Electron Diffraction and Structural Imaging II

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: closed (29 February 2024) | Viewed by 15704

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NanoMEGAS SPRL, Rue Èmile Claus 49 bte 9, 1050 Brussels, Belgium
Interests: electron crystallography; precession electron diffraction; nano-materials; organic pharmaceuticals; cultural heritage materials
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Department of Physics & Astronomy, The University of Texas at San Antonio, San Antonio, TX, USA
Interests: electron microscopy; metallic nanostructures; metal-oxides and ferroelectrics; crystallography of interfaces
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Department of Earth Sciences, University of Pisa, Via S. Maria 53 - 56126 Pisa, Italy
Interests: electron crystallography; minerals; porous materials; nano-materials
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Guest Editor
NanoMEGAS SPRL, Rue Èmile Claus 49 bte 9, 1050 Brussels, Belgium
Interests: precession electron diffraction; electron crystallography; phase and orinentation mapping, strain mapping; cultural heritage material
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Special Issue Information

Dear Colleagues,

Over the last decade, electron diffraction (ED) and structural imaging have received renewed interest from the scientific community due to the advances in TEM instrumentation (Cs correctors, direct detection cameras, 4D STEM) and the introduction of new techniques, such as beam precession, 3D electron diffraction and ptychography. Thus, the atomic structural characterization of various types of materials (functional materials, energy materials, zeolites, minerals, organic compounds, pharmaceuticals and proteins) has become possible at the nm scale.

In particular, ED requires a far lower energy dose when compared to conventional imaging techniques, and therefore allows for the investigation of very beam-sensitive materials. ED is nowadays used for the atomic structure determination of new compounds (down to 50 nm in size), for the acquisition of phase, orientation and strain mapping, for the determination of electric fields and for the study of amorphous materials, which otherwise could not be studied by laboratory X-ray or synchrotron methods. Moreover, the development of in situ sample holders (gas, liquid, heating, etc.) has allowed the study of (bio-) materials under close-to-natural conditions and of real time reactions.

All these novel applications rely on or strongly benefit from the intrinsic symmetry of condensed matter at the atomic scale. Conventional crystals belong to one of the possible 230 space groups in 3D space, while the description of incommensurate materials requires a more complex formalism based on four to six dimensions. Even 2D or amorphous systems rely on specific assumptions of symmetry. Dynamic crystalline and symmetry evolution and phase transformations are characterized by external stimuli using in situ microscopy methods.

Due to huge success in our first Special Issue (12 contributions from the experts in Electron Diffraction and Electron Microscopy in our first issue; https://www.mdpi.com/journal/symmetry/special_issues/Electron_Diffraction_Structural_Imaging), we proposed Volume II of the Special Issue in Symmetry entitled “Electron Diffraction and Structural Imaging-Volume II”.

In this context, we welcome contributions covering any aspect of ED, structural imaging and other related in situ techniques, which make use of consolidated or advanced TEM instrumentation and have potential applications for a wide range of materials. Abstract Submission Deadline: 31st May, 2022.

Dr. Partha Pratim Das
Dr. Arturo Ponce-Pedraza
Dr. Enrico Mugnaioli
Dr. Stavros Nicolopoulos
Guest Editors

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Keywords

  • nanomaterials
  • electron diffraction
  • 4D STEM
  • serial ED
  • 3D ED
  • microED
  • direct detection cameras
  • ptychography
  • in situ
  • atomic imaging

Published Papers (9 papers)

