scholarly journals Evolution of Clays in Cretaceous Marly Series (Álava Block, Basque Cantabrian Basin, Spain): Diagenesis and Detrital Input Control

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 40 ◽  
Author(s):  
Javier Arostegui ◽  
Xabier Arroyo ◽  
Fernando Nieto ◽  
Blanca Bauluz
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Clay Mineralogy ◽  
Tectonic Deformation ◽  
Total Charge ◽  
Carbonate Sediments ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Input Control ◽  
Diagenetic Evolution

Two stratigraphic sections of carbonate sediments with significant thickness differences and without appreciable tectonic deformation were studied near the trough and on a threshold zone at the Álava Trough. Such characteristics make them appropriate to analyze the influence of a slow progression of the diagenesis over the original clay suite. X Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Analytical Electron Microscopy (AEM) techniques were applied in natural and alkylammonium-treated samples. Diagenesis slightly modified the clay mineralogy, the disappearance of smectite, and the variation in the content and ordering of the I/S mixed layer, with burial being the most noteworthy process. The total charge in the 2:1 expandable layers of smectite and I/S shows a slight increase, preferentially located on tetrahedral sheets, with depth. The data suggest a moderate diagenesis grade for the studied materials. The combination of techniques allowed identification of several types of detrital micaceous phases, as well-crystallized K-rich micas, Na-K micas, mica-chlorite stacks, and illites, with an expandable behaviour after the alkylammonium treatment. The total charge of illites did not change with diagenesis, suggesting their detrital origin. This research shows that the detrital assemblage masks the diagenetic evolution in the basin, which indicates the importance of the combination of different techniques to infer correctly the diagenetic grade in a sedimentary basin.

Crystal Chemistry and Microstructures of Uranyl Phosphates

1997 ◽  
Vol 506 ◽  
Author(s):  
Y. Suzuki ◽  
T. Murakami ◽  
T. Kogure ◽  
H. Isobe ◽  
T. Sato
Keyword(s):  
Electron Microscopy ◽  
Crystal Chemistry ◽  
Analytical Electron Microscopy ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Uranyl Phosphate ◽  
Uranyl Phosphates ◽  
Form Solid Solution

ABSTRACTThe crystal chemistry and microstructures of saleeite (Mg(UO2PO4)2•10H2O) and metatorbernite (Cu(UO2PO4)2•8H2O), from Koongarra, Australia and Shinkolobwe, Congo, were examined by X-ray diffraction analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis, transmission electron microscopy (TEM) and analytical electron microscopy. The uranyl phosphates consist of uranyl phosphate layers with cations and waters in the interlayers. The IR spectra of saleeite and metatorbernite show the presence of hydroxyls in the interlayers in addition to water molecules. The d002 spacings of the hydrated phases of saleeite and metatorbernite up to 300°C reveal that the uranyl phosphate layers themselves are quite stable in the temperature range although the interlayer water molecules are lost easily. The presence of a mixed phase of saleeite and metatorbernite is confirmed in the micrometer and nanometer scales. However, SEM and TEM examination suggest saleeite and metatorbemite generally grow separately, and rarely form solid solution or interstratification. The results imply that U is retained in uranyl phosphate minerals even when the temperature at around repositories increases, and that saleeite and metatorbernite precipitate independently from solution according to their solubilities even when Mg2+ and Cu2+ coexist in solution.

Kaolin in the net-like horizon of laterite in Hubei, south China

Clay Minerals ◽  
2009 ◽  
Vol 44 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Hanlie Hong ◽  
Zhaohui Li ◽  
Muzhuang Yang ◽  
Ping Xiao ◽  
Huijuan Xue
Keyword(s):  
Electron Microscopy ◽  
South China ◽  
Energy Dispersive Spectrometer ◽  
Clay Mineralogy ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Chemical Index ◽  
Mineral Components ◽  
Chemical Index Of Alteration ◽  
Matrix Components

