bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microanalysis of Alloy Nanoparticles
Authors: Scott John Henry J 
Published: July 2020

Abstract
Nanoparticles and other nanostructured samples are developing into an increasingly important class of materials. Because of their small size (diameters less than 100 nm), reduced dimensionality, and large surface areas, nanoparticles often exhibit unusual physical, optical, mechanical, and electronic properties. In addition to providing valuable model systems in the pure sciences, nanoparticles are proving useful in technological applications, showing promise as biomedical imaging contrast agents, data storage media, magnetic inks and toners, ferrofluids, and as precursors for advanced compacted materials. Fulfilling this potential depends on characterizing the chemical inhomogeneities of the nanoparticles (and their surfaces) with very high spatial resolution. In this paper I examine the quantitative microanalysis of nanoparticles— electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray spectrometry (EDS)— using transition metal alloy particles (Fig. 1) as a case study.
The microanalysis of nanoparticles presents unique challenges to the analyst because of the very small length scales in the system.
Complex Atomic-Scale Structures in Solids by a Combination of Theory and Microscopy
Authors: Pantelides S T , Pennycook S J , Chisholm M F , Maiti A , Yan Y , Reboredo F , Ferconi M 
Published: July 2020

Abstract
Modern high-performance computers are now capable of calculations that can be used to determine the preferred atomic arrangements in complex systems. Both first-principles and semiempirical approaches have been developed with complementary capabilities. At the same time, powerful transmission electron microscopes have been developed that yield direct atomic-scale images of crystals and extended defects such as dislocations, grain boundaries and buried interfaces. This paper presents several examples where a synergistic approach combining theoretical results, Z-contrast scanning transmission electron microscopy, and spatially resolved electron energy loss spectroscopy (EELS) have led to the elucidation of complex atomic structures. In some cases, theory predicts, experiment confirms and expands and theory revisits; in other cases, observations come first and theory helps put together a comprehensive picture or goes beyond the original observations with new predictions. In both cases, equilibrium structures, impurity or stressinduced structural transformations, and dynamical processes such as diffusion, segregation or precipitation are elucidated in great detail.
Bonding and Stability of Metal/Ceramic Interfaces
Authors: Alber U , Schweinfest R , Riihle M 
Published: July 2020

Abstract
Metal/ceramic interfaces play a crucial role in materials science and for various industrial purposes. In technical applications these interfaces are often exposed to high temperatures and different atmospheres. This often results in a change of the mechanical stability via the morphology and electronic structure of the interfaces. We present a comprehensive analytical electron microcopy (AEM) and fracture mechanics study of this connection on a metal/ceramic-interface model system: Cu/ α-Al2O3.
The specimens were produced by UHV diffusion bonding of bulk Cu to (α-Al2O3 single crystals. Two different Cu materials were used, either pure Cu (noted: Cu) or Cu containing 83±12 ppm oxygen (noted: Cu(O)). After bonding the interfaces were annealed in an oxygen partial pressure at 1000°C between 20 and 120 h. Four point bending tests showed an increase of the fracture energy for the Cu(O)/α -Al2O3-interfaces compared to the Cu(O)/α-Al2O3-interfaces by a factor of 5±2.
Microanalysis of CaWO4 And ErTaO4 Coatings In Oxide Fiber Reinforced Alumina Matrix Composites
Authors: Kim S T , Dravid V P , Sambasivan S , Goettler R W 
Published: July 2020

Abstract
Ceramic matrix composites (CMC's) rely on designed weaknesses in order to provide toughening mechanisms during failure. Specifically, the fiber/matrix interface is well established as the parameter having the most influence on CMC fracture behavior, as first noted by Sambell. With proper design, this interface can allow fracture energy to dissipate by two mechanisms: an increase in crack path tortuosity and frictional energy dissipation through fiber pullout.
One design approach in the area of oxide-based CMC's which has seen considerable success recendy has been in the use of “weakly bonding” oxide coating materials placed between the fiber and the matrix phases. Such CMC systems rely on the formation of a weak interface between the fiber and the coating itself to promote the desired fracture behavior. The most notable example of such a coating material is monazite, LaPO4, as observed by Morgan et al.
Local Dielectric Function Of Biogenic and Geological Polymorphs of CaCO3 Via Transmission Eels
Authors: Katti Kalpana S , Frech Daniel , Qian Maoxu , Sarikaya Mehmet 
Published: July 2020

