Observation of [100] and [010] dark line defects in optically degraded znsse-based leds by transmission electron microscopy

1996 ◽  
Vol 25 (2) ◽  
pp. 239-243 ◽  
Author(s):  
L. Salamanca-Riba ◽  
L. H. Kuo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Line ◽  
Transmission Electron ◽  
Line Defects ◽  
Dark Line Defects

Transmission electron microscopy of 〈100〉 dark line defects in CdZnSe quantum well structures

1995 ◽  
Vol 67 (26) ◽  
pp. 3862-3864 ◽  
Author(s):  
G. D. U’Ren ◽  
G. M. Haugen ◽  
P. F. Baude ◽  
M. A. Haase ◽  
K. K. Law ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Well ◽  
Dark Line ◽  
Quantum Well Structures ◽  
Transmission Electron ◽  
Line Defects ◽  
Dark Line Defects

High-resolution Transmission Electron Microscopy of dislocations in intermetallic compounds

1995 ◽  
Vol 53 ◽  
pp. 76-77
Author(s):  
M.J. Mills
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Intermetallic Compounds ◽  
Structural Information ◽  
Critical Role ◽  
Atomic Level ◽  
Low Energy ◽  
Transmission Electron ◽  
Line Defects

The fine structure of dislocations plays a critical role in determining the macroscopic mechanical behavior Intermetallic compounds. Many of the technologically important characteristics of these compounds, an example their strength at high temperatures, appear to be determined by intricate details of dislocation stucture at the atomic level. High resolution transmission electron microscopy (HREM) offers the etential to obtain structural information at this level by observing these line defects in an "end-on" configuration.Samples of HREM images of several important dislocation types in Ni3Al and TiAl are shown in Figures through 3. Each of these particular dislocation types (i.e. Burgers vectors and line directions) tend to be longly favored in these compounds, indicating that along these line directions the dislocations are likely have either low mobility or low energy.

scholarly journals High Resolution STEM Images of the Human Tooth Enamel Crystals

2021 ◽  
Vol 11 (16) ◽  
pp. 7477
Author(s):  
José Reyes-Gasga ◽  
Etienne F. Brès
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Tooth Enamel ◽  
Dark Field ◽  
Human Tooth ◽  
Dark Line ◽  
Human Tooth Enamel ◽  
Transmission Electron ◽  
Annular Dark Field

High-resolution scanning transmission electron microscopy (STEM) images of human tooth enamel crystals, mainly in the high-angle annular dark-field (STEM-HAADF) mode, are presented in this work along the [1000], [10-11]. and [1-210] directions. These images allow knowing some structural details at the nanometric level of the human tooth enamel crystals and of the central dark line (CDL) observed at their centers. The transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images of the CDL showed the Fresnel contrast. In the STEM bright-field (STEM-BF) and annular-dark-field (STEM-ADF) images, the CDL was observed as an unstrain hydroxyapatite (HAP)-like zone but surrounded by a strained zone. In the STEM-HAADF images, the CDL appeared with a weak contrast, and its contrasts’ thickness was registered between 3 and 8 Å. The arrangement obtained in the STEM-HAADF images by identifying the bright points with the Ca atoms produced the superposition of the HAP atomic sites, mainly along the [0001] direction. The findings provide further information on the structure details at the center of enamel crystals, which favors the anisotropic carious dissolution at the CDL.

Aberration-Corrected Transmission Electron Microscopic Study of the Central Dark Line Defect in Human Tooth Enamel Crystals

2016 ◽  
Vol 22 (5) ◽  
pp. 1047-1055 ◽  
Author(s):  
José Reyes-Gasga ◽  
Joseph Hémmerlé ◽  
Etienne F. Brès
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tooth Enamel ◽  
Dark Field ◽  
Human Tooth ◽  
Dark Line ◽  
Human Tooth Enamel ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Aberration Corrected

AbstractAngstrom resolution images of human tooth enamel (HTE) crystallites were obtained using aberration-corrected high-resolution transmission electron microscopy and atomic-resolution scanning transmission electron microscopy in the modes of bright field, annular dark field, and high-angle annular dark-field. Images show that the central dark line (CDL) defect observed around the center of the HTE crystals is a site for caries formation in the HTE and has a thickness of ~0.2 nm. Results also suggest that the CDL goes through one of the OH− planes.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

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