bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Intrinsic Formation Of Localized Electronic States At [001] Tilt Grain Boundaries In YBa2Cu3O7 And Their Effect On Jc
Authors: Buban J P , Browning N D 
Published: July 2020

Abstract
Grain boundaries have long been known to have a deleterious effect on the superconducting critical current that can be carried by YBa2Cu3O7-δ. Recent theoretical analyses have proposed that the origin of this behavior may be band bending, which results in the depletion of charge carriers at the grain boundaries. For this to occur in these p-type superconductors there must, by definition, be a high density of localized donor states in the boundary plane. Here we describe a structural feature intrinsic to all [001] tilt boundaries that may be the origin of these localized states.
Direct atomic-resolution images of asymmetric [001] tilt grain boundary structures have been obtained using the Z-contrast imaging technique. The grain boundaries are observed to be composed of distinct structural units, as shown in figure 1. Within these structural units, a 2×1 reconstruction of the CuO columns is seen to occur. This reconstruction, which is caused by the constraint imposed on the structure by the sizes of the component atoms, leads to effective oxygen vacancies in the grain boundary plane (figure 2). Further oxygen annealing of the boundary cannot fill these vacancies as there is no space in the structure for more oxygen atoms.
On The Formation Of Diffusion Layer Between Cr Film And Glass
Authors: Jiang N , Silcox J 
Published: July 2020

Abstract
Chromium films are commonly used as a metal “glue” layer because of good adhesion to glass. It is believed that an intermediate oxide layer is formed during deposition, since Cr has a very strong affinity for oxygen. For example, a graded Cu/Cr/CrOx/SiO2 structure ensures excellent adhesion of Cu to glass, whereas Cu exhibits poor adhesion to most dielectrics. In our recent study, however, a diffusion layer, Cr2O3+SiOy, was observed between CrOx and SiO2 (glass) substrate. It is quite likely that this diffusion layer is responsible for the good adhesion of Cr film to glass.
The relative compositions of the major components across the interface are shown in Fig 1. A Cr film was evaporated on Corning Code 1737 glass (Al2O3-B2O3-SiO2 with ˜67at.% Si02) substrate at room temperature (RT) and subsequently covered with about lOnm Cu. A 5nm'wide diffusion layer is seen. The corresponding regions are also indicated in Fig 2, an Annular Dark Field (ADF) image whose contrast is approximately proportional to the density if the thickness is assumed uniform.
Determination Of Coherency Strains Around Particles In Ni-Al Alloys By HREM And CBED
Authors: Calderon H A , Cruz JJ , Calzado L , Kisielowski C , Wang YC , Kilaas R 
Published: July 2020

Abstract
Quantitative evaluation of coherency strains in Ni-12 at.% Al alloys has been performed by means of high resolution electron microscopy (HREM) and convergent beam electron diffraction (CBED) techniques. The alloy Ni-12 at.%Al is composed of two phases, the disordered fee Ni-Al solid solution and the coherent Ni3Al (γ') particles with an LI2 structure. The presence of γ' particles can impart excellent mechanical properties to these alloys. However these particles coarsen if subject to high temperature with an important reduction of mechanical properties. Coarsening of coherent particles in solid alloys is driven by the decrease of surface and elastic energies. The effect of surface energy is well understood but that of the elastic energy still requires experimental investigation. The source of elastic interaction between particles is the lattice parameter mismatch between particles and matrix. Evaluation of the elastic strain fields around particles can give some insight into the elastic interaction between particles and thus into the coarsening mechanism from an experimental viewpoint.
On-Line Semi-Automatic Measurement of Individual Crystal Orientations in Heavily Deformed Materials in the TEM
Authors: Zaefferer S 
Published: July 2020

