ALTERED RHYTHMIC SULPHIDE BANDS IN THE WEISSLIEGEND SANDSTONE IN THE RUDNA MINE (FORE-SUDETIC MONOCLINE, POLAND)

2017 ◽  
pp. 61-78 ◽  
Author(s):  
Marek Radliński ◽  
Zbigniew Sawłowicz
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Hydrogen Sulphide ◽  
Copper Sulphide ◽  
Ore Mineralization ◽  
Iron Bearing ◽  
Scanning Electron ◽  
Copper Sulphides

Two cross sections of Weissliegend sandstones from the Rudna Mine, containing copper sulphide rhythmic banding, were studied. Analyses were performed using optical polarizing (PLM) and scanning electron (SEM-EDS) microscopy and XRD. Rhythmites have different sulphide compositions and undergone different alterations. In cross section RZA rhythmites are composed of copper sulphides, mainly digenite, and strongly altered to covellite and atacamite by secondary processes. Primary rhythmites were probably formed via reaction between hydrogen sulphide from the overlying shale and copper-bearing solutions in the sandstone. Extensive weathering and mining waters were probably resposible for atacamite formation, although other possibillities are also considered. In cross section RGM rhythmites are composed of Cu–Fe sulphides (bornite and chalcopyrite) and pyrite. This distinct mineralogy may result from a reaction of hydrogen sulphide from the overlying shale with copper- and iron-bearing solutions. Dissolution of pyrite or iron monosulphides present in the sandstone could enrich the solutions in iron. Primary ore mineralization was overlapped by a secondary mineralization of slightly different composition.

MASSIVE COPPER SULPHIDE MINERALIZATION IN DOLOMITES FROM THE LUBIN MINE (FORE-SUDETIC MONOCLINE)

2017 ◽  
pp. 29-48 ◽  
Author(s):  
Piotr Król ◽  
Zbigniew Sawłowicz
Keyword(s):  
Cross Sections ◽  
Copper Sulphide ◽  
Copper Deposits ◽  
Sulphide Mineralization ◽  
Ore Mineralization ◽  
First Time ◽  
Mineralizing Fluids ◽  
Scanning Electron

Massive ore mineralization in dolomites is described for the first time from the Fore-Sudetic copper deposits. Three cross-sections from the Lubin Mine were studied using polarized optical (PLM) and scanning electron (SEM-EDS) microscopy, also cathodoluminescence (CL) and XRD. Massive mineralization, composed mainly of chalcocite with calcite admixture, occurs in dolomites as horizontal pseudovein, locally underlain by clay-carbonate breccia and shale. Underlying dolomites were partly calcitized (dedolomitized). Various calcite generations are characterized in detail. A model of the formation of massive mineralization is proposed. Mesotectonic intralayer movements caused the cracking of dolomite layers and the formation of breccia. Calcitization led to both dedolomitization and the partial infilling of cracks. Mineralizing fluids infilled the cracks completely, partly replacing calcite and adjacent rocks.

scholarly journals Cross-Sectional Geometry and the Intermetallics Structure in a High Pressure Die Cast Mg-Al Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 1579-1584 ◽  
Author(s):  
A.V. Nagasekhar ◽  
Carlos H. Cáceres ◽  
Mark Easton
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Circular Cross Section ◽  
Al Alloy ◽  
Cross Sectional ◽  
The Core ◽  
Die Cast ◽  
Increased Strength ◽  
Scanning Electron

Specimens of rectangular and circular cross section of a Mg-9Al binary alloy have been tensile tested and the cross section of undeformed specimens examined using scanning electron microscopy. The rectangular cross sections showed three scales in the cellular intermetallics network: coarse at the core, fine at the surface and very fine at the corners, whereas the circular ones showed only two, coarse at the core and fine at the surface. The specimens of rectangular cross section exhibited higher yield strength in comparison to the circular ones. Possible reasons for the observed increased strength of the rectangular sections are discussed.

A Simulation of Electron Scattering in Metals and its Application for Scanning Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 420-421
Author(s):  
Masatoshi Kotera ◽  
Ryoji Ijichi ◽  
Takafumi Fujiwara ◽  
Hiroshi Suga ◽  
David B. Wittry
Keyword(s):  
Elastic Scattering ◽  
Conduction Band ◽  
Cross Section ◽  
Conduction Electron ◽  
Electron Scattering ◽  
Cross Sections ◽  
Electron Ionization ◽  
Plasmon Excitation ◽  
Electron Trajectories ◽  
Scanning Electron

