scholarly journals A comparison of HREM and weak beam transmission electron microscopy for the quantitative measurement of the thickness of ferroelectric domain walls

1999 ◽  
Vol 48 (6) ◽  
pp. 717-723 ◽  
Author(s):  
M. Foeth ◽  
A. Sfera ◽  
P. Stadelmann ◽  
P.-A. Buffat
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantitative Measurement ◽  
Domain Walls ◽  
Ferroelectric Domain ◽  
Weak Beam ◽  
Transmission Electron ◽  
Beam Transmission

HREM study of ferroelectric domain wall in barium titanate

1994 ◽  
Vol 52 ◽  
pp. 566-567
Author(s):  
Laurent. Normand ◽  
Alain. Thorel ◽  
Yvan. Montardi
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Barium Titanate ◽  
Domain Walls ◽  
Ferroelectric Phase ◽  
Ferroelectric Domain ◽  
Transmission Electron ◽  
The One

This study focuses on High Resolution Transmission Electron Microscopy of barium titanate in its tetragonal ferroelectric phase, and especially on the structure of domain walls. This phase is stable between about 0 °C and 130 °C. During cooling, at 130 °C barium titanate changes from a cubic parraelectric phase to a tetragonal ferroelectric phase. In this phase the spontaneous polarisation is along one of the six [001] pseudo-cubic directions. Two types of domains can be formed during the phase transition :90° and 180° domains. In 90° domains the polarisation is at 90° from the polarisation of the next domain (exactly 2* ArcTan(a/c) if a and c are the lattice parameters). For these domains the domain walls are <110< type planes ; In 180° domains the polarisation is at 180° from the one in the next domain. 180° domain walls are <100< type plane and are assumed to be purely ferroelectric.

Characterization of superdislocation dissociations in Al66Ti25Cr9 with transmission electron microscopy observations and image simulations

1998 ◽  
Vol 13 (3) ◽  
pp. 610-624 ◽  
Author(s):  
Mukul Kumar ◽  
K. J. Hemker
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Displacement Fields ◽  
Superlattice Dislocation ◽  
Weak Beam ◽  
Transmission Electron ◽  
Beam Transmission ◽  
Simulated Images ◽  
Image Simulations

The nature of dissociated superlattice dislocation cores in Al66Ti25Cr9, deformed at room temperature, has been characterized by weak-beam transmission electron microscopy (TEM) and comparison of experimental images with computer-simulated images. The displacement fields associated with narrowly dissociated APB- and SISF-dissociated ‹110› superdislocations were calculated to account for the asymmetry in dislocation contrast and led to a better understanding of the formation of images. Such calculations are a powerful aid, when coupled with image simulations, in distinguishing the “real” intensity peaks from the supplementary peaks that can be generated under experimental imaging conditions. While both APB- and SISF-dissociated superdislocations were identified, the vast majority of superdislocations were determined to be APB-dissociated. Corrected values of the fault energies (γAPB and γSISF ) have been measured for this alloy. These energies and the observed dissociations are shown to be self-consistent.

The Application Of Weak Beam Transmission Electron Microscopy To The Study Of Heterogeneous Precipitation On Dislocation Lines

1977 ◽  
Vol 35 ◽  
pp. 180-181
Author(s):  
R.M. Allen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heterogeneous Precipitation ◽  
Weak Beam ◽  
Transmission Electron ◽  
Fine Precipitate ◽  
Beam Transmission ◽  
Theoretical Considerations ◽  
Dislocation Dissociation ◽  
Precipitate Structure

Theoretical considerations indicate that the strain-sensitive nature of weak beam transmission electron microscopy warrants application of the technique to problems requiring the resolution of complex microstructures (1). Indeed, weak beam microscopy has already become a valuable tool for observing dislocation dissociation (1), crystalline interfaces (2), and fine precipitate structure (3). In this vein, experiments to determine the possible benefits of employing weak beam microscopy in the examination of heterogeneous nucleation on dislocation lines have been performed on samples of Al-3.87 wt.% Zn-1.79 wt.% Mg. Specimens were solutionized, lightly deformed, and then aged for various times at 150°C prior to observation. Figure 1 is a comparison of a bright field and a weak beam micrograph taken of the same region in a sample aged 18 hrs. The precipitates are the stable η (MgZn2) phase.

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