Visualization of clay minerals at the atomic scale

Clay Minerals ◽  
2020 ◽  
pp. 1-16
Author(s):  
Toshihiro Kogure
Keyword(s):  
Electron Microscopy ◽  
Clay Minerals ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Layer Stacking ◽  
Incoherent Imaging ◽  
Dose Imaging ◽  
Stacking Disorder

Abstract This review demonstrates that high-resolution transmission electron microscopy (HRTEM) imaging of clay minerals or phyllosilicates with an incident electron beam along the major zone axes parallel to the constituting layers, in which the contrast corresponds to individual cation columns in the images obtained, is indispensable for elucidating the enigmatic structures of these minerals. Several kinds of variables for layer stacking, including polytypes, stacking disorder and the interstratification of various kinds of unit layers or interlayer materials, are common in phyllosilicates. Local and rigorous determination of such variables is possible only with HRTEM, although examination as to whether the results obtained by the HRTEM images from limited areas represent the whole specimen should be made using other techniques, such as X-ray diffraction. Analysis of these stacking features in clay minerals provides valuable insights into their origin and/or formation processes. Recent state-of-the-art techniques in electron microscopy, including incoherent imaging, superior resolutions of ~0.1 nm and low-dose imaging using new recording media, will also contribute significantly to our understanding of the true structures of clay minerals.

scholarly journals The Occurrence of Authigenic Clay Minerals in Alkaline-Saline Lakes, Pantanal Wetland (Nhecolândia Region, Brazil)

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 718
Author(s):  
Isis Armstrong Dias ◽  
Leonardo Fadel Cury ◽  
Bruno Guimarães Titon ◽  
Gustavo Barbosa Athayde ◽  
Guilherme Fedalto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Clay Minerals ◽  
Saline Lakes ◽  
Clay Fraction ◽  
Water Bodies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Fine Clay ◽  
Pantanal Wetland

Mg clay minerals are usually associated with carbonates in alkaline-saline environments, precipitated from solution and/or transformation from other minerals. The aim of this research is to identify the mineralogy and geochemistry of clay minerals in different alkaline lakes in the Nhecolândia region, the southernmost region of the Pantanal wetland (Brazil). Sediment samples were analyzed by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and transmission electron microscopy. Water samples were analyzed, determining their main cations and anions, in order to understand their relationship with the clays. The analyses allowed classifying the water bodies as saline, oligosaline and freshwater lakes. The sediments are composed mainly of quartz and a fine-clay fraction, dominated by illite, kaolinite and smectite. The XRD results showed illite and smectite mixed-layered in the saline lakes at Barranco Alto farm, whereas at Nhumirim farm, trioctahedral smectite was only observed in one lake. The smectite minerals were normally identified coupled with calcite at the top of the sequences, associated with exopolymeric substances (EPS) in the lakes, suggesting that these minerals are precipitating due to the physical-chemical and biological conditions of the water bodies.

Laccase Biosensor Based on Ag-Doped TiO2 Nanoparticles on CuCNFs for the Determination of Hydroquinone

NANO ◽  
2016 ◽  
Vol 11 (12) ◽  
pp. 1650132 ◽  
Author(s):  
Jie Yang ◽  
Dawei Li ◽  
Zengyuan Pang ◽  
Qufu Wei
Keyword(s):  
Electron Microscopy ◽  
Storage Stability ◽  
Electrochemical Impedance ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
New Material ◽  
And Storage

A novel nanomaterial composed of copper and carbon nanofibers (CuCNFs) decorated with Ag-doped TiO2 (Ag–TiO[Formula: see text] nanoparticles was prepared through electrospinning, carbonization and solvothermal treatment. The composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). The obtained composites were mixed with laccase and Nafion to construct novel hydroquinone biosensor. The electrochemical behavior of the novel biosensor was studied using cyclic voltammetry (CV) and chronoamperometry. The results demonstrated that the biosensor possessed a wide detection linear range (1.20–176.50[Formula: see text][Formula: see text]M), a good selectivity, repeatability, reproducibility and storage stability. This work provides a new material to design more efficient laccase (Lac) based biosensor for hydroquinone detection.

Clay minerals in hydrothermally altered basalts from Middle Atlas, Morocco

Clay Minerals ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 67-77 ◽  
Author(s):  
A. Dekayir ◽  
M. Amouric ◽  
J. Olives
Keyword(s):  
Electron Microscopy ◽  
Clay Minerals ◽  
Crystallization Process ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Equilibrium Conditions ◽  
Transmission Electron ◽  
Middle Atlas ◽  
Higher Temperature ◽  
Main Components

AbstractClay minerals occur as replacements of olivine, pyroxenes, plagioclase and interstitial materials, and as vesicle fillings, in altered basalts from the Middle Atlas (Morocco). Phyllosilicates are the main components of this alteration process. They have been characterized here by optical microscopy, X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy as saponite, talc, corrensite and chlorite. The homogeneity of the chemical compositions of these phyllosilicates, in different alteration environments, probably means that they are controlled by the composition of the hydrothermal fluid. Talc-saponite-corrensite (with dominant saponite) is the clay mineral association most frequently observed (corrensite being more abundant in the vesicular levels of the basalts). Such an association, with no evidence of albite and zeolite, suggests that these basalts have suffered minimal alteration at relatively low temperatures. Another association, chlorite-corrensite, was detected in a deeper (vesicular) sample, probably resulting from a slightly higher temperature. Lastly, only discrete phyllosilicates (i.e. no random mixed-layer minerals) were observed. This suggests that near-equilibrium conditions prevailed during this alteration stage and that a dissolution-crystallization process was the main mechanism of transformation.

