Primitive clay precursors formed on feldspar

1987 ◽  
Vol 24 (3) ◽  
pp. 506-527 ◽  
Author(s):  
Kazue Tazaki ◽  
W. S. Fyfe
Keyword(s):  
Major Element ◽  
Depth Profiling ◽  
Original Structure ◽  
Lattice Image ◽  
Reactive Iron ◽  
Transmission Electron ◽  
Lattice Images ◽  
Diffraction Patterns ◽  
Clay Layers ◽  
Clay Formation

High-resolution transmission electron microscopy of clay formation on K-feldspar has revealed the existence of intermediate states between feldspar and crystalline clay products. During the earliest weathering stages of K-feldspar, a primitive clay precursor forms on the feldspar surface that is spotted by ion oxides. This reactive iron is incorporated into the primitive clay precursors, which have an ultrathin 150–200 Å (1 Å = 0.1 nm) circular form and 14–20 Å lattice images or long, curled fiber forms with varied lattice image spacings. The electron diffraction patterns of primitive clay precursors show diffuse rings at 2.65, 2.04, and 1.51 Å, suggesting low crystallinity, random orientation, and partial inheritance of the original structure. EDX step scanning analysis showed that the major-element concentrations of Si, Al, and K tend to decrease from unaltered parts to altered parts of precursors with substantial increase in Fe. Auger depth profiling showed the thickness of the primitive clay layers is 150–300 Å. The primitive clay precursors may well precede formation of spheroidal particles of halloysite, squat cylinders of halloysite or hexagonal crystalline, and tabuler halloysite (7 Å). SEM, XRD, SIMS, and SAM data support the TEM results.

7-beam lattice images of (110) oriented Ge

1978 ◽  
Vol 36 (1) ◽  
pp. 290-291
Author(s):  
J.R. Parsons ◽  
C.W. Hoelke
Keyword(s):  
Image Features ◽  
Objective Lens ◽  
Lattice Plane ◽  
Lattice Image ◽  
Crystalline Defects ◽  
Transmission Electron ◽  
Lattice Images ◽  
Electron Microscopes ◽  
Structural Aspects ◽  
Beam Lattice

The direct imaging of a crystal lattice has intrigued electron microscopists for many years. What is of interest, of course, is the way in which defects perturb their atomic regularity. There are problems, however, when one wishes to relate aperiodic image features to structural aspects of crystalline defects. If the defect is inclined to the foil plane and if, as is the case with present 100 kV transmission electron microscopes, the objective lens is not perfect, then terminating fringes and fringe bending seen in the image cannot be related in a simple way to lattice plane geometry in the specimen (1).The purpose of the present work was to devise an experimental test which could be used to confirm, or not, the existence of a one-to-one correspondence between lattice image and specimen structure over the desired range of specimen spacings. Through a study of computed images the following test emerged.

The ultrastructure of coccoliths from the marine alga Emiliania huxleyi (Lohmann) Hay and Mohler: an ultra-high resolution electron microscope study

1983 ◽  
Vol 219 (1215) ◽  
pp. 111-117 ◽  
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Emiliania Huxleyi ◽  
Growth Patterns ◽  
Lattice Image ◽  
Nucleation Sites ◽  
Resolution Electron ◽  
Lattice Images ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns

The calcite coccoliths from the alga Emiliania huxleyi (Lohmann) Hay and Mohler have been studied by ultra-high resolution electron microscopy. This paper describes the two different types of structure observed, one in the upper elements, the other in the basal plate, or lower element. The former consisted of small, microdomain structures of 300-500 Å (1 Å = 10 -10 m) in length with no strong orientation. At places along these elements, and particularly in the junction between stem and head pieces, triangular patterns of lattice fringes were observed indicating multiple nucleation sites in the structure. In contrast, the lower element consisted of a very thin single crystalline sheet of calcite which could be resolved into a two dimensional lattice image, shown by a computer program that is capable of simulating electron diffraction patterns and lattice images to be a [421] zone of calcite. A possible mechanism for these growth patterns in the formation of coccoliths is discussed, together with the relevance of such mechanisms to biomineralization generally.

A novel intergrowth structure between ReO3-type and tetragonal tungsten bronze-type in the Zr/Nb/W/O system

1996 ◽  
Vol 52 (6) ◽  
pp. 917-922 ◽  
Author(s):  
F. Krumeich ◽  
G. Liedtke ◽  
W. Mader
Keyword(s):  
Tungsten Bronze ◽  
Regular Structure ◽  
Structure Model ◽  
Tungsten Bronze Structure ◽  
Tetragonal Tungsten Bronze ◽  
Transmission Electron ◽  
Monoclinic Lattice ◽  
Lattice Images ◽  
Diffraction Patterns ◽  
First Time

