scholarly journals Characterisation of chemically related asbestos amphiboles of actinolite: proposal for a specific differentiation in the diagram (Si apfu versus Mg/Mg+Fe2+)

2018 ◽  
Vol 9 ◽  
pp. 16 ◽  
Author(s):  
Maxime Misseri ◽  
Didier Lahondere
Keyword(s):  
New Caledonia ◽  
Polarized Light ◽  
Chemical Analyses ◽  
Massif Central ◽  
X Ray ◽  
Calcic Amphibole ◽  
Transmission Electron ◽  
The Subject ◽  
Representative Points ◽  
Armorican Massif

Aggregates and rocks from quarries located in metropolitan France and New Caledonia, all likely to contain asbestiform amphiboles, were analysed by a routine laboratory (AD-LAB). Morphological observations were made using transmission electron microscopy and chemical analyses were obtained with energy dispersive X-ray spectroscopy. The chemical analyses obtained from amphiboles were treated in such a way that they could be plotted in a diagram (Si apfu versus Mg/Mg+Fe2+). The points corresponding to analysed particles, classified as asbestos, define a broader compositional domain than that corresponding to the compositional areas of actinolite and tremolite. The creation of two new domains is proposed. Samples of basic metavolcanics and amphibolites collected by the Geological and Mining Research Bureau (BRGM) in different quarries of the Armorican Massif and the Massif Central containing calcic amphibole fibres have been the subject of polarized light microscope and electron microprobe analyses. The representative points of the spot chemical analyses performed on the very fine and ultrafine fibres are contained in the range defined previously. The diagram that has been determined from chemical analyses coupled with morphological and dimensional observations can help the “routine laboratories” to better characterise asbestiform calcic amphiboles, but it also allows comparisons with geological observations.

Clay minerals in the Namacotche Pegmatite Group from Zambezia Province, Mozambique: main constituents of late-stage secondary paragenesis

Clay Minerals ◽  
2008 ◽  
Vol 43 (4) ◽  
pp. 597-613 ◽  
Author(s):  
M. A. Sequeira Braga ◽  
C. Leal Gomes ◽  
J. Duplay ◽  
H. Paquet
Keyword(s):  
Electron Microscopy ◽  
Clay Minerals ◽  
Late Stage ◽  
Polarized Light ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Close Relationship ◽  
Xrd Patterns

AbstractNamacotche gem-bearing pegmatites of Alto Ligonha pegmatite district are heterogeneous, strongly fractionated, and have large Li and Ta and extremely large Cs contents. Clay samples were collected in fracture infillings and dilation cavities with gemstones and were studied using X-ray diffraction (XRD), polarized light microscope, scanning electron microscopy-energy dispersive spectroscopy, high-resolution transmission electron microscopy and chemical analyses. The <2 μm fraction contains cookeite, illite, illite-smectite and suggested irregular mixed-layer cookeite-smectite, beidellite, montmorillonite, kaolinite and goethite.The XRD patterns of chlorite and their d values suggest the presence of ‘di-trioctahedral chlorite’ similar to cookeite-Ia polytype. Cookeite chemical analyses show that Li contents range from 0.82 to 1.08 atoms per half unit cell.A close relationship has been established between occurrences of gemstones and clay minerals. Some important textures and crystal chemistry are discussed.The main gemstones related to the Namacotche Pegmatite are: morganite (pink cesian beryl), kunzite (spodumene) and elbaite tourmaline. As the mechanisms responsible for the gemstone formation take place at low temperature, the clay minerals paragenesis cookeite ± cookeite-smectite interstratification ± beidellite + montmorillonite ± illite-smectite interstratification, represents a late-stage secondary paragenesis, generated by hydrothermal alteration.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Electron Microprobe Analyses and X-Ray Diffraction Study of SrSi2

1966 ◽  
Vol 10 ◽  
pp. 409-421
Author(s):  
G. M. Faulring ◽  
E. S. Malizie
Keyword(s):  
Electron Microprobe ◽  
Polarized Light ◽  
Surface Preparation ◽  
Unit Cell ◽  
Intensity Data ◽  
Beam Size ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Probable Space

AbstractAlthough the phase SrSi2 has been previously recognized, it has been described only briefly in the literature.An alloy comprised of FeSi2, silicon, and the SrSi2 phase was examined on the electron microprobe. Optical and electron scanning images are correlated with X-ray scanning images for iron, silicon, calcium, and strontium. Quantitative microprobe analyses were made and corrected for absorption and the atomic number effect by several noncomputer methods. The corrections include as variables the X-ray intensities measured at several accelerating voltages. The effects of varying the electron beam size and accelerating potential are included. The results are compared to chemical analyses. The advantages of varying the accelerating voltage when correcting intensity data, increasing the beam size when surface preparation is a factor, and the importance of surface preparation at low accelerating voltages are discussed.An X-ray diffraction examination showed that the phase SrSi2 has a cubic unit cell with an a0 of 6.515 Å. There are four molecules per unit cell, and the most probable space group appears to be P213. The density was calculated as 3.45 (observed density >3.3).Metallographic observations with ordinary and polarized light and microhardness measurements are included.