Abstract
The measurement of individual crystal orientations in heavily deformed materials is of great importance especially for the study of recrystallization mechanisms. The electron backscattering diffraction (EBSD) technique which is frequently used nowadays in the SEM for these kind of studies has three important drawbacks: first, its spatial resolution is limited to about 0.5 μm, second, the sample deformation is limited to only about 60 %, and third, the dislocation microstructure cannot be observed. All these problems can be overcome using a micro beam diffraction technique in the TEM. Two techniques can be distinguished, the Kikuchi pattern technique and the spot pattern technique. With a spatial resolution of down to about 10 nm they arc well suited for orientation measurements in highly deformed material. Nevertheless, since spot patterns are less sensible to deformation the spot technique is the ultimate choice in the case a most highly deformed material. An automatic procedure for the evaluation of spot patterns has been developed and, together with the Kikuchi technique, implemented in a computer program for the on-line analysis of crystal orientations at the TEM. The new procedure and its applications to highly deformed materials is the subject of this presentation. Spot patterns are less sensitive to the sample deformation than Kikuchi patterns due to the differences in the diffraction geometry and due to the relaxation of the Bragg diffraction conditions for spot patterns.
Orientation Imaging Microscopy in the TEM
Authors: Baggethun P , Weiland H 
Published: July 2020

Abstract
There is a range of techniques now available for the study of crystallographic orientation in materials. Among these, Orientation Imaging Microscopy (OIM) for the SEM is being increasingly applied. This technique is, however, limited by the spatial resolution of the SEM (∼0.5 μm). TEM orientation measurements and imaging provides the necessary alternative to SEM measurements due to the much higher spatial resolution of the TEM (∼10 μm). In TEM crystal orientation measurements Kikuchi patterns are preferred over selected area spot patterns due to higher accuracy and spatial resolution. The earliest means of automation of TEM orientation measurements involved the use of digital scanners and beam deflection measurment for computerized semi-automatic indexing of the patterns. In recent years fully automatic on-line orientation determination has been developed. This has come about as a result of the advances in image processing for automatic indexing of backscatter Kikuchi patterns in the SEM, and the emergence of slow-scan CCD cameras with a large dynamic range.
Calculation of Absorptive Potentials Using Debye's Model of Lattice Dynamics
Authors: Anstis G R 
Published: July 2020

Abstract
To have an understanding of many imaging and diffraction effects relating to high-energy electrons it is essential to take into account the vibrations of the atoms of the solid being examined. Einstein's model of the vibrations takes the atoms to be independent oscillators. Debye's model includes the effects of correlated atomic motion and is more accurate in describing simple solids. Electrons which exchange energy with the solid through a change in the vibrational state of the solid are incoherent with respect to the incident electron wave and may be considered as being absorbed out of the incident wave field. Yoshioka and Kainuma showed how to calculate the components of the absorptive potential, which is imaginary rather than real, and pointed out that they depend on the direction of the incident wave. The components of the imaginary potential vgh (im) are not simply a function of g-h, unlike those of the real potential describing elastic scattering. Here g and h represent vectors in reciprocal space. Using Debye's model and assuming that the speeds of the three components of acoustic waves in the solid are equal we find
New Applications of Electron Diffraction in Pharmaceutical Industry: Polymorph Determination of GP Ilb/IIIa Antagonist, Roxifiban, Using a Combination of Electron Diffraction and Synchrotron X-ray Powder Diffraction Techniques
Authors: Li Z G , Harlow R L , Foris C M , Li H , Ma P , Vickery R D , Maurin M B 
Published: July 2020

Abstract
Recently, it was reported that electron diffraction can be used to determine polymorphs in pharmaceutical industry [1]. The term polymorph refers to substances that have the same chemical formula but different crystal structures. Polymorphism has played an important role in drug development, production and litigation [2]. Synthesized and crystallized under different conditions, polymorphs may have different physical and chemical properties as well as bioavailabilities. The conventional techniques used to identify polymorphs.sometimes fail to differentiate definitively between two structurally similar polymorphs such as roxifiban, a very promising cardiovascular drug discovered recently at DuPont Pharmaceuticals [3,4]. Bulk and tapped densities of Form I and II, for example, were found to vary from 0.23 and 0.37 g/ml for Form I to 0.07 and 0.19 g/ml for Form II, respectively. These differences were of some concern given the low drug load in the solid dosage form. Unit cell parameters and atomic coordinates of crystalline polymorphs can routinely be determined by single-crystal xray diffraction techniques if suitably large crystals are available. However, many organic compounds tend to grow needle and plate-like crystals that never achieve a large enough volume for single-crystal studies. Such was the case with forms I and II of roxifiban.
Characterization and Representation of Crystallographic Texture Fields in Processed Alloys
Authors: Miller MP , Turner TJ , Sutliff JA 
Published: July 2020

