bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic structure determination of NIO-ZRO2(CaO) and NI-ZRO2(CaO) interfaces using Z-contrast imaging and EELS
Authors: Dickey E.C. , Dravid V.P. , Nellist P. , Wallis D.J. , Browning N. D. , Pennycook S.J.
Published: June 2020

Combining atomic-resolution imaging with spatially resolved electron energy loss spectroscopy (EELS) is a powerful approach to probing the geometric, chemical and electronic aspects of internal interfaces. By elucidating these interrelated constituents of interface structure, one can begin to understand the influence of the interface atomic structure on relevant bulk material properties, deducing atomic structure/property relationships. The combined Z-contrast and EELS approach was applied to two types of heterophase interfaces: oxide-oxide (NiO-ZrO2) and metal-oxide (Ni-ZrO2). The interface structure will be discussed in light of these experiments and compared to previous HREM results.
Pinning of 90° domain boundaries at interface dislocations in BaTiO3/LaAIO3 {100}
Authors: Dai Z.-R. , Wang Z.L. , Duan X.F. , Zhang J.
Published: June 2020

Epitaxially grown BaTiO3 thin films have potential applications in microelectronics and integrated photonics. The ferroelectric property of this material is largely determined by the domain structure. It is believed that the structure of the substrate would have profound effect on the quality of BaTiO3 epitaxial thin films. This paper reports our studies on the pinning of 90° domain boundaries at interface dislocations.

Epitaxial BaTiO3 thin films were deposited on single crystalline LaAIO3 (100) substrates at 800°C by metal-organic chemical vapor deposition (MOCVD). Cross-section specimens of the films were studied at 200 kV using an JEOL 2010 high-resolution transmission electron microscope (HRTEM).
Computer simulations for the TEM bend contour technique
Authors: Kolosov Vladimir Yu. , Thölén Anders R.
Published: June 2020

In this paper we give a short overview of two TEM applications utilizing the extinction bend contour technique (BC) giving the advantages and disadvantages; especially we consider two areas in which the BC technique remains unique. Special attention is given to an approach including computer simulations of TEM micrographs.

BC patterns are often observed in TEM studies but are rarely exploited in a serious way. However, this type of diffraction contrast was one of the first to be used for analysis of imperfections in crystalline foils, but since then only some groups have utilized the BC technique. The most extensive studies were performed by Steeds, Eades and colleagues. They were the first to demonstrate the unique possibilities of the BC method and named it real space crystallography, which developed later into the somewhat similar but more powerful convergent beam method. Maybe, due to the difficulties in analysis, BCs have seldom been used in TEM, and then mainly to visualize different imperfections and transformations.
Electronic structure studies of conducting polymers by electron energy-loss spectroscopy
Authors: Fink J.
Published: June 2020

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.

Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.
Quantitative high-resolution electron microscopy (HREM) of defects in ordered polymers
Authors: Wilson Patricia M. , Martin David C.
Published: June 2020

Efforts in our laboratory and elsewhere have established the utility of low dose high resolution electron microscopy (HREM) for imaging the microstructure of crystalline and liquid crystalline polymers. In a number of polymer systems, direct imaging of the lattice spacings by HREM has provided information about the size, shape, and relative orientation of ordered domains in these materials. However, because of the extent of disorder typical in many polymer microstructures, and because of the sensitivity of most polymer materials to electron beam damage, there have been few studies where the contrast observed in HREM images has been analyzed in a quantitative fashion.

Here, we discuss two instances where quantitative information about HREM images has been used to provide new insight about the organization of crystalline polymers in the solid-state. In the first, we study the distortion of the polymer lattice planes near the core of an edge dislocation and compare these results to theories of dislocations in anisotropic and liquid crystalline solids. In the second, we investigate the variations in HREM contrast near the edge of wedge-shaped samples. The polymer used in this study was the diacetylene DCHD, which is stable to electron beam damage (Jc = 20 C/cm2) and highly crystalline. The instrument used in this work was a JEOL 4000 EX HRTEM with a beam blanidng device. More recently, the 4000 EX has been installed with instrumentation for dynamically recording scattered electron beam currents.
Mean inner potential measurements of polymer latexes by transmission electron holography
Authors: Wang Young-Chung , Libera Matthew
Published: June 2020

Because polymeric materials consist primarily of light elements, weak contrast is often observed when imaging polymer microstructure in a transmission electron microscope. Preferential staining of microstructural features by heavy elements such as osmium, ruthenium, or uranium is commonly used to induce amplitude contrast. Because of its ability to recover the entire exit-face electron wavefunction, transmission electron holography raises the possibility of using phase contrast to measure polymer microstructure without the need for heavy-element stains. Under kinematic scattering conditions, the phase shift, ΔΦ, imposed on an incident high-energy electron wave is given by the product of the electron-optical refractive index, neo, and the specimen thickness, t: Δφ=(2π/λ)(neo−1)t. The refractive index is related to the specimen’s mean coulombic (inner) potential Φ0: neo−1 = (e |Φ0|/E) [(E0+E)/(2E0+E)] = CEΦ0 where e is the electron charge, E is the kinetic energy of the incident electrons, E0 is the rest energy, and CE is an energy-dependent constant. Quantitative measurements of Φ0 and neo can be made using holographic phase imaging to determine from specimens of known thickness.
A standard method for the preparation of polymers and plastics for microstructural examination by grinding and polishing techniques
Authors: Cavaleri M.E. , Seitz D.S.
Published: June 2020