WOOD ULTRASTRUCTURE OF ANCIENT BURIED LOGS OF FITZROYA CUPRESSOlDES

IAWA Journal ◽  
2007 ◽  
Vol 28 (2) ◽  
pp. 125-137 ◽  
Author(s):  
María A. Castro ◽  
Fidel A. Roig
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Polarized Light ◽  
Energy Dispersive ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Ancient Wood ◽  
Subfossil Wood ◽  
Anatomy And Ultrastructure

The anatomy and ultrastructure of subfossil wood of Fitzroya cupressoides from the late Pleistocene (>50,000 14C years before present) were compared with those of extant F. cupressoides trees from southern Chile, using light microscopy (polarized light and ftuorescence), scanning electron microscopy coupled with an energy dispersive X-ray spectroscopy system, and transmission electron microscopy. The ancient wood showed an unchanged gross wood structure, loss of cell wall birefringence, loss of lignin autoftuorescence, and a loss of the original microfibrillar pattern. The energy dispersive X-ray spectroscopy analysis indicated higher than normal contents of S, Cl, and Na in subfossil wood. Ultrastructural modifications in the cell wall of the subfossil wood could have important implications for further studies involving isotopic and wood anatomical measurements of ancient wood.

scholarly journals Electrochemical Hydrogen Evolution over Hydrothermally Synthesized Re-Doped MoS2 Flower-Like Microspheres

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4631 ◽  
Author(s):  
Juan Aliaga ◽  
Pablo Vera ◽  
Juan Araya ◽  
Luis Ballesteros ◽  
Julio Urzúa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Evolution ◽  
Photoelectron Spectroscopy ◽  
Charge Transfer Resistance ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
Transfer Resistance ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

In this research, we report a simple hydrothermal synthesis to prepare rhenium (Re)- doped MoS2 flower-like microspheres and the tuning of their structural, electronic, and electrocatalytic properties by modulating the insertion of Re. The obtained compounds were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Structural, morphological, and chemical analyses confirmed the synthesis of poorly crystalline Re-doped MoS2 flower-like microspheres composed of few stacked layers. They exhibit enhanced hydrogen evolution reaction (HER) performance with low overpotential of 210 mV at current density of 10 mA/cm2, with a small Tafel slope of 78 mV/dec. The enhanced catalytic HER performance can be ascribed to activation of MoS2 basal planes and by reduction in charge transfer resistance during HER upon doping.

Surface Structural Techniques Applied to Interfaces

MRS Bulletin ◽  
1990 ◽  
Vol 15 (9) ◽  
pp. 38-41 ◽  
Author(s):  
I.K. Robinson
Keyword(s):  
Internal Surface ◽  
Amorphous Solid ◽  
Interface Roughness ◽  
Misfit Dislocations ◽  
Ion Scattering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Subject ◽  
Medium Energy Ion Scattering

An interface is an internal surface, the boundary between two media which may be crystalline, amorphous solid, or liquid. Its close similarity with a surface, a solid-vacuum boundary, suggests that many of the powerful techniques available for studying surfaces might be applied to the interface structure problem. The extent to which this is possible is the subject of this article.The techniques to be discussed in this article include low energy electron diffraction (LEED), medium energy ion scattering (MEIS), x-ray diffraction, and x-ray reflectivity. (The most widely used method, transmission electron microscopy (TEM), is the subject of a separate article in this issue of the MRS BULLETIN.) To summarize what we will find, surface methods were developed to be nonpenetrating in order to have surface sensitivity. This works against us in the interface situation by requiring the use of extremely thin samples, at least on one side of the interface. This means special handling of samples in some cases and raises the possibility of artifac-tual results. Of the three methods, x-ray diffraction is the most penetrating and least surface sensitive; it probably has the greatest potential for widespread use in interface science.This article defines structure as “atomic structure” for this purpose: we are interested in the coordinates of atoms at the interface and their relation to bulk structures on one or both sides. For this reason, we will consider only interfaces that are crystalline on at least one side. Since crystals are by far our strongest structural reference point, much less can be said about other interfaces. We will also consider the morphology of an interface, defined as the boundary of the crystal(s) that demarcates the interface, also at the atomic level. This is most apparent in the form of interface roughness. The roles of strain and misfit dislocations in interface formation, also studied by these techniques, are outside the scope of this article.

scholarly journals Improved Pulse-Controlled Conductance Adjustment in Trilayer Resistors by Suppressing Current Overshoot

