Coexisting nanoscale phases of K-illite, NH4,K-illite and NH4-illite-smectite: an organic nitrogen contribution in the hydrothermal system of Harghita Bãi, East Carpathians, Romania

Clay Minerals ◽  
2019 ◽  
Vol 54 (1) ◽  
pp. 27-40 ◽  
Author(s):  
Iuliu Bobos
Keyword(s):  
Analytical Electron Microscopy ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Interlayer Cation ◽  
Direct Crystallization ◽  
Selected Area Electron Diffraction ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Mixed Layers ◽  
East Carpathians

AbstractNitrogen influx was identified in the Harghita Bãi area, where the mechanism of NH4+-fixation in illitic clays is relevant for the N-input budget estimation. The nanotextural features of K-illite (K-I), NH4,K-I and NH4-illite-smectite (NH4-I-S) mixed layers observed in argillic-altered andesitic rocks from the hydrothermal area of Harghita Bãi (East Carpathians) were studied by X-ray diffraction, infrared spectroscopy and transmission and analytical electron microscopy (TEM-AEM). The texture of undisturbed argillic-altered andesite rocks exhibits chaotic intergrowths of randomly oriented and curved illitic packets with abundant pore spaces and high porosity between packets. The TEM images of K-I and NH4,K-I intergrowths show subparallel packets with clear contacts, exhibiting a diffuse contrast across layers. The thicknesses of K-I and NH4,K-I packets range from 150 to 500 Å, and 1Md and 1M polytypes were identified by selected area electron diffraction patterns. Crystal chemistry of K-I, NH4,K-I and NH4-I-S was carried out by AEM. A third interlayer cation Na+ beside K+ was detected in several NH4,K-I packets. The NH4,Na,K-I packets interleaved with NH4,K-I or NH4-I-S (12% smectite layers) packets were also identified by TEM. The thicknesses of NH4,Na,K-I packets range from 300 to 1200 Å, with abundant lenses and lenticular layer separation along the boundaries between them. The 1Md polytype dominates the NH4,Na,K-I packets. Straight and parallel packets, continuous 00l layers and collapsed swelling layers at the boundary of individual NH4-I (5% smectite layers) packets with thicknesses ranging from 20 to 95 Å were observed. The nanotextural observations indicate direct crystallization of NH4-I crystals within a NH4-I-S series from a pore fluid, where NH4-I packets occupy void spaces previously occupied by fluids.

Vermiculite-like minerals in low-grade metasediments from the Coastal Range of central Chile

Clay Minerals ◽  
2002 ◽  
Vol 37 (2) ◽  
pp. 221-234 ◽  
Author(s):  
M. D. Ruiz Cruz ◽  
E. Puga ◽  
L. Aguirre ◽  
M. Vergara ◽  
D. Morata
Keyword(s):  
Mixed Layer ◽  
Analytical Electron Microscopy ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Prograde Metamorphism ◽  
Central Chile ◽  
X Ray ◽  
Analytical Electron ◽  
Mixed Layers ◽  
Coastal Range

AbstractMixed-layer minerals with optical properties similar to metamorphic vermiculite were identified in rocks belonging to a Palaeozoic and a Triassic formation separated by an angular unconformity and exposed in the Coastal Range of central Chile. Both formations are affected by low-grade metamorphism. The mixed-layer minerals were studied by optical microscopy, X-ray diffraction (XRD), electron microprobe (EMPA), and transmission/ analytical electron microscopy (TEM/AEM). Two types of phyllosilicates were identified: chlorite-vermiculite and mica-chlorite, which are present in the Palaeozoic and Triassic rocks respectively. Chlorite-vermiculite mixed layers form packets with well-defined boundaries and mainly show 1:1 ordered sequences. On the contrary, mica-chlorite mixed layers show, in most cases, random sequences evolving laterally toward chlorite. The AEM data indicate compositions close to that of chlorite in the ternary Si-Al- (Fe+Mg+Mn) diagrams for both types of mixed-layer phyllosilicates. Relative to the coexisting chlorite, they have lower (Fe+Mg) contents, and a higher Si/Al ratio. They are interpreted as products of the transformation of chlorite, developed during prograde metamorphism, and probably represent intermediate, metastable phases, in the chlorite to biotite transformation.