Abstract
This paper focuses on the differences of physical properties, specifically local dielectric function, of biogenic and geological mineral CaCO3. The goal is to assess the role of organism in forming biogenic inorganic materials. Local dielectric functions of biogenic and geological minerals were determined by transmission electron energy loss spectroscopy using a previously developed strategy.
Previous work on microstructural characterization of biological hard tissues, e.g., abalone shells, has shown variations in terms of defects, morphology, crystallography, and organization of nano- and microstructures in two biological polymorphs of calcium carbonate, calcite and aragonite, in the prismatic and nacreous regions, respectively. In the abalone, the outer (1-5 mm thick) region of the shell is composed of calcite crystallites (1-5 μm diameter) with columnar organization perpendicular to shell plane. On the inner region, 1-10 mm thick nacre is composed of aragonite crystallites (0.5 μm thick and 5 -10 μm edge-length) forming flat platelets, parallel to the shell plane.
Quantitative Hrtem of Twin Boundaries in Compound Semiconductors and Metals Using Non-Linear Least-Squares Methods
Authors: Cohen Dov , Campbell Geoffrey H , King Wayne E , Barry Carter C 
Published: July 2020

Abstract
The analysis of the atomic structure of grain boundaries is often performed through the use of high-resolution transmission electron microscopy (HRTEM). A complication of the HRTEM technique is the inability to analyze directly the experimental images in order to determine projected atomic models of lattice defects. Since contrast features in HRTEM images, in general, do not correspond directly to atomic positions, experimental images are typically evaluated qualitatively through comparison with image simulation. Recently, the interest in quantitatively measuring the atomic structure of internal interfaces for comparison with theoretical calculations has motivated the development of computational methodologies to analyze HRTEM images.123 In this paper, the quantitative analysis of HRTEM images of twin boundaries in semiconductors and metals is described.
AΣ=3 coherent twin boundary in GaP was imaged along the &lt;110&gt; zone in a JEOL-4000EX HRTEM at Sandia National Laboratories, Livermore.
Determination Of Rigid-Body Lattice Translations Across Antiphase and Twin Boundaries in Compound Semiconductors
Authors: Cohen Dov , Medlin D L , Barry Carter C 
Published: July 2020

Abstract
The physical properties of crystalline materials are dependent on the presence and nature of planar defects such as grain boundaries within the crystalline lattice. A comprehensive understanding of a material's properties requires a detailed knowledge of the atomic structure and chemistry of such defects. In general, the crystal orientation relationship at grain boundaries and related planar defects are described in geometric terms, such as the coincidence-site lattice (CSL) model. However, geometric models do not take account of the atomic bonding across grain boundaries whose characteristics differ from that in the bulk. In general, defect structures may relax from the exact CSL orientation in order to minimize the energy of the interface. Lattice relaxations can manifest as a local rearrangement of the atoms close to the boundary and/or rigid-body lattice translations which perturb the relative positions of the grains far from the interface.
Atomic Structures of Inversion Domain Boundaries and Dislocations in Sintered ALN
Authors: Yan Yanfa , Chisholm M F , Pennycook S J 
Published: July 2020

Abstract
A1N is an attractive material because of its mechanical, thermal and electronic properties. However, these properties are often adversely altered by extended defects such as inversion domain boundaries (IDBs), and through impurities associated with the defects, especially oxygen. Thus to improve the properties of the material it is important to understand the structures of the defects. A number of studies have been carried out to characterize these defects using fringe contrast, weak-beam, convergent-beam electron diffraction and conventional high-resolution phase contrast imaging. These techniques all require the use of model structures for data interpretation. In this paper, we report a direct determination of the structures of IDBs and dislocation cores in A1N by highresolution Z-contrast imaging using a 300 kV VG HB603U scanning transmission electron microscope, with a probe size of 1.3 Å.
Bandstructure Near Misfit Dislocations in Si Quantum Wells
Authors: Batson PE 
Published: July 2020

Abstract
High electron mobility structures have been built for several years now using strained silicon layers grown on SixGe(1-x) with x in the 25-40% range. In these structures, a thin layer of silicon is grown between layers of unstrained GeSi alloy. Matching of the two lattices in the plane of growth produces a bi-axial strain in the silicon, splitting the conduction band and providing light electron levels for enhanced mobility. If the silicon channel becomes too thick, strain relaxation can occur by injection of misfit dislocations at the growth interface between the silicon and GeSi alloy. The strain field of these dislocations then gives rise to a local potential variation that limits electron mobility in the strained Si channel. This study seeks to verify this mechanism by measuring the absolute conduction band shifts which track the local potential near the misfit dislocations.
In Situ Electron Holography of Grain Boundary Schottky Barrier Dynamics in 0.5 Wt% NB Doped SrTiO3 36.8° Symmetric Tilt Bicrystals
Authors: Johnson KD , Dravid VP 
Published: July 2020

