On the four-axis hexagonal reciprocal lattice and its use in the indexing of transmission electron diffraction patterns

1968 ◽  
Vol 25 (1) ◽  
pp. 81-91 ◽  
Author(s):  
P. R. Okamoto ◽  
G. Thomas
Keyword(s):  
Electron Diffraction ◽  
Reciprocal Lattice ◽  
Transmission Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns

Transmission Electron Diffraction Analysis by Computer

1970 ◽  
Vol 28 ◽  
pp. 40-41
Author(s):  
R.A. Ploc ◽  
G.H. Keech
Keyword(s):  
Electron Diffraction ◽  
Input Data ◽  
Reciprocal Lattice ◽  
Computer Programme ◽  
Transmission Electron Diffraction ◽  
Usual Procedure ◽  
Transmission Electron ◽  
Complex Shapes ◽  
Computer Input ◽  
Diffraction Effects

An unambiguous analysis of transmission electron diffraction effects requires two samplings of the reciprocal lattice (RL). However, extracting definitive information from the patterns is difficult even for a general orthorhombic case. The usual procedure has been to deduce the approximate variables controlling the formation of the patterns from qualitative observations. Our present purpose is to illustrate two applications of a computer programme written for the analysis of transmission, selected area diffraction (SAD) patterns; the studies of RL spot shapes and epitaxy.When a specimen contains fine structure the RL spots become complex shapes with extensions in one or more directions. If the number and directions of these extensions can be estimated from an SAD pattern the exact spot shape can be determined by a series of refinements of the computer input data.

Computer-Aided Indexing and Simulation of Transmission Electron Diffraction Patterns

1975 ◽  
Vol 33 ◽  
pp. 222-223
Author(s):  
Prakash Rao ◽  
R. P. Goehner
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Computer Programs ◽  
Transmission Electron Diffraction ◽  
Lattice Constants ◽  
Transmission Electron ◽  
Computer Aided ◽  
Flow Diagrams ◽  
Diffraction Patterns ◽  
Orientation Determination

The process of indexing electron diffraction patterns is well established and reasonably straightforward. However, in the more complicated crystal systems (e.g. hexagonal, rhombohedral, orthorhombic and monoclinic), indexing and orientation determination is not always simple. In order to considerably ease the tedium of routinely indexing such electron diffraction patterns, automation of the procedure has been carried out in our laboratory by the use of two computer programs written in conversational Fortran.Simplified flow diagrams of the two programs are shown in Figure 1. The first program (Figure 1a) indexes diffraction spots whose x and y coordinates are obtained from an experimental pattern and supplied, along with crystal structure, lattice constants, space group restrictions, camera constant, and the position and angle errors allowable.

STEM Electron Diffraction from Areas less than 30Å; Application to Amorphous Films

1975 ◽  
Vol 33 ◽  
pp. 218-219
Author(s):  
R. H. Geiss
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Thick Film ◽  
Amorphous Films ◽  
Single Crystal Diffraction ◽  
Gold Particles ◽  
Transmission Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns

A technique of selective micro-area transmission electron diffraction has been developed using the Philips 301 TEM with a scanning (STEM) attachment. With this technique we are able to obtain electron diffraction patterns from selected areas less than 30 Å in diameter or about 103 atoms! This is to be compared with the best published results which show selected area diffraction (SAD) from areas at least 100 Å in diameter, approximately 105 atoms, or the conventional SAD techniques applicable to areas down to 2000 Å diameter, approximately 5 x 106 atoms. (The number of atoms was calculated assuming a 50 Å thick film of a f.c.c. structure with ao = 5 Å.) The selected micro-area capability was proven by experimentally obtaining discrete single crystal diffraction patterns from an array of evaporated gold particles some less than 30 Å diameter and separated by 30 Å or less, Fig. 1.

scholarly journals Calculation, Simulation, and Screen Graphic Display of Complex TED Patterns with the PC Program “Pattern”

1998 ◽  
Vol 6 (9) ◽  
pp. 16-17
Author(s):  
Corneliu Sårbu
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Crystallographic Orientation ◽  
Image Contrast ◽  
Practical Observation ◽  
Graphic Display ◽  
Transmission Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Structure Research

It is well known to electron microscopists working in the field of materials structure research that the importance of transmission electron diffraction patterns (TED) is: (i) establishing the crystallographic orientation correlations revealed during the practical observation of multiphase specimens and (ii) the knowledge of exact crystallographic orientation of a single crystal area in the specimen relating to image contrast interpretation.

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