Microstructural Studies of Pulsed-Laser Irradiated Graphite Surfaces

1985 ◽  
Vol 51 ◽  
Author(s):  
J. S. Speck ◽  
J. Steinbeck ◽  
G. Braunstein ◽  
M. S. Dresselhaus ◽  
T. Venkatesan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Outer Boundary ◽  
Pyrolytic Graphite ◽  
Areal Density ◽  
Uniform Density ◽  
Fine Grain ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Diffraction Patterns

ABSTRACTThe surface structures of laser-irradiated samples of highly oriented pyrolytic graphite (HOPG) have been investigated using optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). The samples were irradiated with a 30 ns ruby laser (λ = 6943 !A) pulse with energy fluences ranging from 0.1 to 3.0 J cm−2. Optically, the specimens show a damage region approximately 5 mm in diameter. The surface structure displays three characteristic regions: an outer boundary characterized by submicron carbon spheroids resting on the surface; an inner boundary characterized by both submicron spheroids and 1 to 5 [m ‘torn’ carbon layers which appear to have broken away from the graphite surface after irradiation; a central region characterized by a uniform density of spheroids and a pattern of surface upheavals which trace out a grain pattern similar to that of the pristine substrate. Electron diffraction patterns taken on the irradiated region indicate an ultra-fine grain 2-dimensionally ordered carbon. Qualitative trends in the areal density of different microstructural features are presented. In addition, a simple model explaining the observed features is given. All observations are consistent with the rapid solidification of liquid carbon.

Nanostructural characterizations of hydrogen-permselective Si–Co–O membranes by transmission electron microscopy

2009 ◽  
Vol 24 (2) ◽  
pp. 372-378 ◽  
Author(s):  
Shinji Fujisaki ◽  
Koji Hataya ◽  
Tomohiro Saito ◽  
Shigeo Arai ◽  
Yuji Iwamoto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gas Permeation ◽  
Hydrogen Gas ◽  
Transmission Electron Microscopy Micrographs ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Diffraction Patterns ◽  
Permeation Properties

Nanostructural characterizations of liquid metal–organic precursors-derived cobalt-doped amorphous silica (Si–Co–O) membranes supported on a mesoporous anodic alumina capillary (MAAC) tube were performed to study their unique high-temperature hydrogen gas permeation properties. Cross-sectional scanning transmission electron microscopy images and selected-area electron diffraction patterns indicated that the metal cobalt and the different oxidation states of cobalt oxides (CoO and Co3O4) nanocrystallites having a size range of 5–20 nm were in situ formed in the mesopore channels of the MAAC tube. In addition, high-resolution transmission electron microscopy micrographs and electron energy loss spectroscopy elemental mapping images indicated that the highly dense Co-doped amorphous Si–O formed within the mesopore channels of the MAAC tube. These nanostructural features could contribute to the hydrogen-selective permeation properties observed for the membranes.

scholarly journals Automated Crystal Orientation Mapping by Precession Electron Diffraction-Assisted Four-Dimensional Scanning Transmission Electron Microscopy Using a Scintillator-Based CMOS Detector

2021 ◽  
Vol 27 (5) ◽  
pp. 1102-1112
Author(s):  
Jiwon Jeong ◽  
Niels Cautaerts ◽  
Gerhard Dehm ◽  
Christian H. Liebscher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Scanning Transmission Electron Microscopy ◽  
Angular Resolution ◽  
Transmission Electron ◽  
Orientation Mapping ◽  
Scanning Transmission ◽  
Precession Electron Diffraction ◽  
Diffraction Patterns

The recent development of electron-sensitive and pixelated detectors has attracted the use of four-dimensional scanning transmission electron microscopy (4D-STEM). Here, we present a precession electron diffraction-assisted 4D-STEM technique for automated orientation mapping using diffraction spot patterns directly captured by an in-column scintillator-based complementary metal-oxide-semiconductor (CMOS) detector. We compare the results to a conventional approach, which utilizes a fluorescent screen filmed by an external charge charge-coupled device camera. The high-dynamic range and signal-to-noise characteristics of the detector greatly improve the image quality of the diffraction patterns, especially the visibility of diffraction spots at high scattering angles. In the orientation maps reconstructed via the template matching process, the CMOS data yield a significant reduction of false indexing and higher reliability compared to the conventional approach. The angular resolution of misorientation measurement could also be improved by masking reflections close to the direct beam. This is because the orientation sensitive, weak, and small diffraction spots at high scattering angles are more significant. The results show that fine details, such as nanograins, nanotwins, and sub-grain boundaries, can be resolved with a sub-degree angular resolution which is comparable to orientation mapping using Kikuchi diffraction patterns.

