Structure Analysis ◽  
Diffraction Data ◽  
Crystal Structure Analysis ◽  
Electron Diffraction Data ◽  
Perfect Agreement ◽  
Bonding Scheme

Ab-initio crystal structure analysis of organic materials from electron diffraction data is presented. The data were collected using the automated electron diffraction tomography (ADT) technique. The structure solution and refinement route is first validated on the basis of the known crystal structure of tri-p-benzamide. The same procedure is then applied to solve the previously unknown crystal structure of tetra-p-benzamide. In the crystal structure of tetra-p-benzamide, an unusual hydrogen-bonding scheme is realised; the hydrogen-bonding scheme is, however, in perfect agreement with solid-state NMR data.

Structure refinement using precession electron diffraction tomography and dynamical diffraction: theory and implementation

2015 ◽  
Vol 71 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Lukáš Palatinus ◽  
Václav Petříček ◽  
Cinthia Antunes Corrêa
Keyword(s):  
Electron Diffraction ◽  
Rotation Axis ◽  
Structure Refinement ◽  
Three Dimensional ◽  
Electron Diffraction Data ◽  
Diffraction Tomography ◽  
Three Dimensional Model ◽  
Data Set ◽  
Dynamical Diffraction ◽  
Precession Electron Diffraction

Accurate structure refinement from electron-diffraction data is not possible without taking the dynamical-diffraction effects into account. A complete three-dimensional model of the structure can be obtained only from a sufficiently complete three-dimensional data set. In this work a method is presented for crystal structure refinement from the data obtained by electron diffraction tomography, possibly combined with precession electron diffraction. The principle of the method is identical to that used in X-ray crystallography: data are collected in a series of small tilt steps around a rotation axis, then intensities are integrated and the structure is optimized by least-squares refinement against the integrated intensities. In the dynamical theory of diffraction, the reflection intensities exhibit a complicated relationship to the orientation and thickness of the crystal as well as to structure factors of other reflections. This complication requires the introduction of several special parameters in the procedure. The method was implemented in the freely available crystallographic computing systemJana2006.

scholarly journals SUePDF: a program to obtain quantitative pair distribution functions from electron diffraction data

2017 ◽  
Vol 50 (1) ◽  
pp. 304-312 ◽  
Author(s):  
Dung Trung Tran ◽  
Gunnar Svensson ◽  
Cheuk-Wai Tai
Keyword(s):  
Electron Diffraction ◽  
Electron Scattering ◽  
Diffraction Data ◽  
Amorphous Materials ◽  
Fourier Transforms ◽  
Distribution Functions ◽  
Electron Diffraction Data ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Pair Distribution Functions

SUePDFis a graphical user interface program written in MATLAB to achieve quantitative pair distribution functions (PDFs) from electron diffraction data. The program facilitates structural studies of amorphous materials and small nanoparticles using electron diffraction data from transmission electron microscopes. It is based on the physics of electron scattering as well as the total scattering methodology. A method of background modeling is introduced to treat the intensity tail of the direct beam, inelastic scattering and incoherent multiple scattering. Kinematical electron scattering intensity is scaled using the electron scattering factors. The PDFs obtained after Fourier transforms are normalized with respect to number density, nanoparticle form factor and the non-negativity of probability density.SUePDFis distributed as free software for academic users.

Automated diffraction tomography combined with electron precession: a new tool for ab initio nanostructure analysis

2009 ◽  
Vol 1184 ◽  
Author(s):  
Ute Kolb ◽  
Tatiana Gorelik ◽  
Enrico Mugnaioli
Keyword(s):  
Electron Diffraction ◽  
Ab Initio ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Direct Methods ◽  
Electron Diffraction Data ◽  
Diffraction Tomography ◽  
Diffraction Mode ◽  
Structure Solution

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 structures ab 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 for ab initio structure solution by direct methods for simple crystal structures only, while precessed data allowed structure solution and refinement in all of the studied cases.

Structure analysis of titanate nanorods by automated electron diffraction tomography

2011 ◽  
Vol 67 (3) ◽  
pp. 218-225 ◽  
Author(s):  
Iryna Andrusenko ◽  
Enrico Mugnaioli ◽  
Tatiana E. Gorelik ◽  
Dominik Koll ◽  
Martin Panthöfer ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Sodium Titanate ◽  
Electron Diffraction Data ◽  
Monoclinic Space Group ◽  
Diffraction Tomography ◽  
X Ray ◽  
Unknown Phase ◽  
Transmission Electron ◽  
Edge Dislocations ◽  
New Phase

A hitherto unknown phase of sodium titanate, NaTi3O6(OH)·2H2O, was identified as the intermediate species in the synthesis of TiO2 nanorods. This new phase, prepared as nanorods, was investigated by electron diffraction, X-ray powder diffraction, thermogravimetric analysis and high-resolution transmission electron microscopy. The structure was determined ab initio using electron diffraction data collected by the recently developed automated diffraction tomography technique. NaTi3O6(OH)·2H2O crystallizes in the monoclinic space group C2/m. Corrugated layers of corner- and edge-sharing distorted TiO6 octahedra are intercalated with Na+ and water of crystallization. The nanorods are typically affected by pervasive defects, such as mutual layer shifts, that produce diffraction streaks along c*. In addition, edge dislocations were observed in HRTEM images.

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