Abstract
Electrical phenomena such as positive temperature coefficient of resistance (PTCR), grain boundary layer capacitance, and varistors are controlled by Schottky barriers to current transport formed in grain boundary regions. These grain boundary potential barriers are a result of charged defect accumulation, either through equilibrium segregation or kinetic diffusion processes. Recent work on Nb and Mn doped BaTiO3 highlights the importance of substitutional defects which activate grain boundary trap states and give rise to the PTCR effect. The dynamic interaction of charge carriers with such trap states also produces the rapid electrical breakdown characteristic of varistors. This study explores the issues of defect species, space charge, and electrical transport in donor doped SrTi03 by electron holography and electron energy loss spectroscopy.
The specific defect species and mechanisms of current transport through donor doped SrTiO3 remain unresolved because of the difficulty in connecting defect distributions (structural information) and resultant Schottky barrier effects (chemical information).
Dose-Rate Dependence of Radiation Damage in Polymers
Authors: Egerton RF , Rauf I 
Published: July 2020

Abstract
Three aspects of radiation damage are of concern to electron microscopists: changes in crystallographic or molecular structure, mass loss and change in chemical composition. Structural change can be monitored from the fading of diffraction patterns or from loss of fine structure in an energy-loss spectrum. Total mass loss, in the form of a reduction in inelastic-scattering power, can be observed from the low-loss spectrum. Mass loss can also be monitored from energy-loss ionization edges, with the advantage that the loss of particular elements can be studied separately. It is possible to assign a characteristic dose De for the disappearance of a particular element.
At room temperature, the amount of damage usually depends on the accumulated dose (exposure) but not on the dose rate (current density). However, cooling the specimen tends to reduce mass loss, probably because of the reduced diffusion coefficients.
Dose Limited Resolution
Authors: Van Dyck D , den Dekker AJ , Sijbers J , Bettens E 
Published: July 2020

Abstract
1. Introduction
The definition of resolution as introduced by Lord Rayleigh [1] is related to the width of the point spread function of the imaging device. In this definition, noise has not been taken into account. Another definition of resolution has been introduced by Rose [2] in the field of radar and TV. Here the resolution is defined in terms of the dose (D) (i.e. number of imaging particles per unit area) and the signal to noise ratio SNR (i.e. the minimal contrast) A third definition of resolution is based on the idea that the microscope is a communication channel between the object and the observer. The resolution can then be rephrased as the amount of information that is transmitted by the channel in the sense as defined by Shannon [3] as a number of bits per unit area. This definition however does not describe how this information can be deduced and what its precision is.
Effects of Fast Secondary Electrons on Spatiallyresolved Low-Loss Eels of Polystyrene
Authors: Siangchaew K , Libera M 
Published: July 2020

Abstract
A good understanding of the effect of electron irradiation on polymers is necessary in order to optimally utilize the spectroscopic information and resolution of spatially-resolved electron energy-loss spectroscopy (EELS). This investigation studies the effect of electron irradiation on the low-loss spectroscopic signal and spatial resolution obtainable from polystyrene (PS) homopolymer. Because of the conjugated valence electron distribution associated with its pendant phenyl ring, polystyrene is relatively stable under electron irradiation and has well characterized spectroscopic fingerprints including a notable π—π* transition circa 7eV (1). In addition, polystyrene is used as a positive photoresist because it can cross-link effectively when exposed to an electron irradiation (2).
The critical dose characterizing degradation of aromatic polymers is of the order 1-10 C/cm2 (3). In practice, the dose delivered to a specimen is determined both by electron probe size and probe current.
Morphology Study of Polystyrene-Polybutadiene-polycaprolactone (PS-b-PB-b-PCL), Polybutadiene-Polycaprolactone (PB-b-PCL), and Polystyrene-Polycaprolactone (PS-b-PCL) Semicrystalline Block Copolymers
Authors: Kim G , Jackson C L , Gyldenfeldt F v , Balsamo V , Libera M , Stadler R , Han C C 
Published: July 2020

