A remark on ab initio indexing of electron backscatter diffraction patterns

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Adam Morawiec
Keyword(s):  
Single Crystal ◽  
Ab Initio ◽  
Diffraction Data ◽  
Electron Backscatter Diffraction ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Electron Backscatter ◽  
Diffraction Patterns ◽  
Backscatter Diffraction

There is a growing interest in ab initio indexing of electron backscatter diffraction (EBSD) patterns. The methods of solving the problem are presented as innovative. The purpose of this note is to point out that ab initio EBSD indexing belongs to the field of indexing single-crystal diffraction data, and it is solved on the same principles as indexing of patterns of other types. It is shown that reasonably accurate EBSD-based data can be indexed by programs designed for X-ray data.

scholarly journals Single-crystal diffraction data from powder samples via SFX

2014 ◽  
Vol 70 (a1) ◽  
pp. C1449-C1449
Author(s):  
Tao Zhang ◽  
Shifeng Jin ◽  
Yuanxin Gu ◽  
Yao He ◽  
Haifu Fan
Keyword(s):  
Single Crystal ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Monte Carlo Integration ◽  
X Ray Diffraction ◽  
Single Crystal Diffraction ◽  
Single Experiment ◽  
X Ray ◽  
Powder Samples ◽  
Diffraction Patterns

With the serial femtosecond crystallography (SFX) [1] using hard X-ray free-electron laser as light source, it is possible to obtained three-dimensional single-crystal diffraction data from powder samples consisting of submicron crystal grains. This offers two advantages. First, complicated crystal structures far beyond the ability of powder X-ray diffraction analysis now can be solved easily; second, mixtures of two or more crystalline components can be examined in a single experiment. The percentage of each component can be determined accurately and the crystal structure of them can be solved readily. Simulating calculations were performed with a mixture of two different kinds of zeolites. The program suite CrystFEL [2] was used for simulating SFX diffraction patterns, diffraction indexing and Monte-Carlo integration of diffraction intensities. The program suite SHELX [3] was used for structure determination. Satisfactory results have been obtained and will be discussed in detail.

Reverse Monte Carlo refinements of nanoscale atomic correlations using powder and single-crystal diffraction data

2012 ◽  
Vol 45 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Victor Krayzman ◽  
Igor Levin
Keyword(s):  
Monte Carlo ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Reverse Monte Carlo ◽  
Single Crystal Diffraction ◽  
Total Scattering ◽  
X Ray ◽  
Simultaneous Fitting ◽  
Diffraction Patterns

Combined refinements of local atomic structure that involve simultaneous fitting of powder-averaged and single-crystal data were implemented as an extension to the publicly availableRMCProfilesoftware. The refinements employ the reverse Monte Carlo method to fit neutron total scattering data, the neutron Bragg profile, extended X-ray absorption fine structure (EXAFS) and structured diffuse scattering in electron diffraction. The procedure was tested using simulated data generated for a realistic model of perovskite-like KNbO3, which exhibits strongly correlated Nb and O displacements. The results indicated that fitting the powder data (i.e.total scattering or total scattering plus EXAFS) alone fails to reproduce the nanoscale range of displacement correlations. Simultaneous fitting of the powder data and the patterns of diffuse intensity in single-crystal electron diffraction patterns returns significantly more accurate correlation characteristics. The approach and the computer software described in this contribution are not limited to electron diffraction patterns as other types of single-crystal diffraction data (i.e.X-ray or neutron) can be included in the fit.

scholarly journals Diffracting-grain identification from electron backscatter diffraction maps during residual stress measurements: a comparison between the sin2ψ and cosα methods

2019 ◽  
Vol 52 (4) ◽  
pp. 828-843 ◽  
Author(s):  
Dorian Delbergue ◽  
Damien Texier ◽  
Martin Lévesque ◽  
Philippe Bocher
Keyword(s):  
Residual Stress ◽  
Grain Size ◽  
Tilt Angle ◽  
Measurement Errors ◽  
Electron Backscatter Diffraction ◽  
Measurement Techniques ◽  
Single Exposure ◽  
X Ray ◽  
Electron Backscatter ◽  
Backscatter Diffraction

