bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain boundary composition in silicon nitride
Authors: Bradley S. A. , Karasek K. R.
Published: June 2020

Since one of the major factors for controlling creep properties in silicon nitride components is the addition of sintering aids, determination of the composition of the resulting intergranular second phases becomes very important. High resolution electron microscopy has been used to investigate the crystalline or non-crystalline character of the grain boundary while analytical electron microscopy studies have focused on the composition of the grain boundary pockets. As sintering aid additions and processing become more complex, multiple second phases are produced. Ascertaining the composition of the grain boundaries and grain boundary pockets is necessary for correlating the microstructure with the creep properties.

A dedicated VG HB-5 scanning transmission electron microscope was used to measure the composition of grain boundaries and grain boundary pockets of silicon nitride.
Influence of W additions in rapidly solidified nial
Authors: Locci I. E. , Nathal M. V.
Published: June 2020

The B2 aluminide NiAl has potential as a high temperature structural material, although its lack of low temperature toughness is a major obstacle. One strategy for improving low temperature toughness is by grain refinement. Fortunately, fine grained intermetallics appear to retain their strengths to much higher fractions of their melting point than do pure metals and alloys. The purpose of this study was to investigate the effects of melt spinning and small W additions on the grain size and stability of NiAl.

Two alloys of the same matrix composition, equiatomic NiAl, were examined. One also contained 0.5 W at% (NiAl+W). The alloys were cast as ribbon ∼45 pm thick by ∼2.5 mm wide using a free jet melt spinning apparatus. To simulate consolidation conditions, sections of ribbon were annealed for 1 hour at either 1273 or 1573 °K in purified argon. Optical, X-ray and electron analyses of the as-spun and annealed ribbons were performed.
Rutherford backscattering & TEM studies of nitrogen, oxygen & argon incorporation in sputter-deposited titanium nitride films
Authors: Brown J.M. , Baiocchi F.A. , Williams D.S. , Beairsto R.C. , Knoell R.V. , Murarka S.P.
Published: June 2020

Titanium nitride films are incorporated into semiconductor device fabrication to form both contacts and diffusion barriers. These films are often deposited by means of reactive sputtering of a titanium nitride target in an argon atmosphere. During the course of the deposition process, gaseous components may be incorporated into the films resulting in changes in their physical and electrical properties.

The stress and resistivity of titanium nitride films have been measured as a function of several processing variables: i) target power, ii) substrate bias, iii) pressure and iv) N2/Ar ratio. The concentration of oxygen, nitrogen and argon and their distribution throughout the films were measured using Rutherford Backscattering Spectroscopy of 2.12MeV helium ions generated in a General Ionex 1.7MV accelerator.
High-resolution microscopy of twin boundaries in gold
Authors: Krakow William , Smith David A.
Published: June 2020

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.
Faceted antiphase boundaries in GaAs grown on Ge
Authors: Cho N.-H. , McKernan S. , Carter C.B. , Wagner K.
Published: June 2020

Interest has recently increased in the possibility of growing III-V compounds epitactically on non-polar substrates to produce device quality material. Antiphase boundaries (APBs) may then develop in the GaAs epilayer because it has sphalerite structure (face-centered cubic with a two-atom basis). This planar defect may then influence the electrical behavior of the GaAs epilayer. The orientation of APBs and their propagation into GaAs epilayers have been investigated experimentally using both flat-on and cross-section transmission electron microscope techniques. APBs parallel to (110) plane have been viewed at the atomic resolution and compared to simulated images.

Antiphase boundaries were observed in GaAs epilayers grown on (001) Ge substrates. In the image shown in Fig.1, which was obtained from a flat-on sample, the (110) APB planes can be seen end-on; the faceted APB is visible because of the stacking fault-like fringes arising from a lattice translation at this interface.
Structure-property relationships of PE/PP sandwiched films
Authors: Petermann J. , Broza G. , Rieck U. , Jaballah A. , Kawaguchi A.
Published: June 2020

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.

Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.
Cryo-TEM of micellar solutions
Authors: Burns Janet L. , Talmon Yeshayahu
Published: June 2020

Micelles are aggregates of amphiphilic molecules, i.e., molecules that have both a hydrophilic and a hydrophobic (lyophilic) moiety. These aggregates, in equilibrium with free molecules, may attain various shapes: spherical, spheroidal, or cylindrical, depending on concentration, temperature, and presence of other solutes in the system. In all of these aggregates the hydrophilic “heads” are in contact with water, and the hydro-phobic “tails” form a non-aqueous domain within the micelle. When the solvent is non-aqueous the situation is reversed; “inverted micelles” form where the hydrophobic “tails” point outwards into the solvent. Most structural data on micellar systems have come from indirect methods such as NMR, light and x-ray scattering. Interpretation of these data is model dependent. Only TEM is capable of producing direct images of micellar aggregates. However, precaution should be taken to preserve the labile microstructures of these systems during specimen preparation.
High-resolution scanning electron microscopy
Authors: Nagatani T.
Published: June 2020

Although the main development of scanning electron microscopy (SEM) has been accomplished mostly by the Cambridge group and it has not been changed so much for about two decades, it should be noted that there have been two important developments to pursuing high resolution of better than 1nm.