Abstract
Deformation and thermal processing operations can produce structurally heterogeneous and anisotropic alloys. Thick, hot-rolled aluminum plate is an excellent example of such a material. Due to the plate size and thermomechanical conditions experienced by the plate during processing, significant gradients in material structure arise. These gradients are especially strong in the through-thickness or normal direction (ND) of the plate. In AA 7050, an aluminum alloy developed for thick plate applications, gradients in microporosity, grain morphology and crystallographic texture are known to exist. These features have been linked to material properties and performance measures in this alloy. Recent advances in high speed machining technology have made it possible to consider thick AA 7050 plate for an increasingly large number of airframe components. Because of its inherent heterogeneity, however, designing flight-critical components machined from AA 7050 plate will require one to quantify and mathematically represent the variation of the relevant microstructural gradients.
Development of BKD Hardware: Accomplishments and Opportunities
Authors: Schwarzer RA 
Published: July 2020

Abstract
Automated Crystal Orientation Measurement/Mapping (ACOM) as used in the SEM by unattended interpretation of Backscatter Kikuchi Patterns from bulk surfaces (BKP)* has become an invaluable new technique for the quantitative characterization of microstructure on a grain-specific level. The principal objectives are to relate grain orientations and misorientations directly to grain location in the specimen surface, to determine the character of misorientations and grain/phase boundary planes, and to calculate derived entities such as microtexture and anisotropic local materials properties. These quantities are commonly depicted in pseudo-colors on the scanning grid to form Crystal Orientation Maps (COM) or similar “images” of the microstructure. Stereological as well as orientation related data, as most sensitive indicators of the production process and use of a material, are readily available for basic research and quality control. The three-dimensional representation of microstructure by consecutive sectioning is still a challenge to enable the study of inhomogeneity beneath the surface and the three-dimensional connectivity of multiphase material. Dynamic experiments are a further promising application of this new technique in the SEM.
A Low Cost EBSD System: Implementation and Application
Authors: Pierron Xavier , Daghlian Charles , Baker Ian 
Published: July 2020

Abstract
Electron Back-Scatter Diffraction (EBSD) is a technique used for obtaining microtextural information from bulk samples in the scanning electron microscope (SEM). number of good commercial systems provide hardware and software to acquire and analyze the electron back scatter patterns (EBSP). The systems come with tools to visualize crystal orientation, and map grain and grain boundaries. However money is always in short supply, and for studies which do not require mapping, we have found it more economical to build our own EBSP system using readily available off-the-shelf components.
An EBSP's are formed by the intersection of the diffracted back scattered electrons with a phosphor screen placed in their path. We acquire this pattern by viewing the phosphor.screen through a view port with a CCD video camera which is configured for on-chip integration. On-chip integration allows the signal to be amplified without extensive electronic noise. We made a port cover for the right-hand port of the DSM-962 SEM on which a 2” diameter view window is fitted.
Grain Size Analysis Using Automated-EBSP
Authors: Sutliff J A 
Published: July 2020