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.

Estimation of Quartz in Small Biological Specimens with Transmission Electron Microscopy at 100 KV

1974 ◽  
Vol 32 ◽  
pp. 70-71
Author(s):  
Glenn R. Smith ◽  
Krishna Seshan ◽  
Jerome J. Wesolowski ◽  
Axel G. Berner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Mass Concentration ◽  
Oxygen Plasma ◽  
Human Lung ◽  
X Ray Diffraction ◽  
X Ray ◽  
Biopsy Specimens ◽  
Transmission Electron

Determination of the mass concentration of quartz in small biopsy specimens for clinical diagnostic purposes often cannot be performed by x-ray diffraction and light microscopy. A technique utilizing transmission electron microscopy (TEM) was used to determine the quartz concentration in a human lung specimen taken from a patient suspected of having silicosis.The sample was prepared for examination by low temperature incineration in an oxygen plasma. The inorganic residue was suspended in 0.5 percent Parlodion in amyl acetate. Grids were coated with the sample suspension and subsequently shadowed with a thin film of carbon. Standard quartz particles were prepared in a similar manner.

Zn-rich smectite from the Silver Coin Mine, Nevada, USA

Clay Minerals ◽  
2015 ◽  
Vol 50 (4) ◽  
pp. 417-430 ◽  
Author(s):  
S. Kaufhold ◽  
G. Färber ◽  
R. Dohrmann ◽  
K. Ufer ◽  
G. Grathoff
Keyword(s):  
Electron Microscopy ◽  
Ir Spectroscopy ◽  
Fine Fraction ◽  
Structural Formula ◽  
X Ray Diffraction ◽  
Geochemical Environment ◽  
X Ray ◽  
Silver Coin ◽  
Transmission Electron

AbstractMore than 100 minerals have been reported from the Silver Coin Mine, Nevada USA; five new minerals have been discovered here, due to the unusual geochemical environment. The present study reports on the investigation of a greenish clayey sample from the Silver Coin Mine. After the separation of a fine fraction to enrich the clay minerals, sauconite, a rare Zn-rich smectite, was found by X-ray diffraction (XRD) and was further characterized by differential thermal analysis (DTA), infrared (IR) spectroscopy and scanning electron microscopy (SEM). The Zn-rich smectite is accompanied by illite, minor kaolinite/halloysite and traces of gibbsite (as was indicated by the IR spectroscopy). The occurrence indicates an acidic environment probably caused by oxidation of sulfides.The determination of the structural formula, to further characterize the Zn-rich smectite, was difficult because of the multi-clay mineral assembly. However, different SEM-EDX (energy dispersive X-ray) approaches as well as transmission electron microscopy (TEM)-EDX analysis helped to characterize the smectite as Al-rich sauconite with some exchangeable K+.

Synthesis and Characterizations of Metal Oxide-Sulfonic Acid Functionalized ZSM-5 for Photocatalytic Degradation and Adsorption of Dimethylarsenic Acid

2014 ◽  
Vol 699 ◽  
pp. 994-999 ◽  
Author(s):  
Alias Mohd Yusof ◽  
Nur Nadira Sulaiman ◽  
Hadi Nur
Keyword(s):  
Electron Microscopy ◽  
Absorption Band ◽  
Ultra Violet ◽  
Arsenic Species ◽  
Zinc Nitrate ◽  
X Ray Diffraction ◽  
Alkyl Groups ◽  
Transmission Electron ◽  
Stretching Vibration

TiO2 and ZnO were incorporated into ZSM-5 using titanium tetrachloride and zinc nitrate as the precursors respectively. The functional group of ZSM-5 was further modified using mercaptopropyl trimethoxysilane (MPTS). This method was used to produce a two-in-one composite namely TiO2-ZSM5-SH and ZnO-ZSM5-SH which holds the abilities to degrade organic pollutants as well as to remove them from the environment. Determination of the composition and morphology of all synthesized catalyst complexes were characterized using Fourier Transformed Infrared (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HR-TEM). Results obtained indicated that the average diameters for TiO2-ZSM5-SH particles are 2.398 μm, slightly larger than the diameter of ZnO-ZSM5-SH particles with an average of 1.8067 μm. Both TiO2-ZSM5-SH and ZnO-ZSM5-SH appeared as sphere-like shape and amorphous since both metal oxides were incorporated into the ZSM-5 pores. The compositions of these complexes were proven by the presence of a strong silica absorption band showing the existence of Si-O stretching vibrations and SiO2 asymmetric vibrations in the synthesized complexes. For TiO2-ZSM5-SH, the Ti-O stretching vibration can be seen at 3467.29 cm-1 and at 1637.86 cm-1 while Zn-O absorption band appeared at 455.52 cm-1 in ZnO-ZSM5-SH. The symmetric and asymmetric vibrations of –CH2 and –CH3 indicate the existence of alkyl groups in the ZSM-5. The ability of catalyst complexes synthesized as photocatalyst were applied and tested on the photodegradation of dimethylarsenic acid (DMA) under ultra violet (UV) radiation which showed that these catalyst complexes are proven be able to degrade DMA into less toxic intermediates and are able to adsorb the remaining arsenic species from the aqueous solutions.

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