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.

Mixed-layer mica-chlorite in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain)

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 307-324 ◽  
Author(s):  
M. D. Ruiz Cruz
Keyword(s):  
Electron Microscopy ◽  
Mixed Layer ◽  
Analytical Electron Microscopy ◽  
Low Grade ◽  
X Ray ◽  
Betic Cordilleras ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Microscopy Data ◽  
Ray Patterns

AbstractMixed-layered phyllosilicates with composition intermediate between mica and chlorite were identified in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain), and studied by X-ray diffraction, and transmission and analytical electron microscopy. They occur both as small grains in the rock matrix, and associated with muscovitechlorite stacks. Transmission electron microscope observations revealed a transition from chlorite to ordered 1:1 interstratifications through complex 1:2 and 1:3 interstratifications. Analytical electron microscopy data indicate a composition slightly different from the sum of discrete trioctahedral chlorite and dioctahedral mica. The types of layer transitions suggest that mixed-layer formation included two main processes: (1) the replacement of a brucite sheet by a cation sheet in the chlorite structure; and (2) the precipitation of mica-like layers between the chlorite layers. The strongest diffraction lines in oriented X-ray patterns are: 12.60 Å (002), 7.98 Å (003), 4.82 Å (005) and 3.48 Å (007).

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).

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.

High Spatial Resolution Assessment of the Structure, Composition, and Electronic Properties of Nanowire Arrays

2001 ◽  
Vol 635 ◽  
Author(s):  
M.S. Sander ◽  
A.L. Prieto ◽  
Y.M. Lin ◽  
R. Gronsky ◽  
A.M. Stacy ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electronic Properties ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Analytical Electron Microscopy ◽  
Nanowire Arrays ◽  
Composition Gradient ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Electron Energy Loss

AbstractWe have employed transmission electron microscopy (TEM) and analytical electron microscopy to perform preliminary assessment of the structure, composition and electronic properties of nanowire arrays at high spatial resolution. The two systems studied were bismuth and bismuth telluride nanowire arrays in alumina (wire diameters ~40nm), both of which are promising for thermoelectric applications. Imaging coupled with diffraction in the TEM was employed to determine the grain size in electrodeposited Bi2Te3 nanowires. In addition, a composition gradient was identified along the wires in a short region near the electrode by energy-dispersive x-ray spectroscopy. Electron energy loss spectroscopy combined with energy-filtered imaging in the TEM revealed the excitation energy and spatial variation of plasmons in bismuth nanowire arrays.

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

The Use of ELNES for Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 664-665
Author(s):  
A.J. Craven ◽  
M. MacKenzie
Keyword(s):  
Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Analytical Electron Microscopy ◽  
Local Environment ◽  
Edge Structure ◽  
Similar Shape ◽  
Analytical Electron ◽  
Electron Energy Loss ◽  
Combining Information

The performance of many materials systems depends on our ability to control the distribution of atoms on a nanometre or sub-nanometre scale within those systems. This is as true for steels as it is for semiconductors. A key requirement for improving their performance is the ability to determine the distribution of the elements resulting from processing the material under a given set of conditions. Analytical electron microscopy (AEM) provides a range of powerful techniques with which to investigate this distribution. By combining information from different techniques, many of the ambiguities of interpretation of the data from an individual technique can be eliminated. The electron energy loss near edge structure (ELNES) present on an ionisation edge in the electron energy loss spectrum reflects the local structural and chemical environments in which the particular atomic species occurs. Thus it is a useful contribution to the information available. Since a similar local environment frequently results in a similar shape, ELNES is useful as a “fingerprint”.

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.

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