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2462
Author(s):  
Hojeong Ryu ◽  
Sungjun Kim
Keyword(s):  
Photoelectron Spectroscopy ◽  
Switching Behavior ◽  
Chemical Analyses ◽  
Cross Point ◽  
Nonlinear Characteristics ◽  
X Ray ◽  
Si3n4 Layer ◽  
Transmission Electron ◽  
Bilayer Device ◽  
Resistance State

In this work, we demonstrate the enhanced synaptic behaviors in trilayer dielectrics (HfO2/Si3N4/SiO2) on highly doped n-type silicon substrate. First, the three dielectric layers were subjected to material and chemical analyses and thoroughly investigated via transmission electron microscopy and X-ray photoelectron spectroscopy. The resistive switching and synaptic behaviors were improved by inserting a Si3N4 layer between the HfO2 and SiO2 layers. The electric field within SiO2 was mitigated, thus reducing the current overshoot in the trilayer device. The reset current was considerably reduced in the trilayer device compared to the bilayer device without a Si3N4 layer. Moreover, the nonlinear characteristics in the low-resistance state are helpful for implementing high-density memory. The higher array size in the trilayer device was verified by cross-point array simulation. Finally, the multiple conductance adjustment was demonstrated in the trilayer device by controlling the gradual set and reset switching behavior.

scholarly journals Sulfidation mechanisms of Fe(iii)-(oxyhydr)oxide nanoparticles: a spectroscopic study

2018 ◽  
Vol 5 (4) ◽  
pp. 1012-1026 ◽  
Author(s):  
Naresh Kumar ◽  
Juan Lezama Pacheco ◽  
Vincent Noël ◽  
Gabrielle Dublet ◽  
Gordon E. Brown
Keyword(s):  
Sulfur Oxidation ◽  
Oxidation Products ◽  
Oxide Nanoparticles ◽  
Chemical Analyses ◽  
X Ray ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Dissolved Sulfide ◽  
Wet Chemical ◽  
X Ray Absorption

We used synchrotron-based X-ray absorption spectroscopy, transmission electron microscopy, and wet chemical analyses to study the sulfidation mechanism(s) and sulfur oxidation products from the reaction of ferrihydrite, goethite, and hematite nanoparticles with dissolved sulfide at different S/Fe molar ratios under anaerobic condition.

An Electron Microscopy Method for Bulk Sample Analysis for Presence of Asbestos

1997 ◽  
Vol 3 (S2) ◽  
pp. 769-770
Author(s):  
Daniel Barron ◽  
Laszlo J. Kecskes
Keyword(s):  
Electron Microscopy ◽  
Polarized Light ◽  
Bulk Sample ◽  
Traditional Use ◽  
Entire Volume ◽  
X Ray ◽  
Transmission Electron ◽  
Microscopy Method ◽  
Quantitative Identification ◽  
Electron Microscopy Method

A method has been developed to identify asbestos-bearing samples. This technique, using scanning and transmission electron microscopy (SEM/TEM) coupled with X-ray fluorescent spectroscopy (XFS), X-ray elemental spectral analysis (EDS/EDAX), and X-ray diffractometry (XRD), supplements the traditional use of dispersion staining and polarized-light optical microscopy. The traditional method is subject to a statistical variance associated with analyzing a small volume of sample and projecting the results to the entire volume of the sample which in many cases is non homogeneous. [1] The simultaneous use of the aforementioned analyses in the new method improves the quantitative identification of highly heterogeneous unknowns.The primary purpose of this study was to determine the essential steps of the identification process that will serve as the basis in the development of an automated particle/fiber recognition program. Five commercially pure asbestos samples of actinolite, amosite, chrysotile, crocidolite, and tremolite, and four common ‘household’ samples were examined.

The Electron Microscope in Earth Sciences

1978 ◽  
Vol 36 (3) ◽  
pp. 404-419
Author(s):  
H.R. Wenk
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Atomic Scale ◽  
Rock Deformation ◽  
Environmental Geology ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes

Over the last ten years the electron microscope has become well-established in mineralogical research and what used to be an exotic instrument has found its way into several geology departments. The rapidly growing literature on electron microscopy in mineralogy has recently been summarized (Wenk et al., 1976) and there is not much point in systematically reviewing progress of the last two years. Philosophy and techniques remained largely the same except that there is more emphasis on high resolution, and energy dispersive X-ray detectors have become standard attachments of electron microscopes. Instead I would like to use some examples studied at the Geology Department at Berkeley during the last few months to illustrate a variety of applications in materials which could not be investigated with conventional techniques such as light microscopy, standard chemical analyses and X-ray diffraction. Geology is a broad science which ranges from the study of crystal structures on the atomic scale to processes taking place during mountain building on the scale of the size of continents. The transmission electron microscope has been used in such diverse fields as crystallography, petrology, rock deformation, stratigraphy and environmental geology.

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