Most notably, use of a field emission gun developed by Crewe et al for the scanning transmission electron microscope (STEM) to form a fine electron beam has been most effective in SEMs due to its high brightness and low energy spread. Thus, several models of field emission (FE) SEMs have been developed in the early ’70s and commercialized with a resolution of 2∼3nm at around 30kV.

The second development is to use a highly excited objective lens. The specimen has to be set inside the pole-pieces (so-called “in-lens” type).
What does the biologist want from the physical scientist?
Authors: Beer Michael
Published: June 2020

The Biologist is interested in discovering and then understanding the chemical processes in organisms. Crucial in his analysis is a knowledge of the structure of the system at various levels. At the level of the cell he must recognize the positions of particular macromolecules. For proteins or nucleoproteins this is best done with labeled antibodies. Inorganic ions like calcium or sodium can be localized by X-ray microprobe or EELS. From the designer he requires instruments in which the distribution of these species is not altered by the data collection. Specimen stability is favored by low temperature and efficient collection of data. That means simultaneous detection of all possible scattering events. Rapid display of the results as abundances requires computers of sufficient capability.

Similar procedures look promising in the analysis of the structure of nucleic acid-protein complexes. Nucleic acids can be traced through phosphorus and protein through sulphur or perhaps carbon to nitrogen ratio.
Correlative video enhanced DIC-LM, HVEM, and low-voltage high-resolution SEM in the study of surface and internal ultrastructure
Authors: Albrecht Ralph M. , Olorundare Olufunke E. , Bielich Howard W. , Simmons Scott R.
Published: June 2020

Previously we have found high voltage electron microscopy (HVEM) and conventional scanning electron microscopy (SEM) to be useful in investigating relationships between surface and subsurface structure. The use of directly conjugated 5nm and 18nm colloidal gold-ligand or colloidal gold-antibody has been useful with HVEM and SEM to determine the location of surface membrane associated glycoproteins relative to surface and internal ultrastructure. Using the platelet as a model system, we have demonstrated cytoskeletal rearrangement coincident with the activation-associated shape change response. Furthermore the activity and location of the receptor (membrane glycoprotein complex IIb IIIa) for fibrinogen and several other RGD sequence-containing “adhesive” proteins is related to the structure and cytoskeletal organization of the platelet. The receptor is present, but unable to bind whole ligand, on discoid and spherical platelets (small ligand fragments and monoclonal antibody or peptide sequences specific for the active site can, however, bind).
The preparation and study of a holey polymer film
Authors: Vinson Phillip K.
Published: June 2020

A holey carbon grid (HCG) consists of a TEM grid with a holey polymer film (HPF) attached to its surface and a carbon coating to provide mechanical stability and electrical conductivity. HCGs have found wide use in the preparation of liquid samples for cryo-TEM. These grids increase the number of sample sites by as much as three orders of magnitude and aid in the formation of fairly uniform, thin specimen films (< 250 nm). Several methods have been reported for the production of HPFs for specimen support. Unfortunately, most methods are unreliable, often producing films with pseudo-holes and large continuous film regions. Essential to improving any technique is an understanding of the process mechanisms involved. This paper describes a technique, modified from Refs. 1 and 2, for preparing HPFs and suggests a drying mechanism to explain the results.
Nonspecific structures seen in diagnostic muscle biopsies
Authors: Caughey R. C. , Kalyan-Raman U. P.
Published: June 2020

In a period of two years we have analyzed 50 muscle biopsies using the transmission electron microscope. Six nonspecific structures consisting of filamentous bodies, tubular aggregates, paracrystalline mitochondrial inclusions, honeycomb arrays, concentric laminated bodies, and finger print profiles were observed in 47 of 50 cases. In order to know the significance of these structures in muscle biopsies, we correlated their occurrence with their clinical history, histological findings, and histochemistry.

The biopsies were initially fixed in 2.5% glutaraldehyde (pH. 7.5, 500 mOsm), then randomly minced and post fixed in 1% osmium tetroxide. All biopsies were processed with and without uranyl acetate en bloc staining in Walpole's buffer before ethanol dehydration. They were embedded in Epon 812 epoxy resin, sectioned, and stained with uranyl acetate and lead citrate before evaluation with a JEOL, JEM 100 C Transmission Electron Microscope. All grid squares of six different blocks were scanned to evaluate the ultra-structural pathology.
Effects of Zn deficiency on thymus of growing rats
Authors: Yamashiro S. , Bast T. , Bray T.M. , Bettger W.J.
Published: June 2020

Zinc (Zn) deficiency is thought to cause depressed immune function in both the cell mediated and humoral aspects of the system. Alteration of lymphocyte maturation and migration has been observed in Zn-deficiency and marked reduction of the lymphocyte number was noted in the thymus of the pups fed Zn-deficient diet. Other alterations include parakeratosis of the squamous epithelia of digestive system and skin.