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Research

13 pages, 3142 KiB  
Article
Determination of Na+ Cation Locations in Nanozeolite ECR-1 Using a 3D ED Method
by Taylan Örs, Irena Deroche, Corentin Chatelard, Mathias Dodin, Raquel Martinez-Franco, Alain Tuel and Jean-Louis Paillaud
Symmetry 2024, 16(4), 477; https://doi.org/10.3390/sym16040477 - 15 Apr 2024
Viewed by 1001
Abstract
Until now, the comprehensive structural analysis of single crystals of zeolite ECR-1, an aluminosilicate with the EON topology, has been hindered owing to the submicron dimensions of the obtained crystals. Additionally, this zeolite, which is characterized by a topology comprising alternating periodic building [...] Read more.
Until now, the comprehensive structural analysis of single crystals of zeolite ECR-1, an aluminosilicate with the EON topology, has been hindered owing to the submicron dimensions of the obtained crystals. Additionally, this zeolite, which is characterized by a topology comprising alternating periodic building units of MAZ and MOR layers, exhibits stacking faults that impede accurate refinement through the Rietveld method. In this report, we present, for the first time, the structure of ECR-1 elucidated by studying a nanocrystal with a significantly reduced number of stacking faults. The sample used was synthesized hydrothermally using trioxane as the organic structure-directing agent. The structure determination was conducted using precession electron diffraction (PED) at 103 K. Partial dehydration occurred owing to the high vacuum conditions in the TEM sample chamber. From the dynamical refinement (Robs = 0.097), 8.16 Na+ compensating cations were localized on six distinct crystallographic sites, along with approximately four water molecules per unit cell. Furthermore, a canonical Monte Carlo computational study was conducted to compare the experimental cationic distribution and location of water molecules with the simulation. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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14 pages, 5749 KiB  
Article
Investigating Cathode Electrolyte Interphase Formation in NMC 811 Primary Particles through Advanced 4D-STEM ACOM Analysis
by Kevyn Gallegos-Moncayo, Justine Jean, Nicolas Folastre, Arash Jamali and Arnaud Demortière
Symmetry 2024, 16(3), 301; https://doi.org/10.3390/sym16030301 - 4 Mar 2024
Viewed by 1283
Abstract
This study focuses on NMC 811 (LiNi0.8Mn0.1Co0.1O2), a promising material for high-capacity batteries, and investigates the challenges associated with its use, specifically the formation of the cathode electrolyte interphase (CEI) layer due to chemical reactions. [...] Read more.
This study focuses on NMC 811 (LiNi0.8Mn0.1Co0.1O2), a promising material for high-capacity batteries, and investigates the challenges associated with its use, specifically the formation of the cathode electrolyte interphase (CEI) layer due to chemical reactions. This layer is a consequence of the position of the Lowest Unoccupied Molecular Orbital (LUMO) energy level of NMC 811 that is close to the Highest Occupied Molecular Orbital (HOMO) level of liquid electrolytes, resulting in electrolyte oxidation and cathode surface alterations during charging. A stable CEI layer can mitigate further degradation by reducing the interaction between the reactive cathode material and the electrolyte. Our research analyzed the CEI layer on NMC 811 using advanced techniques, such as 4D-STEM ACOM (automated crystal orientation mapping) and STEM-EDX, focusing on the effects of different charging voltages (4.3 V and 4.5 V). The findings revealed varying degrees of degradation and the formation of a fluorine-rich layer on the secondary particles. Detailed analysis showed that the composition of this layer differed based on the voltage: only LiF at 4.5 V and a combination of lithium fluoride (LiF) and lithium hydroxide (LiOH) at 4.3 V. Despite LiF’s known stability as a CEI protective layer, our observations indicate that it does not effectively prevent degradation in NMC 811. The study concluded that impurities and unwanted chemical reactions leading to suboptimal CEI formation are inevitable. Therefore, future efforts should focus on developing protective strategies for NMC 811, such as the use of specific additives or coatings. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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17 pages, 10688 KiB  
Article
Characterisation of Microstructure and Special Grain Boundaries in LPBF AlSi10Mg Alloy Subjected to the KoBo Extrusion Process
by Przemysław Snopiński and Krzysztof Matus
