B22-P-09The misorientation change in lenticular martensite by Electron Backscattered Diffraction and Convergent Beam Kikuchi Line Diffraction Pattern

Microscopy ◽  
2015 ◽  
Vol 64 (suppl 1) ◽  
pp. i107.1-i107
Author(s):  
Ya-Ling Chang ◽  
Yu-Ting Tsai ◽  
Po-Yu Chen ◽  
Jer-Ren Yang
Keyword(s):  
Diffraction Pattern ◽  
Electron Backscattered Diffraction ◽  
Kikuchi Line ◽  
Convergent Beam

Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

Using the TEM Condenser Lens to Switch between Image and Diffraction Modes

2013 ◽  
Vol 21 (2) ◽  
pp. 40-40
Author(s):  
Lydia Rivaud
Keyword(s):  
Electron Microscope ◽  
Diffraction Pattern ◽  
Transmission Electron Microscope ◽  
Condenser Lens ◽  
Selected Area Diffraction Pattern ◽  
Transmission Electron ◽  
Set Up ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

Central to the operation of the transmission electron microscope (TEM) (when used with crystalline samples) is the ability to go back and forth between an image and a diffraction pattern. Although it is quite simple to go from the image to a convergent-beam diffraction pattern or from an image to a selected-area diffraction pattern (and back), I have found it useful to be able to go between image and diffraction pattern even more quickly. In the method described, once the microscope is set up, it is possible to go from image to diffraction pattern and back by turning just one knob. This makes many operations on the microscope much more convenient. It should be made clear that, in this method, neither the image nor the diffraction pattern is “ideal” (details below), but both are good enough for many necessary procedures.

OrientXplot: a program to analyse and display relative crystal orientations

2015 ◽  
Vol 48 (4) ◽  
pp. 1330-1334 ◽  
Author(s):  
Ross Angel ◽  
Sula Milani ◽  
Matteo Alvaro ◽  
Fabrizio Nestola
Keyword(s):  
Single Crystals ◽  
Diffraction Pattern ◽  
Euler Angles ◽  
Electron Backscattered Diffraction ◽  
Orientation Data ◽  
User Control ◽  
Crystal Orientations ◽  
Orientation Matrix ◽  
Crystallographic Axes

Orientations of single crystals are usually determined by diffraction experiments. Indexing of a diffraction pattern from one crystal leads to the determination of its `orientation matrix', which defines the orientation of its crystallographic axes relative to a set of reference axes associated with the diffractometer. Crystal orientations can also be described in terms of Euler angles, especially from electron backscattered diffraction measurements.OrientXplotis a Windows program that reads all common types of orientation matrices, as well as orientation data such as Euler angles. The program calculates and displays the relative orientations of pairs of crystals, such as twins or inclusion crystals trapped inside host crystals.OrientXplotcan manipulate (under user control) the orientation matrices to allow for ambiguities in indexing that arise from crystal symmetries. Orientation data can be displayed on a stereogram or output in numerical form for plotting in external programs.

Thickness dependence of the intensities of the 200 forbidden reflections in the TiBe2 diamond type structure

1988 ◽  
Vol 46 ◽  
pp. 826-827
Author(s):  
Dang-Rong Liu ◽  
D. B. Williams
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Convergent Beam Electron Diffraction ◽  
Type Structure ◽  
Beam Electron ◽  
Space Group ◽  
X Ray ◽  
Electron Diffraction Technique ◽  
Convergent Beam ◽  
Diamond Type

It is interesting to note that for the diamond type structure of Si, Ge and diamond, the forbidden {200} reflections in the exact <100> orientation diffraction pattern cannot be seen. In contrast, we also note a standing controversy over the structure of the MgAl2O4, spinel. Its structure was determined long ago by x-ray powder method as Fd3m (the diamond type). However, its electron diffraction pattern taken in the <100> orientation shows weak {200} reflections, which are taken as evidence that the spinel should have the space group F43m (the blende type), rather than Fd3m. Others speculate that these {200} reflections result from the high order Laue zone (HOLZ) reflections, and the spinel should be Fd3m. Nevertheless, still others think that these analyses are not conclusive. We have carefully studied the space group of TiBe2 using the convergent beam electron diffraction technique, and unambiguously demonstrated that its space group must be Fd3m.

Efficient Algorithms for Computer Diffraction Pattern Analysis

1981 ◽  
Vol 39 ◽  
pp. 244-245
Author(s):  
J. B. Warren
Keyword(s):  
Diffraction Pattern ◽  
Automated Analysis ◽  
Radiation Detectors ◽  
Line Pair ◽  
Kikuchi Line ◽  
Beam Sample ◽  
Consistent Manner ◽  
Kikuchi Lines ◽  
Position Sensitive ◽  
Diffraction Patterns

The increasing availability of position-sensitive radiation detectors has facilitated the automated analysis of electron diffraction patterns with computers. One problem that lends itself to solution by these methods is the computation of the electron beam-sample orientation from Kikuchi patterns. A precise orientation is required for a wide variety of problems including the determination of grain boundary misorientations, precipitate-matrix relationships and the computer simulation of crystal defect images. In all of these investigations the beam-sample relationship is required for several sample orientations and computational labor can be excessive unless some form of automated analysis is employed.If a position-sensitive detector composed of two arrays of elements is placed at the electron microscope phosphor screen position, the orientation can be determined directly from the diffraction pattern. As shown in Fig. 2, a rectangular detector array would detect many Kikuchi lines and the algorithm used to interpret data must be able to determine which Kikuchi line pairs are suitable for use in computation, choose the proper (hkl) lattice plane associated with the Kikuchi line pair, and finally index the chosen line pairs in a consistent manner.

