scholarly journals Lithologic Characterization and Micropore Structures of Gas Shale Strata: An example from the Midra Shale of Western Qatar

2021 ◽  
Author(s):  
Fadhil N. Sadooni ◽  
Hamad Al-Saad Al-Kuwari ◽  
Ahmad Sakhaee-Pour ◽  
Wael S. Matter ◽  
Indra Gunawan
Keyword(s):  
Magnesium Content ◽  
Gas Shale ◽  
Hydrocarbon Reservoir ◽  
Shark Teeth ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Large Foraminifera ◽  
Geochemical Analyses ◽  
20 Nm ◽  
Depositional Setting

Gas shale is the future hydrocarbon reservoir of Qatar. The Qatari geologic section has had important successions of gas shale at different geologic times including the Eocene Midra shale, the Cretaceous Ratawi and Nahr Umr, and the Paleozoic Qusaibah and Unayzah formations. Shale samples were collected from the outcrops of the Midra Shale in Dukhan and Umm Bab areas. Samples were subjected to geochemical analyses using XRD and RXF. Selected samples were examined under SEM and TEM microscopes. All the studied samples contain palygorskite as the main mineral and, in some cases, the only mineral present, as indicated by X-ray diffraction patterns. XRF analysis shows palygorskite range from ideal palygorskite (equal aluminum and magnesium content) to aluminous palygorskite where no magnesium is recorded. The most common other minor minerals are halite, quartz, calcite, and other clay minerals: illite, smectite and sepiolite. The palygorskite chain phyllo silicates results in a fibrous habit with channels running parallel to the fiber length. Images from Transmission Electron Microscopy (TEM) clearly show the presence of bundled lath-like crystals of palygorskite 5 to 20 nm in width and several micrometers in length. The Midra Shale was deposited in a shallow marine shelf that was subjected to clastic influx from the nearby land. Although, the Midra contains many elements that support deposition under marine conditions such as large foraminifera and shark teeth, the presence of fully developed shale horizons indicate a mixed marine-continental depositional setting. Most of the micropores are channels associated with the palygorskite laths as can be seen from the TEM images or some dissolution pores that resulted from halite and gypsum dissolution by meteoric water.

Ordered Structure in GalnP/AIGalnP Quantum Wells and p-Doped Multiquantum Well AIGalnp Laser Diodes

1991 ◽  
Vol 240 ◽  
Author(s):  
Toshiaki Tanaka ◽  
Hironori Yanagisawa ◽  
Shin-Ichiro Yano ◽  
Shigekazu Minagawa
Keyword(s):  
Quantum Wells ◽  
Hole Concentration ◽  
Laser Diodes ◽  
Ordered Structure ◽  
Transmission Electron ◽  
Zinc Doping ◽  
Low Threshold ◽  
Diffraction Patterns ◽  
20 Nm ◽  
Multiquantum Well

ABSTRACTZinc doping is performed on the GalnP/AIGalnP multiquantum well (MQW) structure with the aim of dissolving the ordered atomic arrangement which results in higher quantum levels and therefore shorter lasing wavelengths. It is shown that the photoluminescence (PL) peak wavelength gradually shortens with doping and decreases by 20 nm when the hole concentration reaches 1×1018 cm−3, while the PL relative intensity becomes half that of an undoped MQW layer. Therefore, a moderate level of zinc doping of around 4∼5×1017 cm−3 is desirable to shorten the PL wavelength without decreasing the crystal quality. Transmission electron nano-diffraction patterns confirm that the ordered structure in the MQW layers disappears as the hole concentration increases. On the basis of this data, uniformly p-doped and modulation p-doped MQW laser diodes are fabricated and their characteristics are compared with the undoped MQW lasers. CW operation is achieved at wavelengths of 631 to 633 nm, which is 10 nm shorter than the 643 nm in an undoped MQW laser. Comparatively low threshold currents of 73 and 88 mA are attained for uniformly p-doped and modulation p-doped MQW lasers, respectively. However, they are about 20∼30 mA higher than those of the undoped MQW lasers. This results from the large overflow of electrons from the active layer, and the fact that the differential gain becomes smaller in the 630-nm band.

