scholarly journals Clay mineral genesis and chemical evolution in the Miocene sediments of Somosaguas, Madrid Basin, Spain

Clay Minerals ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 187-201 ◽  
Author(s):  
O. Fesharaki ◽  
E. García-Romero ◽  
J. Cuevas-González ◽  
N. López-Martínez
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clay Minerals ◽  
Analytical Electron Microscopy ◽  
Source Area ◽  
Alluvial Fan ◽  
Granitic Rocks ◽  
Central System ◽  
Transmission Electron ◽  
Spanish Central System

AbstractA mineralogical and microtextural study of Somosaguas Miocene deposits, located in the Madrid Basin (western Madrid, Spain), was carried out using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and optical microscopy, whereas crystal chemistry data were obtained by analytical electron microscopy-transmission electron microscopy and electron icroprobe analysis. Four stratigraphic sections were studied, compising detrital rocks representing intermediate and distal facies from alluvial fan deposits. The predominant source area of these sediments was the granitic rocks of the Spanish Central System with a lesser contribution of metamorphic rocks. Clayey arkoses are the most abundant rocks of these sections, typical of granite alteration under warm, semi-arid climates. The mineralogy is characterized by phyllosilicates, followed by feldspars and quartz. The data obtained reveal mineral mixtures of detrital (quartz, feldspars, kaolinite, micas and chlorite), transformed (illite and beidellite) and neoformed (montmorillonite) origin. Clay minerals resulted from interactions between detrital minerals and meteoric waters. Two trends of degradation of micas are detected. The first shows a transition from muscovites and dioctahedral illites, to beidellites. The other trend is defined by the biotite degradation to beidellites with different layer charge and octahedral Fe content. Montmorillonites were neoformed from the hydrolysis and weathering of primary minerals (feldspars and muscovite). Magnesian clay minerals such as sepiolite, palygorskite and trioctahedral smectites, extremely abundant in the centre of the basin, were not detected in Somosaguas sediments.

scholarly journals Analytical High-resolution Electron Microscopy Reveals Organ-specific Nanoceria Bioprocessing

2017 ◽  
Vol 46 (1) ◽  
pp. 47-61 ◽  
Author(s):  
Uschi M. Graham ◽  
Robert A. Yokel ◽  
Alan K. Dozier ◽  
Lawrence Drummy ◽  
Krishnamurthy Mahalingam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Organ Specific

This is the first utilization of advanced analytical electron microscopy methods, including high-resolution transmission electron microscopy, high-angle annular dark field scanning transmission electron microscopy, electron energy loss spectroscopy, and energy-dispersive X-ray spectroscopy mapping to characterize the organ-specific bioprocessing of a relatively inert nanomaterial (nanoceria). Liver and spleen samples from rats given a single intravenous infusion of nanoceria were obtained after prolonged (90 days) in vivo exposure. These advanced analytical electron microscopy methods were applied to elucidate the organ-specific cellular and subcellular fate of nanoceria after its uptake. Nanoceria is bioprocessed differently in the spleen than in the liver.

scholarly journals Identification of interstratified mica and pyrophyllite monolayers within chlorite using advanced scanning/transmission electron microscopy

2019 ◽  
Vol 104 (10) ◽  
pp. 1436-1443
Author(s):  
Guanyu Wang ◽  
Hejing Wang ◽  
Jianguo Wen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Clay Minerals ◽  
Scanning Transmission Electron Microscopy ◽  
Dark Field ◽  
Chemical Compositions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

Abstract Interstratified clay minerals reflect the weathering degree and record climatic conditions and the pedogenic processes in the soil. It is hard to distinguish a few layers of interstratified clay minerals from the chlorite matrix, due to their similar two-dimensional tetrahedral-octahedral-tetrahedral (TOT) structure and electron-beam sensitive nature during transmission electron microscopy (TEM) imaging. Here, we used multiple advanced TEM techniques including low-dose high-resolution TEM (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging combined with energy-dispersive spectroscopic (EDS) mapping to study interstratified layers in a chlo-rite sample from Changping, Beijing, China. We demonstrated an interstratified mica or pyrophyllite monolayer could be well distinguished from the chlorite matrix by projected atomic structures, lattice spacings, and chemical compositions with advanced TEM techniques. Further investigation showed two different transformation mechanisms from mica or pyrophyllite to chlorite: either a 4 Å increase or decrease in the lattice spacing. This characterization approach can be extended to the studies of other electron-beam sensitive minerals.

