Special Issue "Electron Diffraction and Structural Imaging II"

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

Deadline for manuscript submissions: 31 May 2023 | Viewed by 2643

Special Issue Editors

Dr. Partha Pratim Das
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Guest Editor
NanoMEGAS SPRL, Rue Èmile Claus 49 bte 9, 1050 Brussels, Belgium
Interests: electron crystallography; precession electron diffraction; nano-materials; organic pharmaceuticals; cultural heritage materials
Special Issues, Collections and Topics in MDPI journals
Dr. Arturo Ponce-Pedraza
E-Mail Website
Guest Editor
Department of Physics & Astronomy, The University of Texas at San Antonio, San Antonio, United States
Interests: electron microscopy; metallic nanostructures; metal-oxides and ferroelectrics; crystallography of interfaces
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Dr. Enrico Mugnaioli
E-Mail Website
Guest Editor
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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Dr. Stavros Nicolopoulos
E-Mail Website
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
Special Issues, Collections and Topics in MDPI journals

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

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

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

Published Papers (3 papers)

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Research

Article
Structure Determination Feasibility of Three-Dimensional Electron Diffraction in Case of Limited Data
Symmetry 2022, 14(11), 2355; https://doi.org/10.3390/sym14112355 - 08 Nov 2022
Viewed by 524
Abstract
During the last two decades, three-dimensional electron diffraction (3D ED) has undergone a renaissance, starting with the introduction of precession (Precession Electron Diffraction Tomography, PEDT) that led to variations on the idea of collecting as much of the diffraction space as possible in [...] Read more.
During the last two decades, three-dimensional electron diffraction (3D ED) has undergone a renaissance, starting with the introduction of precession (Precession Electron Diffraction Tomography, PEDT) that led to variations on the idea of collecting as much of the diffraction space as possible in order to solve crystal structures from sub-micron sized crystals. The most popular of these acquisition methods is based on the continuous tilting/rotation of the crystal (so-called Microcrystal Electron Diffraction, MicroED) akin to the oscillating crystal method in X-ray crystallography, which was enabled by the increase of sensitivity and acquisition speed in electron detectors. While 3D ED data is more complex than the equivalent X-ray data due to the higher proportion of dynamical scattering, the same basic principles of what is required in terms of data quality and quantity in order to solve a crystal structure apply; high completeness, high data resolution and good signal-to-noise statistics on measured reflection intensities. However, it may not always be possible to collect data in these optimum conditions, the most common limitations being the tilt range of the goniometer stage, often due to a small pole piece gap or the use of a non-tomography holder, or the position of the sample on the TEM grid, which may be too close to a grid bar and then the specimen of interest becomes occluded during tilting. Other factors that can limit the quality of the acquired data include the limited dynamic range of the detector, which can result on truncated intensities, or the sensitivity of the crystal to the electron beam, whereby the crystallinity of the particle is changing under the illumination of the beam. This limits the quality and quantity of the measured intensities and makes structure analysis of such data challenging. Under these circumstances, traditional approaches may fail to elucidate crystal structures, and global optimization methods may be used here as an alternative powerful tool. In this context, this work presents a systematic study on the application of a global optimization method to crystal structure determination from 3D ED data. The results are compared with known structure models and crystal phases obtained from traditional ab initio structure solution methods demonstrating how this strategy can be reliably applied to the analysis of partially complete 3D ED data. Full article
(This article belongs to the Special Issue Electron Diffraction and Structural Imaging II)
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Article
On the Mechanism Controlling the Relative Orientation of Graphene Bi-Layers
Symmetry 2022, 14(4), 719; https://doi.org/10.3390/sym14040719 - 02 Apr 2022
Cited by 1 | Viewed by 896
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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Article
Two New Organic Co-Crystals Based on Acetamidophenol Molecules
Symmetry 2022, 14(3), 431; https://doi.org/10.3390/sym14030431 - 22 Feb 2022
Cited by 1 | Viewed by 711
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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