Journal ArticleDOI
High-resolution reflex images of defects in crystals
L. A. Bursill,J. C. Barry +1 more
TLDR
In this article, a simple geometrical analysis suggests that the contrast is an artifact caused by spherical aberration in the microscope objective lens, which is explained by weak phase approximation.Abstract:
Iijima (1975) obtained a series of electron microscope images of crystallographic shear planes (CSPs) in tungsten trioxide, some of which showed light and dark bands accompanying the defect having a periodicity of approximately 20 A. This oscillatory contrast was interpreted, using the weak phase approximation (Cowley and Iijima 1972), as resulting from small displacement of cations from their original positions. We have obtained electron micrographs of CSPs in magnesium-doped rutile which show oscillatory contrast similar to that observed by Iijima. A simple geometrical analysis suggests that the contrast is an artifact caused by spherical aberration in the microscope objective lens. The many-beam dynamical theory of electron diffraction and the method of periodic continuation were used to calculate the image of widely-spaced, unstrained CSPs. The computer-simulated images showed light and dark bands adjacent to the CSP and a similar variation in spacing for changing objective lens defocus as di...read more
Citations
More filters
Journal ArticleDOI
Twinning dislocations in haematite iron ore
L. A. Bursill,R. L. Withers +1 more
TL;DR: In this paper, the coordination polyhedra produced by the operation of the observed twinning elements across {1012} composition planes leads to a simple description of the interface structure whereby Fo atoms occupy tetrahedrally coordinated sites.
Journal ArticleDOI
Electron-optical imaging of Ti6O11 at 1·6 Å point-to-point resolution
L. A. Bursill,G. J. Wood +1 more
TL;DR: In this paper, point-to-point resolutions of better than 1·7 A have been obtained for Ti6O11 using ultra-high-resolution objective lens pole-pieces and a specially constructed goniometer.
Journal ArticleDOI
A projected potential image of a defect in an ordered alloy
W. M. Stobbs,Richard Portier +1 more
TL;DR: In this article, the authors used an objective lens with a spherial aberration coefficient Cs of 0.7 mm and a low incident beam divergence (α = 0.2 mrad) to obtain point-to-point resolution of ∼1.6 A.
Journal ArticleDOI
Anwendungen der Neutronenstreuung in der Chemie
R. E. Lechner,Christian Riekel +1 more
References
More filters
Journal ArticleDOI
Numerical evaluations of N‐beam wave functions in electron scattering by the multi‐slice method
P. Goodman,A. F. Moodie +1 more
TL;DR: A method for numerical evaluation of N-beam diffraction amplitudes and intensities is described in this article, based on the multi-slice formulation of Cowley and Moodie.
Journal ArticleDOI
n-Beam lattice images. V. The use of the charge-density approximation in the interpretation of lattice images
TL;DR: In this paper, the simple infinite-aperture charge-density approximation to lattice imaging is extended to include the effects of finite aperture and objective-lens spherical aberration.
Journal ArticleDOI
Electron Microscope Image Contrast for Thin Crystal
John M. Cowley,Sumio Iijima +1 more
TL;DR: In this paper, a very aproximate treatment of the phase contrast due to defocussing of phase objects having large phase shifts is evolved and shown to give a qualitativity correct account of the observations.
Journal ArticleDOI
High-resolution electron microscopy of crystallographic shear structures in tungsten oxides
TL;DR: In this paper, a model for growth and ordering of the CS planes is discussed, and a large distortion of the W0 6 octahedra sharing their edges at the CS plane has been directly recognized in electron micrographs.
Journal ArticleDOI
On the aggregation of wadsley defects in slightly reduced rutile
L. A. Bursill,B. G. Hyde +1 more
TL;DR: In this paper, electron micrographs of a small proportion of specimens from a sample of slightly reduced rutile, TiO1·9986, show groups of parallel fringes that are interpreted as oxygen-deficient lamellae of CS planes parallel to {132}.