Abstract
This work discusses using the automated Electron BackScatter Pattern (EBSP) technique of electron diffraction in the Scanning Electron Microscope (SEM) for measuring grain size in polycrystalline materials. A quantitative analysis of 2-D grain size from a standard metallographic section can be made in less than one hour using an automated-EBSP system on a traditional SEM and dedicated analysis software. Thus, the automated EBSP technique provides a useful and cost-effective way to determine grain size. A common measure used to describe grain size is mean intercept length (MIL) and the present discussion will be limited to determining MIL using EBSP.
Grain size analysis using optical microscopy is strongly influenced by sample preparation, which involves etching of the polished section to reveal boundaries. Boundaries that are to be avoided in determining MIL, such as sub-grain boundaries and twin boundaries, may be revealed and mistaken for random high angle boundaries.
Effects of Scan Rate and Electron Dose on the Secondary Electron Contrast of Liquids in Environmental SEM (ESEM)
Authors: Stokes DJ , Thiel BL , Donald AM 
Published: July 2020

Abstract
We report the effects of scan rate/electron dose on the secondary electron contrast in liquid systems, studied by Environmental Scanning Electron Microscopy (ESEM). Understanding the mechanisms for SE contrast is essential: previous observations of oil-water emulsions have revealed useful SE contrast between the dispersed and continuous phases, attributed to differences in the electronic structure of these molecular liquids. However, it has been found that large oil droplets for example, have a propensity to give SE contrast that can be inverted (relative to the continuous water phase) as a function of scan rate/electron dose, as shown in Figures 1 & 2. In the ‘grabbed’ image, Figure 1, the scan rate is a relatively rapid 2.1 frames/sec. and results in the expected image of oil droplets with lower SE signal intensity than the surrounding water phase. However, the intensity of the oil droplets changes dramatically when the scan rate is slowed, such that the droplets appear bright. Figure 2 shows the same region of sample as in Figure 1, but with image acquisition over 30 seconds. The same contrast inversion can occur at rapid scan rate if higher magnification is used. Effects such as this could result in ambiguous interpretation of ESEM images. However, useful information may be gathered as to the dielectric nature of the medium — a property related to molecular structure. We note that similar scan rate-dependent effects have been observed in ESEM studies of solid samples, although the mechanisms responsible have yet to be rigorously established.
Environmental SEM Study of Sodium Alginate Beads
Authors: Mansfield John , Eiselt Petra , Yeh Julia , Mooney David J 
Published: July 2020

Abstract
A variety of porous materials are used in a number of tissue-engineering applications such as cell transplantation and drug delivery. They provide a temporary scaffolding for a large cell mass, however they must have a fully interconnected pore structure. One such material is sodium alginate, a naturally derived polysaccharide which is isolated from seaweed. Sodium alginate can de dissolved in water to form a highly viscous solution that can be cross-linked in the presence of divalent cations (e.g., Ca2+) to form what is known a as hydrogels. We have developed a method for the fabrication of porous beads of sodium alginate and have attempted to measure the pore size, density and distribution in the beads. Characterization of the pore size and distribution is necessary to determine if the material is appropriate to promote cellular in-growth. The characterization procedures have been limited to conventional scanning electron microscopy (SEM) and mercury intrusion porosimetry. There has been some concern as to the potential introduction of artifacts (spatial distortion) during dehydration and sample preparation during these characterizations.
In-Situ Shape Transformation and Melting of Platinum Nanocrystals
Authors: Wang ZL , Petroski J , Green T , El-Sayed MA 
Published: July 2020

Abstract
The catalytic activity and selectivity of nanosize colloidal platinum (Pt) nanocrystals may depend strongly on their sizes and shapes. To determine the shape dependent catalytic behavior of Pt nanocrystals, two key steps are involved. First, shape controlled Pt nanocrystals must be synthesized at a high yield. Secondly, the passivation layer on the nanocrystal must be removed in order to measure the catalytic selectivity and activity while the particle shape is preserved. The former had been successfully demonstrated by us that platinum nanoparticles with a high percentage of cubic-, tetrahedral- and octahedral-like shapes, respectively, can be synthesized by a colloidal chemistry method [1,2]. The growth of the shape controlled Pt nanocrystal has been found to be the result of kinetic process [3]. To measure the shape dependent catalytic activity and selectivity of the Pt nanocrystals, the capping polymer must be removed. One method could be annealing the nanocrystals supported on a substrate for evaporating the capping polymer. Several questions, however, must be considered: (1) how high does the annealing temperature need to be to remove the capping polymer while the particle shape is still preserved? (2) to what temperature is the particle shape still stable? (3) is there a temperature induced shape transformation due to surface diffusion? (4) how high is the melting point of the Pt particles? and (5) what is the effect of substrate on nanoparticle melting? These questions have not only fundamental importance, but also practical impact on the catalysis applications of the particles because the chemical reaction may take place at a higher temperature.
Micro X-ray Fluorescence of Particles Using a Laboratory X-ray Source and Capillary Optics
Authors: Swider JR , Jach T , Steel E 
Published: July 2020

