bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origins of fine particles in a power-plant plume as determined using individual-particle analysis
Authors: Katrinak Karen A. , Hurley John P. 
Published: June 2020

Individual particles from the fine fraction of samples of entrained ash from a coal-burning power plant were analyzed using an automated scanning electron microscope with an energydispersive x-ray spectrometer. The particles were of concern as a probable cause of high levels of opacity in the plant emissions. Both the mass loading and the number size distribution of fine particles peak in the size range of 0.4 to 0.8 μm diameter.Most of the fine particles are Na-, S-, P-, or Cl-rich. The coal is likely to be the major source for these particles. Minerals and organically-associated metals in the coal can remain in the solid phase during combustion, forming ash particles of varied sizes, including those in the submicron range. Elements are also vaporized during combustion, and Na- and S-bearing particles may form when gas-phase Na2SO4 condenses homogeneously in the convective pass of the boiler. Phosphate and chloride particles may also condense homogeneously.
Structural phenomena in the growth of carbon nanotubes
Authors: Jiao Jun 
Published: June 2020

HREM studies of the carbonaceous material deposited on the cathode of a Huffman-Krätschmer arc reactor have shown a rich variety of multiple-walled nano-clusters of different shapes and forms. The preparation of the samples, as well as the variety of cluster shapes, including triangular, rhombohedral and pentagonal projections, are described elsewhere.The close registry imposed on the nanotubes, focuses attention on the cluster growth mechanism. The strict parallelism in the graphitic separation of the tube walls is maintained through changes of form and size, often leading to 180° turns, and accommodating neighboring clusters and defects. Iijima et. al. have proposed a growth scheme in terms of pentagonal and heptagonal defects and their combinations in a hexagonal graphitic matrix, the first bending the surface inward, and the second outward. We report here HREM observations that support Iijima’s suggestions, and add some new features that refine the interpretation of the growth mechanism. The structural elements of our observations are briefly summarized in the following four micrographs, taken in a Hitachi H-8100 TEM operating at an accelerating voltage of 200 kV and with a point-to-point resolution of 0.20 nm.
The origins of high-resolution secondary-electron microscopy
Authors: Scheinfein M.R. , Drucker J.S. , Weiss J.K. 
Published: June 2020

The production or generation of SE by focused, fast electron beams is a multistage process which includes excitation of target electrons by the energetic incident beam, subsequent decay yielding hot SE, transport to the surface, and transmission over the surface potential barrier. The ultimate spatial resolution of a SE image formed by scanning a well focussed probe across a surface is limited by the excitation events' spatial derealization through the transverse momentum transferred to the specimen.The accepted model for SE production is not well characterized since it is extremely difficult to separate experimentally the generation, transport and transmission processes during a given SE creation event. Here, we examine the SE generation pathway by correlating SE of a given energy produced by an initial inelastic excitation using time coincidence detection. This technique can be used, for example, to isolate the role of plasmon decay in the SE generation process. The experiments were performed in a Vacuum Generators HB501-S UHV scanning transmission electron microscope (STEM), operating at base pressures of 5 × 10−11 torr.
Explanation of the high resolution backscattered electron image in the scanning electron microscope by the twin-population theory historical review
Authors: Wells Oliver C. 
Published: June 2020

Several different “twin-population” theories have been proposed to explain the high resolution backscattered electron (BSE) image in the scanning electron microscope (SEM). In all of these, the BSE are divided into local BSE that give an image having a resolution that is significantly better than the electron penetration depth R and diffused BSE that give a less sharp image. Other theories attach more importance to the diffused BSE.The BSE image was originally proposed by von Ardenne in 1940 with the specimen at right angles to the incident electron beam (Fig. 1). This has been summarised by McMullan. Von Ardenne predicted high resolution secondary electron (SE) imaging by local SE (now called SE-I) and pointed out the advantages of low voltage operation, but failed to realise that there was a high resolution BSE signal also. McMullan distinguished between the BSE image as defined above (Fig. 2(b)) where the principal contrast mechanism is compositional and the reflected electron image in which the sample is tilted by typically 45° and forward-scattered BSE are collected (Fig. 2(a)).
A study of ordered domains in Ga0.5In0.5P Grown by MOVPE
Authors: Zhu Jane G. , Friedman D. J. , Al-Jassim M. M. , Olson J. M. 
Published: June 2020