Electronic Cone Illumination with the Conventional Transmission Electron Microscope

1977 ◽  
Vol 35 ◽  
pp. 72-73
Author(s):  
William Krakow
Keyword(s):  
Electronic Device ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Hollow Cone ◽  
Transmission Electron ◽  
Lissajous Figures ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Diffraction Patterns ◽  
Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

Deviations from Ideal Decagonal Symmetry in Electron Diffraction Patterns of the “Decagonal” Phase in the Al-Co-Cu Alloy System

1991 ◽  
Vol 49 ◽  
pp. 914-915
Author(s):  
Atul S. Ramani ◽  
Earle R. Ryba ◽  
Paul R. Howell
Keyword(s):  
Electron Microscope ◽  
Alloy System ◽  
Nominal Composition ◽  
Dimensional Lattice ◽  
3 Dimensional ◽  
Decagonal Phase ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Lattice Periodicity ◽  
Diffraction Patterns

The “decagonal” phase in the Al-Co-Cu system of nominal composition Al65CO15Cu20 first discovered by He et al. is especially suitable as a topic of investigation since it has been claimed that it is thermodynamically stable and is reported to be periodic in the dimension perpendicular to the plane of quasiperiodic 10-fold symmetry. It can thus be expected that it is an important link between fully periodic and fully quasiperiodic phases. In the present paper, we report important findings of our transmission electron microscope (TEM) study that concern deviations from ideal decagonal symmetry of selected area diffraction patterns (SADPs) obtained from several “decagonal” phase crystals and also observation of a lattice of main reflections on the 10-fold and 2-fold SADPs that implies complete 3-dimensional lattice periodicity and the fundamentally incommensurate nature of the “decagonal” phase. We also present diffraction evidence for a new transition phase that can be classified as being one-dimensionally quasiperiodic if the lattice of main reflections is ignored.

An Interactive Minicomputer Program for the Indexing and Simulation of Electron Diffraction Patterns

1976 ◽  
Vol 34 ◽  
pp. 542-543
Author(s):  
R.P. Goehner ◽  
W.T. Hatfield ◽  
Prakash Rao
Keyword(s):  
Electron Diffraction ◽  
Real Time ◽  
Pattern Analysis ◽  
Flow Diagram ◽  
Hard Copy ◽  
Time Analysis ◽  
Real Time Analysis ◽  
Transmission Electron ◽  
One Step ◽  
Diffraction Patterns

Computer programs are now available in various laboratories for the indexing and simulation of transmission electron diffraction patterns. Although these programs address themselves to the solution of various aspects of the indexing and simulation process, the ultimate goal is to perform real time diffraction pattern analysis directly off of the imaging screen of the transmission electron microscope. The program to be described in this paper represents one step prior to real time analysis. It involves the combination of two programs, described in an earlier paper(l), into a single program for use on an interactive basis with a minicomputer. In our case, the minicomputer is an INTERDATA 70 equipped with a Tektronix 4010-1 graphical display terminal and hard copy unit.A simplified flow diagram of the combined program, written in Fortran IV, is shown in Figure 1. It consists of two programs INDEX and TEDP which index and simulate electron diffraction patterns respectively. The user has the option of choosing either the indexing or simulating aspects of the combined program.

Effects of High-Energy Ions on Synthetic Quartz

1972 ◽  
Vol 30 ◽  
pp. 544-545
Author(s):  
Joseph J. Comer ◽  
Charles Bergeron ◽  
Lester F. Lowe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Energy ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
High Energy Ions ◽  
Diffraction Patterns ◽  
Dauphiné Twinning ◽  
Beam Damage

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.