scholarly journals Processing of Copper by Hydrostatic Extrusion – Studies of Microstructure and Properties

2016 ◽  
Vol 61 (3) ◽  
pp. 1575-1580
Author(s):  
B. Leszczyńska-Madej ◽  
M. W. Richert ◽  
I. Nejman ◽  
P. Zawadzka
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Statistical Analysis ◽  
Scanning Transmission Electron Microscopy ◽  
Pure Copper ◽  
Hydrostatic Extrusion ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Diffraction Patterns

AbstractThe present study attempts to apply HE to 99.99% pure copper. The microstructure of the samples was investigated by both light microscopy and scanning transmission electron microscopy (STEM). Additionally, the microhardness was measured, the tensile test was made, and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns, misorientation was determined. The obtained results show that microstructure of copper deformed by hydrostatic extrusion (HE) is rather inhomogeneous. The regions strongly deformed with high dislocation density exist near cells and grains/subgrains free of dislocations. The measurements of the grain size have revealed that the sample with an initial in annealed-state grain size of about 250 μm had this grain size reduced to below 0.35μm when it was deformed by HE to the strain ε=2.91. The microhardness and UTS are stable within the whole investigated range of deformation.

Template-Assisted Fabrication of Double-Shelled Nanotubes Composed of Inner Shell Pb(Zr0.52Ti0.48)O3 and Outer Shell TiO2 by Sol-Gel Process with Spin-Coating Technique

2011 ◽  
Vol 1292 ◽  
Author(s):  
Y. C. Choi ◽  
S. Y. Cho ◽  
S. D. Bu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spin Coating ◽  
Sol Gel ◽  
Outer Shell ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Scanning Transmission ◽  
Diffraction Patterns

ABSTRACTDouble-shelled nanotubes composed of inner shell Pb(Zr0.52Ti0.48)O3 (PZT) and outer shell TiO2 are successfully fabricated by a spin coating of each sol-gel solution on porous anodic alumina template. Field emission transmission electron microscopy images show that they have a ~ 10 nm wall thickness. The selected area electron diffraction patterns show that they have two mixed crystalline phases of tetragonal PZT and anatase TiO2. The analyses of scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy confirm their uniform distribution of each element.

D-STEM: A Parallel Electron Diffraction Technique Applied to Nanomaterials

2010 ◽  
Vol 16 (5) ◽  
pp. 614-621 ◽  
Author(s):  
K.J. Ganesh ◽  
M. Kawasaki ◽  
J.P. Zhou ◽  
P.J. Ferreira
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Dark Field ◽  
Transmission Electron ◽  
Electron Diffraction Technique ◽  
Scanning Transmission ◽  
Stem Image ◽  
Diffraction Imaging ◽  
Diffraction Patterns

AbstractAn electron diffraction technique called D-STEM has been developed in a transmission electron microscopy/scanning transmission electron microscopy (TEM/STEM) instrument to obtain spot electron diffraction patterns from nanostructures, as small as ∼3 nm. The electron ray path achieved by configuring the pre- and postspecimen illumination lenses enables the formation of a 1–2 nm near-parallel probe, which is used to obtain bright-field/dark-field STEM images. Under these conditions, the beam can be controlled and accurately positioned on the STEM image, at the nanostructure of interest, while sharp spot diffraction patterns can be simultaneously recorded on the charge-coupled device camera. When integrated with softwares such as GatanTMSTEM diffraction imaging and Automated Crystallography for TEM or DigistarTM, NanoMEGAS, the D-STEM technique is very powerful for obtaining automated orientation and phase maps based on diffraction information acquired on a pixel by pixel basis. The versatility of the D-STEM technique is demonstrated by applying this technique to nanoparticles, nanowires, and nano interconnect structures.

scholarly journals Surface-Limited Electrodeposition of Continuous Platinum Networks on Highly Ordered Pyrolytic Graphite

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 721 ◽  
Author(s):  
Filippo Farina ◽  
Giorgio Ercolano ◽  
Sara Cavaliere ◽  
Deborah Jones ◽  
Jacques Rozière
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Pyrolytic Graphite ◽  
Reduction Reaction ◽  
X Rays ◽  
Highly Ordered Pyrolytic Graphite ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Energy Conversion Devices

