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.

Letter to the Editor: Image Formation in the High-Resolution Transmission Electron Microscope

2004 ◽  
Vol 10 (4) ◽  
pp. 397-399 ◽  
Author(s):  
Michael A. O'Keefe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Transmission Electron Microscope ◽  
Recent Article ◽  
National Laboratory ◽  
Image Formation ◽  
Transmission Electron ◽  
The One

A recent article in these pages compares STEM images with an image obtained with the One-Ångstrom Microscope (OÅM) at Lawrence Berkeley National Laboratory (LBNL). Although the experimental work is of excellent quality, Diebold et al. (2003) offer an incorrect explanation of the image formation process in the high-resolution transmission electron microscope. It is important that this misinterpretation be corrected before it comes to be accepted as factual by other scientists who are not expert in the field of high-resolution transmission electron microscopy.

Electron microscopy of the commensurate-incommensurate phase transition with the discommensuration network in 1T-TaS2

1990 ◽  
Vol 48 (4) ◽  
pp. 168-169
Author(s):  
Takashi Ishiguro ◽  
Hiroshi Sato
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Phase Transitions ◽  
High Resolution ◽  
Low Temperature ◽  
Transmission Electron ◽  
Continuous Rotation ◽  
T Phase ◽  
New Phase

Phase transitions of lT-TaS2 both on cooling from the incommensurate (IC) phase and on heating from the commensurate (C) phase are investigated by high resolution (HR) transmission electron microscopy because phase transitions are strongly hysteretic. The phases which had been identified were Normal(T>543K,no modurated wave, the Cdl2 type of structure, ao=0.336nm co=0.590nm), IC(354K< T< 543K), NC(non-commensurate or nearly commensurate, 185K<T<353K) and C(T<K). On heating from the C phase, the new phase called the T phase (nearly commensurate triclinic ) appears between 200K and 280K, and that has the discommensuration (DC) network. The HR observations at low temperature reveal both the three dimentional structure of the C phase and the DC network structure of the T phase.On cooling from the IC phase, the structure of the NC phase is essentially incommensurate in the basal plane and a continuous rotation of the moduration direction towards the C phase occurs.

scholarly journals Особенности структуры германия, обработанного в планетарной мельнице

2020 ◽  
Vol 62 (10) ◽  
pp. 1597
Author(s):  
Т.А. Гордеева ◽  
Д.А. Овсянников ◽  
М.Ю. Попов ◽  
Б.А. Кульницкий ◽  
В.Д. Бланк
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Diamond Powder ◽  
Planetary Mill ◽  
Transmission Electron ◽  
Germanium Powder

In this work high-resolution transmission electron microscopy (HRTEM) studies of germanium powder obtained as a result of processing in a planetary mill in the presence of (5-25%) of diamond powder have been performed. As a result of processing sample contains twins on {111} plane and packaging defects in germanium. Phase 9R was detected in which the following sequence of layers takes place: ...BABCBCACA... In some particles, there was a partial or complete phase transition of GeI → GeIV and GeI → GeIII.

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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