Symmetry 2023, 15(9), 1634; https://doi.org/10.3390/sym15091634 - 24 Aug 2023
Cited by 2 | Viewed by 1117
Abstract
Grain boundary engineering (GBE) enhances the properties of metals by incorporating specific grain boundaries, such as twin boundaries (TB). However, applying conventional GBE to parts produced through additive manufacturing (AM) poses challenges, since it necessitates thermomechanical processing, which is not desirable for near-net-shape [...] Read more.
Grain boundary engineering (GBE) enhances the properties of metals by incorporating specific grain boundaries, such as twin boundaries (TB). However, applying conventional GBE to parts produced through additive manufacturing (AM) poses challenges, since it necessitates thermomechanical processing, which is not desirable for near-net-shape parts. This study explores an alternative GBE approach for post-processing bulk additively manufactured aluminium samples (KoBo extrusion), which allows thermo-mechanical treatment in a single operation. The present work was conducted to examine the microstructure evolution and grain boundary character in an additively manufactured AlSi10Mg alloy. Microstructural evolution and grain boundary character were investigated using Electron Back Scattered Diffraction (EBSD) and Transmission Electron Microscopy (TEM). The results show that along with grain refinement, the fraction of Coincidence Site Lattice boundaries was also increased in KoBo post-processed samples. The low-Σ twin boundaries were found to be the most common Coincidence Site Lattice boundaries. On the basis of EBSD analysis, it has been proven that the formation of CSL boundaries is directly related to a dynamic recrystallisation process. The findings show prospects for the possibility of engineering the special grain boundary networks in AM Al–Si alloys, via the KoBo extrusion method. Our results provide the groundwork for devising GBE strategies to produce novel high-performance aluminium alloys. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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17 pages, 2932 KiB  
Article
Making the Most of 3D Electron Diffraction: Best Practices to Handle a New Tool
by Khai-Nghi Truong, Sho Ito, Jakub M. Wojciechowski, Christian R. Göb, Christian J. Schürmann, Akihito Yamano, Mark Del Campo, Eiji Okunishi, Yoshitaka Aoyama, Tomohiro Mihira, Naoki Hosogi, Jordi Benet-Buchholz, Eduardo Carmelo Escudero-Adán, Fraser J. White, Joseph D. Ferrara and Robert Bücker
Symmetry 2023, 15(8), 1555; https://doi.org/10.3390/sym15081555 - 8 Aug 2023
Cited by 5 | Viewed by 3040
Abstract
Along with the adoption of three-dimensional electron diffraction (3D ED/MicroED) as a mainstream tool for structure determination from sub-micron single crystals, questions about best practices regarding each step along the workflow, from data collection to structure solutions, arise. In this paper, we discuss [...] Read more.
Along with the adoption of three-dimensional electron diffraction (3D ED/MicroED) as a mainstream tool for structure determination from sub-micron single crystals, questions about best practices regarding each step along the workflow, from data collection to structure solutions, arise. In this paper, we discuss three particular aspects of a 3D ED/MicroED experiment which, after hundreds of structures solved in Rigaku’s laboratories, we have found to be important to consider carefully. First, for a representative model system of a hydrated compound (trehalose dihydrate), we show that cryo-transfer of the sample into the diffractometer is an effective means to prevent dehydration, while cooling of the sample without cryo-transfer yields a marginal improvement only. Next, we demonstrate for a small (tyrosine) and a large (clarithromycin) organic compound, how a simplified and fast workflow for dynamical diffraction calculations can determine absolute crystal structures with high confidence. Finally, we discuss considerations and trade-offs for choosing an optimal effective crystal-to-detector distance; while a long distance is mandatory for a protein (thaumatin) example, even a small molecule with difficult diffraction behavior (cystine) yields superior results at longer distances than the one used by default. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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11 pages, 4456 KiB  
Article
Scanning Precession Electron Tomography (SPET) for Structural Analysis of Thin Films along Their Thickness
by Sara Passuti, Julien Varignon, Adrian David and Philippe Boullay
Symmetry 2023, 15(7), 1459; https://doi.org/10.3390/sym15071459 - 22 Jul 2023