AbstractThe clay mineralogy and chemical composition of the white veins, red matrix and both Fe- and Mn-bearing nodules occurring in a laterite profile in Hubei, south China were investigated using X-ray diffraction, scanning electron microscopy equipped with an energy-dispersive spectrometer, and high-resolution transmission electron microscopy. The results show that the mineral components of the red matrix are mainly quartz, kaolinite, halloysite, goethite and minor illite, whereas the white net-like veins contain mostly quartz, kaolinite, halloysite, and illite. In the net-like horizon, the chemical index of alteration (CIA, the ratio of Al2O3/(Al2O3+CaO+K2O+Na2O)) and the TiO2/Al2O3 ratio are 89.8% and 0.021 for the white vein and 90.7% and 0.025 for the red matrix, respectively. Both white-vein and red-matrix components have similar TiO2/Al2O3 ratios, and are similar to the ratio 0.027 of the unaltered bedrock. The similarity in TiO2/Al2O3 values indicates that all three portions of the laterite soil share the same origin. Also, although the white-vein and red-matrix components differ in Fe2O3 abundance, the similar CIA values do imply similar degrees of alteration. The Fe-bearing and Mn-bearing nodules were produced by the local accumulation of Fe2O3 and MnO, respectively. Halloysite in the weathering profile occurs in two different morphologies, tubular and platy crystals. Tubular halloysite occurs both in the red matrix and the Fe-bearing nodule whereas platy halloysite occurs only in the white vein and Mn-bearing nodule assemblages. Crystallization of small tubular halloysite from Si and Al concretions in the red matrix is observed, indicating that the morphology of these crystals in the weathering environment is mainly controlled by Fe3+ cations, whereas platy halloysite may be derived from the hydration of kaolinite.

Origin of mixed-layered (R1) muscovite-chlorite in an anchizonal slate from Puncoviscana Formation (Salta Province, Argentina)

Clay Minerals ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 317-332 ◽  
Author(s):  
M. Do Campo ◽  
F. Nieto
Keyword(s):  
Electron Microscopy ◽  
Mixed Layer ◽  
Analytical Electron Microscopy ◽  
Aqueous Fluid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Dioctahedral Mica ◽  
Mixed Layering

AbstractMica-chlorite mixed-layering was identified by X-ray diffraction (XRD) as a major or subordinate constituent in several slates of the Puncoviscana Formation from Sierra de Mojotoro (Eastern Cordillera, NW Argentina). In order to determine the crystallochemical characteristics of these mixed-layered sequences and interpret their petrological meaning, anchizonal slate P90 was chosen for TEM observations. In this slate, dioctahedral mica and chlorite form interleaved phyllosilicate grains (IPG) or stacks, up to 110 um long, preferentially oriented with (001) planes at a high angle to the slaty cleavage but also oblique to S0.In agreement with XRD results, the main phyllosilicates identified by transmission electron microscopy (TEM) were dioctahedral mica and random mixed-layer muscovite-chlorite, with chlorite in subordinate amounts and scarce smectite. In the lattice-fringe images of mixed-layer packets, a sequence of irregular stacking that produced apparent 24 Å (10 + 14) layers was observed, but it was frequently possible to distinguish the 10 Å layers from adjacent 14 Å layers. In nearly all packets, 14 Å layers prevail, exhibiting 14 Å:10 Å ratios between 1:1 and 3:1. Some elongated lenticular fissures which are probably a consequence of layer collapse caused by the TEM vacuum were identified in these packets. The straight, continuous appearance of lattice fringes plus the scarce evidence of collapsed layers identified suggest that these packets correspond principally to mixed-layer muscovite-chlorite, which is confirmed by analytical electron microscopy analyses. However, smectite-like layers are probably the third component of some of these mixed-layer sequences, which may account for their high Si and low (Fe + Mg) contents, their low interlayer charge in relation to theoretical interlayer muscovite-chlorite, and for the presence of Ca in the interlayer site.Textural relationships between chlorite and muscovite packets in IPG along with the observed transformations from 14 Å to 10 Å along the layer, is compatible with a prograde metamorphic replacement of chlorite in stacks by dioctahedral mica layers, probably in the presence of an aqueous fluid.