Characterization of pulsed laser deposited MoS2 by transmission electron microscopy

1993 ◽  
Vol 8 (11) ◽  
pp. 2933-2941 ◽  
Author(s):  
S.D. Walek ◽  
M.S. Donley ◽  
J.S. Zabinski ◽  
V.J. Dyhouse
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Solid Phase ◽  
Analytical Electron Microscopy ◽  
Pulsed Laser ◽  
Cross Sectional ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Novel Method

Molybdenum disulfide is a technologically important solid phase lubricant for vacuum and aerospace applications. Pulsed laser deposition of MoS2 is a novel method for producing fully dense, stoichiometric thin films and is a promising technique for controlling the crystallographic orientation of the films. Transmission electron microscopy (TEM) of self-supporting thin films and cross-sectional TEM samples was used to study the crystallography and microstructure of pulsed laser deposited films of MoS2. Films deposited at room temperature were found to be amorphous. Films deposited at 300 °C were nanocrystalline and had the basal planes oriented predominately parallel to the substrate within the first 12–15 nm of the substrate with an abrupt upturn into a perpendicular (edge) orientation farther from the substrate. Spherically shaped particles incorporated in the films from the PLD process were found to be single crystalline, randomly oriented, and less than about 0.1 μm in diameter. A few of these particles, observed in cross section, had flattened bottoms, indicating that they were molten when they arrived at the surface of the growing film. Analytical electron microscopy (AEM) was used to study the chemistry of the films. The x-ray microanalysis results showed that the films have the stoichiometry of cleaved single crystal MoS2 standards.

Evidence of a Precursor in the Neoformation of Palygorskite — New Data by Analytical Electron Microscopy

Clay Minerals ◽  
1994 ◽  
Vol 29 (2) ◽  
pp. 255-264 ◽  
Author(s):  
M. Suarez ◽  
J. M. Martin Pozas ◽  
M. Robert ◽  
F. Elsass
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Arid Environment ◽  
Relative Increase ◽  
Climatic Conditions ◽  
Early Diagenesis ◽  
Alluvial Fan ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Small Basin

AbstractThe rocks of the palygorskite deposit at Bercimuel (Segovia, Spain) have been studied by transmission electron microscopy and microanalysis. These rocks correspond to the zone of convergence of two alluvial fan systems that have filled the small basin of the River Riaza and would originally have been composed of illite and quartz silts. Among the accumulations of palygorskite it is possible to observe surrounded particles of micromicas that have undergone dissolution and opening thereby giving rise to disordered illite-smectite mixed-layer clays. This process continued up to the individualization of structural relics formed of units of 1–5 layers. At the same time, the chemical composition was modified with a loss of K and Al and a relative increase in Si and Mg, progressively evolving towards the composition of palygorskite. The paleogeographic position of the deposits, and the climatic conditions (arid environment), appear to be the dominant factors in the neoformation of palygorskite by alteration of the original sediments. The basic mineralogical process could be referred to as ‘early diagenesis’ in the formation of calcretes.

Energy-filtering Transmission Electron Microscopy in materials and life science

1994 ◽  
Vol 52 ◽  
pp. 936-937
Author(s):  
L. Reimer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Analytical Electron Microscopy ◽  
Edge Structure ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Plasmon Loss ◽  
Electron Energy Loss

Energy-filtering transmission electron microscopy can be realized by an imaging filter lens in thecolumn of a TEM, a post-column electron energy-loss spectrometer or a dedicated STEM. This offers new possibilities in analytical electron microscopy by combining the operation modes of electron-spectroscopic imaging (ESI), electron-spectroscopic diffraction (ESD) and the record of an electron energy-loss spectrum (EELS).ESI can be used in the zero-loss mode to remove all inelastically scattered electrons. Thicker amorphous and crystalline specimens can be observed without chromatic aberration and with a transmissionof 10−3 up to 80(110) and 150(200) μg/cm2 at 80(120) keV, respectively. This results in a condiserable increase of scattering, phase and Bragg contrast, especially for low Z material because the ratio of inelastic-to-elastic cross section increases as 20/Z with decreasing atomic number. In future energy-filtered high-resolution crystal-lattice images will offer us a better comparison with dynamical simulations. Plasmon loss filtering can be applied for a better separation of phases (e.g. precipitates in a matrix), which differ in their plasmon loss by about 1 eV. Owing to intersections of the energy loss spectra, different parts of a specimen can change their contrast when tuning the selected energy window. Structures containing non carbon atoms will beconsiderably increased in a bright field like contrast relative to the carboneous matrix just below the carbon K edge (structure—sensitive imaging).