One of the fundamental objectives of microstructural examination of manufactured materials is to gain a more complete understanding of the relationships between the manufacturing processes, the microstructure and texture of the material, and the product's performance. This objective, however, can only be achieved if the examination specimens are repeatably produced and are free of thermal, mechanical and chemical alterations, as well as artifacts, damage, or defects resulting from the specimen preparation process. It is also imperative that surface finish of the specimen be appropriate for the microscopical techniques to be used. The preparation process must provide specimens in a timely fashion, generally within a few tens of minutes or at most a few hours for typical industrial/manufacturing situations. Although designed for much harder more rigid materials, the general grinding and polishing techniques used in petrographic and metallographic specimen preparation can also be used for plastics and polymers. ASTM Committee E-4 on Metallography has a task group (TG-E04.01.05) which is preparing a standard guide for the preparation of polymeric specimens based on the ASTM E3-95 standard.
Application of various modes of scanning-probe microscopies in polymer systems
Authors: Meier Dale J.
Published: June 2020

The invention of the scanning tunneling microscope (STM) by Binnig and Rohrer in 1982 demonstrated an unparalleled ability to image materials at the sub-nanometer scale. The invention rapidly lead to an explosion of applications of STM in a wide variety of fields. However, imaging by an STM is essentially limited to materials which are conductive, or could be made conductive, so many materials of interest could not be imaged by STM. This limitation was removed a few years later (1985) by the invention of the atomic force microscope (AFM) by Binnig, Quate and Gerber, in which imaging is based on the response of a soft cantilever beam to the contact forces between an ultra-fine probe tip and a sample. The cantilever/probe systems could be made sensitive enough to enable the AFM to easily resolve atomic or molecular level features.
In-Situ measurements of plane spacing during electromigration in a passivated AI line
Authors: Wang P.-C. , Noyan I. C. , Liniger E. G. , Hu C.-K. , Cargill G. S.
Published: June 2020

To determine the effect of confinement on the material transport that occurs during electromigration, in-situ x-ray strain measurements were conducted along the length of a passivated Al line that was first heated (in two steps) to 267°C and then subjected to current flow.

The specimen geometry used in the experiment is shown in Figure 1. Further details can be obtained from references 1,2. The Al in the line and the contact pads had a grain size of the order of the film thickness (0.5 μm) and exhibited strong 111 texture with a range of ±5 degrees. The W pads also exhibited strong 110 texture and had much finer grain size. The x-ray measurements were carried out on the NSLS X-26C beamline using a focussing tapered capillary for collimating the beam. The irradiated area on the line was a 10μmx10μm square. The Al 111 plane spacing (d111) was measured using white beam (Laue) diffraction with a solid-state detector. This plane spacing was measured at different locations along the line.
Computer-Assisted Analysis of Multi-Color Confocal Microscopic Datasets: Automated Light Microscopic Discrimination of Synaptic Relationships
Authors: Wessendorf M , Beuning A , Cameron D , Williams J , Knox C
Published: June 2020

Multi-color confocal scanning-laser microscopy (CSLM) allows examination of the relationships between neuronal somata and the nerve fibers surrounding them at sub-micron resolution in x,y, and z. Given these properties, it should be possible to use multi-color CSLM to identify relationships that might be synapses and eliminate those that are clearly too distant to be synapses. In previous studies of this type, pairs of images (e.g., red and green images for tissue stained with rhodamine and fluorescein) have been merged and examined for nerve terminals that appose a stained cell (see, for instance, Mason et al.). The above method suffers from two disadvantages, though. First, although it is possible to recognize appositions in which the varicosity abuts the cell in the x or y axes, it is more difficult to recognize them if the apposition is oriented at all in the z-axis—e.g., if the varicosity lies above or below the neuron rather than next to it. Second, using this method to identify potential appositions over an entire cell is time-consuming and tedious.
Principal Component Analysis as a Strategy for Multispectral Acquisition of Images
Authors: Ingram P. , Kopf D. A. , LeFurgey A.
Published: June 2020

Principal Component Analysis (PCA) has been used by many authors to improve the statistical accuracy and interpretation of multispectral images in a variety of settings from the analysis of satellite radar images to mapping of biological cells and tissues. In this work we describe a strategy to characterize analytical data from biological cryosections by objectively using a scatterplot routine from PCA images to generate masks on the original STEM image; in this way control of the acquisition of spectral data can be performed in a statistically optimal manner.

