The structure of nano-twinned rhombohedral YCuO2.66 solved by electron crystallography

2019 ◽  
Vol 75 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Holger Klein ◽  
V. Ovidiu Garlea ◽  
Céline Darie ◽  
Pierre Bordet
Keyword(s):  
Electron Diffraction ◽  
Two Dimensions ◽  
Electron Diffraction Data ◽  
Electron Crystallography ◽  
One Dimensional ◽  
X Ray ◽  
Spin Interactions ◽  
Structure Solution ◽  
Precession Electron Diffraction ◽  
Frustrated Spin

In the search for frustrated spin interactions, a YCuO2.66 phase has been synthesized by a treatment under oxygen pressure of YCuO2.5. X-ray powder diffraction and electron diffraction studies have been conducted. Electron diffraction shows that the sample is twinned on a 10 nm scale. Precession electron diffraction data obtained from a twinned crystal was treated in order to obtain intensities corresponding to only one of the orientations of the twins. From this data a structure solution was obtained where, as in YCuO2.5, the Cu atoms form triangular planes. The Cu atoms are linked in two dimensions by oxygen atoms in the present structure whereas in YCuO2.5 they are only linked in one-dimensional chains.

scholarly journals Combining precession electron diffraction data with X-ray powder diffraction data to facilitate structure solution

2008 ◽  
Vol 41 (6) ◽  
pp. 1115-1121 ◽  
Author(s):  
Dan Xie ◽  
Christian Baerlocher ◽  
Lynne B. McCusker
Keyword(s):  
Electron Diffraction ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Electron Diffraction Data ◽  
Powder Diffraction Data ◽  
Powder Charge ◽  
X Ray ◽  
Structure Solution ◽  
Precession Electron Diffraction ◽  
Using Data

Information derived from precession electron diffraction (PED) patterns can be used to advantage in combination with high-resolution X-ray powder diffraction data to solve crystal structures that resist solution from X-ray data alone. PED data have been exploited in two different ways for this purpose: (1) to identify weak reflections and (2) to estimate the phases of the reflections in the projection. The former is used to improve the partitioning of the reflection intensities within an overlap group and the latter to provide some starting phases for structure determination. The information was incorporated into a powder charge-flipping algorithm for structure solution. The approaches were first developed using data for the moderately complex zeolite ZSM-5, and then tested on TNU-9, one of the two most complex zeolites known. In both cases, including PED data from just a few projections facilitated structure solution significantly.

scholarly journals Structural Analysis of Ligand Protected Smaller Metallic Nanocrystals by Atomic Pair Distribution Function Under Precession Electron Diffraction

2019 ◽  
Author(s):  
M. Mozammel Hoque ◽  
Sandra Vergara ◽  
Partha P. Das ◽  
Daniel Ugarte ◽  
Ulises Santiago ◽  
...  
Keyword(s):  
Distribution Function ◽  
Electron Diffraction ◽  
Pair Distribution Function ◽  
Electron Diffraction Data ◽  
Face Centered Cubic ◽  
X Ray ◽  
Atomic Pair Distribution Function ◽  
Atomic Pair ◽  
Pdf Analysis ◽  
Precession Electron Diffraction

Atomic pair distribution function (PDF) analysis has been widely used to investigate nanocrystalline and structurally disordered materials. Experimental PDFs retrieved from electron diffraction (ePDF) in transmission electron microscopy (TEM) represent an attractive alternative to traditional PDF obtained from synchrotron X-ray sources, when employed on minute samples. Nonetheless, the inelastic scattering produced by the large dynamical effects of electron diffraction may obscure the interpretation of ePDF. In the present work, precession electron diffraction (PED-TEM) has been employed to obtain the ePDF of two different sub-monolayer samples ––lipoic acid protected (~ 4.5 nm) and hexanethiolated(~ 4.2 nm, ~ 400-kDa core mass) gold nanoparticles­­––randomly oriented and measured at both liquid-nitrogen and room temperatures, with high dynamic-range detection of a CMOS camera. The electron diffraction data were processed to obtain ePDFs which were subsequently compared with PDF of different ideal structure-models. The results demonstrate that the PED-ePDF data is sensitive to different crystalline structures such as monocrystalline (truncated octahedra) versus multiply-twinned (decahedra, icosahedra) structuresof the face-centered cubic gold lattice. The results indicate that PED reduces the residual from 46% to 29%; in addition, the combination of PED and low temperature further reduced the residual to 23%, which is comparable to X-ray PDF analysis. Furthermore, the inclusion of PED resulted in a better estimation of the coordination number from ePDF. To the best of our knowledge, the precessed electron-beam technique (PED) has not been previously applied to nanoparticles for analysis by the ePDF method.

