Formation of CdxHg1-xTe Layers on CdTe after NP-Etching and HgTe-Graphite Pasting

2003 ◽  
Vol 763 ◽  
Author(s):  
Yanfa Yan ◽  
K.M. Jones ◽  
X. Wu ◽  
M.M. Al-Jassim
Keyword(s):  
Electron Microscopy ◽  
Chemical Composition ◽  
High Resolution ◽  
Thin Layer ◽  
Thermal Annealing ◽  
High Resolution Electron Microscopy ◽  
Epitaxial Relationship ◽  
Single Crystalline ◽  
Resolution Electron ◽  
Cdte Films

AbstractWe report on our investigation of the microstructure and chemical composition at the CdTe/Te-rich interfaces generated by NP-etching polycrystalline and single-crystalline CdTe films and followed with HgTe-graphite pasting and thermal annealing. We find that after this process, a thin layer of CdxHg1-xTe forms between CdTe and Te-rich layers, giving a structure like CdTe/CdxHg1-xTe/Te. High-resolution electron microscopy reveals that the CdxHg1-xTe layer has an epitaxial relationship with the CdTe. No CdxHg1-xTe layer has been observed in bromine/methanol-etched samples or samples with intentionally deposited Te layers.

HREM Analysis of ∑3 ﹛112﹜ Tilt Grain Boundaries in Au Bicrystals Observed in Projection

2000 ◽  
Vol 6 (S2) ◽  
pp. 1044-1045
Author(s):  
C.J.D. Hetherington ◽  
U. Dahmen
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Thin Layer ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
Phase 1 ◽  
High Resolution Electron Microscopy ◽  
Twin Plane ◽  
Stacking Fault ◽  
Resolution Electron

Grain boundaries in fee metals with low stacking fault energy are known to undergo extended relaxations that can at times lead to a thin layer of a different structure. In Cu, for example, it has been found that ∑3﹛ 112﹜ boundaries relax into a 9R phase [1]. In this work, we have used high resolution electron microscopy to investigate the atomic structure of ∑3 grain boundaries in mazed bicrystal films of Au. Using ﹛111﹜ Ge surfaces as a template, Au bicrystals can be grown in two orientation variants, related to each other by a 60° rotation about the surface normal. As described previously, such films have a strong tendency to facet onto the coherent twin plane parallel to the substrate [2], also known as “double positioning” [3]. If films are made very thin, the likelihood for such in-plane boundaries to lie in the foil decreases, and it becomes possible to observe the atomic structure of edge-on interfaces along <111>.

Catalyst-Free Synthesis of Single-Wall Boron Nitride Nanotubes via Laser Ablation

2000 ◽  
Vol 633 ◽  
Author(s):  
Roland S. Lee ◽  
Julie Gavillet ◽  
Marc Lamy de la Chapelle ◽  
Jean-Lou Cochon ◽  
Daniel Pigache ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Laser Ablation ◽  
Chemical Composition ◽  
High Resolution ◽  
Boron Nitride ◽  
Energy Loss ◽  
High Resolution Electron Microscopy ◽  
Boron Nitride Nanotubes ◽  
Resolution Electron ◽  
Electron Energy Loss

AbstractBoron nitride nanotubes (BN-NTs) were synthesized in “mass” quantities (∼0.6 g/h) using a continuous CO2 laser ablation reactor described in the literature [1]. High-resolution electron microscopy (HRTEM) analyses have shown the nanotubes to be organized in “ropes” comprising ∼10 tubes. Analysis of HRTEM images indicate that the majority of the tubes are zig-zag. The chemical composition of the tubes was confirmed using electron energy loss spectroscopy (EELS) analysis, which also determined that nanoparticles terminating tube ends were composed of pure boron covered by BN fullerene-like “cages”. The growth mechanism of the nanotubes seems to be “root-based” with tubes growing from boron nanoparticles dispersed throughout the samples; the non-particle-terminated ends of the tubes exhibit flat “caps” characteristic of BN-NTs [2].

Carbothermal reduction and nitridation reaction of SiOx and preoxidized SiOx: Formation of α-Si3N4 fibers

1994 ◽  
Vol 9 (9) ◽  
pp. 2330-2340 ◽  
Author(s):  
P.D. Ramesh ◽  
K.J. Rao
Keyword(s):  
Electron Microscopy ◽  
Nuclear Magnetic Resonance ◽  
Chemical Composition ◽  
High Resolution ◽  
Carbothermal Reduction ◽  
Amorphous Material ◽  
High Resolution Electron Microscopy ◽  
Partial Pressures ◽  
Resolution Electron ◽  
Nitridation Reaction

The chemical composition of amorphous SiOx has been analyzed by oxidation studies and is found to be SiO1.7. SiO1.7 appears to be a monophasic amorphous material on the basis of 29Si nuclear magnetic resonance, high resolution electron microscopy, and comparative behavior of a physical mixture of Si and SiO2. Carbothermal reduction and nitridation reactions have been carried out on amorphous SiO1.7 and on amorphous SiO2 obtained from oxidation of SiO1.7. At 1623 K reactions of SiO1.7 lead exclusively to the formation of Si2N2O, while those of SiO2 lead exclusively to the formation of Si3N4. Formation of copious fibers of α-Si3N4 was observed in the latter reaction. It is suggested that the partial pressure of SiO in equilibrium with reduced SiO1.7 and SiO2 during the reaction is the crucial factor that determines the chemistry of the products. The differences in the structures of SiO2 and SiO1.7 have been considered to be the origin of the differences in the SiO partial pressures of the reduction products formed prior to nitridation. The effect of the ratios, C:SiO1.7 and C:SiO2, in the reaction mixture as well as the effect of the temperature on the course of the reactions have also been investigated.