If a set of images are obtained, the corresponding set of Principal Component (PC) images are easily generated. Mathematically, the PC images are the projection of the original images onto a set of orthogonal, complete axes that are the eigenvectors of the symmetric variance-covariance matrix obtained by summing the product of corresponding pixels in each element pair across the entire image (or selected region thereof). The corresponding eigenvalues are the variance contribution of each eigenimage to the total variance of the original set of images. When sorted into order of decreasing variance, the first PC axis represents the greatest covariance that can be found among all the elements; the second represents the largest remaining covariance orthogonal to the first axis and so on. The computation time required for such a calculation is about 10 seconds for eight 128x128 images for a 35 MHz 68040 processor.
Smoke-Derived Cues for Seed Germination in the Post-Fire Recruiter Emmenanthe Penduliflora
Authors: Egerton-Warburton L.M. , Platt K.A. , Thomson W.W.
Published: June 2020

Wildfires are typically associated with the destruction of vegetation. However, in the chaparral of southern California, fires are responsible for the persistence of many species. In these communities, vegetative regrowth is accompanied by a striking post-bum recruitment of species from a flush of seed germination. Typically, the flora is dominated by “fire annuals” or those species in which occur primarily in the first year after fire and persist thereafter as deeply dormant seeds held in the seed bank until the next fire. Emmenanthe penduliflora (Hydrophyllaceae) is a prominent fire annual and possesses dormant seeds which germinate in response to smoke, extract of charred wood or nitrate-N. The underlying mechanism for these responses is unknown. Consequently, we initiated a systematic assessment of the ultrastructure of dormant (8% germination) versus smoke-treated seeds (79%) to identify changes which may be associated with the germination of E. penduliflora seeds.
Spatial Resolution of Electron Backscatter Diffraction in a FEG-SEM
Authors: Kenik Edward A.
Published: June 2020

Crystallographic information can be determined for bulk specimens in a SEM by utilizing electron backscatter diffraction (EBSD), which is also referred to as backscatter electron Kikuchi diffraction. This technique provides similar information to that provided by selected area electron channeling (SAEC). However, the spatial resolutions of the two techniques are limited by different processes. In SAEC patterns, the spatial resolution is limited to ˜2 μm by the motion of the beam on the specimen, which results from the angular rocking of the beam and the aberration of the probe forming lens. Therefore, smaller incident probe sizes provide no improvement in spatial resolution of SAEC patterns. In contrast, the spatial resolution for EBSD, which uses a stationary beam and an area detector, is determined by 1) the incident probe size and 2) the size of the interaction volume from which significant backscattered electrons are produced in the direction of the EBSD detector. The second factor is influenced by the accelerating voltage, the specimen tilt, and the relative orientation of scattering direction and the specimen tilt axis.
Determining Deformation, Recovery and Recrystallization Fractions from Orientation Imaging Microscopy (OIM) Data
Authors: Wright S. I. , Dingley D. J. , Field D. P.
Published: June 2020

While orientation imaging microscopy (OIM) via automatic analysis of electron backscatter diffraction patterns (EBSPs) has become routine, methods for analyzing results obtained by OIM are still maturing. Interrogating the OIM data to distinguish between deformed, recovered and recrystallized material in a polycrystalline sample is one example. An advantage for using OIM data in such a case is that the corresponding textures can also be determined providing more information regarding these processes. This work reports on two different approaches for distinguishing between these structures from OIM data on a sample of partially recrystallized low-alloy steel.

The first approach is, in a sense, patterned after that used in optical microscopy; where, deformed material can be identified because it is more deeply etched than recrystallized material. A similar approach Can be used in OIM by considering the quality of EBSPs. EBSPs from deformed material are more diffuse than patterns obtained from recovered or recrystallized material. At each measurement point in an OIM scan an image quality (IQ) parameter is determined for the corresponding EBSP. The IQ is mapped onto a gray scale and an image is formed from the OIM data as shown in Fig. 1. In this image the measurement points are shaded so that points with associated EBSPs of high IQ receive a lighter shade of gray than points with a lower IQ. The deformed regions can then be identified by the darker regions in the OIM map. However, this method has some drawbacks. The first is that the IQ parameter is not sensitive enough to distinguish recovered material from recrystallized material.
SEM-ECP Analysis of Grain-Boundary Character Distribution in Polycrystalline Materials
Authors: Watanabe Tadao
Published: June 2020

As demonstrated early 1980’s (1), the scanning electron rnicrocopy-electron channelling pattern (SEM-ECP) technique is very powerful in determination of orientation of individual grains and the character of grain boundaries in polycrystalline materials. Figure 1(a) and (b) show SEM and ECP images of a grain boundary in polycrystal line iron-6.5 mass % silicon ribbon produced by rapid solidification and subsequent annealing. We can intuitively recognize from the SEM-ECP image that the character of the boundary is of <100> tilt type with about 7° misorientation angle. This kind of direct observation is very useful for a study of grain boundary migration and grain growth.

