bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Mirrors Model: Some Analytical Solutions for Generating the Constrained Coinsident-Site-Lattice and its Application to Bi2Sr2Ca1Cu2O8+δ Grain Boundaries
Authors: Volkov VV , Zhu Yimei 
Published: July 2020

Abstract
A knowledge of grain boundaries (GBs) and interfaces is essential in establishing the relationship between the structural details of the boundaries and the strength of superconducting coupling and critical current densities at the boundaries in textured Bi cuprates. As a step towards such understanding, we studied GB crystallography and lattice mismatch using the constrained Coincidence-Site-Lattice (cCSL) theory. We note that to characterize arbitrary GBs in a complex system such as Bi2212, it would be desirable to find some simple analytical solutions for the cCSL approach.
We report our new concept of a “two-mirrors” model (2M-model), which allow us, in principle, to find sufficient conditions to generate corresponding analytical solutions for CSL (or cCSL), when it is applied to crystals with cubic, hexagonal, or orthorhombic symmetry. The 2M-model is based on the fact that any boundary can be described by rotating one crystal relative to the other along a common axis.
Application Of Field-Emission Tem To Investigating Flux Pinning Mechanism In Superconductors
Authors: Tonomura Akira 
Published: July 2020

Abstract
Magnetic vortices in superconductors have become directly and dynamically observable[l] by Lorentz microscopy in our 300 kV field-emission TEM[2]. Since material defects can also be observed simultaneously though the images are defocused, the microscopic flux pinning mechanism can be directly observed. Using this technique, we observed when and how vortices trapped at artificial defects were depinned.
Artificial point defects were produced by the irradiation of a focused Ga ion beam. Electron microscopy revealed that the defect consisted of a pit 300 Å in radius surrounded by entangled dislocations. The depth of a pit increased with the ion dose.
We first investigated the pinning force of individual defect: by observing the depinning of vortices from defects produced with various ion-doses. When a force was exerted on vortices trapped at the defects by changing the magnetic field and increased, we found that the pinning force of defects increased with the ion doses.
Observation and Theoretical Prediction of Structure in Amorphous Carbon and Related Materials
Authors: McKenzie DR , McCulloch DG , Goringe CM , Merchant AR 
Published: July 2020

Abstract
Covalently bonded materials of the light elements B, C, N, O and Al form an interesting series of structures which are readily prepared by physical vapour deposition methods. The most important structural issues are the degree of positional order (that is, whether the material is amorphous or nano phase crystalline) and for alloys, the degree of site occupancy order (that is, the extent of ‘chemical’ order). We propose that the degree of positional order is dependent on the bond angle stiffness of the covalent bonding and the degree of chemical order is dependent on the energy difference of bonds between like and unlike atoms (see figure 1).
The observation of structure in these materials is conveniently carried out by electron optical techniques in an electron microscope. The techniques of value are (a) Energy Filtered Electron Diffraction, and (b) Electron Energy Loss Spectroscopy (EELS).
Silicon Carbide Amorphization by Electron Irradiation
Authors: Bentley J 
Published: July 2020

Abstract
Observations made more than ten years ago1 showed that SiC could be made amorphous at cryogenic temperatures by in-situ 300kV electron irradiation. However, high-voltage electron microscope (HVEM) results indicate a threshold voltage of 725 kV for amorphization of SiC at 140 K. In addition, a recent review exposes the considerable uncertainty in the literature regarding displacement energies for SiC. Therefore, further experiments have been performed in a Philips CM30 (LaB6 cathode) with a Gatan double-tilt cooling holder in an attempt to determine the threshold voltage for amorphization at ∼ 140 K. Sintered α-SiC (defected 6H polytype), beam direction B=&lt; 1120 &gt;, and probes containing ∽ 75 nA in ∽0.5 μm, were used. Amorphization occurred in &lt;10 min at 300 kV and after ∽60 min at 180 kV (Fig. 1); visible darkening occurred at lower voltages and doses. Similar behavior occurred for B=[0001]. The critical dose for amorphization was measured as a function of accelerating voltage.
RDF Analysis of Radiation-Amorphized SiC using a field Emission Scanning Electron Microscope
Authors: Bell David C , Garratt-Reed Anthony J , Hobbs Linn W 
Published: July 2020