Abstract
Micro X-ray fluorescence (micro-XRF) is a useful nondestructive technique for multielement analysis of samples from a few hundred to a few micrometers in size. Micro-XRF is usually performed at synchrotron sources where element sensitivities are not compromised by micrometer spatial collimation of high flux beams. Ideally, micro-XRF would not have the burden of transporting samples to a synchrotron facility, but could be performed on a laboratory or portable scale. At the National Institute of Standards and Technology we are developing a micro-XRF system that combines a polycapillary optic with a standalone X-ray tube. This optic not only transmits the X-ray beam over 80 mm, but also focuses the beam to an area smaller than the unfocused beam size. The fine resolution combined with a high intensity produces a tool for laboratory scale micro-XRF analyses.
The X-ray focusing optic is a tapered, glass polycapillary optic. This optic, contained in an approximately 5 × 70 mm steel cylinder, transmits and focuses incoming X-rays to a spot 9.5 mm from the optic exit.
Fabrication of Organic Supramolecular Micro-Structures: Pre-Organization, Epitaxial Surface Recognition and Controlled Growth in a Model System of Biomineralization
Authors: Childs S , Hagen K , Apkarian R 
Published: July 2020

Abstract
In order to understand the systematic fabrication of hierarchical structures found in biominerals, the process nature uses in the biosynthesis of systems with complex morphology and precise internal molecular organization must be mimicked. The multi-component organic supramolecular system reported here is a kinetically controlled model that demonstrates the three stages of biomineralization: supramolecular pre-organization, interfacial molecular recognition, and cellular processing.
Three molecular components are used in this system: acetic acid (HOAc), benzene, and Kemp's Triacid (l,3,5-Trimethylcyclohexane-l,3,5-tricarboxylic acid or KTA). KTA and HOAc cocrystallize as hydrogen bonded aggregates of KTA dimers capped by four HOAc molecules. KTA and benzene co-crystallize with benzene acting as spacers between one dimensional hydrogen bonded rod-like structures of KTA. Growth of microcrystalline KTA/benzene was initiated by immersing single crystals of KTA/HOAc in 1 mL of benzene for 10-120 sec. The product was isolated on filter paper and mounted with carbon tape on an aluminum stub. The samples were coated with ∼10 nm of 60/40 Au/Pd prior to imaging at 15 kV in a DS-130/LaB6 SEM or at 5kV in a DS-130FE SEM.
Ultravibratomy Applied in Ultrathin Sectioning Results in Sections Without Distortions and Compression.
Authors: Studer Daniel , Gnagi Helmut 
Published: July 2020

Abstract
When resins are ultrathin sectioned they are compressed in the sectioning direction. The amount of compression depends very much on the sectioning angle on one hand, and on the properties of the resin on the other hand. Shortening of the sections in the sectioning direction is in the range of 5 to 35%. Even more compression occurs during cryosectioning of vitreous samples at very low temperatures (-170°C); the range was measured to be 30 to 60% (1).
To reduce these compression phenomena, there is basically only one approach possible. The sectioning angle has to be reduced as much as possible. In the past it was shown that by reducing the knife angle from 45° to 35°, a reduction of compression by appoximately one third was achieved (2). The problem with diamond knives is, that the smaller the knife angle, the more susceptible the cutting edge becomes. In practice angles smaller than 35° are not used because of this limitation.