Observation of ferroelectric domain boundaries in BaTiO3 with REM

1992 ◽  
Vol 50 (1) ◽  
pp. 360-361
Author(s):  
Feng Tsal
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Ferroelectric Material ◽  
Crystal Surfaces ◽  
Etching Technique ◽  
Surface Steps ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Reflection Electron Microscopy ◽  
Etched Surface

The earlier work of transmission electron microscopy(TEM) on ferroelectric domains have been concentrated on the studies of domain configurations and contrast theory, Scanning electron microscopy(SEM) is also used to study ferroelectric material surfaces and has revealed various domain boundaries on the chemical-etched surface of BaTiO3. However, the method is destructive and largely dependent on the etching technique. Reflection electron microscopy (REM) has recently been developed to study crystal surfaces, especially the surface defects such as surface steps and emerging dislocations. This paper presents the observation of 90° domain boundaries in BaTiO3 single crystal with REM and concentrates on the contrast of 90° domain boundaries.

Contrasts of planar defects in reflection electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 1004-1005
Author(s):  
Feng Tsai ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Practical Importance ◽  
Theoretical Treatment ◽  
Crystal Surfaces ◽  
Planar Defects ◽  
Surface Steps ◽  
Surface Reconstructions ◽  
Domain Boundaries ◽  
Reflection Electron Microscopy

Reflection electron microscopy (REM) has been used to study surface defects such as surface steps, dislocations emerging on crystal surfaces, and surface reconstructions. However, only a few REM studies have been reported about the planar defects emerging on surfaces. The interaction of planar defects with surfaces may be of considerable practical importance but so far there seems to be only one relatively simple theoretical treatment of the REM contrast and very little experimental evidence to support its predications. Recently, intersections of both 90° and 180° ferroelectric domain boundaries with BaTiO3 crystal surfaces have been investigated by Tsai and Cowley with REM.The REM observations of several planar defects, such as stacking faults and domain boundaries have been continued by the present authors. All REM observations are performed on a JEM-2000FX transmission electron microscope. The sample preparations may be seen somewhere else. In REM, the incident electron beam strikes the surface of a crystal with a small glancing angle.

Reflection Electron Microscopy and Diffraction from Crystal Surfaces

1983 ◽  
Vol 31 ◽  
Author(s):  
J.M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Surface Structure ◽  
Crystal Surfaces ◽  
Local Composition ◽  
Surface Steps ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Reflection Electron Microscopy ◽  
Electron Microscopes ◽  
Geometric Effects

ABSTRACTThe recent revival of techniques for the imaging of crystal surfaces, using electrons forward-scattered in the RHEED mode and employing modern electron microscopes, has lead to the introduction of valuable new methods for the study of surface structure. Either fixed beam or scanning transmission electron microscopy (STEM) instruments may be used and in each case a lateral resolution of 10Å or better is possible. Simple theoretical treatments suggest that the contrast from surface steps may be attributed to a combination of phase-contrast, diffraction contrast and geometric effects. With a STEM instrument the image information can be combined with information on the local composition and crystal structure by use of microanalysis and microdiffraction techniques. Examples of applications include studies of the surface structure of metals, semiconductors and oxides, and the surface reactions.

Reflection electron microscopy of ferroelectric domains

1994 ◽  
Vol 52 ◽  
pp. 568-569
Author(s):  
Feng Tsai ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Crystal Surface ◽  
Dark Field ◽  
Ferroelectric Domain ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Crystal Surfaces ◽  
Domain Boundaries ◽  
Reflection Electron Microscopy

The intersections of ferroelectric domain boundaries with crystal surfaces have been studied by optical microscopy. The method is widely used but usually of low resolution. Transmission electron microscopy (TEM) can provide high-resolution images but may not be appropriate for studying crystal surfaces. Scanning electron microscopy (SEM) has also been used to study the intersections of ferroelectric domain boundaries with the surfaces of ferroelectric crystals. However, the resolution is still low and is destructive if an etched crystal surface is used. Other alternatives have also been attempted to study ferroelectric domain boundaries on surfaces, such as scanning tunneling microscopy (STM), atomic force microscopy (AFM). But, no reports have been known so far.On the other hand, reflection electron microscopy (REM), as a branch of dark-field imaging technique dedicated for surface studies in TEM, has been developed to study crystal surfaces, surface reconstruction and surface defects with a resolution of about 10Å. It has been considered as a powerful technique to study surface defects and may be used to study the ferroelectric domain boundaries emerging on surfaces.