Abstract
Abstract
Fast electrons are a particularly useful chemical and structural probe for the small sample volumes associated with ion- or fast electron-irradiation-induced amorphization, because of their much stronger interaction with matter than for X-rays or neutrons, and also because they can be readily focused to small probes. Three derivative signals are particularly rich in information: the angular distribution of scattered electrons (which is utilized in both diffraction and imaging studies); the energy loss spectrum of scattered electrons (electron energy loss spectroscopy, or EELS); and the emission spectrum of characteristic X-rays resulting from ionization energy losses (energy dispersive X-ray spectroscopy, or EDXS). We have applied the first two to the study of three amorphized compounds (AIPO4, SiO2, SiC) using MIT's Vacuum Generators HB603 field-emission (FEG) scanning transmission electron microscope (STEM), operating at 250 kV and equipped with a Gatan digital parallel-detection electron energy-loss spectrometer (digiPEELS).
Microstructure in Nanophase and Amorphous Boron-Based Thin Films
Authors: Medlin DL , McCarty KF , Buchenauer DA , Dibble D , Poker DB 
Published: July 2020

Abstract
Boron-based thin film materials have numerous uses ranging from application as hard and refractory protective coatings to potential employment in wide-band gap semiconductor electronics. Of particular interest are the boron carbides, nitrides, oxides, and phosphides. These compounds exhibit a broad range of structural and bonding variations. The crystalline form of elemental boron is based on an arrangement of 12-atom boron icosahedra positioned at the vertices of a rhombohedral lattice. Related materials, such as B4C, and B12P, also possess structures closely related to this icosahedrally coordinated prototype. However, the structural coordination of the boron carbides and phosphides will vary with composition. For instance, BP possesses a tetrahedrally coordinated zinc-blende structure, and the carbon-rich boron carbides will form in a graphitic structure. Boron nitride has the added complication that for the same composition (BN) multiple bonding and polytypic variations are possible: both soft, graphitic sp2-rich (e.g., hexagonal and rhombohedral BN) and hard, diamond-like sp3-rich phases (e.g., cubic and wurtzitic BN) can be formed.
Studies of Hexagonal Pt and Au Nanocluster Superlattices
Authors: Newcomer Provencio P , Martin J E , Odinek J G , Wilcoxon J P 
Published: July 2020

Abstract
We have recently synthesized superlattices of Pt and Au nanoclusters grown by inverse micelle techniques. The monodisperse nanosize metal clusters used in this study were synthesized as surfactant aggregates surrounded by an oil-like environment (inverse micelle), a technique developed and patented at Sandia. Reaction byproducts, such as excess surfactant and inorganic ion salts, are often separated from the metal clusters using liquid chromatography size exclusion techniques; however, the Pt and Au nanoclusters in this study have been fractionated using a liquid-liquid technique. The nanoclusters are capped with a ligand.
Two-dimensional hexagonal arrays formed readily on surfaces, and large twinned three-dimensional crystals form from solution. Both the cluster size and the size of the capping ligand can be controlled to form superlattices having a range of lattice parameters. We have found that the capping agent exerts a marked influence on the tendency of these clusters to order.
Self-Assembled Cobalt Oxide Nanocrystals with Tetrahedral Shape
Authors: Yin JS , Wang ZL 
Published: July 2020

Abstract
Nanocrystal materials are an emerging research field of chemistry, physics and materials science. The size and shape specificity of nanocrystals suggests them as building blocks for constructing selfassembly passivated nanocrystals superlattices (NCS's) or nanocrystals arrays (NCA) [1-6]. In this paper, NCAs of CoO with controlled tetrahedral shape are reported and their structural stability is examined by in-situ TEM.
Cobalt oxide nanocrystals were synthesized by chemical decomposition of Co2(CO)8 in toluene under oxygen atmosphere, as given in detail elsewhere [1].Sodium bis(2-ethylhexyl) sulfosuccinate (Na(AOT)) was added as a surface active agent, forming an ordered monolayer passivation (called the thiolate) over the nanocrystal surface. The particle size was controlled by adjusting the wt.% ratio between the precursor and Na(AOT). The as-prepared solution contained Co, CoO and possibly C03O4 nanoparticles, and pure CoO nanoparticles were separated by applying a small magnetic field, which is generated by a horseshoe permanent magnet in vertical direction.
Monalayer Arrangement of Pt Nanoparticles
Authors: Green T C , Petroski J M , Wang Z , El-Sayed M 
Published: July 2020