scholarly journals Electron and X-ray diffraction – two worlds united

2014 ◽  
Vol 70 (a1) ◽  
pp. C926-C926
Author(s):  
Ute Kolb ◽  
Yasar Krysiak ◽  
Tatiana Gorelik ◽  
Enrico Mugnaioli
Keyword(s):  
Electron Diffraction ◽  
Structure Refinement ◽  
Amorphous State ◽  
Two Dimensions ◽  
Sufficient Information ◽  
X Ray ◽  
Cell Parameters ◽  
Extra Information ◽  
Structure Solution ◽  
Diffraction Patterns

Small crystals structure solution usually done with X-ray powder diffraction (XRPD) provides bulk information and is powerful for in-situ investigations. Peak overlap in the one-dimensional data causes problems e.g. for polyphasic or impure samples and large cell parameters thus peak indexing and intensity extraction are the main issues where x-ray powder data may be supported by extra information. Electrons sample smaller volumes but strong coulombic interaction cause multiple scattering effects changing intensities often so strong that a structure solution is becoming impossible. Nevertheless, oriented electron diffraction patterns may provide sufficient information to support indexing or the assignment of impurity peaks in the case of low quality x-ray powder pattern. Reciprocal space tomography [1] uses a series of non-oriented diffraction patterns for which dynamical effects are significantly reduced and an enhanced amount of independent reflections sampled allows "ab-initio" crystal structure solution using established X-ray structure solution packages. Although structure refinement based on kinematical intensities is stable, achievable R values of 10-30% are high and final refinement may be performed based on X-ray powder data. Scanning transmission electron microscopy (STEM) for crystal tracking and nano electron diffraction (NED) is suitable for beam sensitive material, agglomerated particles, twins or intergrown phases on crystals down to 30nm size [2, 3]. Interesting properties of nanocrystalline materials are driven mainly by twinning, defects, disorder in one or two dimensions down to the amorphous state. Here low data completeness or uncertain intensity determination causes problems in structure solution. Here a mean structure may be determinable serving as a basis for disorder description and being used as a starting model being refined onto X-ray powder data maybe supported by a combination of the diffraction methods or by adding extra information.

Direct space structure solution from precession electron diffraction data: Resolving heavy and light scatterers in Pb13Mn9O25

2010 ◽  
Vol 110 (7) ◽  
pp. 881-890 ◽  
Author(s):  
Joke Hadermann ◽  
Artem M. Abakumov ◽  
Alexander A. Tsirlin ◽  
Vladimir P. Filonenko ◽  
Julie Gonnissen ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Space Structure ◽  
Electron Diffraction Data ◽  
Structure Solution ◽  
Precession Electron Diffraction

scholarly journals Combing electron diffraction techniques for structure solution

2014 ◽  
Vol 70 (a1) ◽  
pp. C369-C369
Author(s):  
Andrew Stewart
Keyword(s):  
Electron Diffraction ◽  
Electron Diffraction Data ◽  
Data Sets ◽  
Data Set ◽  
Space Group ◽  
X Ray ◽  
Structure Solution ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

The last few years have seen a revolution in the field of 3D electron diffraction or diffraction tomography. We have moved from only acquiring a few low index zone axis patterns to full tomographic data sets recording all accessible areas of reciprocal space. These new larger data sets have made it easier for structure solution techniques such as direct methods from the x-ray world to be applied to the electron diffraction data for structure solution. While structure solution with tomographic electron diffraction is non trivial when compared to the x-ray case it is significantly easier than it was a few years ago. Mugnaioli et al. We are now in a situation where the most difficult and time consuming step can be the assignment of the space group to a data set. Electron diffraction has many advantages over the x-ray case in terms of the manner in which we can manipulate the electron beam. This allows the collection to convergent beam diffraction (CBD) or large angle convergent beam diffraction (LACBED) patterns, via the recently developed technique by Beanland et al. These techniques can make the assignment of space group significantly easier affair, and the path to structure solution a lot smoother. We will present the combination of data from tomographic, selected area (SA) and nano-beam (NBD) datasets, with diffraction from tomographic LACBED experiments where using the strengths of each technique can be leveraged for a much quicker route to structure solution.

scholarly journals Precession electron diffraction – a topical review

IUCrJ ◽  
2015 ◽  
Vol 2 (1) ◽  
pp. 126-136 ◽  
Author(s):  
Paul A. Midgley ◽  
Alexander S. Eggeman
Keyword(s):  
Electron Diffraction ◽  
Method Development ◽  
Scanning System ◽  
Local Orientation ◽  
Electron Crystallography ◽  
X Ray ◽  
X Ray Crystallography ◽  
Topical Review ◽  
Crystal Texture ◽  
Precession Electron Diffraction