X-ray diffraction (XRD) is a widely used technique to evaluate residual stresses in crystalline materials. Several XRD measurement methods are available. (i) The sin2ψ method, a multiple-exposure technique, uses linear detectors to capture intercepts of the Debye–Scherrer rings, losing the major portion of the diffracting signal. (ii) The cosα method, thanks to the development of compact 2D detectors allowing the entire Debye–Scherrer ring to be captured in a single exposure, is an alternative method for residual stress measurement. The present article compares the two calculation methods in a new manner, by looking at the possible measurement errors related to each method. To this end, sets of grains in diffraction condition were first identified from electron backscatter diffraction (EBSD) mapping of Inconel 718 samples for each XRD calculation method and its associated detector, as each method provides different sets owing to the detector geometry or to the method specificities (such as tilt-angle number or Debye–Scherrer ring division). The X-ray elastic constant (XEC) ½S 2, calculated from EBSD maps for the {311} lattice planes, was determined and compared for the different sets of diffracting grains. It was observed that the 2D detector captures 1.5 times more grains in a single exposure (one tilt angle) than the linear detectors for nine tilt angles. Different XEC mean values were found for the sets of grains from the two XRD techniques/detectors. Grain-size effects were simulated, as well as detector oscillations to overcome them. A bimodal grain-size distribution effect and `artificial' textures introduced by XRD measurement techniques are also discussed.

scholarly journals Crystal orientation and detector distance effects on resolving pseudosymmetry by electron backscatter diffraction

2021 ◽  
Vol 54 (2) ◽  
pp. 513-522
Author(s):  
Edward L. Pang ◽  
Christopher A. Schuh
Keyword(s):  
Crystal Orientation ◽  
Electron Backscatter Diffraction ◽  
Detector Distance ◽  
Recent Emergence ◽  
Distance Effects ◽  
Electron Backscatter ◽  
Sample Position ◽  
Position And Orientation ◽  
Diffraction Patterns ◽  
Backscatter Diffraction

Accurately indexing pseudosymmetric materials has long proven challenging for electron backscatter diffraction. The recent emergence of intensity-based indexing approaches promises an enhanced ability to resolve pseudosymmetry compared with traditional Hough-based indexing approaches. However, little work has been done to understand the effects of sample position and orientation on the ability to resolve pseudosymmetry, especially for intensity-based indexing approaches. Thus, in this work the effects of crystal orientation and detector distance in a model tetragonal ZrO2 (c/a = 1.0185) material are quantitatively investigated. The orientations that are easiest and most difficult to correctly index are identified, the effect of detector distance on indexing confidence is characterized, and these trends are analyzed on the basis of the appearance of specific zone axes in the diffraction patterns. The findings also point to the clear benefit of shorter detector distances for resolving pseudosymmetry using intensity-based indexing approaches.

Comparison of Workability of ZK60A Alloy Depending on Casting Methods

2012 ◽  
Vol 630 ◽  
pp. 35-40
Author(s):  
K.H. Jung ◽  
B. Ahn ◽  
S. Lee ◽  
D.S. Choi ◽  
Y.S. Lee ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Continuous Casting ◽  
Elevated Temperatures ◽  
Electron Backscatter Diffraction ◽  
Die Casting ◽  
Inspection System ◽  
Compression Tests ◽  
X Ray ◽  
Electron Backscatter ◽  
Backscatter Diffraction

In this research, the effect of casting methods on the workability of magnesium alloy ZK60A was investigated by comparing two different billets, fabricated by semi-continuous casting and die casting. To determine the workability of the materials, uniaxial compression tests were conducted at different elevated temperatures and strain rate of 0.01/s. In addition, the X-ray inspection system and electron backscatter diffraction (EBSD) were employed to compare their internal defects and microstructures, respectively. The workability of ZK60A depending on the casting methods is discussed based on the obtained experimental results.

Leverage analysis of X-ray single crystal diffraction data from orthopyroxene and pigeonite

2002 ◽  
Vol 14 (4) ◽  
pp. 773-783 ◽  
Author(s):  
Marcello Merli ◽  
Fernando Cámara ◽  
Chiara Domeneghetti ◽  
Vittorio Tazzoli
Keyword(s):  
Single Crystal ◽  
Diffraction Data ◽  
Single Crystal Diffraction ◽  
X Ray
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