Abstract
Formation of metallic nanoparticles produces an increased surface area per unit volume of material, which provides potential applications in enhancing surface catalyzed reactions. Recently, attention has been focused on moving from the solution based syntheses to solid phase materials by arranging such particles into well ordered 2- and 3- dimensional structures, or forming cluster engineered materials that posses well defined structures. Such studies have shown the importance of size, size distribution, and shape of particles upon self assembled monolayers. We have recently prepared shape-controlled Pt nanoparticles with ﹛111﹜ (tetrahedral), ﹛100﹜ (cubic), and mixed ﹛111﹜ - ﹛100﹜ (truncated octahedral) faces. To study how these faces may orient to form particle point superlattice structures we have prepared monolayer distributions of Pt particles in humidity chambers for analysis by TEM.
Our shape controlled Pt particle synthesis yields between 60 and 80 % cubes, tetrahedra, or truncated octahedra with average diameters ≥ 7 nm.
Nano-Characterization of Industrial Heterogeneous Catalysts
Authors: Liu J , Ebner JR 
Published: July 2020

Abstract
Catalyst characterization plays a vital role in new catalyst development and in troubleshooting of commercially catalyzed processes. The ultimate goal of catalyst characterization is to understand the structure-property relationships associated with the active components and supports. Among many characterization techniques, only electron microscopy and associated analytical techniques can provide local information about the structure, chemistry, morphology, and electronic properties of industrial heterogeneous catalysts. Three types of electron microscopes are usually used for characterizing industrial supported catalysts: 1) scanning electron microscope (SEM), 2) scanning transmission electron microscope (STEM), and 3) transmission electron microscope (TEM). Each type of microscope has its unique capabilities. However, the integration of all electron microscopic techniques has proved invaluable for extracting useful information about the structure and the performance of industrial catalysts.
Commercial catalysts usually have a high surface area with complex geometric structures to enable reacting gases or fluids to access as much of the active surface of the catalyst as possible.
In Situ Oxidation and Reduction of Small Pd Particles on Silica
Authors: Crozier Peter A , Sharma Renu 
Published: July 2020

Abstract
Palladium based catalyst have technological applications in catalytic converters in automobile industry for the combustion of NOx and CO gasses. Pd can also adsorb up to 900 times its volume H2 and is useful for purifying H2. Electron holography studies with model Pd on silica catalysts [1] show that under some circumstances, the Pd particles may form voids. The reason for the formation of these voids and the conditions under which they are formed are not well understood. We have done in situ and ex situ studies on oxidation and reduction of similar model Pd/SiO2 to develop a better understanding of the conditions under which voids are formed.
The catalyst samples were prepared by impregnating silica with acetyl acetoneate (acac) and oxidizing in air and then reducing in H2 at 300°C [1]. High resolution images (Fig. 1) of Pd particles show a central feature with low contrast attributed to the presence of voids.
Electron Holography and Digital Imaging for Analysis of Nanostructured Materials
Authors: Allard L F , Voelkl E , Datye A K , Carim A H 
Published: July 2020

Abstract
Many nanostructured materials are formed from powder precursors having ultra-fine particle sizes. Techniques of electron microscopy have proven invaluable for characterizing the structure of the precursor materials in order to better understand the fundamental processes that govern consolidation of the materials into the final nanophase structures. In recent years, the rapidly developing technique of electron holography has increasingly been applied for characterizing particle morphologies. The advent of the modern field emission microscope, which offers beam coherency sufficient to produce high contrast interference fringes for optimum hologram formation, and especially the availability of digital camera systems for hologram acquisition and rapid processing have both combined to bring electron holography to the forefront of techniques for characterization of nanostructured materials.
Electron holograms typically yield phase images that can give quantitative information on crystal morphologies, but much additional information can result from digital processing of holograms.
Atomic Structure of Interfaces: Link of Atomistic Calculations with High Resolution Electron Microscopy
Authors: Vitek V 
Published: July 2020