This paper discusses advantages of the SEM-ECP technique for the precise determination of the character of grain boundary and for statistical analysis of grain boundaries to bridge roles of individual grain boundaries and bulk properties in a polycrystal. The new microstructural parameter associated with grin boundary termed “grain boundary character distribution (GBCD)” which was introduced by the present author (2,3) and has been utilized in designing and engineering grain boundaries in order to produce desirable and/or high bulk performance in polycrystalline materials (4,5). GBCD describes the type and the frequency of different types of grain boundaries, ie. random general boundaries and special boundaries like low-angle boundaries and low Σ coincidence boundaries.
Microstructure of artificial 45° [001] tilt grain boundaries in YBCO films grown on (001) MgO
Authors: Huang Y. , Vuchic B.V. , Buchholz D.B. , Merkle K.L. , Chang R.P.H.
Published: June 2020

It is well known that high-angle grain boundaries in YBa2Cu3O7−x (YBCO) show weak-link effects and behave as Josephson junctions. This kind of grain boundary junction (GBJ) has potential applications in magnetic field measurement and electronic devices. This work studies the microstructure of artificially made GBJs in YBCO films on (001) MgO and the mechanism of the boundary formation, with the goal to improve the GBJ quality and obtain a better understanding of the junctions’ transport properties.

Ion-sputter-induced epitaxy is used to form YBCO films with isolated 45° [001] tilt grain boundaries. Prior to YBCO film growth the (001) MgO substrate is selectively sputtered by a low energy Ar ion beam. A portion of the substrate remains non-sputtered by protecting the surface with a patterned photoresist mask. After removing the mask, a YBCO film is grown on the substrate using pulsed organometallic molecular beam epitaxy (POMBE). Under suitable conditions single crystal YBCO c-axis films can be reproducibly obtained in both the sputtered and non-sputtered regions. The orientation between the films and the substrate has been examined by both x-ray diffraction and electron diffraction. The in-plane orientation relation is [110]YBCO//[100]MgO on the non-sputtered epitaxially polished MgO and [100]YBCO//[100]MgO on the sputtered MgO. Thus, 45° tilt boundaries are formed in the film at the boundary between the sputtered and non-sputtered substrate regions.
Tele-Presence Microscopy/LabSpace: An Interactive Collaboratory for use in Education and Research
Authors: Zaluzec Nestor J.
Published: June 2020

Computerized control of scientific instrumentation has been successfully implemented in recent years to facilitate the indirect operation or remote observation of a wide variety of equipment including the full range of electron microscopes. The concept is, however, usually applied in it’s simplest sense, namely-the direct one-to-one functional replacement of “local operation” of equipment by a remote workstation. While the microscope is clearly central to the our research, real collaboration will not be achieved simply by creating a networked interface to a microscope for remote scientists. This is merely a simple exercise in computer programming and digital control. For true distributed collaboration (either in research and/or teaching) to be successful, all of the aspects of the research/teaching environment must be considered. For example, the investigators must be able to talk to and see each other while running an instrument, and they should be able to do everything else they would normally do if they were in the same laboratory. This includes sharing experimental data, review previous experiments, write papers, talk over coffee and even visiting each other in their office to plan current and/or future work. The TelePresence Microscopy (TPM) /LabSpace project attempts to bridge the gap between simple “remote microscopy” and true collaboration, by integrating protocols, tools, and interactive links to instrumentation, data (real-time as well as archived), and audio-visual communications. The initial goal of this project has been to create a virtual space, accessible via the Internet, where microscopists and their colleagues, who are distributed across the nation or the world, can meet, talk, plan their research, and also run their experiments.
Generation, Processing, and Transferring of CCD Camera Images in Electron Crystallography
Authors: Li Z. G. , Liang L. , Harlow R. L. , Lehman K.E. , Herron N.
Published: June 2020

Recently, CCD camera has been more and more used in the electron microscopy particularly for electron crystallography [1]. Use of CCD camera in this field as a recording medium possesses many significant advantages over conventional photographic films. A CCD camera has a very high dynamic range (reliable) and produces images directly in digital form which can be conveniently processed and transferred. We have initiated a program to obtain crystal structural information of plate-like materials by processing electron diffraction data from a CCD detector. As part of our program, we have developed a complete and routine procedure to convert images to diffraction data (h, k, l’s and intensities).

Figure 1 is a schematic representation of the procedure. Images are initially obtained using a 1024×1024 Gatan CCD camera (model 794) which was attached to JEM-2000EX electron microscope. The collection of the images is controlled by a MAC computer which also stores the data and allows the data to be viewed. Then, the digitized electron diffraction patterns are transferred to a Sun station computer where, using Khoros software, the CCD images are processed. The Khoros system is a very complete image analysis and image processing software developed by University of New Mexico [2].
Development Of a Semi-In-Lens Digital FE-SEM
Authors: Yamamoto Y , Yamada A. , Negishi T. , Kobayashi T. , Watanabe N. , Miyokawa T. , Tamura N. , Nielsen C.
Published: June 2020

Observation of new materials such as semiconductor, polymer and compounds, with a Field Emission Scanning Microscope (FE-SEM) has been increasingly important in recent years. As the integration scale of semiconductor device as well as nanometer fabrication scale of the new materials are increasing, a high resolution FE-SEM became indispensable for research and development.