High Resolution Imaging of As-Grown Sapphire Surfaces

1985 ◽  
Vol 62 ◽  
Author(s):  
Tung Hsu ◽  
S. R. Nutt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Features ◽  
High Resolution Imaging ◽  
Sapphire Surface ◽  
Surface Steps ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Resolution Imaging ◽  
Surface Facets

ABSTRACTSurfaces of commercially grown edge-defined film-fed growth sapphire (EFG α-Al2O3) were studied in the electron microscope using both reflection electron microscopy (REM) and conventional transmission electron microscopy (TEM). The as-grown sapphire surface, ostensibly {1120}, was characterized by “rooftop” structures which were often locally periodic. These rooftop structures consisted of alternating {1120} facets and additional facets inclined a few degrees. The crystallography of the surface facets was analyzed using REM imaging of bulk specimens, and trace analysis of back-thinned plan section TEM specimens. Surface roughness was measured by stylus profilometry. and these measurements were compared to the electron microscopy observations. Fine structural features parallel to <0110> directions were also observed in both REM and TEM experiments, and these were attributed to surface steps of atomic scales.

Nucleation, Cluster Growth, and Structure of Crystalline C60 and C70

1992 ◽  
Vol 270 ◽  
Author(s):  
Nan Yao ◽  
S. K. Behal ◽  
C. F. Klein ◽  
M. M. Disko ◽  
S. C. Fung ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Strain Field ◽  
Surface Defects ◽  
Surface Strain ◽  
Cluster Growth ◽  
Twin Structure ◽  
Transmission Electron ◽  
Initial Nucleation ◽  
Reflection Electron Microscopy ◽  
Diffraction Patterns

ABSTRACTThe nucleation and cluster growth of C60 and C70 crystallites on various substrates at ambient temperature have been investigated using electron microscopy. It was found that the initial nucleation is closely associated with surface defects, and the fullerenes are much more strongly bonded to each other than to the substrate. Sublimed C60 or C70 crystallites nucleate at the step edge in the liquid state and are aligned with the step walls and terraces through the process of coalescence. Reflection Electron Microscopy (REM) studies have shown an abnormal profile of C60 grown crystals as a result of the interaction of C60 molecules with the surface strain field during crystal growth. Transmission electron diffraction patterns reveal a twin structure with (110) habit plane for the low temperature ordered phase.

Dynamics of In Cluster Growth During InP(110) Surface Dissociation Studied by in-situ Reflection Electron Microscopy

1995 ◽  
Vol 404 ◽  
Author(s):  
M. Gajdardziska-Josifovska ◽  
M. H. Malay ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
Contact Angle ◽  
Annealing Process ◽  
Cluster Growth ◽  
Surface Cluster ◽  
Surface Steps ◽  
Transmission Electron ◽  
Annealing Effects ◽  
Reflection Electron Microscopy

AbstractAnnealing effects on InP (110) surfaces were observed in situ using a modified ultrahighvacuum transmission electron microscope equipped with a specimen heating holder. Reflection electron microscopy (REM) was used to record the dynamics of nucleation and growth of liquid In clusters at 650°C, following the desorption of P from the surface. These droplets showed no preference for nucleation at surface steps, and the steps appeared stationary throughout the annealing process. Two distinct types of In cluster growth rates and shape evolutions were detected. A model was developed to decouple height and length information in the REM images. Contact angle and volume above the InP(110) surface were calculated from the dynamic data. The change of contact angle with time provides evidence for sub-surface cluster etching.