Abstract
Since interfaces and grain boundaries affect critically many properties of materials, their atomic structure has been investigated very extensively using computer modeling. Most of these calculations have been made using semi-empirical central-force descriptions of atomic interactions, recently primarily the embedded-atom type many-body potentials. Owing to the approximate nature of such schemes, a connection with experimental observations that can validate the calculations is essential. The high resolution electron microscopy (HREM) is such experimental technique and it has, indeed, been frequently combined with calculations of interfacial structure and chemistry. In fact such a link is not only important for verification of the results of computer modeling but also crucial for meaningful interpretation of HREM observations. Hence, coupling the atomistic modeling with HREM is a synergistic procedure. It not only leads to better understanding of interfacial structures but may contribute significantly to the validation and assessment of limits of the schemes used for the description of atomic interactions.
Monte Carlo Simulation of Solute-Atom Segregation at Grain Boundaries In Single-Phase Binary Face-Centered Cubic Alloys
Authors: Seidman David N , Rittner John D , Udler Dmitry 
Published: July 2020

Abstract
Solute-atom segregation to grain boundaries has been of interest since the 1930's when it was realized that some steels were susceptible to failure by intergranular fracture when certain impurities were present. Segregation of impurities or intentionally added alloying elements at grain boundaries can greatly affect various grain boundary properties, which in turn affect numerous macroscopic properties. Materials phenomena that have been linked to grain boundary segregation include temper brittleness, fatigue strength, adhesion, precipitation, diffusional creep, intergranular corrosion, and grain boundary diffusivity. Although grain boundary segregation has been extensively studied for many years, the effects of different grain boundary structures on segregation was generally not considered. It has been established both experimentally and theoretically that the level of segregation varies from grain boundary to grain boundary in the same alloy, but there is little direct information on how grain boundary structure influences segregation.
Investigating Atomic Scale Structure-property Relationships at Grain Boundaries
Authors: Browning N D , Moltaji H O , James E M , Stemmer S , Buban J P , Zaborac J 
Published: July 2020

Abstract
Although grain boundaries are known to dominate the bulk properties of many technologically important materials, in most cases there is no fundamental atomic scale understanding of why they should have such an effect. One of the problems in developing this understanding is that conventional structure determination techniques, such as phase contrast imaging in TEM or Z-contrast imaging in STEM, produce only a 2-dimensional projection of the crystal structure. Atomic scale compositional changes must be simulated and a unique interpretation is clouded by boundary reconstructions and strain effects. Furthermore, neither technique provides any information on the local changes in the electronic structure that are critical for both the electrical and mechanical properties of the boundary.
EELS provides a means to quantify local changes in both composition and electronic structure. However, without a knowledge of the structure, interpretation of any observed changes at grain boundaries is extremely difficult.
Microstructure of Josephson Junctions: Effect on Supercurrent Transport in YBCO Grain Boundary and Barrier Layer Junctions
Authors: Merkle K L , Huang Y 
Published: July 2020

Abstract
The electric transport of high-temperature superconductors, such as YBa2Cu307-x (YBCO), can be strongly restricted by the presence of high-angle grain boundaries (GB). This weak-link behavior is governed by the macroscopic GB geometry and the microscopic grain boundary structure and composition at the atomic level. Whereas grain boundaries present a considerable impediment to high current applications of high Tc materials, there is considerable commercial interest in exploiting the weak-link-nature of grain boundaries for the design of microelectronic devices, such as superconducting quantum interference devices (SQUIDs). The Josephson junctions which form the basis of this technology can also be formed by introducing artifical barriers into the superconductor. We have examined both types of Josephson junctions by EM techniques in an effort to understand the connection between microstructure/chemistry and electrical transport properties. This knowledge is a valuable resource for the design and production of improved devices.
Field Emission Scanning Electron Microscopy Studies of Industrial Polymers - A Survey
Authors: Osten EF , Smith MS 
Published: July 2020

