Orientation of Single Crystals by Back-Reflection Laue Pattern Simulation

10.1142/3290 ◽  
1999 ◽  
Author(s):  
C Marín ◽  
E Diéguez
Keyword(s):  
Single Crystals ◽  
Laue Pattern ◽  
Back Reflection ◽  
Pattern Simulation

Orientation of Back Reflection Laue Photographs: A Semi-Automated Approach

1975 ◽  
Vol 19 ◽  
pp. 725-734 ◽  
Author(s):  
R. P. Goehner
Keyword(s):  
Computer Simulation ◽  
Single Crystals ◽  
Stereographic Projection ◽  
Crystallographic Plane ◽  
Polycrystalline Materials ◽  
Laue Pattern ◽  
X Ray ◽  
Lattice Constants ◽  
Stereographic Triangle ◽  
Back Reflection

Computer simulation of back reflection Laue patterns now provides the means to plot Laue patterns for any crystal system in any orientation. This capability makes it possible to determine, rapidly and accurately, the orientation of single crystals and large grains in polycrystalline materials even in cases where little or no symmetry is displayed in the Laue photograph. A set of standard Laue patterns is first simulated to cover the stereographic triangle of the crystal being studied. The Laue photograph obtained from the crystal, or grain, is compared with the set of simulated Laue patterns. The pattern most similar to the photograph is used to determine the (HKL) values of three Laue spots. The (HKL) values of these spots and half their angular separations from the x-ray beam, along with the lattice constants, are used by a computer program to calculate the (HKL) value of the crystallographic plane perpendicular to the x-ray beam. A simulated Laue pattern can now be obtained in exactly the same orientation and it can be drawn directly to the scale of the Laue photograph. Thus the validity of the orientation can be easily verified by direct comparison. The (HKL) value of the crystallographic plane perpendicular to the x-ray beam can also be used to plot a stereographic projection of the crystal poles. Therefore, the complete orientation of the crystal can be determined.

A method for the indexation of back-reflection Laue X-ray photographs

2009 ◽  
Vol 42 (6) ◽  
pp. 1203-1204
Author(s):  
F. A. Sidokhine ◽  
E. F. Sidokhine ◽  
A. F. Sidokhine
Keyword(s):  
Single Crystals ◽  
Traditional Method ◽  
Crystal Orientation ◽  
X Ray ◽  
Back Reflection ◽  
Diffraction Patterns

This article presents a variation of the traditional method for indexing and determining the crystal orientation from Laue back-photographs with a demonstration of its applicability to low-quality diffraction patterns from imperfect metallic single crystals.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

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