Materials-science applications of novel methods for the analysis of electron-diffraction patterns

1992 ◽  
Vol 50 (2) ◽  
pp. 1444-1445
Author(s):  
G.J.C. Carpenter ◽  
Y. Le Page
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Interplanar Spacing ◽  
Convergent Beam Electron Diffraction ◽  
Phase Identification ◽  
Primitive Cell ◽  
Transmitted Beam ◽  
Analytical Microscopy ◽  
Diffraction Patterns ◽  
Convergent Beam

Electron diffraction provides a highly effective method for the identification of microscopic, crystalline phases in the solid state. The following examples are given to illustrate applications of three new analytical methods to typical problems in analytical microscopy of materials.Phase identification using convergent beam electron diffraction (CBED) patterns can often be simplified when measurements from the zero and high order Laue zones (ZOLZ and HOLZ) are combined to calculate the primitive cell volume, Vc. Defining g1 and g2 as two primitive vectors in the ZOLZ (e.g. two non-collinear spots closest to the transmitted beam) the volume of the primitive reciprocal cell is;Vc* = g1 × g2 . H,where H is the reciprocal interplanar spacing calculated from the diameter(s) of the HOLZ ring(s). This calculation can be performed without indexing the pattern. The inverse of Vc* is the volume of the primitive cell, Vc, which is easily compared with literature data for possible phases.

A library of convergent-beam electron diffraction patterns

1986 ◽  
Vol 44 ◽  
pp. 688-691
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Transmission Electron ◽  
Yield Information ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Electron Energy Loss

One of the most important advancements of the transmission electron microscopy (TEM) in recent years has been the development of the analytical electron microscope (AEM). The microanalytical capabilities of AEMs are based on the three major techniques that have been refined in the last decade or so, namely, Convergent Beam Electron Diffraction (CBED), X-ray Energy Dispersive Spectroscopy (XEDS) and Electron Energy Loss Spectroscopy (EELS). Each of these techniques can yield information on the specimen under study that is not obtainable by any other means. However, it is when they are used in concert that they are most powerful. The application of CBED in materials science is not restricted to microanalysis. However, this is the area where it is most frequently employed. It is used specifically to the identification of the lattice-type, point and space group of phases present within a sample. The addition of chemical/elemental information from XEDS or EELS spectra to the diffraction data usually allows unique identification of a phase.

On-Line Measurement of Foil Thickness from Convergent Beam Electron Diffraction Patterns

1982 ◽  
Vol 40 ◽  
pp. 694-695
Author(s):  
J. Bentleyt ◽  
G. L. Lehman
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Foil Thickness ◽  
Beam Electron ◽  
Line Measurement ◽  
On Line ◽  
Graphical Technique ◽  
Diffraction Patterns ◽  
Convergent Beam

Accurate values of foil thickness are required in many materials science applications, such as for measurement of defect concentrations and for x-ray microanalysis absorption corrections. Kelly et al. demonstrated that convergent beam electron diffraction (CBED) patterns can be analyzed using a simple graphical technique to give values for foil thickness with ±2% accuracy. More recently, Allen extended the treatment to make use of both maxima and minima in the CBED disks. The technique requires a knowledge of the d-spacing of the reflection, the electron wavelength, an evaluation of the deviation parameter, si, associated with the i-th fringe in the diffracted beam disk, and the assignment of a set of constants to "index" the fringes.

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