Three groups of seven, weanling, male Wistar rats each were fed diets containing either 1.1 ppm Zn (deficient) or supplemented with 100 ppm Zn ad libitum (control) or the Zn supplemented diet limited to the amount consumed by those on the deficient diet (pair-fed) for 3 weeks. Details of the diet compositions have been reported previously (7). The animals were weighed at the onset and end of the experiment. The organ was weighed after it was fixed in Karnovsky's fixative and small pieces of the tissue were post-fixed in 2.0%, OsO4 for electron microscopy.
Calcium phosphate cements as binders for hydroxylapatite particles for bone repair
Authors: Hanker J. S. , Giammara B. L. , Lupton C. R. , Chow L. C.
Published: June 2020

Calcium phosphate cements (CPCs) are under study for dental applications such as root canal filling or sealing and pulp capping. Upon setting they are converted principally to hydroxyapatite, the mineral constituent of bone. The presence of a small amount of fluoride or hydroxyapatite in the cement mixture hastens the setting time. Nevertheless, the CPCs set much more slowly than plaster of Paris (calcium sulfate hemihydrate) when moistened with water or dilute phosphoric acid.

Hydroxylapatite (HA) is hydroxyapatite which has been processed either by sintering or firing into a dense ceramic or made into porous particles. Plaster has been found very useful as a binder to prevent the scatter of HA particles implanted for jawbone reconstruction. The composite HA/plaster implants can be tailored to fit the site during surgery or preformed and sterilized prior to surgery.
Immunoelectron microscopic localization of α2u-globulin in the male rat kidney after gasoline administration
Authors: Garg B.D. , Olson M.J. , Li L. , Mancini M.A. , Roy A.K.
Published: June 2020

Exposure of male rats to unleaded gasoline and other volatile hydrocarbons causes acute nephrotoxicity with accumulation of hyalin droplets (HD) in epithelial cells of the proximal convoluted tubules (PCT). We have shown that HD accumulated after gasoline intoxication are partially composed of α2u-globulin, a protein found exclusively in adult male rats. Ultrastructural examination revealed HD to be enlarged phagolysosomes (secondary lysosomes). Metabolites of gasoline hydrocarbons are hypothesized to bind reversibly to α2u-globulin, perhaps limiting lysosomal degradation of this protein. α2u-Globulin accumulation may also result from hydrocarbon-mediated inhibition of lysosomal proteolytic enzyme activity. These studies were conducted to determine the distribution of α2u-globulin within epithelial cells of PCT during gasoline intoxication.

Male F-344 rats were administered unleaded gasoline or 0.9% NaCl solution (2.0 mL/Kg, p.o., once daily, nine days) and 2 mm slices of saline-perfused kidney were fixed by immersion in 2.5% glutaraldehyde, 0.1 M sodium cacodylate (pH 7.4).
Fibrinogen binding to activated thrombocytes
Authors: O'Toole E. T.
Published: June 2020

Avian thrombocytes (TC) are involved in hemostasis through a fibrinogen (Fib) mediated process. Although Fib acts to bridge cells, the localization of Fib binding sites on cells has not been characterized. Described is Fib binding to TC activated either for aggregation while in suspension or following adhesion to formvar. Use of colloidal gold both conjugated to the ligand, Fib, and indirectly as an immuno-gold probe against an antibody specific for the Fib receptor, enabled visualization of the binding regions. Fib receptor 3-D organization was revealed by serial reconstructions of TC aggregates and by whole cell mount stereo microscopy.

Pigeon TC, obtained from citrated (1:9) blood by differential centrifugation, were washed in Ca++ free Puck's saline G (pH 6.5). Pigeon Fib was conjugated to 15 nm gold by vortexing and used to facilitate TC aggregation to 0.5 U/ml thrombin and 3 mM Ca++.
Effects of dasheen mosaic virus and a large bacilliform particle on the anatomy and ultrastructure of Colocasia esculenta (L.) Schott (Araceae)
Authors: Stein B. D. , Strauss M. S.
Published: June 2020

Taro, Colocasia esculenta (L.) Schott (Araceae) is a monocot grown as a starchy root crop in much of the tropics and subtropics. It is subject to a number of fungal, bacterial, and viral diseases. Viral diseases have inhibited the cultivation of taro in parts of New Guinea and the Solomon Islands where taro is an integral part of the culture. Two different viruses, a Rhabdovirus, the Large Bacilliform Particle (LBP), and a smaller bacilliform virus, are the cause. Dasheen Mosaic Virus, a Potyvirus, has been found wherever taro is cultivated and produces a leaf mottle but is not lethal to plants.