In a recent research, the scanning electron microscope(SEM) has been shown to provide spatial resolution of less than 0.5nm. With the knowledge of the ultimate resolution or the factor which controls the resolution, it is possible to optimize the specimen preparation method and the choice of various electron beam parameters (eg. acceleration voltage etc.) For a precise discussion of the SEM image, it is necessary to take into account not only the signal (electron) production and the propagation in a specimen and its emission from the surface, but also electron trajectories in vacuum toward the detector. However, electron scattering process in the specimen does not depend on the detection system, and the resolution is mainly attributed to the spatial distribution of the electron emission from the specimen surface. Here, we focused on the electron scattering mechanisms in metals and developed a Monte Carlo simulation model of electron trajectories. Also, this simulation is applied to evaluate a compositional contrast in the SEM.In the present study electron interactions with atomic potential, inner-shell electrons, conduction electrons are taken into account. Cross sections calculated by the present model are shown in Fig.1 for [l]elastic scattering, [2]inner-shell (1s, 2s, 2p for Al) electron ionization, [3]conduction electron ionization through non-radiative plasmon decay, and [4] stable plasmon excitation in the conduction band electrons for Al. For the elastic scattering, the Mott cross section is used. For inner-shell electron ionizations by an electron collision, the Gryzinski equation is used. In order to express the plasmon-electron interaction in a free electron gas at the conduction band, the Lindhard treatment is used. This treatment is based on the random phase approximation in the dielectric response function of metals. The cross section is shown in a unit of the inverse mean free path. The cross sections for conduction electron ionization and the plasmon excitation agree with the data of Tung, Ashley, and Ritchie. Cross sections for inner-shell electron ionization, which Tung et al. have derived using the generalized oscillator strength, are also shown in Fig.1 for a comparison.

Disptacement of Arsenic from Substitutional Sites in Silicon by MEV HE+ Irradiation

1985 ◽  
Vol 45 ◽  
Author(s):  
E A Maydell-Ondrusz ◽  
I H Wilson ◽  
K G Stephens
Keyword(s):  
Electron Beam ◽  
Single Crystals ◽  
Cross Section ◽  
Cross Sections ◽  
Electron Beam Irradiation ◽  
Arsenic Concentration ◽  
Beam Irradiation ◽  
Mbe Growth ◽  
Silicon Doped ◽  
Scanning Electron

ABSTRACTCross-sections were determined for displacement of arsenic from substitutional sites in silicon by 1.5MeV He+ ions. Results are presented for channelled and random incidence on (111) and (100) silicon, doped by arsenic implantation and annealed by scanning electron beam irradiation. Layers doped during MBE growth were also studied for comparison.Inner L-shell ionisation of host atoms is proposed to explain the observed displacement cross-section and its variation with arsenic concentration. The results are used to indicate the limits for using Rutherford backscattering and channelling techniques to measure the substitutionality of dopants in single crystals.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

SEM analysis of fish scale cross sections: A technique study

1992 ◽  
Vol 50 (1) ◽  
pp. 744-745
Author(s):  
M.E. Lee ◽  
A. Moller ◽  
P.S.O. Fouche ◽  
I.G Gaigher
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cross Sections ◽  
Soft Tissues ◽  
Close Association ◽  
Sem Analysis ◽  
Fish Scale ◽  
Fish Scales ◽  
Micro Structures ◽  
Scanning Electron

Scanning electron microscopy of fish scales has facilitated the application of micro-structures to systematics. Electron microscopy studies have added more information on the structure of the scale and the associated cells, many problems still remain unsolved, because of our incomplete knowledge of the process of calcification. One of the main purposes of these studies has been to study the histology, histochemistry, and ultrastructure of both calcified and decalcified scales, and associated cells, and to obtain more information on the mechanism of calcification in the scales. The study of a calcified scale with the electron microscope is complicated by the difficulty in sectioning this material because of the close association of very hard tissue with very soft tissues. Sections often shatter and blemishes are difficult to avoid. Therefore the aim of this study is firstly to develop techniques for the preparation of cross sections of fish scales for scanning electron microscopy and secondly the application of these techniques for the determination of the structures and calcification of fish scales.

Analytical and High-Resolution EM Study of Crystalline Phases formed at Metal-Ceramic Interface

1990 ◽  
Vol 48 (2) ◽  
pp. 426-427
Author(s):  
N. Merk ◽  
A. P. Tomsia ◽  
G. Thomas
Keyword(s):  
Cross Section ◽  
Dissimilar Materials ◽  
Ceramic Materials ◽  
Electron Micrograph ◽  
Scanning Electron Micrograph ◽  
Structural Applications ◽  
Metal Ceramic ◽  
The Subject ◽  
Ceramic Compounds ◽  
Scanning Electron

A recent development of new ceramic materials for structural applications involves the joining of ceramic compounds to metals. Due to the wetting problem, an interlayer material (brazing alloy) is generally used to achieve the bonding. The nature of the interfaces between such dissimilar materials is the subject of intensive studies and is of utmost importance to obtain a controlled microstructure at the discontinuities to satisfy the demanding properties for engineering applications . The brazing alloy is generally ductile and hence, does not readily fracture. It must also wett the ceramic with similar thermal expansion coefficient to avoid large stresses at joints. In the present work we study mullite-molybdenum composites using a brazing alloy for the weldment.A scanning electron micrograph from the cross section of the joining sequence studied here is presented in Fig. 1.

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