Structural study of deactivation of gallosilicate catalysts

1993 ◽  
Vol 51 ◽  
pp. 726-727
Author(s):  
C. Choi-Feng ◽  
J. B. Hall ◽  
B. J. Huggins ◽  
D. Li ◽  
J. A. Kaduk ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Analytical Electron Microscopy ◽  
Light Olefins ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Low Reaction Temperature ◽  
Different Temperatures

Gallosilicate molecular sieves with an MFI structure are very promising catalysts for upgrading light olefins and paraffins to aromatics. Gallosilicate catalysts are quite stable at low reaction temperature, however, when subjected to high temperature, gallosilicate catalysts deactivate rapidly. The activity and selectivity of these catalysts are greatly influenced by both framework and non-framework gallium. Although the framework gallium imparts acidity to the sieve, the nature of the non-framework gallium is unclear. In the present study, combined techniques of analytical electron microscopy (AEM), high resolution transmission electron microscopy (HREM) and X-ray diffraction (XRD) have been applied to study the fate of framework and non-framework gallium in progressively deactivated gallosilicate molecular sieve catalysts. To study this progressive process, fresh gallosilicate molecular sieve and the gallosilicate catalysts (with 40% Cab-O-Sil matrix) subjected to steaming treatments at different temperatures and durations were characterized.The microstructure of fresh gallosilicate catalysts consists of highly crystalline molecular sieve which is uniformly distributed in the amorphous supporting matrix (Fig. 1).

scholarly journals Ammonium-bearing micas in very low-grade metapelites: micro- and nano-texture and composition

Clay Minerals ◽  
2018 ◽  
Vol 53 (2) ◽  
pp. 105-116 ◽  
Author(s):  
Blanca Bauluz ◽  
Fernando Nieto
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Iberian Range ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Ir Transmission ◽  
Electron Energy Loss ◽  
Two Populations

ABSTRACTThe present study examines the micro- and nano-texture and composition of ammonium-bearing and potassium micas in very-low grade metamorphic black Silurian shales from the SE Iberian Range (NE Spain). Two organic-rich shales were studied by X-ray diffraction (XRD), infrared spectroscopy (IR), transmission electron microscopy (TEM), analytical electron microscopy (AEM) and electron energy loss spectroscopy (EELS). The XRD showed the presence of two populations of micas: pure K micas with d001 = 9.98 Å and ammonium-bearing micas with larger d001 values (10.08 Å and 10.05 Å). The latter values indicate NH4 contents between 13 and 29% in the interlayer, which was confirmed by IR. Interstratifications of smectite and mica layers in the mica packets were not detected by XRD and TEM. Mica packets with sizes ranging from 100 to 250 Å show disordered polytypes and (001) lattice fringes that reflect the presence of K- and NH4-bearing layers (9.9–10.2 Å).The combination of AEM and EELS analyses on powdered and lamellar samples indicates that micas have typical dioctahedral compositions with highly variable K contents. This variation in K is consistent with the presence of K and NH4 in the interlayers, even though the NH4 and K are not distributed homogeneously; rather they are segregated in nm-sized domains in the mica interlayer.

Contrasted mineralogical composition of the laterite cover on serpentinites of Nkamouna-Kongo, southeast Cameroon

Clay Minerals ◽  
2009 ◽  
Vol 44 (2) ◽  
pp. 221-237 ◽  
Author(s):  
R. Yongue–Fouateu ◽  
M. Yemefack ◽  
A. S. L. Wouatong ◽  
P. D. Ndjigui ◽  
P. Bilong
Keyword(s):  
Electron Microscopy ◽  
Microprobe Analysis ◽  
Clay Mineralogy ◽  
Mineralogical Composition ◽  
Ultramafic Rocks ◽  
Flow Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Close Relationship

AbstractFour drill cores along a lateritic hill in Nkamouna-Kongo (southeast Cameroon) were studied using microprobe analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and infrared spectroscopy. The main objective of the study was to investigate the occurrence of clay silicates while evaluating the Ni-Co content of the laterite for potential mineral exploitation. The thick lateritic profiles (>40 m deep) developed on serpentinized ultramafic rocks have an Fe-rich clayey fraction, with goethite as the main mineralogical constituent and secondary quartz and relicts of magnetite-maghemite as accessory minerals. Silicate clays are less abundant and occur mainly towards the top of the profiles. At the summit of the interfluve, kaolinite and some gibbsite are associated with goethite. Along the slopes, at the bottom of profiles, the weathered bedrock shows the presence of smectite (Fe-beidellite) and kaolinite, probably due to slower water-flow conditions. Towards the top of the profile in the lower clay, ferruginous and upper clay horizons, only kaolinite remains with gibbsite, after the leaching of silica and soluble cations following repeated remobilization-recrystallization processes. At the summit, where the downward movement of water is rapid, no smectite was identified. As a whole, the mineralogical composition of the material varies in close relationship with the drainage, leading to a contrasted clay mineralogy marked by the presence of Fe-beidellite and kaolinite at the bottom, and that of kaolinite and gibbsite at the summit of the profiles.