Colocasia esculenta cv K268 corms, infected with virus, were obtained from Michael Pearson, Department of Botany, University of Papua New Guinea, Port Moresby, New Guinea. Upon planting some of the corms produced leaves with virus symptoms. Others were symptomless but symptoms could be induced by stress.
Immunogold labeling of cell surface antigens: The Scanning Electron Microscope approaches.
Authors: de Harven E. , Soligo D. , He S. , Christensen H. , Bootsma G.
Published: June 2020

The scanning electron microscope (SEM) has been used for many years to visualize the distribution of various antigens expressed on cell surfaces. Several markers were used for that purpose, as reviewed by Molday; they were recognized on cell surfaces on the basis of their size and/or shape. However, it is only after colloidal gold particles were demonstrated to be markers of almost universal applicability that the significance of inmuno-SEM in cell biology became evident. The unique properties of the colloidal gold marker can be summarized as follows: it can be prepared in a range of sizes (5 to 40 nm) which accommodates well the resolution of both TEM and SEM; under the light microscope it can be seen as a red stain, or under polarized light epi-illumination; almost all proteins can easily be electrostatically conjugated to it, without noticeable alteration of their biological properties;
Protein electron crystallography by 400kV cryo-microscopy
Authors: Chiu Wah , Brink Jaap , Soejima Toshinori , Schmid Michael F.
Published: June 2020

Protein electron crystallography can provide a reconstruction detailed enough for the polypeptide chain of a membrane protein to be traced (1). However, there remain a number of technical problems associated with this technique that must be overcome before it can become a routine tool for high resolution three-dimensional structural analysis of protein crystals. A 400 kV electron microscope has been demonstrated to be advantageous for enhancement of resolution and contrast in images of protein crystals (1,2) because of a reduction in chromatic aberration effects. This paper addresses the question of experimental strategy in data collection for thin protein crystals with a 400 kV cryo-microscope. We will use crotoxin complex and T4 DNA helix destabilizing protein as examples of thin crystals to illustrate our approach.

Crotoxin complex forms highly ordered crystals with different thicknesses among different crystals. In order to simplify sorting out data from the various crystals for 3-dimensional merging, it is desirable to collect as much data as possible from a single crystal.
Embedding resins: An historical perspective
Authors: Mollenhauer Hilton H.
Published: June 2020

There are several factors that were requisites for the biological applications of electron microscopy. One of these was, clearly, the development of a matrix substance that could infiltrate biological material and encapsulate tissue components so that they could be thin sectioned and examined under an electron beam. Without such matrix substances, examination of tissue as we know it today, would not be possible.

Perhaps the start of practical electron microscopy in the context stated above was the application of methacrylate resins for tissue embedment. Methacrylates have a very low viscosity and maintain this viscosity until polymerization is initiated (for days or weeks if one should wish). The two most commonly used methacrylates were n-butyl (soft) and n-methyl (hard) which could be mixed in various proportions to yield almost any block hardness. Methacrylates can be cross-linked with divinyl benzene to improve stability but this was not commonly done. Methacrylates are very easy to section which was an important aspect at the time since sectioning had to be done with glass knives.
Parallel Electron Energy Loss Spectroscopy of a Cu-Be Alloy
Authors: Strutt A.J. , Williams D.B.
Published: June 2020

Although the Cu-Be binary system has been studied by previous investigators and recently reviewed, no direct measurements have been made concerning the chemistry of the γ-phase, which has a nominal stoichiometry CuBe. Quantitative parallel electron energy loss spectroscopy (PEELS) has been used in this investigation of a Cu, 1.8 wt.% Be, 0.3 wt.% Co alloy to determine a section of the γ/(α+γ) phase boundary of the Cu-Be phase diagram. Sections of alloy (in sheet form) were encapsulated in evacuated quartz capsules to prevent oxidation and isothermally aged in the temperature range 400 - 600°C. TEM specimens were prepared by punching disks from the sheet, dimpling and ion milling. Spectra were acquired using a Philips EM400 TEM/STEM in the TEM image mode, and with a Gatan parallel recording EELS spectrometer. The acquisition mode allowed for the use of a relatively large (yet accurately known) collection angle. The incident beam convergence angle was also determined, so that a beam convergence correction could be used to calculate the true collection angle.
Difference mode EXELFS with parallel-detection EELS
Authors: Kundmann Michael K. , Krivanek Ondrej L.
Published: June 2020

Parallel detection has greatly improved the elemental detection sensitivities attainable with EELS. An important element of this advance has been the development of differencing techniques which circumvent limitations imposed by the channel-to-channel gain variation of parallel detectors. The gain variation problem is particularly severe for detection of the subtle post-threshold structure comprising the EXELFS signal. Although correction techniques such as gain averaging or normalization can yield useful EXELFS signals, these are not ideal solutions. The former is a partial throwback to serial detection and the latter can only achieve partial correction because of detector cell inhomogeneities. We consider here the feasibility of using the difference method to efficiently and accurately measure the EXELFS signal.

An important distinction between the edge-detection and EXELFS cases lies in the energy-space periodicities which comprise the two signals. Edge detection involves the near-edge structure and its well-defined, shortperiod (5-10 eV) oscillations. On the other hand, EXELFS has continuously changing long-period oscillations (∼10-100 eV).
Ultra-high resolution backscattered imaging
Authors: Joy David C
Published: June 2020

A recent paper by Ogura displays backscattered electron (BSE) images from a bulk, layered structure of AlAs/GaAs with repeat spacings of the order of 10nm. Typically BSE images are thought of as being inherently limited in resolution to a level which is of the order of a fraction of the Bethe range of the incident electrons, which for the beam energy and specimen used in these experiments would be of the order of 5 μm. The purpose of this paper is, therefore, to examine the conditions required for the nanometer level resolution achieved in this case.