Atomic ordering in III-V alloys is known to influence the physical properties of these materials. Therefore, the understanding and the control of the formation of ordered alloys are very important. Ordering in Ga0.5In0.5P, which is lattice matched to GaAs, occurs on two out of four {111} planes, i.e., . The substrate orientation can affect the selection between the two ordered variants. Studies on atomic ordering in III-V alloys have been carried out during the past several years.Transmission electron microscopy (TEM) and selected-area diffraction have been used in this study to investigate the ordered domains in Ga0.5In0.5P layers. The samples were grown on misoriented (100) GaAs substrates, mostly 2° towards [001] unless otherwise specified, by metalorganic vapor phase epitaxy at 670°C with a growth rate ∼5 μm/hr. The layer thicknesses range from 1.5 to 12 μm. Plan-view specimens were prepared by chemical etching from the substrate sides and examined using a Philips CM30 microscope operated at 300 kV.
In situ HREM of interface interactions
Authors: Sinclair Robert , Konno Toyohiko J. 
Published: June 2020

We have applied in situ high-resolution electron microscopy (HREM) to the study of interface reactions, particularly in metal-semiconductor systems. There is contrasting behavior whether or not the manufactured interface undergoes a chemical reaction. The in situ technique allows determination of the reaction mechanisms on an atomic scale.Reactive interfaces are characterized by systems in which new chemical compounds are formed (e.g., silicides for metal-silicon interfaces, metal gallides and arsenides for GaAs, etc.). We found that the equilibrium phase formation is often preceded by a solid-state amorphization reaction. In situ observations allow very precise measurement of the reaction rate in a sufficient temperature range to confirm that this process is diffusion controlled. Crystallization of the amorphous material can be followed as well as the development of any crystallographic orientation relationships. A ledge growth mechanism can easily be distinguished from a random process.It might be expected that non-reactive interfaces are stable upon heating.
HREM and AEM study of Pt/SiC interface annealed at high temperature
Authors: Bow J.S. , Porter L.M. , Kim M.J. , Carpenter R.W. , Davis R.F. 
Published: June 2020

High temperature applications of SiC semiconductor devices will be essentially limited by the metal/SiC interface interconnect properties. Pt/SiC was reported to have more stable and better electrical properties than other metal/6H-SiC after annealing above 700°C under UHV condition. Some work on the Pt/SiC interface has been conducted by AES and other low spatial resolution surface techniques, but there is no detailed direct image data reported. Here, we characterize the microstructure of the Pt/SiC interface after high temperature annealing in UHV at near atomic resolution and reported the first nanospectroscopic energy loss data for the system.As-deposited Pt film is polycrystalline with grain size of 10 ± 3 nm (Fig.l). The thin amorphous layer visible at the interface in Fig.l, gradually disappearing in the thick regions, was attributed to oxygen-induced ion-milling damage. Similar results were observed frequently in other metal/ceramic system. We consider the amorphous layer to be due to residual oxygen on the ceramic surface during synthesis, since trace oxygen was only detected at the as-deposited Pt/6H-SiC interface.
Thin-specimen preparation for heterophase interfaces
Authors: Lyman C. E. , Anderson R. , Malis T. 
Published: June 2020

Imaging and analysis of heterophase interfaces in cross-sectional view requires demanding thin specimen preparation techniques. The term heterophase refers to the juxtaposition of a heavy and a light element or a metal and an insulator on either side of the interface. No single thinning method can be recommended for all such interfaces in all materials. In fact, the desired information might, of necessity, only be obtained by the use of several methods. This paper provides an overview of three different thinning methods for heterophase interfaces: conventional ion-beam thinning (IBT), tripod polishing (TP), and ultramicrotomy (UM).The ideal thin specimen of a heterophase interface is rarely achieved. Regardless of the final thinning method, the information obtainable often depends on the mechanical alignment of the interface prior to final thinning. Typical alignment parameters are: 1) angle between interface and specimen surface, 2) crystallographic orientation about the normal to the interface, and 3) lateral location of thinned area along interface.
Nucleation and initial growth of Pd2Si crystals on Si(111)
Authors: Tong Xianghong , Pohland Oliver , Murray Gibson J. 
Published: June 2020