Since these new materials are often non-conducting and charging, metal coating, minimum electron dose technique or rapid scanning must be used to observe the surface morphology. Furthermore, all the operational sequences have been required to be drastically simplified.

We have developed a semi-in-lens fully digital FE-SEM which can obtain high resolution secondary electron images (SEI) with minimum influence of charging at the specimen. An outline of this new FE-SEM is shown in Fig. 1. The electron optical system (EOS) is based on the conventional FESEM (H. Kazumori et al, 1994) with a cold field emission gun (C-FEG), giving a guaranteed resolution of 2.5 nm at an accelerating voltage of lkV. It is possible to select ten scan speeds from 0.28s to 121s in the vertical direction with 1280 × 1024 pixels and average and integrate the SEI signals at the ambient scan speed.
Evaluation of Commercial Tritium Standards: A Significant Source of Error in Quantitative Autoradiography
Authors: Nissanov J. , Rioux L.
Published: June 2020

Using quantitative receptor autoradiography (QAR), it is possible to investigate the distribution of ligand binding sites as well as binding affinity. Accuracy in this technique is critically dependent on the quality of available radioactive calibration standards. For autoradiography using tritiated ligands, commercial 3H standards are available. These are also used, after cross-calibrating, as convenient standards for short-lived radioisotopes for which commercial standards are not available. A common practice in QAR is to appose these standards, each a slide containing 14 plastics of known radioactive concentration, along with the tissue sections on each sheet of x-ray film and to use these to produce a calibration curve and assign absolute concentration to densitometric measurements taken from the film. Typically, experimenters use multiple standards in their studies and directly compare data calibrated using different calibration sets. To our knowledge, only one study has tested the implicit assumption that the standards, once corrected for decay, are equivalent. That study concluded that the variability among standards is low. We revisit the issue.
ZAF, PAP, Φ(ρz), α-FACTOR..: A Comparison of the Relative Accuracies of The Alphabet Soup of Correction Factors for “Non-Optimized” Samples
Authors: Armstrong John T.
Published: June 2020

The ultimate practical test of the utility of a correction procedure for quantitative x-ray microanalysis is how well the analyses of standards of interest conform to their known compositions. Many papers have been published testing various correction algorithms by processing data from sets of quantitative analyses through the corrections and then comparing the resulting error histograms {e.g., Fig. 1). The best correction procedure is usually considered to be the method that results in error histograms with the minimum mean relative error and the smallest standard deviation for the distribution of relative errors. Such evaluations can be misleading for a number of reasons: (1) the correction procedure may have been “adjusted” by adding empirical factors to produce superior results for a particular type of specimen. If the test data either include these data or include samples of similar composition to those employed for the refinement, the results may appear artificially good and may not work nearly as well for other types of specimens. (2) The analytical data used for testing may itself be flawed, either because the samples were not actually the compositions they were thought to be (or the sample surface analyzed was not the same composition as that published for the bulk material); or because the surface or the sample was contaminated, rough or charging; or because the analytical conditions were not well controlled. (Many of the published k-factors used in evaluating correction procedures [e.g., ref. 1] were obtained in the early days of microbeam analysis, using instruments having poor control over high voltage and beam current stability with low spectrometer take-off angles.) (3) The analytical data may contain specimens analyzed under unusual conditions {e.g,, very high or veiy low accelerating potentials) that may have very large corrections dominating the data set that may never be encountered in normal analysis.
Low-voltage EDS of magnesium ferrite Dendrites in a FEG-SEM
Authors: Johnson Matthew T. , Anderson Ian M. , Bentley Jim , Carter C. Barry
Published: June 2020

Energy-dispersive X-ray spectrometry (EDS) performed at low (≤ 5 kV) accelerating voltages in the SEM has the potential for providing quantitative microanalytical information with a spatial resolution of ∼100 nm. In the present work, EDS analyses were performed on magnesium ferrite spinel [(MgxFe1−x)Fe2O4] dendrites embedded in a MgO matrix, as shown in Fig. 1. spatial resolution of X-ray microanalysis at conventional accelerating voltages is insufficient for the quantitative analysis of these dendrites, which have widths of the order of a few hundred nanometers, without deconvolution of contributions from the MgO matrix. However, Monte Carlo simulations indicate that the interaction volume for MgFe2O4 is ∼150 nm at 3 kV accelerating voltage and therefore sufficient to analyze the dendrites without matrix contributions.

Single-crystal {001}-oriented MgO was reacted with hematite (Fe2O3) powder for 6 h at 1450°C in air and furnace cooled. The specimen was then cleaved to expose a clean cross-section suitable for microanalysis.
SEM/EDS Analysis of Boron in Waste Glasses with Ultrathin Window Detector and Digital Pulse Processor
Authors: Luo J.S. , Wolf S.F. , Ebert W.L. , Bates J.K.
Published: June 2020

Borosilicate glass has been selected for immobilizing radioactive wastes because of its chemical durability and ability to incorporate many different elements.Boron is an important component in the borosilicate waste glass: its addition facilitates the processibility of glass by lowering its viscosity. In addition, the release of boron is used to measure the corrosion progress during laboratory tests that determine the durability of a glass. Analysis of boron that is present in waste glasses and in the reaction products that form during the reaction of glass is important for understanding the reaction kinetics and mechanism of glass corrosion.

