1
|
Burkhardt U, Winkelmann A, Borrmann H, Dumitriu A, König M, Cios G, Grin Y. Assignment of enantiomorphs for the chiral allotrope β-Mn by diffraction methods. SCIENCE ADVANCES 2021; 7:7/20/eabg0868. [PMID: 33990329 PMCID: PMC8121419 DOI: 10.1126/sciadv.abg0868] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
The assignment of enantiomorphs by diffraction methods shows fundamental differences for x-rays and electrons. This is particularly evident for the chiral allotrope of β-Mn. While it is not possible to determine the sense of chirality of β-Mn with established x-ray diffraction methods, Kikuchi pattern simulation of the enantiomorphs reveals differences, if dynamical electron diffraction is considered. Quantitative comparison between experimental and simulated Kikuchi patterns allows the spatially resolved assignment of the enantiomorph in polycrystalline materials of β-Mn, as well as the structurally strongly related phase Pt2Cu3B. On the basis of enantiomorph distribution maps, crystals were extracted from enantiopure domains by micropreparation techniques. The x-ray diffraction analyses confirm the assignment of the Kikuchi pattern evaluations for Pt2Cu3B and do not allow to distinguish between the enantiomorphs of β-Mn.
Collapse
Affiliation(s)
- Ulrich Burkhardt
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany.
| | - Aimo Winkelmann
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Kraków, Poland.
| | - Horst Borrmann
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - Andreea Dumitriu
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - Markus König
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - Grzegorz Cios
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Kraków, Poland
| | - Yuri Grin
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany.
| |
Collapse
|
2
|
Morawiec A. Indexing of diffraction patterns for determination of crystal orientations. ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES 2020; 76:719-734. [PMID: 33125355 DOI: 10.1107/s2053273320012802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 09/21/2020] [Indexed: 11/10/2022]
Abstract
The task of determining the orientations of crystals is usually performed by indexing reflections detected on diffraction patterns. The well known underlying principle of indexing methods is universal: they are based on matching experimental scattering vectors to some vectors of the reciprocal lattice. Despite this, the standard attitude has been to devise algorithms applicable to patterns of a particular type. This paper provides a broader perspective. A general approach to indexing of diffraction patterns of various types is presented. References are made to formally similar problems in other research fields, e.g. in computational geometry, computer science, computer vision or star identification. Besides a general description of available methods, concrete algorithms are presented in detail and their applicability to patterns of various types is demonstrated; a program based on these algorithms is shown to index Kikuchi patterns, Kossel patterns and Laue patterns, among others.
Collapse
Affiliation(s)
- Adam Morawiec
- Polish Academy of Sciences, Institute of Metallurgy and Materials Science, Reymonta 25, Krakow 30-059, Poland
| |
Collapse
|
3
|
Naresh-Kumar G, Bruckbauer J, Winkelmann A, Yu X, Hourahine B, Edwards PR, Wang T, Trager-Cowan C, Martin RW. Determining GaN Nanowire Polarity and its Influence on Light Emission in the Scanning Electron Microscope. NANO LETTERS 2019; 19:3863-3870. [PMID: 31035764 DOI: 10.1021/acs.nanolett.9b01054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The crystal polarity of noncentrosymmetric wurtzite GaN nanowires is determined nondestructively in the scanning electron microscope using electron backscatter diffraction (EBSD). The impact of the nanowire polarity on light emission is then investigated using cathodoluminescence (CL) spectroscopy. EBSD can determine polarity of noncentrosymmetric crystals by interrogating differences in the intensity distribution of bands of the EBSD pattern associated with semipolar planes. Experimental EBSD patterns from an array of GaN nanowires are compared with theoretical patterns produced using dynamical electron simulations to reveal whether they are Ga- or N-polar or, as in several cases, of mixed polarity. CL spectroscopy demonstrates the effect of the polarity on light emission, with spectra obtained from nanowires of known polarity revealing a small but measurable shift (≈28 meV) in the GaN near band edge emission energy between those with Ga and N polarity. We attributed this energy shift to a difference in impurity incorporation in nanowires of different crystal polarity. This approach can be employed to nondestructively identify polarity in a wide range of noncentrosymmetric nanoscale material systems and provide direct comparison with their luminescence.
Collapse
Affiliation(s)
- G Naresh-Kumar
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - J Bruckbauer
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - A Winkelmann
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
- Laser Zentrum Hannover e.V. , 30419 Hannover , Germany
| | - X Yu
- Department of Electronic and Electrical Engineering , University of Sheffield , Sheffield S1 3JD , U.K
| | - B Hourahine
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - P R Edwards
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - T Wang
- Department of Electronic and Electrical Engineering , University of Sheffield , Sheffield S1 3JD , U.K
| | - C Trager-Cowan
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - R W Martin
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| |
Collapse
|
4
|
Wilkinson AJ, Collins DM, Zayachuk Y, Korla R, Vilalta-Clemente A. Applications of multivariate statistical methods and simulation libraries to analysis of electron backscatter diffraction and transmission Kikuchi diffraction datasets. Ultramicroscopy 2019; 196:88-98. [DOI: 10.1016/j.ultramic.2018.09.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 09/16/2018] [Accepted: 09/20/2018] [Indexed: 11/28/2022]
|
5
|
Brodu E, Bouzy E. A New and Unexpected Spatial Relationship Between Interaction Volume and Diffraction Pattern in Electron Microscopy in Transmission. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2018; 24:634-646. [PMID: 30516124 DOI: 10.1017/s1431927618015441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The finding of this study is that the interaction volume in electron microscopy in transmission is well ordered laterally, with a remarkable and unexpected consequence being that lateral subsections of the interaction volume produce subsections of the Kikuchi diffraction pattern. It makes the microstructure of samples directly visible in Kikuchi patterns. This is first illustrated with polycrystalline Ti-10Al-25Nb with an on-axis transmission Kikuchi diffraction set-up in a scanning electron microscope. It is then shown via a Monte Carlo simulation and a large-angle convergent-beam electron diffraction experiment that this phenomenon finds its origin in the nature of the differential elastic and quasi-elastic cross sections. This phenomenon is then quantified by a careful image analysis of Kikuchi patterns recorded across a vertical interface in a silicon sample specifically designed and fabricated. A Monte Carlo simulation reproducing all the geometric parameters is conducted. Experiments and simulations match very well qualitatively, but with a slight quantitativity gap. The specificity of the thermal diffuse scattering cross-section, not available in the simulation, is thought to be responsible for this gap. Beside Kikuchi diffraction, the case of diffraction spots and diffuse background present in the pattern is also discussed.
Collapse
Affiliation(s)
- Etienne Brodu
- 1Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux (LEM3),Université de Lorraine,UMR CNRS 7239,57045 Metz,France
| | - Emmanuel Bouzy
- 1Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux (LEM3),Université de Lorraine,UMR CNRS 7239,57045 Metz,France
| |
Collapse
|