Expanding behaviour, structural disorder, regular and random irregular interstratification of 2:1 layer-silicates studied by high-resolution images of transmission electron microscopy

Clay Minerals ◽  
1986 ◽  
Vol 21 (5) ◽  
pp. 827-859 ◽  
Author(s):  
H. Vali ◽  
H. M. Köster
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Epoxy Resin ◽  
Clay Minerals ◽  
Central Zone ◽  
Double Layers ◽  
X Rays ◽  
Ammonium Ions ◽  
Transmission Electron

AbstractExpanding and non-expanding layers of interstratified clay minerals have been examined by high-resolution transmission electron microscopy. Permanent expansion of swelling layers under the electron beam was achieved by intercalation of n-alkylammonium ions, especially the octadecylammonium ion. Oriented flakes of clay minerals were prepared by embedding the expanded or non-expanded clay minerals in epoxy resin, followed by centrifugation before hardening of the resin. The minerals were then cut perpendicular to 001 using an ultramicrotome. Crystals of macroscopic trioctahedral vermiculites show homogeneous interplanar distances of 24 Å after intercalation of octadecylammonium ions. Crystals of dioctahedral soil vermiculites often show a central zone with non-expanding 10 Å layers; the outer zone shows a disturbed layer sequence extensively expanded by n-alkylammonium ions. After embedding in epoxy resin, vermiculites show stable 9·2 Å interplanar spacings but smectites expand to 13 Å. Montmorillonites of the Wyoming type show curved stacks of layers. Most of the layer stacks of montmorillonites of the Cheto type are split and disordered aggregates of single layers are formed. Crystals of illites and glauconites are built up of aggregated small stacks of 10 Å layers, the layer stacks consisting of 10 layers. Mostly the boundaries of the layer stacks are parallel to their 001 planes; sometimes low-angle boundaries are found. The dimensions of the layer stacks, ∼ 100 Å thick and some hundreds of Å in plane, are equal to the dimensions of the domains of coherent scattering of X-rays. The border layers between the layer stacks are identical with those 5 to 10% of layers which swell with glycerol or ethylene glycol during X-ray analysis. Some of the layer stacks of illite and glauconite crystals are expanded by octadecylammonium ions within a fortnight. The other stacks show unchanged 10 Å spacings. The different expanding behaviour of different layer stacks reflects the heterogeneity of the layer-charge distribution in the mica clay minerals. K-bentonites show the same expanding behaviour as illites and glauconites but the number of layers expanding with octadecylammonium ions is greater in K-bentonites than in illite crystals. Expanded mixed-layered minerals of the illite-smectite type show a different layer stacking sequence from illites. Random irregular stacking of mica layers with expanded layers are recognized rather than coherent stacks of mica layers. The crystals have a stepped morphology, perhaps effected by translations along the 001 plane. After reaction of the rectorite from Garland County with octadecylammonium ions, the non-expanded mica layers and the expanded smectite-like layers can be distinguished. The heterogeneity of the interlayer charges of the smectite layers is documented by the formation of alkyl double-layers with 17 Å spacings and alkyl triple-layers with 21 Å spaces in irregular sequence. The ‘rectorite’ from the Goto Mine expands nearly homogeneously in comparison with the rectorite from Garland County. After reaction with octadecylammonium ions, interplanar spacings of mostly 31 Å are observed but rarely spacings of 27 Å. The smectite layers of the corrensite from Kaubenheim are expanded by tetradecyl-ammonium ions to 18 Å spacings by formation of alkyl double-layers. A regular 1 : 1 layer structure of 14 Å chlorite layers and expanded 18 Å smectite layers with total spacing of 32 Å can be observed. Muscovite and pyrophyllite are not expandable by n-alkyl-ammonium ions within a fortnight. However, sporadic layers of celadonite crystals are expanded. Generally the 10 Å or 9·2 Å layers extend over the whole crystals of the three minerals. In celadonite crystals, disorder is caused sporadically by interrupted layers or slightly enlarged layer spacings.

High Resolution Tem Studies of β-Alumina Type Structures

1983 ◽  
Vol 31 ◽  
Author(s):  
K. J. Morrissey ◽  
Z. Elgat ◽  
Y. Kouh ◽  
C. B. Carter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Analytical Electron Microscopy ◽  
Image Simulation ◽  
Commercial Alumina ◽  
Transmission Electron ◽  
Analytical Electron ◽  
High Resolution Tem ◽  
High Resolution Images

ABSTRACTHigh resolution transmission electron microscopy (HRTEM) has been used to study structures found in secondphase particles in commercial alumina compacts. Analytical electron microscopy has been used to identify elements present in the particles. Computer image simulation has been used for both the structural interpretation of high resolution images and predicting the effect which the presence of other elements would have on the observed structures.

Sign in / Sign up

Export Citation Format

Share Document