Cited by 1 | Viewed by 1185
Abstract
Accurate structure analysis of epitaxial perovskite thin films is a fundamental step towards the ability to tune their physical properties as desired. Precession-assisted electron diffraction tomography (PEDT) has proven to be an effective technique for performing ab initio structure solutions and refinements for [...] Read more.
Accurate structure analysis of epitaxial perovskite thin films is a fundamental step towards the ability to tune their physical properties as desired. Precession-assisted electron diffraction tomography (PEDT) has proven to be an effective technique for performing ab initio structure solutions and refinements for this class of materials. As the film thickness or the region of interest (ROI) decrease in size, the capacity to collect PEDT data with smaller electron beams is a key parameter and ROI tracking becomes a major issue. To circumvent this problem, we considered here an alternative approach to acquiring data by combining PEDT with a scan over an area, extracting the intensities collected at different positions and using them to perform accurate structure refinements. As a proof of concept, a Scanning Precession Electron Tomography (SPET) experiment is performed on a 35 nm thick perovskite PrVO3(PVO) film deposited on a SrTiO3 (STO) substrate. This way, it was possible to detect small changes in the PVO structure along the film thickness, from the variation in unit cell parameters to atomic positions. We believe that SPET has the potential to become the standard procedure for the accurate structure analysis of ROIs as small as 10 nm. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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12 pages, 3696 KiB  
Article
Influence of Precession Electron Diffraction Parameters and Energy Filtering on Reduced Density Function Analysis of Thin Amorphous Silica Films—Implications for Structural Studies
by Yu-Jen Chou, Konstantin B. Borisenko, Partha Pratim Das, Stavros Nicolopoulos, Mauro Gemmi and Angus I. Kirkland
Symmetry 2023, 15(7), 1291; https://doi.org/10.3390/sym15071291 - 21 Jun 2023
Viewed by 1101
Abstract
We investigated the influence of precession angle, energy filtering and sample thickness on the structural parameters of amorphous SiO2 thin films from the electron reduced density functions obtained by applying precession electron diffraction. The results demonstrate that the peak positions in the [...] Read more.
We investigated the influence of precession angle, energy filtering and sample thickness on the structural parameters of amorphous SiO2 thin films from the electron reduced density functions obtained by applying precession electron diffraction. The results demonstrate that the peak positions in the electron reduced density functions are generally insensitive to the studied experimental conditions, while both precession angle and energy filtering influence peak heights considerably. It is also shown that introducing precession with small angles of up to 2 degrees and energy filtering results in higher coordination numbers that are closer to the expected theoretical values of 4 and 2 for Si and O, respectively, for data obtained from a thicker sample. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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13 pages, 4161 KiB  
Article
Absolute Structure Determination of Chiral Zinc Tartrate MOFs by 3D Electron Diffraction
by Christian Jandl, Gunther Steinfeld, Keyao Li, Pokka Ka Chuen Pang, Chun Lung Choi, Cengan Wang, Petra Simoncic and Ian D. Williams
Symmetry 2023, 15(5), 983; https://doi.org/10.3390/sym15050983 - 26 Apr 2023
Cited by 4 | Viewed by 1776
Abstract
The absolute structure of the 3D MOF anhydrous zinc (II) tartrate with space group I222 has been determined for both [Zn(L-TAR)] and [Zn(D-TAR)] by electron diffraction using crystals of sub-micron dimensions. Dynamical refinement gives a strong difference in R factors for the correct [...] Read more.
The absolute structure of the 3D MOF anhydrous zinc (II) tartrate with space group I222 has been determined for both [Zn(L-TAR)] and [Zn(D-TAR)] by electron diffraction using crystals of sub-micron dimensions. Dynamical refinement gives a strong difference in R factors for the correct and inverted structures. These anhydrous MOFs may be prepared phase pure from mild hydrothermal conditions. Powder X-ray diffraction indicates that isostructural or pseudo-isostructural phases can be similarly prepared for several other M2+ = Mg, Mn, Co, Ni and Cu. I222 is a relatively uncommon space group since it involves intersecting two-fold axes that place constraints on molecular crystals. However, in the case of MOFs the packing is dominated by satisfying the octahedral coordination centers. These MOFs are dense 3D networks with chiral octahedral metal centers that may be classed as Δ (for L-TAR) or Λ (for D-TAR). Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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8 pages, 11432 KiB  