Simulating electron microscope diffraction mode with a Macintosh-based program

1993 ◽  
Vol 51 ◽  
pp. 1210-1211
Author(s):  
J. M. Zuo ◽  
H. R. Zhu ◽  
Andrew Spence
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Recent Trend ◽  
Control Panel ◽  
Diffraction Mode ◽  
Pointing Device ◽  
Control Devices ◽  
Diffraction Patterns ◽  
Convergent Beam

With the recent trend towards to the quantification of electron diffraction patterns, there is an increasing need for simulating the geometry of convergent beam electron diffraction patterns, and especially the high order Laue zone (HOLZ) lines in such patterns. The simulation program is useful in the way that the simulated and the experimental pattern can be compared, and then the important diffraction parameters such as reflection indices, beam directions and lattice constant could be found and used. Here we describe a Macintosh based program, which simulates electron diffraction pattern in the same way as the operation of electron microscope diffraction mode. The program has a control panel with the ‘scroll bar’ control devices for x and y tilt of specimen stage, x and y deflection of diffraction pattern and camera length (see figure 1). The user can change the simulated diffraction pattern by changing the ‘control devices’ with a pointing device such as a mouse.

Contrast of Kossel Patterns in Electron Diffraction

1974 ◽  
Vol 29 (12) ◽  
pp. 1929-1930b ◽  
Author(s):  
F. Fujimoto ◽  
G. Lehmpfuhl
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Hollow Cone ◽  
Angular Aperture ◽  
Kossel Pattern ◽  
Diffraction Patterns ◽  
Convergent Beam

Electron diffraction patterns from a Si crystal taken with a convergent beam of large angular aperture (Kossel pattern) are compared with the diffraction pattern taken with a hollow cone convergent electron beam. For thin crystals the patterns are complementary. This behaviour is discussed.

Convergent-beam electron-diffraction-pattern symmetry of nanodomains in complex lead-based perovskite crystals

2014 ◽  
Vol 70 (6) ◽  
pp. 583-590 ◽  
Author(s):  
Kyou-Hyun Kim ◽  
Jian-Min Zuo
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Local Symmetry ◽  
Convergent Beam Electron Diffraction ◽  
Beam Direction ◽  
Beam Electron ◽  
Simulation Results ◽  
Convergent Beam ◽  
The Relationship

Convergent-beam electron diffraction (CBED) recorded using nanometre-sized probes, in principle, can detect the highest symmetry in a crystal. However, symmetry reduction may occur by overlapping crystal domains along the beam direction. Thus, delineating the relationship between the recorded and the crystal symmetry is important for studying crystals with complex nanodomains. This paper reports a study of the averaged local symmetry of 71°/109° rhombohedral (R), 90° tetragonal (T) and 180° monoclinic (M) nanodomain structures. The averaged symmetry of nanodomain structures is investigated by CBED simulations using the multislice method. The simulation results show that the 71°-R, 109°-R and 90°-T nanodomain structures partially mimic the monoclinic symmetries ofCmandPmthat have been proposed by the adaptive phase model. This study is also compared to the reported experimental CBED patterns recorded from PMN-31%PT.

scholarly journals Particle size and convergent electron diffraction patterns of triangular prismatic gold nanoparticles

2021 ◽  
Vol 67 (4 Jul-Aug) ◽  
Author(s):  
Clemente Fernando-Marquez ◽  
Gilberto Mondragón-Galicia ◽  
Lourdes Bazán-Díaz ◽  
José Reyes-Gasga
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Stacking Faults ◽  
Au Nanoparticle ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Fcc Structure

Convergent beam diffraction (CBED) patterns of nanoparticles are possible. CBED of triangular prismatic shaped Au nanoparticle with focus on diffraction pattern symmetry and forbidden reflections observed along [111] and [112] zone axes are reported in this work. It is well known that the CBED patterns of nanoparticles of 30 nm or less in size only show bright kinematical discs. The dynamic contrast with Kikuchi and sharp HOLZ lines within the bright discs, as observed in CBED of volumetric materials, is well observed in particles larger of 500 nm in size. In addition, it is shown that the 1/3[422] and 1/2[311] weak forbidden reflections observed in the [111] and [112] electron diffraction patterns of these particles do not modify the symmetry of the CBED patterns, but they disappear as the size of the particle increases. The symmetry of the CBED patterns are always observed in concordance with the space group Fm3m (No. 225) of the Au unit cell. The possible explanations for observing forbidden reflections are the incomplete ABC stacking due to surface termination and the stacking faults in the fcc structure.

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