Backscattered electrons can be grouped into two classes, the BSI which are backscattered by a single high angle event soon after their entry into the specimen, and the BSII which are produced as the cumulative result of plural scattering. There is no sharp division between these groups but the two classes can be separated experimentally by energy filtering, since the BSI will have lost little energy in their short transit through the sample.
Precipitation of as in low-temperature MBE-grown gaas
Authors: Twigg M. E. , Fatemi M. , Tadayon B.
Published: June 2020

Recent work, on As rich GaAs buffer layers grown at low temperatures by molecular beam epitaxy (MBE), shows that this material has electronic and materials properties that differ from GaAs grown at higher temperatures. Among the interesting properties of these buffer layers are reduced recombination times and high breakdown voltages useful in power field effect transistors (FETs). We have used TEM, in conjunction with double crystal x-ray rocking curves, in studying GaAs grown and annealed at a variety of temperatures. X-ray rocking curve analysis has separated LT (low temperature) GaAs growth into three ranges of growth temperature: the “low-range” below 215°C, the “mid-range” from 215 to 340°C, and the “high-range” above 340°C. The low-range material is amorphous, as suggested by the presence of only the bulk reflections in the x-ray diffractometei profile and from HRTEM images of the MBE-grown buffer layer. The mid-range is single crystal and defect-free, although larger in lattice parameter than stoichiometric GaAs by as much as 0.08%.
TEM analysis of light emitting porous silicon
Authors: Cole M. W. , Harvey J. F. , Lux R.A. , Eckart D.W.
Published: June 2020

The recent observations of visible light emission from porous silicon layers (PSL) have attracted much interest due to its potential applications in silicon based optoelectronic integrated circuits, optical memories and advanced display systems. To realize these potential applications this material must be fully characterized. Specifically, the microstructure must be studied in order to understand the origin of the light emission. Unfortunately, the issue of the detailed geometry of porous silicon is not fully resolved because of the difficulty in performing transmission electron microscopy (TEM) measurements on these fragile structures. One of the first microstructural studies on visible emitting PSL, presented by Cullis and Canham, showed the material to be composed of needle-like structures having a cross sectional diameter of 3nm. It was suggested that the visible luminescence in this material is due to quantum confinement of these small structures. A major limitation of this work was the method of TEM sample preparation.
The crystal structure of eugaAl
Authors: Brigitte Krause H. , Qian Yonglin
Published: June 2020

A polycrystalline specimen of nominal formula EuGaAl with unknown crystal structure was investigated by various electron microscope techniques; EDS-, SED-, and CBED data were taken on a Philips 400 electron microscope operated at 100kV, HREM data on a Hitachi 9000 microscope operated at 300kV. The EDS data confirmed the composition for the bulk of the material but, in addition, revealed particles with other fractions of the elements. Only the EuGaAl particles were further investigated. The unit cell was determined to be orthorhombic with a ratio: a/b=0.969(2) , a/c=0.234(2) and b/c=0.234(2). The lattice constants are a=4.54(5)Ȧ, b=4.68Ȧ and c=19.97(20)Ȧ. Based on systematic extinctions for hkl reflections with h+l=2n+l, the unit cell was found to be b-centered. CBED patterns of the [001], [100], and [010] zone axes are shown in Fig. 1. The zone axis patterns are in agreement with the above stated data except for diffused (2m+l,2n+l,0)- reflections, not compatible with the above stated systematic absences. But these occurred only occasionally in conjunction with a complicated noncommensurate superlattice pattern.
Characterization of rutile (110) surface structure by REM
Authors: Wang L. , Liu J. , Cowley J. M.
Published: June 2020

Single crystal TiO2 (rutile) (110) surface has been characterized by several experimental techniques. In this paper, we report the investigations of “optically polished” as well as high temperature oxygen annealed rutile (110) surfaces by using reflection electron microscopy (REM) and reflection high energy electron diffraction (RHEED) techniques.

The crystal was purchased, “optically polished” as-received, from Commercial Crystal Laboratories, Inc.. The details in specimen cutting and surface cleaning procedures have been reported previously. The samples were annealed in pure oxygen at 1425°C for 36 h. The experimental observations were carried out in a Philips 400T microscope operated at 120 kV. The REM images were obtained by selecting the specular reflection spots satisfying surface resonance conditions.

Figure 1 is a REM image of as-received rutile (110) surface. The corresponding RHEED pattern is shown in the inset. The azimuthal angle of the incident beam was at 3.9° away from [001] zone axis and the image was formed by choosing (440) specular reflection spot under surface resonance condition.
Use of pattern recognition tools for classifying particles into homogeneous groups
Authors: Hopke Philip K.
Published: June 2020

Computer-controlled scanning electron microscopy (CCSEM) permits the characterization of size, shape, and composition of individual particles and thus provides a rich source of data to identify the origin of ambient airborne particles. The problem is how to make best use of this information. The general procedure has been to assign each particle to a class of similar particles based on its x-ray fluorescence spectrum. The initial efforts developed the class characteristics and classification rules in an empirical fashion. Recent studies have suggested that greater specificity and precision in the subsequent class balance analysis can be obtained if particle classes are more homogeneous.