The intergrowth structure of a zirconium niobium tungsten oxide has been determined by transmission electron microscopy methods. Electron diffraction patterns reveal the parameters of the monoclinic lattice: a = 19.0, b = 3.9 and c = 13.8 Å; β = 93.5°. Additional reflections in higher-order Laue zones indicate the presence of a diagonal glide plane, leading to a larger unit cell. A structure model of composition Zr n Nb8−2n W12+n O56 (0.5 < n < 1) has been derived from high-resolution lattice images. Alternating slabs of ReO3-type and of tetragonal tungsten bronze structure are intergrown coherently. Two five-membered rings of MO6 octahedra belonging to adjacent tetragonal tungsten bronze subcells are connected by having two octahedra in common. For the first time, this arrangement of double pentagons is observed in a regular structure.

scholarly journals Investigation of Lithiated Carbons by Transmission Electron Microscopy and X-Ray Diffraction Analysis

1998 ◽  
Vol 548 ◽  
Author(s):  
T. D. Tran ◽  
X. Y. Song ◽  
K. Kinoshita
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Carbon Black ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Lattice Image ◽  
X Ray ◽  
Storage Mechanism ◽  
Transmission Electron ◽  
Diffraction Patterns

ABSTRACTThe microstructures of lithiated synthetic graphite and carbon black were studied by high- resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analysis. Information about the crystal structure of carbon containing various Li compositions can provide useful insights to our understanding of the Li storage mechanism in carbonaceous materials. Samples with compositions of Li0.93C6or Li0.45C6 were found to contain both stage-one and stage-two compounds. These observations are consistent with XRD data. The changes in sample microstructure as the results of lithiation and exposure to electron irradiation were observed by TEM and recorded over several minutes in the microscope environment. Selected area electron diffraction patterns indicated that the lithiated samples quickly changed composition to LiC 24, which appeared to dominate during the brief analysis period. The layer planes in the lattice image of a disordered carbon black after Li insertion are poorly defined, and changes in the microstructure of these lithiated carbons was not readily apparent. Observations on these lithium intercalation compounds as well as the limitation of the experimental procedure will be presented.

Ordering In Zn0.5Fe0.5Se Epilayers Grown on InP Substrates by Molecular Beam Epitaxy

1991 ◽  
Vol 231 ◽  
Author(s):  
L. Salamanca Riba ◽  
K. Park ◽  
B. T. Jonker
Keyword(s):  
High Resolution ◽  
Ordered Structure ◽  
Cross Sectional ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Lattice Images ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Inp Substrates ◽  
Image Simulations

AbstractWe have observed an ordered structure in Zn0.5Fe0.5Se epilayers grown on (001) InP substrates using transmission electron microscopy. The ordered structure of Zn0.5Fe0.5Se has Fe atoms occupying the (0,0,0) and (½, ½, 0) sites and Zn atoms occupying the (0, ½, ½) and (½, 0, ½) sites in the zinc-blende unit cell. Ordering is observed in both electron diffraction patterns and cross-sectional high-resolution lattice images along the < 100 > and < 110 > directions. This ordered structure consists of alternating ZnSe and FeSe monolayers along the < 100 > and < 110 > directions. Computer image simulations of the high-resolution images under various thicknesses, and defocusing conditions have been obtained and are compared with those obtained experimentally.

Combined Effect of Nano-clay and Nano-carbon Black on Properties of NR Nanocomposites

2005 ◽  
Vol 13 (7) ◽  
pp. 709-719 ◽  
Author(s):  
Jia Qing-xiu ◽  
Wu You-ping ◽  
Xiang Ping ◽  
Ye Xin ◽  
Wang Yi-qing ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Dynamic Properties ◽  
Barrier Properties ◽  
Clay Nanocomposites ◽  
Transmission Electron ◽  
Roll Mill ◽  
Nano Clay ◽  
Diffraction Patterns ◽  
Clay Layers

Natural rubber (NR)/clay/carbon black nanocomposites, filled with 10 phr, 20 phr, and 30 phr of filler (in total) were obtained by adding carbon black (N330) on a two-roll mill to NR/clay nano-compounds prepared by the emulsion compounding method. X-ray diffraction patterns and transmission electron microscope photographs of the nanocomposites showed that both fillers were dispersed randomly in the NR matrix at nano-scale and that the space between the clay layers was filled with carbon black particles. At the same total filler loadings, the mechanical properties of the naocomposites filled with both clay and carbon black, such as moduli at 100% and 300% elongation, tensile strength and tear strength, were greatly improved compared with those of either NR/clay nanocomposites or NR/carbon black nanocomposites. This indicates that the samples with both fillers possessed excellent mechanical properties. It was found that the NR/clay/carbon black nanocomposites retained advantages from both fillers, for example, the processability and dynamic properties were close to those of NR/carbon black nanocomposites, and the gas barrier properties were almost as good as those of NR/clay nanocomposites.