The nucleation and initial stage of Pd2Si crystals on Si(111) surface is studied in situ using an Ultra-High Vacuum (UHV) Transmission Electron Microscope (TEM). A modified JEOL 200CX TEM is used for the study. The Si(111) sample is prepared by chemical thinning and is cleaned inside the UHV chamber with base pressure of 1x10−9 τ. A Pd film of 20 Å thick is deposited on to the Si(111) sample in situ using a built-in mini evaporator. This room temperature deposited Pd film is thermally annealed subsequently to form Pd2Si crystals. Surface sensitive dark field imaging is used for the study to reveal the effect of surface and interface steps.The initial growth of the Pd2Si has three stages: nucleation, growth of the nuclei and coalescence of the nuclei. Our experiments shows that the nucleation of the Pd2Si crystal occurs randomly and almost instantaneously on the terraces upon thermal annealing or electron irradiation.
Orientation relationship between Γ phase and α–Fe in commercial galvanneal steel coating
Authors: Lin C. S. 
Published: June 2020

The steel coatings' forming technology and their resulting mechanical performance are of primary concern to the automobile and appliance industries, for they determine directly the long-term structural integrity of the final products. In automobile industry, steel coating plays a crucial role for extended warranty of their product. The recent trend in coatings is an increase in galvannealed coatings.The iron-zinc compound coatings produced by galvannealing bring about a dramatic improvement, in terms of coating performance, compared to pure zinc coatings. The improvement includes corrosion resistance, weldability and paintability in addition to energy and material efficiency. However, there is still one serious obstacle which prevents the industry-wide use of galvannealing as the dominant steel coating technology: Its powdering and flaking tendency during press forming processes. There are a number of empirical hypotheses which propose that the presence of various Fe-Zn intermetallic phases influences the powdering/flaking tendency of galvannealed coatings. Nevertheless, not enough microstructural information is available except those obtained by SEM and X-ray diffraction.
The application of high-resolution SEM and EPMA to the study of coatings and interfaces of materials
Authors: Goldstein Joseph I. 
Published: June 2020

Microchemical and micro-structural analysis are often required when characterizing coatings and interfaces in materials. For coatings the interface between substrate and coating and between coating and the surface are of particular interest. The scanning electron microscope (SEM) and electron probe microanalyzer (EPMA) are often employed in characterizing interfaces in materials particularly because solid samples can be studied and sample preparation is usually restricted to developing a suitable flat polished surface for analysis. Both these instruments are essentially the same although the EPMA is equipped with wavelength dispersive detectors (WDS) and is dedicated to quantitative microchemical analysis.The spatial resolution for high resolution SEM where microstructural analysis of the surface is desired is now in many ways comparable to the transmission electron microscope (TEM). Magnifications of over 100,000 X are available in SEMs equipped with a field emission gun using the secondary electron mode. Figure 1 shows the interface region of a retained austenite region in the Tazewell iron meteorite shown in both TEM and SEM mode and Figure 2 shows the morphology of crystals, 0.3 μm wide by 1.5 μm long containing ledges 30-50 nm wide in an electrodeposited Zn coating on a steel in both TEM and SEM mode.
Electron microscopy of pulsed-laser-deposited thin films for tribological applications
Authors: Walck Scott D. , Zabinski Jeffrey S. , Donley Michael S. 
Published: June 2020