Data screening and transformation are the initial steps in the analysis procedure. Noise reduction is the first step in analyzing the CCSEM data. Determination of elemental chemistry for individual particles is accomplished by collection of characteristic X-rays. The X-ray fluorescence peaks are obtained as a result of a photon counting process having a Poissonian distribution.
Vibrational spectroscopic techniques for surface and microanalysis of materials
Authors: Koenig Jack L.
Published: June 2020

There is an increasing awareness of the deleterious effects of inhomogeneities on the properties of solids. With this concern comes the need for microanalytical techniques which can yield information not only about the number, size and shape of the inhomogeneities but also their composition and structure. Determination of the structure and composition of the micro-inhomogeneities require the use of spatially-resolved spectroscopic techniques.

Space-resolved spectroscopic techniques are here defined as microanalytical methods which can generate a spectrum spatially resolved in 1, 2 or 3 dimensions from a sample. In one dimension, one obtains a spectral profile, in two-dimensions, a spectral map and in three-dimensions, a spectral image. These spectral methods are ultimately “chemical microscopic” techniques because they couple directly the spectroscopic information (chemical entities) with space information. The maps or images display the spatial distribution of the local chemical environments arising from concentration and structural gradients in the sample. In many cases, very good spectra can be obtained from volumes of a few cubic microns, typically 10−11 grams of matter.
Electron-probe microanalysis of silicon implanted with oxygen and nitrogen
Authors: Dijkstra J.M. , Bastin G.F , Heijligers H.J.M.
Published: June 2020

High dose ion implantation is a promising technique to form a silicon-on-insulator material. Possible ions for implantation are oxygen and nitrogen, to form insulating layers of buried silicon-oxide and silicon-nitride, or a combination of oxygen and nitrogen, to form silicon oxynitride.

One of the problems in analyzing the results of an ion implantation is that it is hard to establish the depth-distribution of the implanted ions in a straight-forward way. Several techniques are available; each of them with their own advantages and disadvantages. A promising approach might be in-depth profiling with the electron probe microanalyzer.

The first step in this analysis method is to accurately measure the k-ratios of all the elements involved at a range of accelerating voltages, starting at as low a voltage as possible.

The second step is to analyze these measurements with a sophisticated multi-layer analysis (MLA) program. In our laboratory we use an MLA program based on our "PROZA"-bulk correction program, of which we previously explained how it can be expanded to a thin film analysis program.
Electrical microcharacterization of Si-TaSi2 eutectic composites
Authors: Hefter J. , Rossoni P. G.
Published: June 2020

Semiconductor-metal eutectic composites, formed by directional solidification from the melt, are composed of arrays of continuous metallic fibers contained within a single-crystal semiconductor matrix. Such composites contain rods having diameters of ≈1 μm with inter-rod spacings on the order of 10 μm. These rods form cylindrical Schottky junctions with the Si and can be used as the basis for a variety of electronic and optoelectronic devices, including photodetectors and bulk field effect transistors. Electron beam induced current (EBIC) measurements permit the determination of the depletion zone surrounding the active regions of a semiconductor material. This method has been used to examine the carrier concentration in a Si-TaSi2 eutectic composite.

A portion of an oval transistor mounted on a semiconducting wafer consisting of Si-TaSi2 eutectic material with contacted rod elements was studied. The rods were selectively contacted by a deposited CoSi2 film which provided an ohmic contact to the TaSi2 rods yet formed a rectifying Schottky barrier with the Si matrix.
Environmental application of LAMMS technique for stone deterioration
Authors: Tsugoshi Takahisa , Hiroi Hidemi , Kikuchi Tadashi , Furuya Keiichi
Published: June 2020

Recently, architecture deterioration, one of serious problems in Europe and America, has become to be observed conspicuously in Japan. It is confirmed that the deterioration is caused due to not only natural weathering but the acid rain. The deterioration mechanism, however, is still unknown. For a environmental sample, a technique of micro- and chemical analysis for insulators is required just like LAMMS. In this study, LAMMS was applied to "Oya-ishi", a kind of green tuff which is a kind of common building stone in the Tokyo and its vicinity, Japan.