Article
On the Mechanism Controlling the Relative Orientation of Graphene Bi-Layers
by Andrei Hernandez-Robles, David Romeu and Arturo Ponce
Symmetry 2022, 14(4), 719; https://doi.org/10.3390/sym14040719 - 2 Apr 2022
Cited by 1 | Viewed by 1717
Abstract
We have measured the relative orientation of rotated graphene bi-layers (RGBs) deposited by chemical vapor deposition and found that there are spontaneously occurring preferred orientations. Measurements were performed using selected area electron diffraction patterns on various regions of the RGBs. These orientations minimize [...] Read more.
We have measured the relative orientation of rotated graphene bi-layers (RGBs) deposited by chemical vapor deposition and found that there are spontaneously occurring preferred orientations. Measurements were performed using selected area electron diffraction patterns on various regions of the RGBs. These orientations minimize the complexity of the lattice defined by the set of all possible Burgers vectors. By using a precise definition of singularity, we have been able to show that all non-singular preferred orientations are special in the sense that their angular distance Δθ to the closest singular orientation also complies with the definition of singularity. Our results show that these special interfaces, named secondary singular interfaces, have simpler displacement fields compared to other non-singular RGBs, implying that interfacial dislocations have fewer Burgers vectors to choose from. Since all observed orientations were found to be either singular or secondary singular, we found evidence that RGBs starting out with rotation angles far from singular orientations re-orient themselves into a nearby secondary singular state in order to simplify their strain fields. Secondary singular orientations also account for the spontaneous formation of high Σ interfaces, although the lack of a precise definition of singularity caused them to remain unnoticed. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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10 pages, 2401 KiB  
Article
Two New Organic Co-Crystals Based on Acetamidophenol Molecules
by Iryna Andrusenko, Joseph Hitchen, Enrico Mugnaioli, Jason Potticary, Simon R. Hall and Mauro Gemmi
Symmetry 2022, 14(3), 431; https://doi.org/10.3390/sym14030431 - 22 Feb 2022
Cited by 1 | Viewed by 1682
Abstract
Herein we present two new organic co-crystals obtained through a simple solution growth process based on an acetamidophenol molecule, either paracetamol or metacetamol, and on 7,7,8,8-tetracyanoquinodimethane (TCNQ). These co-crystals are part of a family of potential organic charge transfer complexes, where the acetamidophenol [...] Read more.
Herein we present two new organic co-crystals obtained through a simple solution growth process based on an acetamidophenol molecule, either paracetamol or metacetamol, and on 7,7,8,8-tetracyanoquinodimethane (TCNQ). These co-crystals are part of a family of potential organic charge transfer complexes, where the acetamidophenol molecule behaves as an electron donor and TCNQ behaves as an electron acceptor. Due to the sub-micron size of the crystalline domains, 3D electron diffraction was employed for the structure characterization of both systems. Paracetamol-TCNQ structure was solved by standard direct methods, while the analysis of metacetamol-TCNQ was complicated by the low resolution of the available diffraction data and by the low symmetry of the system. The structure determination of metacetamol-TCNQ was eventually achieved after merging two data sets and combining direct methods with simulated annealing. Our study reveals that both paracetamol-TCNQ and metacetamol-TCNQ systems crystallize in a 1:1 stoichiometry, assembling in a mixed-stack configuration and adopting a non-centrosymmetric P1 symmetry. It appears that paracetamol and metacetamol do not form a strong structural scaffold based on hydrogen bonding, as previously observed for orthocetamol-TCNQ and orthocetamol-TCNB (1,2,4,5-tetracyanobenzene) co-crystals. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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