Electron Microscopy of Semiconductors Reconstructed Surfaces

1983 ◽  
Vol 31 ◽  
Author(s):  
Pierre M. Petroff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Surface Reconstruction ◽  
Surface Steps ◽  
Transmission Electron ◽  
Dislocation Models ◽  
Reconstructed Surfaces ◽  
Reflection Electron Microscopy ◽  
Reconstructed Surface

ABSTRACTSurface sensitive transmission electron microscopy (SSTEM) and reflection electron microscopy (REM) have been used to analyze the Si (111) 1×1 → 7×7 surface reconstruction. The SSTEM and transmission electron diffraction results for the Si (111) 7×7 surface are interpreted using several possible “surface dislocation” models. The SSTEM and REM techniques have also been applied to the GaAs (100) MBE deposited surfaces. The rough surface topography for the c(4×4) reconstructed surface is attributed to surface steps motions and bunching upon interruption of the MBE deposition.

Reflection electron microscopy of surfaces

1986 ◽  
Vol 44 ◽  
pp. 376-379
Author(s):  
G. Lehmpfuhl ◽  
Y. Uchida
Keyword(s):  
Electron Microscopy ◽  
Surface Topography ◽  
Single Crystals ◽  
Surface Science ◽  
Surface Treatments ◽  
Surface Steps ◽  
Transmission Electron ◽  
Initial Stage ◽  
Bulk Single Crystals ◽  
Reflection Electron Microscopy

In surface science the direct imaging of the surface topography of single crystals is of great interest for the investigation of surface-changing processes. Imaging can be done in transmission electron microscopy (TEM) as well as in reflection electron microscopy (REM) using a diffracted beam with surface-sensitive intensity. Surface steps of atomic height can be imaged with both methods. The highest resolution is obtainable only in transmission; however, for the investigation of surface treatments, the reflection method from bulk single crystals is more suitable, even with a lack of resolution, since the thin TEM specimens are often not mechanically stable against surface treatments. With this technique the initial stage of epitaxy, the influence of surface reactions, corrosion etc. on the surface topography can be investigated. The application of REM requires that two important conditions be met, one concerning the specimen itself. Due to the small angle of observation the image is foreshortened.

The Panoramic Rheed Patterns

1990 ◽  
Vol 48 (1) ◽  
pp. 324-325
Author(s):  
Yootaek Kim ◽  
Tung Hsu
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Diffraction ◽  
Incidence Angle ◽  
High Energy ◽  
Rheed Pattern ◽  
Crystal Surfaces ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
Reflection Electron Microscopy

When applying the reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) methods[1] on the study of crystal surfaces it is necessary to index the RHEED spots and recognize the azimuth of the electron beam direction. This can be difficult because the RHEED pattern, unlike the transmission electron diffraction (TED) pattern, is distorted by the inner potential of the specimen and only one half of the pattern is shown. We found that it is useful, at the beginning of working on a certain surface of a certain crystal, to record a panoramic RHEED pattern by rotating the crystal through a large azimuth angle. This produces a map which is similar to the Kikuchi maps[2] used in transmission electron microscopy (TEM).Two examples of these panoramic RHEED patterns, one from the Pt(111) [3] and the other from α-Al203 (0001) [4,5,6), are shown in Figs. 1 and 2.The transmission Kikuchi maps are recorded using a specimen of suitable thickness such that the Kikuchi lines are strong and the diffraction spots are practically invisible. On the contrary, in making the panoramic RHEED patterns (or RHEED maps) we have no control over the thickness of the specimen. The electron beam enters and exits the same surface of the crystal; therefore, the relative intensities of the Bragg diffracted spots and the Kikuchi lines are not adjustable. The only adjustment lies in choosing the accelerating voltage and the incidence angle of the electrons such that the RHEED pattern has relatively low diffuse scattering.

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

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