Waste glasses have been previously analyzed for B in our laboratory by wavelength-dispersive spectrometry (WDS) in SEM. As can be deduced from Fig. 1, WDS analysis of waste glasses with B concentrations up to 4 wt% yields a line with a slope of 0.4 counts/s/wt%, with a resolution of ˜0.5 wt%. However, EDS is analytically more convenient and advantageous because its high detection efficiency and its ability to simultaneously acquire an entire spectrum. The innovation of the ultra-thin
window has made it possible for an EDS to detect soft x-rays, which are absorbed by a normal Be window.
Electron-Probe Quantitative Energy-Dispersive Analysis of Trace Magnesium Concentrations in Ag-Mg Alloys
Authors: Marinenko R. B.
Published: June 2020

Internally oxidized Ag-Mg alloys are used as sheaths for high Tc superconductor wires because of their superior mechanical properties. The preparation and characteristics of these materials have been reported. Performance of the sheaths depends on the concentration of the magnesium which generally is less than 0.5 wt. percent. The purpose of this work was to determine whether electron probe microanalysis using energy dispersive spectrometry (EDS) could be used to quantitate three different Ag-Mg alloys. Quantitative EDS analysis can be difficult because the AgL escape peak occurs at the same energy (1.25 keV) as the Mg Kα peak. An EDS spectrum of a Ag-Mg alloy wire is compared to a pure Ag spectrum in Fig. 1.
Beyond fingerprinting: simple but quantitative models of EELS fine structure and the cohesion of interfaces
Authors: Muller D. A. , Singh D.J. , Subramanian S. , Sass S.L. , Silcox J. , Batson P.E.
Published: June 2020

Spatially resolved EELS in a STEM provides unique opportunities to examine how local structural and electronic properties can affect macroscopic properties of a solid. Perhaps nowhere else are these connections as pronounced as at interfaces. For instance, H embrittles and B strengthens the grain boundaries in Ni3Al, a prototypical high-temperature intermetallic. EELS measurements of these boundaries have revealed the changes in electronic structure that correlate with the altered mechanical properties of the material.

The interfacial states, which rarely extend more than an atomic layer or so from the boundary, can only be observed with great care. Not only is a stable microscope and very efficient detector required, but also a good understanding of how the probe interacts with the specimen. Artifacts due to radiation damage are a real possibility. If the boundary is examined in a strongly diffracting orientation (as is often the case with special boundaries) probe dechanneling can profoundly alter the measured spectra. This can be avoided by tilting the boundary a few mrad away from the zone axis, which limits the spatial resolution to being sub-nanometer, but not atomic.
Calculations of Cu L2,3 fine structure at grain boundaries
Authors: Rez P. , Maclaren J.M.
Published: June 2020

The segregation of impurities to grain boundaries in metals and alloys has been known for some time to make changes in ductility. Examples of this effect are the embrittlement of copper by the addition of bismuth and the ductilization of Ni3Al by boron impurities. The mechanism by which these dramatic changes in mechanical properties arise is still largely unknown. It has been suggested that embrittling elements draw charge from neighbouring metal atoms while impurities that enhance ductilty act in the opposite way. Changes in the electronic states can be detected as changes in the energy loss spectrum when a small probe in a FEG STEM is moved across the boundary. Recent work by Muller has shown significant differences between the Ni L3 spectrum from grain boundaries in Ni3Al with and without boron. Bruley has shown that a “white line”, indicative of empty Cu d states, appears in the Cu L3 edge from Cu atoms near boundaries where bismuth has segregated.
Spectrum lines across planar interfaces by energy-filtered TEM
Authors: Bentley J. , Anderson Ian M.
Published: June 2020

Electron energy-loss spectrum imaging, in which a spectrum is recorded for each pixel as a focused probe is digitally rastered in a two-dimensional pattern on the specimen, has developed into a practical and powerful microanalytical technique. However, even for only a modest number of pixels, acquisition times can become inconveniently long. One-dimensional data (spectrum lines) are often sufficient for many materials science applications, especially for planar interfaces. As well as producing energy-filtered TEM images (or diffraction patterns), the Gatan imaging filter (GIF™) can be used to acquire spectrum lines in the TEM mode, without the need to form a small probe. The basis for this capability is that for the GIF spectroscopy mode a line focus normal to the energy dispersion direction is employed. Spectra as a function of position (TEM operating in the image mode) or scattering angle (TEM operating in diffraction mode) are thus produced.
Quantitative energy-filtered tem imaging of interfaces
Authors: Bentley J. , Kenik E. A. , Siangchaew K. , Libera M.
Published: June 2020

