Structure and Electrical Conductivity of Amorphous ZnTe and CdTe

1972 ◽  
Vol 50 (20) ◽  
pp. 2512-2519 ◽  
Author(s):  
H. M. Brown ◽  
D. E. Brodie
Keyword(s):  
Electrical Conductivity ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Annealing Temperature ◽  
Nearest Neighbor ◽  
Electron Diffraction Data ◽  
Distribution Analysis ◽  
Amorphous Films ◽  
Higher Temperature ◽  
Nearest Neighbor Distances

Amorphous films of ZnTe and CdTe have been prepared and studied. Electron microscope studies have shown the films to have crystallite diameters of about 25 Å. A radial distribution analysis of the electron diffraction data for ZnTe shows that the first and second nearest neighbor distances are the same as in the bulk crystal and they are consistent with the basic crystalline tetrahedral units being retained in the amorphous phase.The electrical conductivity of ZnTe films has a temperature dependence which varies with the annealing temperature. This is explained by assuming that the extrinsic range is caused by acceptor-like dangling bonds which anneal at lower temperatures (100 °C), but that at higher temperature anneals (400 °C) the film re-crystallizes.

Electron microscope studies on Nd2-xCexCuO4

1991 ◽  
Vol 49 ◽  
pp. 1100-1101
Author(s):  
H. Brigitte Krause
Keyword(s):  
Crystal Structure ◽  
Electron Microscope ◽  
High Resolution ◽  
Synchrotron Radiation ◽  
Electron Diffraction ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Neutron Powder Diffraction ◽  
Electron Diffraction Data ◽  
Tetragonal Unit Cell

The crystal structure of Nd2-xCexCuO4, as determined from neutron powder diffraction and high resolution synchrotron radiation, has been reported in the literature. The space group was found to be Immm. The ratio of the tetragonal unit cell was reported to vary as a function of the compositions with two separate branches resulting in two different ratios for each composition. In addition, commensurate superlattices have been observed and related to ordering, of atoms or vacancies. The present work deals with electron diffraction data on the same samples used for the neutron diffraction work at Argonne National Laboratory. The samples were kindly supplied by Dr. Bogdan Dabrowski.

Characterization of the Structure of a Novel Refractory Alloy Glass – Ni60Nb37Sn3

2002 ◽  
Vol 754 ◽  
Author(s):  
Michelle L. Tokarz ◽  
Matt Daniels ◽  
John C. Bilello ◽  
Zofia Rek
Keyword(s):  
Radial Distribution ◽  
Metallic Glasses ◽  
Hard Sphere ◽  
Nearest Neighbor ◽  
Refractory Alloy ◽  
Scattering Data ◽  
Distribution Analysis ◽  
X Ray ◽  
Nearest Neighbor Distances

ABSTRACTBulk forms of Refractory Alloy Glasses (RAGs) of the composition Ni60Nb37Sn3 have recently been synthesized as part of a larger project for potential use in structural applications. Modeling efforts of such metallic glasses have traditionally involved the use of hard sphere models without regard to potential electron density fluctuations of individual components. X-ray characterization of these materials (in both reflection and transmission modes) provided scattering data necessary for subsequent radial distribution analysis, which gives structural information such as nearest neighbor distances and packing characteristics. A model radial distribution function (RDF) was constructed based upon a hard sphere space filling assumption and compared to the RDFs obtained from experimental scattering data. The experimental RDFs showed no difference from the model RDF within the limit of experimental error, with regard to nearest neighbor distances and coordination numbers of the first two nearest neighbors.Additionally, transmission mode scattering experiments from a white beam x-ray source (E = 2 to 40 keV) demonstrated a through thickness amorphous structure of 2mm thick samples. Converted line profiles from the two-dimensional diffraction patterns from this experiment also showed agreement with reflection mode experiments. Samples of Vitreloy-106 (Zr57Nb5Cu15.4Ni12.6Al10) of similar thicknesses were used as standards due to the well-known behavior of this particular class of metallic glasses.

scholarly journals MicroED: a versatile cryoEM method for structure determination

2018 ◽  
Vol 2 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Brent L. Nannenga ◽  
Tamir Gonen
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Electron Diffraction ◽  
Structure Determination ◽  
Materials Science ◽  
Electron Diffraction Data ◽  
Determination Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Micro-electron diffraction, or MicroED, is a structure determination method that uses a cryo-transmission electron microscope to collect electron diffraction data from nanocrystals. This technique has been successfully used to determine the high-resolution structures of many targets from crystals orders of magnitude smaller than what is needed for X-ray diffraction experiments. In this review, we will describe the MicroED method and recent structures that have been determined. Additionally, applications of electron diffraction to the fields of small molecule crystallography and materials science will be discussed.

Spherulite morphology in thin films of natural rubber

1962 ◽  
Vol 270 (1341) ◽  
pp. 232-241 ◽  
Keyword(s):  
Thin Films ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Natural Rubber ◽  
Single Crystals ◽  
Growth Mechanism ◽  
Electron Irradiation ◽  
Electron Diffraction Data ◽  
Dilute Solution ◽  
Spherulite Morphology

Crystalline ‘spherulites’ grown in ultra-thin films of natural rubber at — 26 °C were examined in the electron microscope. The spherulites form hollow domes, like blisters in the film, which collapse under electron irradiation producing remarkable fibre-like patterns of folds and creases. Within the spherulite, crystalline and amorphous regions coexist and the former appear to grow to a preferred thickness of a few hundred Angstroms with the molecular chains oriented perpendicular to the film. The molecules are thus almost certainly folded as in polymer single crystals grown from dilute solution. Electron diffraction data suggest that relatively large regions of the spherulite correspond to single crystals. A growth mechanism for the spherulites is proposed.

Spherulite Morphology in Thin Films of Natural Rubber

1965 ◽  
Vol 38 (1) ◽  
pp. 33-44
Author(s):  
E. H. Andrews
Keyword(s):  
Thin Films ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Natural Rubber ◽  
Single Crystals ◽  
Growth Mechanism ◽  
Electron Irradiation ◽  
Electron Diffraction Data ◽  
Dilute Solution ◽  
Spherulite Morphology

Abstract Crystalline ‘spherulites’ grown in ultra-thin films of natural rubber at − 26° C were examined in the electron microscope. The spherulites form hollow domes, like blisters in the film, which collapse under electron irradiation producing remarkable fiber-like patterns of folds and creases. Within the spherulite, crystalline and amorphous regions coexist and the former appear to grow to a preferred thickness of a few hundred angstroms with the molecular chains oriented perpendicular to the film. The molecules are thus almost certainly folded as in polymer single crystals grown from dilute solution. Electron diffraction data suggest that relatively large regions of the spherulite correspond to single crystals. A growth mechanism for the spherulites is proposed.

Simple Identification of Electron Diffraction Ring Patterns

1969 ◽  
Vol 27 ◽  
pp. 160-161
Author(s):  
Carolyn Nohr ◽  
Ann Ayres
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Diffraction Ring ◽  
Image Position

Texts on electron diffraction recommend that the camera constant of the electron microscope be determine d by calibration with a standard crystalline specimen, using the equation

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.

Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL

1977 ◽  
Vol 35 ◽  
pp. 24-25
Author(s):  
Douglas L. Dorset ◽  
Anthony J. Hancock
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Surface ◽  
Coherent Scattering ◽  
Crystal Structure Determination ◽  
Electron Diffraction Data ◽  
Polar Group ◽  
Axis Orientation

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus, ab initio crystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).

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