Pulsed laser deposition (PLD) is a novel thin film deposition technique which has recently been applied to tribological materials with great success. PLD has several inherent advantages over conventional deposition techniques, including excellent film adhesion, replication of target chemistry, and low film deposition temperature. Because load-bearing materials are typically hardened, heat treated alloys, these properties of PLD are ideally suited for tribological applications. In addition to being a relatively simple deposition technique, considerable processing flexibility is inherent with PLD. Dense, nonporous, stoichiometric films of solid lubricants, such as MoS2, have been grown having long wear lives with low coefficients of friction. Hard coating materials, such as TiC, have been grown at room temperature that were polycrystalline and had excellent wear properties.A significant feature of pulsed laser deposited (PLD) thin films is the incorporation of spherical particles within the films. Figure 1 shows these particles embedded in a film of PLD MoS2 deposited at room temperature.
Ion microscope and microprobe studies of surfaces and interfaces
Authors: Newbury Dale E. 
Published: June 2020

Secondary ion mass spectrometry (SIMS) in its spatially-resolved forms, the ion microscope and ion microprobe, offers elemental, isotopic, and molecular detection, wide dynamic intensity range spanning major to trace concentrations in the part per million (ppm) range or lower, high lateral spatial resolution in the micrometer to sub-micrometer range, shallow sampling depths to the nanometer range, and the possibility of "microanalytical tomography", the reconstruction of three-dimensional distributions. With this broad range of capabilities, SIMS has special advantages for the characterization of surfaces and interfaces that complement the measurement capabilities of other microanalysis/surface analysis techniques such as electron probe x-ray microanalysis (EPMA), analytical electron microscopy (AEM), Raman and infrared microscopy, scanning Auger electron microanalysis (SAM/AES), and spatially-resolved x-ray photoelectron spectroscopy (XPS). Examples of applications will highlight the special contributions of SIMS to surface/interface characterization studies.1. Surface studiesFigure 1 shows an example of characterization with extreme surface sensitivity. Changes in surface chemistry induced on a passivated silicon surface by scanning tunneling microscopy in air are revealed by time-of-flight secondary ion mass spectrometry (TOF-SIMS).
Low-voltage high-resolution SEM: A valuable resource for the polymer morphologist
Authors: Vezie D. L. , Adams W. W. , Thomas E. L. 
Published: June 2020

The elucidation of polymer morphology has historically been accomplished using optical microscopy (OM), conventional transmission electron microscopy (TEM), X-ray scattering and more recently for crystalline polymers, high resolution TEM (HRTEM). Significant work using scanning electron microscopy (SEM) to study synthetic polymers began in the late 1960's, but for twenty years after these first studies, the smallest features imaged by SEM in polymer samples have typically been 1-10 μm. The evolution of the low voltage high resolution SEM (LVHRSEM) now provides polymer scientists with the opportunity to image structures topographically on the order of 50-100 Å, a level of microstructure important in basic polymer physics research. The potential for improved understanding of polymer morphology is significant, especially when HRSEM data is combined with information from other complementary techniques such as TEM, X-ray scattering, and the scanning probe microscopies (SPM, AFM, STM).The advantages of LVHRSEM over conventional thermionic source SEM as a polymer characterization technique include: i) low keV operation reduces or eliminates charging in uncoated insulating polymers, ii) the high brightness, low energy spread, small spot size field emission gun allows for operation at low keV without significant loss of resolution (practically, resolution on the order of 50 Å at 1.0 keV in a polymer sample is attainable), iii) imaging of surface topography is improved at low keV as the beam/sample interaction volume is smaller and closer to the surface, resulting in more secondary electrons being generated within the secondary electron escape depth, and iv) the immersion lens system improves the signal to noise ratio by decreasing the noise component in the secondary electron signal.
Dislocation decomposition and dissociation in molybdenum disilicide
Authors: Maloy S. A. , Petrovic J. J. , Mitchell T. E. 
Published: June 2020