Quantitative elemental mapping by inner shell core-loss energy-filtered transmission electron microscopy (TEM) with a Gatan Imaging Filter (GIF) interfaced to a Philips CM30 TEM operated with a LaB6filament at 300 kV has been applied to interfaces in a range of materials. Typically, 15s exposures, slit width Δ = 30 eV, TEM magnifications ∼2000 to 5000×, and probe currents ≥200 nA, were used. Net core-loss maps were produced by AE−rbackground extrapolation from two pre-edge windows. Zero-loss I0(Δ ≈ 5 eV) and “total” intensity IT(unfiltered, no slit) images were used to produce maps of t/λ = ln(IT/I0), where λ is the total inelastic mean free path. Core-loss images were corrected for diffraction contrast by normalization with low-loss images recorded with the same slit width, and for changes in thickness by normalization with t/λ, maps. Such corrected images have intensities proportional to the concentration in atoms per unit volume. Jump-ratio images (post-edge divided by pre-edge) were also produced. Spectrum lines across planar interfaces were recorded with TEM illumination by operating the GIF in the spectroscopy mode with an area-selecting slit oriented normal to the energy-dispersion direction. Planar interfaces were oriented normal to the area-selecting slit with a specimen rotation holder.
Multivariate statistical analysis of a series of alchemi spectra
Authors: Anderson Ian M. , Bentley J.
Published: June 2020

Multivariate statistical analysis (MSA) of a series of spectra or images offers an objective and quantitative way to characterize the features of the spectra that vary in a correlated fashion and to determine the number of independently varying components in the series. For example, in a series of spectra showing grain boundary segregation, there may be only one independently varying spectral component, which signifies an increase in the concentrations of the segregants and a corresponding decrease in the concentrations of some of the matrix constituents. The basis of the MSA method has been outlined by Trebbia and Bonnet, with application to the analysis of electron energy-loss spectrum images. Titchmarsh et al., have applied this analysis to a series of energy dispersive X-ray (EDX) spectra for the study of grain boundary segregation. The present paper illustrates the application of MSA methods to a series of EDX spectra acquired for ALCHEMI analysis. The basic method has been modified slightly for the analysis of ALCHEMI data.
Radiation damage and spatial resolution in the EXELFS of inorganic materials
Authors: Haskel D. , Sarikaya M. , Qian M. , Stern E. A.
Published: June 2020

EXELFS, the extended energy loss fine structure superimposed on the high energy loss side past an inner-shell electron excitation in an EELS spectrum, contains quantitative information about the local structure around the scattering atom from which the core electron is excited, similar to that contained in the x ray absorption fine structure (XAFS). Main advantages of the EXELFS technique over XAFS include the relative ease in the former to study the local environments of low Z elements coupled to the higher spatial resolution, imaging and diffraction capabilities of the TEM.

Radiation damage to the sample caused by the energetic electron beam, however, has been an important concern to whether EXELFS can be safely applied to study materials at the nanometer scale. To investigate this question we chose to study Al, SiC and MgO as representatives of three different classes of binding: metallic, covalent and ionic, with the belief that these should exhibit different sensitivities to different mechanisms of radiation damage and hence will be fair representatives of a wide variety of materials.
Corroded spent nuclear fuel examined with EELS
Authors: Buck Edgar C. , Dietz Nancy L. , Bates John K.
Published: June 2020

Direct disposal of spent nuclear fuel (SNF) into the proposed unsaturated geologic repository at Yucca Mountain, NV is being studied at several laboratories, including Argonne National Laboratory. Corrosion tests with SNF are being conducted to understand the long-term behavior of SNF under conditions designed to simulate the unsaturated conditions at the site. The SNF used in this study was the Approved Testing Material (ATM)-106 with a bum-up of 43 MW·d/kg U. A sample of ATM-106 fuel was exposed to dripping simulated groundwater for 271 days; after this time the experiment was terminated and the material removed for further study. Details of the testing methodology have been given by Finn et al.,.

Previous attempts to study SNF with TEM have used ion milled samples, in this study we prepared the samples by ultramicrotomy which reduced the radiological hazard substantially.
Investigation of copt and copt + ZrOx thin films for magnetic storage media using high-resolution analytical electron microscopy
Authors: Ristau R. A. , Barmak K.
Published: June 2020

Materials for very high density magnetic storage media, with capacities of 10 Gbits/in2 and beyond, require high coercivity and high signal to noise ratio. To achieve storage densities of this level engineering of the material to produce very fine, magnetically decoupled domains is necessary. We have characterized the microstructure and microchemistry of 10 nm thick CoPt and CoPt + ZrOx thin films, as deposited and annealed, using transmission electron microscopy (TEM) and nanometer-scale energy dispersive x-ray spectroscopy (EDS).