High Strength Nanoscale Al/Al3Sc Multilayers formed by Interface Reaction

2002 ◽  
Vol 727 ◽  
Author(s):  
M.A. Phillips ◽  
B.M. Clemens ◽  
W.D. Nix
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Interface Reaction ◽  
High Strength ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Hardness Tests ◽  
Analytical Electron ◽  
Nanoindentation Hardness

AbstractPolycrystalline Al/Sc multilayer samples are grown via magnetron sputtering. The deposition of Sc onto Al results in significant intermixing between the two components. Substrate curvature, measured in-situ during deposition, reveals behavior similar to that seen in other systems where a slow diffuser is deposited onto a fast diffuser. The multilayer films are further characterized via transmission electron microscopy (TEM), analytical electron microscopy, and X-ray diffraction (XRD), confirming the intermixing and formation of a coherent crystalline phase, likely to be Al3Sc, in the interfacial regions. Nanoindentation hardness tests show that by adding a few percent of Sc to Al films and carefully controlling the location of the Sc, increases in hardness up to 6 times that of a pure Al film can be obtained.

TEM study of mineral transformations in fired carbonated clays: relevance to brick making

Clay Minerals ◽  
2004 ◽  
Vol 39 (3) ◽  
pp. 333-344 ◽  
Author(s):  
B. Bauluz ◽  
M. J. Mayayo ◽  
A. Yuste ◽  
C. Fernandez-Nieto ◽  
J. M. Gonzalez Lopez
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Small Scale ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Carbonate Decomposition ◽  
Textural Changes ◽  
Mineral Transformations ◽  
Compositional Characterization ◽  
Selection Of

AbstractThis study uses transmission electron microscopy (TEM) and analytical electron microscopy (AEM) supported by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to investigate the mineralogical and textural changes produced in carbonated clays by firing. Sample bars were prepared using raw clays composed of quartz, illite and carbonates with minor amounts of smectite, chlorite, feldspars and Fe oxides. The raw samples were then fired at temperatures of between 800 and 1050°C. The XRD data show that increases in firing temperature result in dehydroxylation of clay minerals, carbonate decomposition and the formation of Ca-bearing silicates (e.g. gehlenite, wollastonite, pyroxenes and anorthite). The sizes of the Ca-silicate crystals make the use of the SEM inappropriate since they lie below the resolution threshold. However, TEM/AEM do provide the required textural and compositional characterization, revealing that there is a broad range of pyroxene compositions, some of which resemble fassaite, and that Ca/Mg ratios increase with temperature. The TEM also shows significant dehydroxylation and vitrification of the clay-rich matrix at T of ~800°C. Observed mineralogical and textural changes probably occurred in a system with a local disequilibrium much like small-scale, high-temperature metamorphic reactions (i.e. pyrometamorphism). The importance of these results is that they enable the selection of more appropriate raw clay composition and firing dynamics (temperature, firing duration and cooling rate) for both the brickmaking industry and brick conservation in the field of cultural heritage.

scholarly journals Nanocomposite powders for new contact materials based on copper and alumina

2008 ◽  
Vol 14 (4) ◽  
pp. 215-218 ◽  
Author(s):  
Marija Korac ◽  
Zeljko Kamberovic ◽  
Milos Tasic ◽  
Milorad Gavrilovski
Keyword(s):  
Electron Microscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Copper Matrix ◽  
X Ray Diffraction ◽  
Characterization Methods ◽  
Contact Materials ◽  
Transmission Electron ◽  
Nanocomposite Powders

This paper is a contribution to characterization of Cu-Al2O3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

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