Abstract
We are using the term "Industrial Polymers" to refer to polymers [plastics] that are produced by the ton or (in the case of films) by the mile. For example, in descending order of world-wide use (tonnage), the top eight of these polymers are polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), styrene polymers (including polystyrene - PS, and acrylonitrile-butadienestyrene/ styrene-acrylonitrile - ABS/SAN), polyesters (PETP), polyurethane (PU), phenolics and aminoplastics.
Industrial polymers, which have been produced by the millions of tons for the last five decades and are of obvious social and economic importance, have been exhaustively characterized. Structural features which affect physical properties and indicate process variables have been studied by many techniques other than microscopy (x-ray diffraction, thermal analysis, rheology, chromatographies, etc.). Microscopy techniques for polymer characterization have been well documented. Our motivation to apply field emission (high resolution) scanning electron microscopy to the study of polymers is: (1) The application of low voltage, high resolution SEM to biological materials is well characterized.
Tem Studies of Single and Double Microdomain Layers of Block Copolymer
Authors: Yao N , Park M , Harrison C , Adamson D H , Chaikin P M , Register R A 
Published: July 2020

Abstract
Diblock copolymers consist of two chemically different polymer chains (or blocks) joined by a covalent bond. Because of the incompatibility between the two blocks and connectivity constraints, diblock copolymers spontaneously self-assemble into microphase-separated nanometer size domains that exhibit ordered morphologies at equilibrium. Commonly observed microdomain morphologies in bulk samples are periodic arrangements of lamellae, cylinders, and spheres. Recent studies show that the thin films of such block copolymers are of great potential for many nanoapplications including nanolithography and template synthesis for inorganic materials. Here, we report TEM studies of osmylated and ozonated thin diblock copolymer films.
An asymmetric block copolymer was synthesized with a composition of 36 kg/mol for the poly(styrene)(PS) block and 11 kg/mole for the poly (butadiene)(PB) block such that the microphase separation produces PB cylinders in a matrix of PS. The films were spin-coated from solution onto thin silicon nitride windows and annealed above the glass transition temperature in vacuum.
In Situ Tem Study of Inert Fillers in Liquid Environment
Authors: Chiou W-A , Lee Y-C , Ishikawa A , Konishi H , Fukushima K , Shriver D F 
Published: July 2020

Abstract
Polymer electrolytes are a topic of interest because of their potential applications in electrochemical devices. However, very few systems exhibit both high conductivities and mechanical strength. Composite polymer electrolytes, composed of conventional polymer electrolytes and inert fillers, provide an avenue to enhance mechanical strength while maintaining ionic conductivity, if the particle sizes of these inert fillers are sufficiently small (&lt; 1 μm in diameter). The determination of the morphology for these inert fillers in polymer matrixes was undertaken to further our understanding of ion transport phenomena in these composite systems. This paper presents an in situobservation of inert fillers in liquid media using environmental TEM.
Surface-modified fume silica was prepared by a two-step process. (1) SiCl4 was used to activate surface silanol (SiOH) groups and generate reactive SiCl groups on the surface of fume silica particles (Aldrich, 7 nm in diameter).
Scanned-Probe Microscopy of Elastomer Blends: Morphology and Mechanical Properties
Authors: Mallamaci Michael P 
Published: July 2020

Abstract
Scanned-probe microscopy (SPM) has found application to a variety of polymer systems, primarily for the examination of surface morphology and the assessment of surface properties. In fact, SPM is unique in its ability to probe both phase morphology and mechanical properties simultaneously. The examination of industrial elastomers and their blends by SPM techniques can provide morphological information historically obtained only by transmission-electron microscopy (TEM). Since contrast with the SPM can be generated by differences in mechanical response of the constituent phases, polymer blends which are difficult to etch or stain for TEM can be successfully examined. In many cases measurements of polymer morphology can be made more easily with SPM, since time-consuming steps associated with thin-section production and staining are not required. Contact and tapping-mode operation along with force modulation and phase measurement can be used to examine phase microstructure, phase morphology, filler type, filler distribution, and viscoelastic response in elastomer systems.