CoPt has a very high coercivity (Hc) when annealed to produce the ordered Ll0 phase. Annealing also increases grain size which reduces the signal to noise ratio. Co-sputtering CoPt with ZrOx was intended to reduce grain size. TEM micrographs in Figure 1 show that grain growth was dramatically reduced in the CoPt + ZrOx films. Essential to the development of optimum material properties are quantified grain size measurements, yet owing to the small grain size and the complexity of TEM images due to diffraction contrast there are few systematic studies of grain size in thin films.
Optimization of the production of a chromium thin-film AEM characterization standard by thermal evaporation
Authors: Repa K. A. , Williams D. B.
Published: June 2020

The need for a chromium standard to characterize the performance of an analytical electron microscope (AEM) and its associated x-ray energy-dispersive spectrometer (XEDS) in quantitative terms which can also be used to realistically compare AEM-XEDS systems has long been recognized and becomes increasingly important as advances in the technology of electron microscopy are made. Previous thermal evaporation of a 100 nm thick chromium film onto a 20 nm carbon support film by the National Institute of Standards and Technology (NIST) provided a useful standard, but attempts to reproduce these results encountered difficulty in achieving consistent adherence to 200 mesh copper grids. These difficuIties are attributed to preexisting stresses in the carbon support film [Fig. 1] and as a result production of self-supporting Cr films was chosen, with the NIST standard serving as a model against which the present specimens were evaluated. Relevant properties of a characterization standard have been well defined and include the thickness, XEDS profile and grain size.
A “filmless” method of acquiring and measuring electron diffraction patterns
Authors: Dufner D. C.
Published: June 2020

Electron diffraction is one of most widely used techniques in the characterization of specimens in the TEM. With the advent of computerization, there is a growing trend toward automation of the measurement and analysis of electron diffraction patterns (EDPs). There are a number of computer programs used for measuring, indexing, and simulating EDPs, some of which are now commercially available. Many of these programs are stand-alone programs which either perform a specific aspect of EDP analysis or require significant user interaction, particularly in the measurement phase. In some cases, the lack of suitable algorithms for measuring EDPs usually limit these programs to the extent that users still have to perform standard procedures of measuring EDPs from negatives or prints to obtain the necessary values needed to complete the execution of these programs. Here, a more convenient means for online acquisition and measurement of EDPs is presented.
An approximation to the dynamical calculation of rheed patterns from rough surfaces
Authors: Lordi S. , Eades J.A
Published: June 2020

RHEED (reflection high energy electron diffraction) is a technique widely used in molecular beam epitaxy (MBE) and for the characterization of surfaces in other contexts. Despite its widespread use, however, the interpretation of RHEED has largely been limited to the use of positions of the reflections with no attempt made to use the intensities in the patterns.

The reasons for this are related to the complexity of RHEED computations. There are several methods which can be used to calculate RHEED intensities from flat surfaces. However, in MBE (and other crystal growth methods) where RHEED is most often used, the surfaces are rough. Of the dynamical methods for calculating RHEED intensities from flat surfaces, only the modified Cowley-Moodie multislice method with the edge patching algorithm can be applied to rough surfaces without making severe approximations. This method is computationally intensive because the ensemble average over the statistical parameters of the surface cannot be done before the dynamical calculations.
Migrating to digital imaging from film
Authors: Minter J. R. , Schlafer K. , Sotak G. , Thom L.
Published: June 2020

Since the invention of the microscope, most images were recorded on photographic film. For transmission electron images, Hamilton and Marchant recognized that most photographic films are “nearly perfect detectors, in that they record the input signal without appreciable loss and do not seriously add to the input noise”. Despite film's efficiency as an image recorder, microscopists complained about the long cycle time between image recording and completion of the final print. Quantitative image analysis of images recorded on film is also time-consuming and expensive because microdensitometers capable of producing high quality and high resolution scans of negatives are slow and expensive.

Over the past few years several new technologies to record light and electron images have been commercialized. The oldest of these are video-rate cameras and TV-rate cameras built with charge coupled devices (CCDs). These are limited by small image size (512 × 478). Larger format digital cameras built using slow-scan CCD cameras have recently been applied to light and transmission electron microscopy. Digital scan generators and frame buffers have been added to scanning electron microscopes.
Practical methods for TEM
Authors: Chien K. , Gonzalez R. , Heusser R. C. , Shiroishi H. , Heathershaw M. L.
Published: June 2020

Multiple sectioning: Two or more core specimens from a kidney needle biopsy can be embedded in single block using an 8-facet silicone rubber embedding mold. Tissue blocks are softened by placing them face down on an 85°C hot plate for one minute and then trimming with a Teflon coated razor blade. This prevents the block face from being deeply fractured which can affect section quality. If glomeruli are found within different cores in a single block, the block face can be retrimmed into multiple mesas and simultaneously thin-sectioned. This method greatly increases the efficiency of both thick and thin sectioning which is extremely helpful when handling more than 1600 cases of renal biopsies in our EM laboratory each year.

Knife Spacer: Due to the difference in thickness between a glass and diamond knife, and also depending on which portion of the diamond knife is being used, the knife stage has to be moved laterally over a long distance when changing from one knife type to the other. Placing a L-shaped spacer, 3 to 5 mm in thickness, on the left side of the stage when sectioning a glass knife will greatly reduce this lateral adjustment.