Molybdenum disilicide(MoSi2) is being investigated as a potential high temperature structural material. It has the tetragonal C11b crystal structure, space group I4/mmm, with a=3.204Å and c=7.848Å. The shortest Burgers vector is <100> and such dislocations are commonly observed. The {110} planes have pseudo-hexagonal symmetry and so the next larger Burgers vectors, 1/2<111> and <110>, both have b = 4.531Å, followed by 1/2<331> and <001> both with b = 7.848Å. The easiest slip systems are {011}<100> and {110}l/2<111>. These have zero Schmid factors for crystals deformed along [001], forcing other systems such as {103}l/2<331> into operation. Here we will describe and discuss TEM observations of dislocations produced in Czochralski-grown MoSi2 single crystals by deformation along the [001] compression axis at temperatures from 1000 to 1500°C.Specimens tested at 1000°C yielded in a series of load drops starting at a stress of 680MPa and continuing to 1400MPa (the limit of the machine) when the plastic strain was 0.3%.
Electron diffraction study of thin cobalt oxide films grown by pulsed laser deposition on zirconia substrates
Authors: McKernan Stuart , Ramamurthy Sundar , Barry Carter C. 
Published: June 2020

The technique of pulsed laser deposition (PLD) has been applied to many different materials systems. Thin films of metal, ceramic, semiconductor and polymer material have successfully been deposited on different substrates. The nature of the deposited film varies according to the target used and the exact conditions under which the deposition occurred. Among other properties, the films may be amorphous or fully crystalline, they may be homogeneous or contain particulates from the target, and the films may be smooth or textured. Because of the nature of the deposition process the films need not be in the thermodynamically lowest energy state. Following earlier work, we have grown several ceramic films on single crystal oxide targets, to characterize the interfacial reactions involved.In this study crystalline cobalt oxide ceramic films have been grown on (001) zirconia substrates by PLD. The deposition was performed in an oxygen partial pressure of ∼ 6 mtorr, with the substrate heated to 750°C.
TEM characterization of synthetic hillebrandite: Structure, microstructure, and dehydration
Authors: Kim Y. J. , Kriven W. M. 
Published: June 2020

Hillebrandite (Ca2SiO4•H2O) occurs in nature as a white, fibrous mineral. Synthetic hillebrandite was prepared hydrothemally from calcia and silica. On heating, hillebrandite dehydrated to β-Ca2SiO4 which is stable at room temperature. The crystal structure, microstructures and the dehydration mechanism of the synthetic hillebrandite prepared by Ishida et. al were investigated by conventional TEM, HREM, and in situ hot-stage TEM.Most hillebrandite fibers showed their fiber axis to be parallel to the b axis and tended to lie on {001} cleavage planes. SADP’s frequently displayed continuous streaking, and corresponding dark field images revealed stacking disorders perpendicular to the fiber axis (Fig. 1). The observed [001] SADP (Fig. 2) was very different from the expected [001] SADP based on published XRD data (space group, P21/a). For all hk0 reflections, (i) if k = odd, no individual spots are shown but weak continuous streaking exists, (ii) if k = 2, reflections of h = even are extinct, and (iii) if k = 4, reflections of h = odd are extinct.
Flux-pinning-related defect structures in melt-processed YBa2Cu3O7-x
Authors: Wang Z. L. , Kontra R. , Goyal A. , Kroeger D. M. , Allard L.F. 
Published: June 2020

Previous studies of Y2BaCuO5/YBa2Cu3O7-δ(Y211/Y123) interfaces in melt-processed and quench-melt-growth processed YBa2Cu3O7-δ using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) have revealed a high local density of stacking faults in Y123, near the Y211/Y123 interfaces. Calculations made using simple energy considerations suggested that these stacking faults may act as effective flux-pinners and may explain the observations of increased Jc with increasing volume fraction of Y211. The present paper is intended to determine the atomic structures of the observed defects. HRTEM imaging was performed using a Philips CM30 (300 kV) TEM with a point-to-point image resolution of 2.3 Å. Nano-probe EDS analysis was performed using a Philips EM400 TEM/STEM (100 kV) equipped with a field emission gun (FEG), which generated an electron probe of less than 20 Å in diameter.Stacking faults produced by excess single Cu-O layers: Figure 1 shows a HRTEM image of a Y123 film viewed along [100] (or [010]).