Samples were collected at six sites in this district as shown in Fig. 1. Sample A and C were taken from fences along the arterial highway. Sample B and D were taken from fences along the back alley. Sample E and F were taken from fences along the alley at residential area. Site A-D were in the center of the Tokyo metropolitan area, and Site E and F were in the northern and western suburbs.
Focusing x rays for microprobe x-ray fluorescence analysis
Authors: Wittry D. B.
Published: June 2020

X-ray microprobes that use focused monochromatic x rays for fluorescence excitation have four significant advantages over electron microprobes that use focused electrons for direct excitation, namely: 1) less background radiation is produced, 2) there is little or no charging of insulating specimens, 3) less damage is caused to the specimen, and 4) the specimen often does not need a high vacuum environment. These advantages result from the difference in interaction of photon and electron beams with matter. In the first place, because the x-ray photon is uncharged, bremsstrahlung which is always obtained with electron bombardment, is not produced by photon bombardment; this results in higher signal/background ratio and can yield lower detection limits by a factor of about 10−2 of those obtained with electron microprobes. Also because the photon is uncharged, the only charging of insulating specimens is due to secondary effects. Second, x-ray photons preferentially excite inner shell electrons as is well known from the large increase in absorption coefficient when the photon energy exceeds the critical excitation energy; this results in less damage for a given number of characteristic x-rays produced in the specimen.
Si(Li) detector for microanalysis cooled by thermoelectric device
Authors: Barkan Shaul
Published: June 2020

Cooling down solid state detecors, with other different way then liquid Nitrogen, is a goal of many vendors and customers since the invention of these detectors. THe disadvantage of the common way of liquid Nitrogen is first the inavailibility of the LN in many uses (like space military and any other applications that are not done inside a well organize Laboratory). The use of LN also considers as a Labor consumer in addition to the big dewar that has to be added to any detector for storing the LN, the boiling of the LN, may cause microphonics problesm and the refiling of the dewar in many Labs is a complicated process due to inconvenience location of the microscope.

In this paper I will show a spectra result of 10mm2 SiLi detector for microanalysis use, cooled by peltier cooler. The peltier cooler has the advantage of non-microphonics and non-labor needed (like adding LN to the dewar).
ELNES of Iron Compounds
Authors: Kurata Hiroki , Nagai Kazuhiro , Isoda Seiji , Kobayashi Takashi
Published: June 2020

Electron energy loss spectra of transition metal oxides, which show various fine structures in inner shell edges, have been extensively studied. These structures and their positions are related to the oxidation state of metal ions. In this sence an influence of anions coordinated with the metal ions is very interesting. In the present work, we have investigated the energy loss near-edge structures (ELNES) of some iron compounds, i.e. oxides, chlorides, fluorides and potassium cyanides. In these compounds, Fe ions (Fe2+ or Fe3+) are octahedrally surrounded by six ligand anions and this means that the local symmetry around each iron is almost isotropic.

EELS spectra were obtained using a JEM-2000FX with a Gatan Model-666 PEELS. The energy resolution was about leV which was mainly due to the energy spread of LaB6 -filament. The threshole energies of each edges were measured using a voltage scan module which was calibrated by setting the Ni L3 peak in NiO to an energy value of 853 eV.
Temperature-Dependent EXELFS of Chemically Ordered and Disordered Fe3Al
Authors: Okamoto James , Ahn Channing , Fultz Brent
Published: June 2020

A parallel detection system makes possible quantitative studies of extended electron energy-loss fine-stucture (EXELFS). We are studying the short-range chemical order and local thermal vibrations of chemically ordered and disordered Fe3Al foils using transmission EXELFS. The average number of Fe atoms in the first nearest-neighbor (1nn) shell surrounding the Al atoms in chemically ordered and chemically disordered materials are determined by comparing our data with ab initio EXAFS calculations. The mean-squared relative thermal displacements between the Al atoms and their 1nn shell are roughly determined by our temperature-dependent data.

Chemically disordered Fe-27at%Al and Fe-25at%Al samples were prepared by piston-anvil quenching. Some samples were annealed at 300 °C for over a day to develop DO3 order. Aluminum K edge spectra were collected with a Gatan 666 parallel detection magnetic prism spectrometer attached to a Philips EM 430 electron microscope. Room temperature spectra were collected from submicron regions of the Fe-27Al samples with 300 keV electrons and a beam current of 10 nA.
Hartree-Slater Calculations of the L23 Edges of 3d Transition Metal Electron Energy Loss Spectra
Authors: Pearson D. H. , Ahn C. C. , Fultz B. , Rez P.
Published: June 2020

A straightforward method for measuring the white line intensities of the L23 absorption edges of 3d transition metal electron energy loss spectra was recently reported by Pearsonet al.[1]. In that analysis, the white line intensities were isolated by assuming that the continuum contribution for the 3d metals could be approximated by an edge shape similiar to that of copper, which has a full 3d band. When normalized to the continuum, the white line intensities were found to decrease linearly with atomic number (or 3d state occupancy). A similar analysis for the 4d metals showed that the white line intensities initially increased, peaked at Nb, and then decreased nearly linearly with atomic number [2]. The white line calculations of Ahnet al.were in qualitative agreement with these results for the 4d metals, but deviated from experimental results for the early 3d metals [3]. In an effort to determine if the continuum L23 edge is indeed copper-like for the early 3d metals we have calculated the continuum edge shapes based on an atomic, one electron model.
An Improved Method for the Preparation and TEM Examination of Sharp Pointed Tips used in APFIM and STM
Authors: Fischione E.A. , Fischione P.E. , Haugh J.J. , Burke M.G.
Published: June 2020