Microcharacterization of Heterogeneous Specimens Containing Tire Dust

1999 ◽  
Vol 589 ◽  
Author(s):  
Marina Camatini ◽  
GAI M Corbetta ◽  
Giovanini F Crosta ◽  
Tigran Dolukhanyan ◽  
Giampaolo Giuiani ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Analytical Electron Microscopy ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Debris Particles ◽  
Microscope Images ◽  
Analytical Electron ◽  
Diffraction Patterns

AbstractThis work is focused on dust or debris produced by the wear of tire tread. Two problems are addressed, which are solved by analytical electron microscopy (AEM): characterization of tire debris and identification of tire debris particles in a heterogeneous specimen. The characteristic morphology, microstructure and elemental composition of tire debris can all be determined by AEM. The scanning electron microscope (SEM) shows that the surface of a tire debris particle has a typical, warped structure with pores. The characteristic elements of tire rubber are S and Zn, which are detected by energy dispersive X ray (EDX) spectroscopy. The identification of rubber particles in heterogeneous debris containing talc and produced by a laboratory abrader is possible by the analytical SEM. Transmission electron microscope images, EDX spectra and selected area electron diffraction patterns characterize tire debris at the sub–micron scale, where the material can no longer be treated as homogeneous.

scholarly journals Microstructure and properties of nano-laminated Y3Si2C2 ceramics fabricated via in situ reaction by spark plasma sintering

2021 ◽  
Vol 10 (3) ◽  
pp. 578-586
Author(s):  
Lin-Kun Shi ◽  
Xiaobing Zhou ◽  
Jian-Qing Dai ◽  
Ke Chen ◽  
Zhengren Huang ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Atomic Scale ◽  
Max Phase ◽  
X Ray Diffraction ◽  
Selected Area Electron Diffraction ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma ◽  
Diffraction Patterns

AbstractA nano-laminated Y3Si2C2 ceramic material was successfully synthesized via an in situ reaction between YH2 and SiC using spark plasma sintering technology. A MAX phase-like ternary layered structure of Y3Si2C2 was observed at the atomic-scale by high resolution transmission electron microscopy. The lattice parameters calculated from both X-ray diffraction and selected area electron diffraction patterns are in good agreement with the reported theoretical results. The nano-laminated fracture of kink boundaries, delamination, and slipping were observed at the tip of the Vickers indents. The elastic modulus and Vickers hardness of Y3Si2C2 ceramics (with 5.5 wt% Y2O3) sintered at 1500 °C were 156 and 6.4 GPa, respectively. The corresponding values of thermal and electrical conductivity were 13.7 W·m-1·K-1 and 6.3×105 S·m-1, respectively.

A Chemical Solution Route to Rapid Synthesis of Homogeneous Bi100−xSbx Alloys Nanoparticles at Room Temperature

2007 ◽  
Vol 7 (2) ◽  
pp. 525-529 ◽  
Author(s):  
Bo Zhou ◽  
Jun-Jie Zhu
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Solution Route ◽  
Diffraction Patterns ◽  
Co Reduction ◽  
Chemical Solution Route

A chemical co-reduction route in aqueous solution was developed to synthesize Bi100−xSbx alloys at room temperature. The hydrolyses of Bi(III) and Sb(III) were effectively avoided by selecting proper raw materials and coordinator. X-ray diffraction analysis indicated that the as-prepared Bi100−xSbx alloys were homogeneous and phase-pure, and the Bi/Sb ratios in the alloys were very close to those in the aqueous solutions. The transmission electron microscope observation showed that the as-prepared Bi100−xSbx (x = 0∼100) alloys were particles with a size of tens of nanometers. The selected area electron diffraction patterns confirmed the high crystallinity, the homogeneousness, and the composition controllability of as-prepared alloys. All these characters and the nanometer-scaled size of the alloys are believed to be beneficial to the thermoelectric property of the Bi100−xSbx alloys.

Analysis of IN-SITU Converted Chrysotile Asbestos Fibers in Sprayed on Fireproofing

1998 ◽  
Vol 4 (S2) ◽  
pp. 480-481
Author(s):  
R. L. Sabatini ◽  
Toshi Sugama ◽  
Leonidas Petrakis
Keyword(s):  
Environmental Protection Agency ◽  
Analytical Electron Microscopy ◽  
Polarized Light ◽  
X Ray Diffraction ◽  
Protection Agency ◽  
Glassy Material ◽  
X Ray ◽  
Asbestos Fibers ◽  
Analytical Electron