Mapping the composition of materials at the atomic level

1992 ◽  
Vol 50 (2) ◽  
pp. 1474-1475
Author(s):  
A. Ourmazd ◽  
F.H. Baumann ◽  
Y. Kim ◽  
C. Kisielowski ◽  
P. Schwander
Keyword(s):  
Imaging Techniques ◽  
Atomic Level ◽  
Objective Lens ◽  
Lattice Imaging ◽  
Electron Microscopic ◽  
Lattice Image ◽  
Crystalline Materials ◽  
Transmission Electron ◽  
Lattice Images ◽  
Compositional Changes

This paper briefly outlines how transmission electron microscopic lattice imaging techniques can be used to map the composition of crystalline materials at the atomic level.Under appropriate conditions, a conventional lattice image is a map of the sample structure, because the dominant reflections used to form lattice images are relatively insensitive to compositional changes in the sample. Such reflections may be termed “structural”. In many cystalline materials, compositional changes occur by atomic substitution on a particular subset of lattice sites. In these systems, compositional changes are accompanied by the appearance of reflections, which we name “chemical”. Such reflections, for example the (200) in the zinc-blende structure, owe their existence to chemical differences between the various atomic species present on the different lattice sites. For fundamental reasons these reflections are often weak; they come about because of incomplete cancellation of out of phase contributions from different sublattices. “Chemical lattice imaging” exploits dynamical scattering to maximize the intensity of such reflections, and uses the objective lens as a bandpass filter to enhance their contribution to the image.

High-resolution transmission electron microscopy: A structural and chemical probe of semiconductor systems

1987 ◽  
Vol 45 ◽  
pp. 332-333
Author(s):  
A. Ourmazd
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Structural Information ◽  
Image Interpretation ◽  
Lattice Image ◽  
Semiconductor Interfaces ◽  
Transmission Electron ◽  
Lattice Images ◽  
The Individual

High Resolution Transmission Electron Microscopy (HRTEM) is now a powerful probe for the structural analysis of semiconductor systems. Lattice images can be obtained in a number of orientations, in at least three of which the individual atomic columns can be resolved. However, there exits an important class of problems, whose resolution requires chemical as well as structural information. The identification of individual atomic columns in compound semiconductors, and the atomic configuration of semiconductor/semiconductor interfaces are two important examples.In general, most reflection used to form a lattice image are not particularly sensitive to chemical changes in the sample. The information content of a typical lattice image is therefore strongly dominated by structural details. On the other hand, reflections such as the (200), which are normally forbidden in the diamond structure, come about in the zinc-blende system because of the chemical differences between the occupants of the two sublattices, and are thus highly chemically sensitive. In the “kinematical” thickness region, where simple image interpretation is possible, such reflections are relatively weak and their contribution to the lattice image is dominated by the stronger and chemically insensitive, allowed reflections.

Planar defects in β-iron disilicide (β-FeSi2) analyzed by transmission electron microscopy and modeling

1992 ◽  
Vol 25 (2) ◽  
pp. 122-128 ◽  
Author(s):  
Y. Zheng ◽  
A. Taccoen ◽  
J. F. Petroff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Model ◽  
Stacking Faults ◽  
Planar Defects ◽  
Iron Disilicide ◽  
Defect Position ◽  
Transmission Electron ◽  
Lattice Images ◽  
Diffraction Patterns

Microplanar defects were observed in β-iron disilicide by transmission electron microscopy. They were identified as (100)[011]/2 intrinsic stacking faults by means of electron diffraction patterns and observed in high-resolution lattice images. A structural model of the faults is proposed here in setting the defect position at x = ¼ within the cell.

Study on Degradation Mechanism of Stress in Generation Process of Coal-Bed Methane

2014 ◽  
Vol 1073-1076 ◽  
pp. 1995-2000
Author(s):  
Xiao Ming Li
Keyword(s):  
Degradation Mechanism ◽  
Eastern China ◽  
Structural Evolution ◽  
Foreland Basin ◽  
Tectonic Stress ◽  
Coal Bed ◽  
Generation Process ◽  
Transmission Electron ◽  
Lattice Images ◽  
Diffraction Patterns

In order to discuss the effect of tectonic stress on the structural evolution of coal, given the importance attached to High-resolution Transmission Electron Microscopy and micro-FTIR analysis, we investigated several aspects of material structures of high-rank Carboniferous period coal, located in the northern foreland basin of the Dabie orogenic belt in eastern China. High powered crystal lattice images of Bright Fields (BF) and Selected Area Diffraction patterns (SAD) of different types of metamorphism in coal were obtained. The organic molecular characters of different metamorphism types coal and the effecting factors are studied. The results show that:(1) the Basic Structural Units (BSU) become increasingly more compact as a function of rising temperature and pressure. Under pressure, the local orientation of molecules is strengthened, the arrangement of BSU speeds up and the degree of order is clearly enhanced; (2) tectonic stress is in favor of the chemistry environment transfer of hydrogen in coal, resulting in the decrease of aliphatic hydrocarbon and the increase of aromatic hydrocarbon in content, and accelerating the polycondensation and ordering of large molecules texture of coal.

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