In the 20 years since precession electron diffraction (PED) was introduced, it has grown from a little-known niche technique to one that is seen as a cornerstone of electron crystallography. It is now used primarily in two ways. The first is to determine crystal structures, to identify lattice parameters and symmetry, and ultimately to solve the atomic structureab initio. The second is, through connection with the microscope scanning system, to map the local orientation of the specimen to investigate crystal texture, rotation and strain at the nanometre scale. This topical review brings the reader up to date, highlighting recent successes using PED and providing some pointers to the future in terms of method development and how the technique can meet some of the needs of the X-ray crystallography community. Complementary electron techniques are also discussed, together with how a synergy of methods may provide the best approach to electron-based structure analysis.

Electron crystallography on polymorphic organics

2003 ◽  
Vol 218 (4) ◽  
Author(s):  
U. Kolb ◽  
G. N. Matveeva
Keyword(s):  
Electron Diffraction ◽  
Structure Analysis ◽  
Polymeric Materials ◽  
Electron Crystallography ◽  
Direct Crystallization ◽  
X Ray ◽  
Solution Strategies ◽  
Structure Solution ◽  
Polymorphic Materials ◽  
Acceleration Voltage

AbstractOrganic materials, such as non-linear optical active compounds (1-(2-furyl)-3-(4-aminophenyl)-2-propene-1-one (FBAPPO) and 1-(2-furyl)-3-(4-benzamidophenyl)-2-propene-1-one (FAPPO)), polymeric materials like the metal coordinated polyelectrolyte (Fe(II) [ditopic bis-terpyridin] (MEPE)) or polymorphic materials (e.g. Cu-phthalocyanine), which do not crystallize big enough for single crystal x-ray structure analysis have been investigated by electron diffraction (ED) at 100 and 300 kV acceleration voltage. Sample preparation (direct crystallization, ultra sonication, ultra microtomy), diffraction strategies (selected area diffraction, nano diffraction, use of double-tilt rotation holder), data collection and data processing as well as structure solution strategies have been chosen dependent on the different requirements of the compounds under investigation. Structure analysis was carried out by simulation using

scholarly journals Single Crystal 3D Rotation Electron Diffraction from Nano-sized Crystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C366-C366
Author(s):  
Xiaodong Zou
Keyword(s):  
Electron Diffraction ◽  
Data Collection ◽  
Data Processing ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structure Determination ◽  
Reciprocal Lattice ◽  
Electron Diffraction Data ◽  
Electron Crystallography ◽  
Structure Solution

Electron crystallography is an important technique for structure analysis of nano-sized materials. Crystals too small or too complicated to be studied by X-ray diffraction can be investigated by electron crystallography. However, conventional TEM methods requires high TEM skills and strong crystallographic knowledge, which many synthetic materials scientists and chemists do not have. We recently developed the software-based Rotation Electron Diffraction (RED) method for automated collection and processing of 3D electron diffraction data. Complete single crystal 3D electron diffraction data can be collected from nano- and micron-sized crystals in less than one hour by combining electron beam tilt and goniometer tilt, which are controlled by the RED – data collection software.3 The unit cell, possible space groups and electron diffraction intensities can be obtained from the RED data using the RED data processing software. The figure below illustrates the data collection and data processing of a zeolite silicalite-1 by RED. 1427 ED frames were collected in less than 1 hour from a crystal of 800 x 400 x 200 nm in size. A 3D reciprocal lattice of silicalite-1 was reconstructed from the ED frames, from which the unit cell parameters and space group were determined (P21/n, a=20.02Å, b=20.25Å, c=13.35Å, alfa=90.130, beta=90.740, gamma=90.030. It was possible to cut the 3D reciprocal lattice perpendicular to any directions and study the reflection conditions. The reflection intensities could be extracted. The structure of the calcined silicalite-1 could be solved from the RED data by routine direct methods using SHELX-97. All 78 unique Si and O atoms could be located and refined to an accuracy better than 0.08 Å. The RED method has been applied for structure solution of a wide range of crystals and shown to be very powerful and efficient. Now a structure determination can be achieved within a few hours, from the data collection to structure solution. We will present several examples including unknown inorganic compounds, metal-organic frameworks and organic structures solved from the RED data. Different parameters that affect the RED data quality and thus the structure determination will be discussed. The methods are general and can be applied to any crystalline materials.

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