A BNL-Grace process has been developed to chemically convert in-situ, the chrysotile fibers of sprayed-on fireproofing products to an unregulated glassy material. The effectiveness of this process has been convincingly demonstrated using Analytical Electron Microscopy and X-Ray Diffraction techniques.Asbestos minerals were used in fireproofing materials because of their excellent physical properties including fire resistance, high tensile strength, heat and electrical insulation, and resistance to acids and alkali. But in 1975 the Environmental Protection Agency began regulating materials containing > 1% asbestos.The new in-situ BNL-Grace process, which uses a foamy solution sprayed directly onto asbestos-containing fireproofing chemically digests essentially all the asbestos fibers, transforming them into harmless materials. After treatment, the fireproofing is no longer a regulated material. The process produces essentially no waste.Our problem was to demonstrate that all of the asbestos was converted and that the remaining materials were no longer regulated. Typical analysis methods use conventional optical and Polarized Light Microscopy (PLM) to measure and observe fibers.

Transient Phase Formation During the Growth of Epitaxial CoSi2 by Annealing of Co/Ti Bi-Layers on (100) Si

1995 ◽  
Vol 402 ◽  
Author(s):  
D. J. Miller ◽  
T. I. Selinder ◽  
K. E. Gray
Keyword(s):  
Electron Microscopy ◽  
Reaction Pathway ◽  
Spinel Phase ◽  
Analytical Electron Microscopy ◽  
Inert Gases ◽  
Native Oxide ◽  
Transient Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analytical Electron

AbstractPhase evolution during the annealing of Co/Ti bi-layers on (100) Si has been studied by x-ray diffraction and analytical electron microscopy. X-ray diffraction performed in situ during annealing revealed a reaction pathway involving the formation of a transient phase when epitaxial CoSi2 films were grown. Analytical electron microscopy was used to identify this phase as a spinel-related phase, isostructural with Co2TiO4. This phase grows as a result of the presence of the Ti interlayer and a small amount of oxygen from the annealing ambient. Annealing in vacuum or other purified inert gases yielded polycrystalline CoSi2 films which form via a different reaction pathway that does not involve a spinel phase. This spinel phase may serve both to reduce the native oxide from the underlying Si substrate and to control interdiffusion between Si and Co during the reaction, thereby promoting epitaxial growth.

scholarly journals Microstructural Characterization of Multiphase Coatings Produced By Chemical Vapor Deposition

1989 ◽  
Vol 168 ◽  
Author(s):  
R. A. Lowden ◽  
K. L. More ◽  
T. M. Besmann ◽  
R. D. James
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Analytical Electron Microscopy ◽  
Chemical Vapor ◽  
Microstructural Characterization ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Analytical Electron ◽  
Scanning Transmission

AbstractChemical vapor deposition has been utilized to produce ternary, multiphase coatings of various compositions of silicon carbide (SiC) with Ti, Cr, and Mo. Thermodynamic calculations have been performed for a variety of experimental conditions in each system. Scanning, transmission and analytical electron microscopy, and X-ray diffraction techniques have been used to characterize the microstructures and to determine compositions.

scholarly journals The effect of the octahedral cations on the dimensions of the palygorskite cell

Clay Minerals ◽  
2007 ◽  
Vol 42 (3) ◽  
pp. 287-297 ◽  
Author(s):  
M. Suárez ◽  
E. García-Romero ◽  
M. Sánchez Del Río ◽  
P. Martinetto ◽  
E. Dooryhée
Keyword(s):  
Analytical Electron Microscopy ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Ionic Radii ◽  
Octahedral Sheet ◽  
X Ray ◽  
Linear Dependency ◽  
Octahedral Cation ◽  
Analytical Electron ◽  
Octahedral Cations

AbstractHigh-resolution synchrotron X-ray diffraction recorded on a collection of palygorskites with different chemical compositions (obtained by analytical electron microscopy) permits unambiguous correlation of the crystallographic parameters a (or a sin β if a monoclinic phase is considered) with the nature of the octahedral sheet, i.e. with both the number of octahedral positions that are occupied and the type of octahedral cation. No significant changes in the lattice parameters b and c are observed. The unit cell modification consists essentially of an expansion in a as the number of cations with larger ionic radii (Mg2+ and Fe3+) predominates over smaller cations (Al3+). A linear dependency of a (or a sin β) on the chemical composition of the octahedral sheet was obtained that can be used for classifying palygorskite into compositional groups, using only conventional diffraction data, without the need for chemical analyses.

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