A Novel TEM Technique for Characterizing As-Grown CVD Diamond Films

1991 ◽  
Vol 49 ◽  
pp. 956-957 ◽  
Author(s):  
Z.L. Wang ◽  
J. Bentley ◽  
R.E. Clausing ◽  
L. Heatherly ◽  
L.L. Horton
Keyword(s):  
Diamond Films ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Dark Field ◽  
Growth Surface ◽  
Specimen Preparation ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
First Time ◽  
Microstructural Studies

Microstructural studies by transmission electron microscopy (TEM) of diamond films grown by chemical vapor deposition (CVD) usually involve tedious specimen preparation. This process has been avoided with a technique that is described in this paper. For the first time, thick as-grown diamond films have been examined directly in a conventional TEM without thinning. With this technique, the important microstructures near the growth surface have been characterized. An as-grown diamond film was fractured on a plane containing the growth direction. It took about 5 min to prepare a sample. For TEM examination, the film was tilted about 30-45° (see Fig. 1). Microstructures of the diamond grains on the top edge of the growth face can be characterized directly by transmitted electron bright-field (BF) and dark-field (DF) images and diffraction patterns.

A library of convergent-beam electron diffraction patterns

1986 ◽  
Vol 44 ◽  
pp. 688-691
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Transmission Electron ◽  
Yield Information ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Electron Energy Loss

One of the most important advancements of the transmission electron microscopy (TEM) in recent years has been the development of the analytical electron microscope (AEM). The microanalytical capabilities of AEMs are based on the three major techniques that have been refined in the last decade or so, namely, Convergent Beam Electron Diffraction (CBED), X-ray Energy Dispersive Spectroscopy (XEDS) and Electron Energy Loss Spectroscopy (EELS). Each of these techniques can yield information on the specimen under study that is not obtainable by any other means. However, it is when they are used in concert that they are most powerful. The application of CBED in materials science is not restricted to microanalysis. However, this is the area where it is most frequently employed. It is used specifically to the identification of the lattice-type, point and space group of phases present within a sample. The addition of chemical/elemental information from XEDS or EELS spectra to the diffraction data usually allows unique identification of a phase.

Examination of Extra Electron Diffraction Spots Observed in Deuterium-Irradiated Silicon by Using Parallel Electron Beam Illumination

1990 ◽  
Vol 48 (2) ◽  
pp. 490-491
Author(s):  
Ryuichiro Oshima ◽  
Shoichiro Honda ◽  
Tetsuo Tanabe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Single Crystal ◽  
Mixed Solution ◽  
Parallel Beam ◽  
Defect Clusters ◽  
Float Zone ◽  
Transmission Electron ◽  
Extra Electron ◽  
Diffraction Patterns

In order to examine the origin of extra diffraction spots and streaks observed in selected area diffraction patterns of deuterium irradiated silicon, systematic diffraction experiments have been carried out by using parallel beam illumination.Disc specimens 3mm in diameter and 0.5mm thick were prepared from a float zone silicon single crystal(B doped, 7kΩm), and were chemically thinned in a mixed solution of nitric acid and hydrogen fluoride to make a small hole at the center for transmission electron microscopy. The pre-thinned samples were irradiated with deuterium ions at temperatures between 300-673K at 20keV to a dose of 1022ions/m2, and induced lattice defects were examined under a JEOL 200CX electron microscope operated at 160kV.No indication of formation of amorphous was obtained in the present experiments. Figure 1 shows an example of defects induced by irradiation at 300K with a dose of 2xl021ions/m2. A large number of defect clusters are seen in the micrograph.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

Modern TEM systems architecture

1986 ◽  
Vol 44 ◽  
pp. 602-605
Author(s):  
U. Gross ◽  
P. Hagemann
Keyword(s):  
Electron Microscope ◽  
Information Gathering ◽  
Systems Architecture ◽  
Control Functions ◽  
Transmission Electron ◽  
New Information ◽  
Comprehensive Information ◽  
Scanning Transmission ◽  
Diffraction Patterns ◽  
Analytical Equipment

By addition of analytical equipment, scanning transmission accessories and data processing equipment the basic transmission electron microscope (TEM) has evolved into a comprehensive information gathering system. This extension has led to increased complexity of the instrument as compared with the straightforward imaging microscope, since in general new information capacity has required the addition of new control hardware. The increased operational complexity is reflected in a proliferation of knobs and buttons.In the conventional electron microscope design the operating panel of the instrument has distinct control elements to alter optical conditions of the microscope column in different modes. As a consequence a multiplicity of control functions has been inevitable. Examples of this are the three pairs of focus and magnification controls needed for TEM imaging, diffraction patterns, and STEM images.

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