A common requirement for both Atom Probe Field-Ion Microscopy (APFIM) and Scanning Tunnelling Microscopy (STM) is a sharp pointed tip for use as either the specimen (APFIM) or the probe (STM). Traditionally, tips have been prepared by either chemical or electropolishing techniques. Recently, ion-milling has been successfully employed in the production of APFIM tips [1]. Conventional electropolishing techniques are applicable to a wide variety of metals, but generally require careful manual adjustments during the polishing process and may also be time-consuming. In order to reduce the time and effort involved in the preparation process, a compact, self-contained polishing unit has been developed. This system is based upon the conventional two-stage electropolishing technique in which the specimen/tip blank is first locally thinned or “necked”, and subsequently electropolished until separation occurs.[2,3] The result of this process is the production of two APFIM or STM tips. A mechanized polishing unit that provides these functions while automatically maintaining alignment has been designed and developed.
In-Situ Electron Energy Loss Spectroscopy of Silicon Carbide Crystals During Electron Irradiation After Hydrogen Ion Implantation
Authors: Hojou Kiichi , Furuno Sigemi , Otsu Hitoshi , Izui Kazuhiko
Published: June 2020

Observations of damage structure and analysis of compositional changes are important to elucidate the fundamental process of radiation damage in ion-irradiated ceramics. We have developed an in-situ observation system consisting of a 100 keV transmission electron microscope linked with both an ion accelerator and a parallel electron energy loss spectrometer (P-EELS), as shown in Fig.1[1,2]. Using this system, the plasmon loss peaks of SiC crystals were found to shift to the lower energy side during hydrogen ion irradiation at room temperature (RT)[3].

The present paper reports the results of in-situ observation and analysis by P-EELS of SiC crystals during hydrogen ion irradiation and the effects of 100keV electron irradiation after hydrogen ion implantation.

Specimens used in the present work were SiC sintered crystals supplied from Hitachi Research Lab., Hitachi LTD. Thin films suitable for electron microscopy were made by 2-4 keV Ar+ions etching after mechanical polishing and then irradiated with 10keV H2+ions by use of ion accelerator combined with EM at RT and 800 °C, respectively.
Gaussian ϕ(ρz) curves: Comparison with other models
Authors: Riveros Alberto , Castellano Gustavo
Published: June 2020

X ray characteristic intensity Ii , emerging from element i in a bulk sample irradiated with an electron beam may be obtained through

where the function ϕi(ρz) is the distribution of ionizations for element i with the mass depth ρz, ψ is the take-off angle and μi the mass absorption coefficient to the radiation of element i.

A number of models has been proposed for ϕ(ρz), involving several features concerning the interaction of electrons with matter, e.g. ionization cross section, stopping power, mean ionization potential, electron backscattering, mass absorption coefficients (MAC’s). Several expressions have been developed for these parameters, on which the accuracy of the correction procedures depends.

A great number of experimental data and Monte Carlo simulations show that the general shape of ϕ(ρz) curves remains substantially the same when changing the incident electron energy or the sample material. These variables appear in the parameters involved in the expressions for ϕ(ρz). A good description of this function will produce an adequate combined atomic number and absorption correction.
Site Occupation of Ternary Element in an Alti Compound by Alchemi
Authors: Yunrong Ren , Ya Xu , Zuqing Sun , Guoliang Chen
Published: June 2020

Site occupation of alloying additions in AlTi compounds is important for high temperature alloys development. In this paper, we intend to locate the ternary element Nb in an AITi compound using the ALCHEMI technique. With the L10_type structure, the planes of either (110) or (001) are composed of Al and Ti atoms alterately. Therefore, the ternary element dissolved in the AITi compound can be easily located by ALCHEMI technique[1,2].

A Specimen of 51.1 at%Al-41.5at%Ti-7.4at%Nb alloy was used. The structure of this specimen is composed of AlTi, Ti3Al, and other intermetallic compounds which were examined by x_ray diffraction and electron diffraction. The electron micrograph of Fig. 1 shows the compounds structure with lamellar features. Lamellae of AlTi phase of about 1 μm in width were chosen for analysis. The composition of this AlTi phase is about 45at%Al, 44at%Ti, and 11 at%Nb by x_ray analysis in non_channelling condition.
Carbide composition changes in a low alloy steel
Authors: Larouk Z. , Pilkington R.
Published: June 2020

Durehete 1055 is a 1%Cr1%Mo¾%V low alloy steel used as bolting material at 565°C. It also contains 0.08%Ti and 0.005%B to improve the creep behaviour, but deleterious properties have been reported, due to the presence of trace elements such as P and Sn. The present work has been an attempt to understand this problem by examining three vacuum melted casts of this steel containing selected additions (wt.%) of 1) 0.08 Ti, 2) 0.08 Ti and 0.02 P; and 3) 0.08 Ti and 0.02 Sn. The material was heat treated for 2h at 980°C, W.Q., and tempered 4h at 680°C, giving a prior austenite grain size of 8 μm. Specimens were then crept for various times at 565°C. After test, metallographic samples were prepared from both the gauge lengths (stressed) and heads (unstressed) to enable the production of carbon extraction replicas. These replicas were examined in a Philips 400T electron microscope, and carbides analysed using EDS.