Structural defects in an epitaxial ZnO∕(011¯2) r-plane sapphire studied by high-resolution electron microscopy and computer simulation

2006 ◽  
Vol 24 (2) ◽  
pp. 264-268 ◽  
Author(s):  
Sung-Hwan Lim
Keyword(s):  
Electron Microscopy ◽  
Computer Simulation ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Structural Defects ◽  
Resolution Electron

scholarly journals Vitrification of Y zeolite and its effects on HREM images

1986 ◽  
Vol 44 ◽  
pp. 774-775
Author(s):  
R. Csencsits
Keyword(s):  
Electron Microscopy ◽  
Computer Simulation ◽  
Electron Microscope ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Systematic Investigation ◽  
Y Zeolite ◽  
Y Zeolites ◽  
Transmission Electron ◽  
Resolution Electron

High resolution electron microscopy (HREM) is a valuable technique for studying catalytic zeolite systems because it gives direct information about the structure and defects present in the structure. The difficulty with doing an HREM study on zeolites is that they become amorphous under electron irradiation. This work is a systematic investigation of the damage of Y zeolites in the transmission electron microscope (TEM); the goals of this study are to determine the mechanism for electron damage and to access the effects of damage in Y zeolites on their HREM images using computer simulation.

Tem/Hrem Structural Characterization of Directionally Solidified Gaas-Cras Eutectic Crystals

1995 ◽  
Vol 398 ◽  
Author(s):  
Sergei Ruvimov ◽  
Zuzanna Liliental-Weber ◽  
Wendy Swider ◽  
Jack Washburn ◽  
Douglas E. Holmes
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Czochralski Method ◽  
High Resolution Electron Microscopy ◽  
Structural Defects ◽  
Directionally Solidified ◽  
Gaas Matrix ◽  
Resolution Electron ◽  
Ordered Array

ABSTRACTConventional and high resolution electron microscopy have been applied to characterize the microstructure of the CrAs-GaAs eutectic. The CrAs-GaAs eutectic crystals were directionally solidified by the Czochralski method in order to produce an ordered array of CrAs rods embedded in a GaAs matrix. The CrAs rods of 2-3 μm in diameter align parallel to the growth axis of the ingot. Where the GaAs matrix is found to contain structural defects, the CrAs rods are effectively defect-free. The CrAs has an orthorombic structure with the parameters a=3.5±0.1 Å, b=6.2±0.1 Å,c=5.7±0.1 Å.The c-axis is close to the direction of solidification.

L12- and L10-like cation-ordered structures in ZrO2–Y2O3 ceramics

2001 ◽  
Vol 16 (6) ◽  
pp. 1806-1813 ◽  
Author(s):  
J. C. Rao ◽  
Y. Zhou ◽  
D. X. Li
Keyword(s):  
Electron Microscopy ◽  
Computer Simulation ◽  
High Resolution ◽  
Annealing Temperature ◽  
High Resolution Electron Microscopy ◽  
Energy Dispersive ◽  
Ordered Structures ◽  
X Ray ◽  
Resolution Electron

Y0.25Zr0.75O2−x and Y0.5Zr0.5O2−y phases, with L12- and L10- like cation-ordered structures, respectively, have been found in ZrO2–Y2O3 ceramics in both the sintered and annealed states. High-resolution electron microscopy, energy-dispersive x-ray spectroscopy and computer simulation have been used to reveal the presence of the phases. The formation of Y0.25Zr0.75O2−x and Y0.5Zr0.5O2−y phases was initiated during the sintering procedure and developed with the increase in annealing temperature and time. Segregation of yttrium, which was prevalent in different regions even within one grain, induced the formation of Y0.25Zr0.75O2−x and Y0.5Zr0.5O2−y phases.

Study of structural defects in zeolites by high-resolution electron microscopy and Fourier analysis methods

1984 ◽  
Vol 42 ◽  
pp. 652-653
Author(s):  
J. M. Domínguez ◽  
D. R. Acosta N.
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Fourier Analysis ◽  
High Resolution Electron Microscopy ◽  
Structural Features ◽  
Atomic Scale ◽  
Structural Defects ◽  
Phase Grating ◽  
Resolution Electron ◽  
Complete Study

For thin crystals and weak-phase objects, the phase grating approximation indicates that intensities are directly proportional to the projected lattice potencial VZ (x, y). Additionnally at the optimum focus condition, i. e. γ = π/2 (see ref. (2) for details) both electron diffraction and optical transform patterns are identical. Therefore, for very thin crystals, i.e. t < 102A, and several types of zeolites, including ZSM-5, Faujasites X, Y, erionites and A-type zeolites, the main assumptions of the phase grating approximation hold, making possible a complete study of structural features taking place at a nearly atomic scale. The method used to characterize the ultraestrncture of those zeolites are high resolution electron microscopy, Fourier analysis in the computer of the digitized micrographs and Laser optical diffractometry.

High Resolution Electron Microscopy and Computer Simulation Studies of the Atomic Structure of Tilt Boundaries in TiO2

1994 ◽  
Vol 357 ◽  
Author(s):  
Yaping Liu ◽  
Imtiaz Majid ◽  
John B. Vander Sande
Keyword(s):  
Electron Microscopy ◽  
Computer Simulation ◽  
High Resolution ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron ◽  
Symmetric Plane ◽  
Tilt Boundaries ◽  
Computer Simulation Studies ◽  
Simulated Images

AbstractThe atomic structure of [001] tilt grain boundaries of Σ25 (210), Σ5 (310), Σ213 (320) and Σ217 (410) in TiO2 (rutile) were studied using high resolution electron microscopy and computer simulation. Regularly separated small steps (1/2 [120] high) and big steps (3/2 [120] high) which contain secondary dislocations were found in the (210) boundary as a result of deviation from the exact Σ5 misorientation and (210) symmetric plane. Similar steps were also found in (310) and (320) boundaries. Flat segments between the steps were found to have very accurate misorientation of their, Σ's and a nearly symmetric boundary plane. Their rigid body translation, volume expansion and relaxed structures were determined by comparing HRTEM images with computer calculated structures and simulated images. An irregular core structure was found in the (410) boundary when its misorientation deviated 2° from the exact Σ17 misorientation.

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