Continuous thin platinum nanoplatelet networks and thin films were obtained on the flat surface of highly ordered pyrolytic graphite (HOPG) by high overpotential electrodeposition. By increasing the deposition time, the morphology of the Pt deposits can be progressively tuned from isolated nanoplatelets, interconnected nanostructures, and thin large flat islands. The deposition is surface-limited and the thickness of the deposits, equivalent to 5 to 12 Pt monolayers, is not time dependent. The presence of Pt (111) facets is confirmed by High Resolution Transmission Electron Microscopy (HRTEM) and evidence for the early formation of a platinum monolayer is provided by Scanning Transmission Electron Microscopy and Energy Dispersive X-rays Spectroscopy (STEM-EDX) and X-ray Photoelectron Spectroscopy (XPS) analysis. The electroactivity towards the oxygen reduction reaction of the 2D deposits is also assessed, demonstrating their great potential in energy conversion devices where ultra-low loading of Pt via extended surfaces is a reliable strategy.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Effects of High-Energy Ions on Synthetic Quartz

1972 ◽  
Vol 30 ◽  
pp. 544-545
Author(s):  
Joseph J. Comer ◽  
Charles Bergeron ◽  
Lester F. Lowe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Energy ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
High Energy Ions ◽  
Diffraction Patterns ◽  
Dauphiné Twinning ◽  
Beam Damage

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.

Magnesium and sulfur in mast cell and basophil granules of lower vertebrates in relation with histamine

1992 ◽  
Vol 50 (2) ◽  
pp. 1596-1597
Author(s):  
Kenichi Takaya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Mast Cell ◽  
Mast Cells ◽  
Tree Frog ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Fresh Frozen ◽  
Ultrathin Sections

Mast cell and basophil granules of the vertebrate contain heparin or related sulfated proteoglycans. Histamine is also present in mammalian mast cells and basophils. However, no histamine is detected in mast cell granules of the amphibian or fish, while it is shown in those of reptiles and birds A quantitative x-ray microanalysis of mast cell granules of fresh frozen dried ultrathin sections of the tongue of Wistar rats and tree frogs disclosed high concentrations of sulfur in rat mast cell granules and those of sulfur and magnesium in the tree frog granules. Their concentrations in tree frog mast cell granules were closely correlated (r=0.94).Fresh frozen dried ultrathin sections and fresh air-dried prints of the tree frog tongue and spleen and young red-eared turtle (ca. 6 g) spleen and heart blood were examined by a quantitative energy-dispersive x-ray microanalysis (X-650, Kevex-7000) for the element constituents of the granules of mast cells and basophils. The specimens were observed by transmission electron microscopy (TEM) (80-200 kV) and followed by scanning transmission electron microscopy (STEM) under an analytical electron microscope (X-650) at an acceleration voltage of 40 kV and a specimen current of 0.2 nA. A spot analysis was performed in a STEM mode for 100 s at a specimen current of 2 nA on the mast cell and basophil granules and other areas of the cells. Histamine was examined by the o-phthalaldehyde method.

Examination of Extra Electron Diffraction Spots Observed in Deuterium-Irradiated Silicon by Using Parallel Electron Beam Illumination

1990 ◽  
Vol 48 (2) ◽  
pp. 490-491
Author(s):  
Ryuichiro Oshima ◽  
Shoichiro Honda ◽  
Tetsuo Tanabe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Single Crystal ◽  
Mixed Solution ◽  
Parallel Beam ◽  
Defect Clusters ◽  
Float Zone ◽  
Transmission Electron ◽  
Extra Electron ◽  
Diffraction Patterns

In order to examine the origin of extra diffraction spots and streaks observed in selected area diffraction patterns of deuterium irradiated silicon, systematic diffraction experiments have been carried out by using parallel beam illumination.Disc specimens 3mm in diameter and 0.5mm thick were prepared from a float zone silicon single crystal(B doped, 7kΩm), and were chemically thinned in a mixed solution of nitric acid and hydrogen fluoride to make a small hole at the center for transmission electron microscopy. The pre-thinned samples were irradiated with deuterium ions at temperatures between 300-673K at 20keV to a dose of 1022ions/m2, and induced lattice defects were examined under a JEOL 200CX electron microscope operated at 160kV.No indication of formation of amorphous was obtained in the present experiments. Figure 1 shows an example of defects induced by irradiation at 300K with a dose of 2xl021ions/m2. A large number of defect clusters are seen in the micrograph.

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