High Resolution Electron Microscopy of DNA

1969 ◽  
Vol 27 ◽  
pp. 268-269
Author(s):  
J.R. White ◽  
T. Roller ◽  
M. Beer ◽  
P. Bartl
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Chemical Composition ◽  
High Resolution ◽  
Carbon Support ◽  
High Resolution Electron Microscopy ◽  
Theoretical Studies ◽  
Resolution Capability ◽  
Similar Chemical ◽  
Resolution Electron

Observations of molecular detail in the electron microscope is limited by the presence of the familiar dotty contrast produced by the evaporated carbon support films commonly employed, resulting in the loss of information well within the resolution capability of modern instruments. While theoretical studies indicate that image contrast from one to three layers of graphite would be almost negligible, such films of 10Å thickness or less would not be expected to be sufficiently robust for use with current techniques for molecule deposition. Nevertheless, crystalline support films of greater thickness (say 100-200Å), should still be superior to disorganized material of similar chemical composition image.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Electron microscopy of rabbit FC crystals

1983 ◽  
Vol 41 ◽  
pp. 730-731
Author(s):  
Robert A. Grant ◽  
Laura L. Degn ◽  
Wah Chiu ◽  
John Robinson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Molecular Replacement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Resolution Electron ◽  
Replacement Technique ◽  
Hydrated Crystal ◽  
Molecular Structure Analysis

Proteolytic digestion of the immunoglobulin IgG with papain cleaves the molecule into an antigen binding fragment, Fab, and a compliment binding fragment, Fc. Structures of intact immunoglobulin, Fab and Fc from various sources have been solved by X-ray crystallography. Rabbit Fc can be crystallized as thin platelets suitable for high resolution electron microscopy. The structure of rabbit Fc can be expected to be similar to the known structure of human Fc, making it an ideal specimen for comparing the X-ray and electron crystallographic techniques and for the application of the molecular replacement technique to electron crystallography. Thin protein crystals embedded in ice diffract to high resolution. A low resolution image of a frozen, hydrated crystal can be expected to have a better contrast than a glucose embedded crystal due to the larger density difference between protein and ice compared to protein and glucose. For these reasons we are using an ice embedding technique to prepare the rabbit Fc crystals for molecular structure analysis by electron microscopy.

High resolution electron microscopy of lanthanum phosphate crystals

1978 ◽  
Vol 36 (1) ◽  
pp. 274-275
Author(s):  
J. C. Wheatley ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Petroleum Industry ◽  
High Resolution Electron Microscopy ◽  
Lanthanum Phosphate ◽  
Good Catalyst ◽  
Resolution Electron ◽  
Good Catalytic Activity ◽  
Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

Possible applications of fraunhofer holography in high resolution electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 222-223 ◽  
Author(s):  
N. Bonnet ◽  
M. Troyon ◽  
P. Gallion
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Transfer Function ◽  
Radiation Damage ◽  
High Resolution Electron Microscopy ◽  
Far Field ◽  
Field Region ◽  
Crystalline Materials ◽  
Resolution Electron ◽  
The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

The observation of solutions in Ni3Nb

1988 ◽  
Vol 46 ◽  
pp. 540-541
Author(s):  
Z.M. Wang ◽  
J.P. Zhang
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Phase Modulation ◽  
High Resolution Electron Microscopy ◽  
Antiphase Domain ◽  
Boundary Area ◽  
Matrix Type ◽  
Resolution Electron ◽  
Domain Boundaries ◽  
Kontorova Model

High resolution electron microscopy reveals that antiphase domain boundaries in β-Ni3Nb have a hexagonal unit cell with lattice parameters ah=aβ and ch=bβ, where aβ and bβ are of the orthogonal β matrix. (See Figure 1.) Some of these boundaries can creep “upstairs” leaving an incoherent area, as shown in region P. When the stepped boundaries meet each other, they do not lose their own character. Our consideration in this work is to estimate the influnce of the natural misfit δ{(ab-aβ)/aβ≠0}. Defining the displacement field at the boundary as a phase modulation Φ(x), following the Frenkel-Kontorova model [2], we consider the boundary area to be made up of a two unit chain, the upper portion of which can move and the lower portion of the β matrix type, assumed to be fixed. (See the schematic pattern in Figure 2(a)).

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