Abstract
Semicrystalline block copolymers containing one crystalline block, such as PCL, show more complicated morphologies than amorphous block copolymers. This is because the microstructure of semicrystalline block copolymers is determined by the interplay between the microphase-separation temperature, crystallization temperature, and glass transition temperatures of the respective blocks. This paper describes initial results of thermodynamic and kinetic effects associated with microphase separation and crystallization in as-cast semicrystalline (PS)0.62(PCL)0.38, (PB)0.2(PCL)0.8 and (PS)0.35(PB)0.15(PCL)0.5 block copolymers, where the subscripts denote the mass fraction of each block.
Semicrystalline block copolymers (PS-b-PCL with Mn=209,000 g/mol, PB-b-PCL with Mn=146,000 g/mol and PS-b-PB-b-PCL with Mn= 150,000 g/mol) were prepared by anionic polymerization. Films were cast from 5% (mass fraction) solutions in toluene into ∼lmm thick films. A relatively slow solvent evaporation over approximately a 10 d period was achieved by partially covering the dishes containing polymer solutions.
Quantitation of the Lateral Orientational Order in Poly(p-Phenylene Terephthalamide) Fibers with X-ray Linear Dichroism Microscopy
Authors: Smith A P , Garcia A , Ade H 
Published: July 2020

Abstract
Determination of internal structure of complex polymeric materials often requires a variety of analytical techniques. One technique that we have developed and recently employed for the first time for quantitative analysis is x-ray linear dichroism microscopy. With sensitivity to the presence and orientation of specific chemical functionalities within polymer molecules, x-ray linear dichroism microscopy provides a powerful tool to probe the internal structure of such molecules. We have used this ability to quantitatively analyze the lateral orientational order (tangential and radial orientation of transverse sections) within different grades of poly(p-phenylene terephthalamide) (Kevlar) fibers.
Kevlar fibers are highly crystalline and possess a complicated internal structure that exhibits lateral radial orientation. Figure 1 shows x-ray micrographs of (a) Kevlar 149, (b) Kevlar 49 and (c) Kevlar 29 fibers imaged at a photon energy specific to the aromatic functionality.
Analysis of the Spatial Variation of Crosslink Density in Superabsorbent Polymers
Authors: Urquhart S G , Ade H W , Mitchell G E , Wilson L , Rightor E G , Dineen M , Hitchcock A P , Neuhaeusler U 
Published: July 2020

Abstract
Superabsorbent polymers are often designed with increased density of crosslinking in the outer layer of the particles in order to improve liquid retention under load. For efficient product design, it is desirable to directly measure the spatial variation in crosslink density. Typically employed techniques (such as solvent uptake or measuring the changes in various mechanical properties such as the modulus) do not provide spatially resolved crosslink density information. We have applied Scanning Transmission X-ray Microscopy to examine the swelling of inhomogenously crosslinked superabsorbent polymers in deionized water and salt water solution.
Scanning Transmission X-ray Microscopy (STXM) is an effective way to study the chemical and morphological character of polymers on a sub micron spatial scale.1 STXM image contrast is based on core electron excitation by x-ray absorption; an interaction that has remarkable chemical sensitivity. Beam damage is less than in TEM microscopes and samples can be examined in wet and in ambient conditions.
Atomic Force Microscopy and Related Techniques: Introduction, Instrumentation and Application to Polymeric Materials
Authors: Musselman Inga Holl 
Published: July 2020

Abstract
Atomic force microscopy (AFM) was introduced in 1986 by Binnig, Quate and Gerber. In this method, a sample is scanned beneath a small, sharp silicon or silicon nitride probe attached to the apex of a flexible cantilever. Cantilever deflection is measured to give height information corresponding to the sample topography. Since AFM relies on tip-sample force interaction, the technique can be applied to insulators as well as to conducting and semiconducting materials. AFM therefore extends local probe studies to an important class of materials which can be difficult to investigate by electron microscopy and spectroscopy techniques owing to problems with sample charging. Among other materials, AFM has been used extensively to characterize the morphology, roughness, nanostructure, chain packing and conformation of polymer surfaces at the nanometer scale.
Early AFM studies of polymers were conducted in the contact mode and included the investigation of polymerized monolayers of n-(2-aminoethyl)-10,12-tricosadiynamide (AE-TDA) and poly(octadecylacrylate) (PODA) at submonolayer coverage.
The Hayashi-nishi Method for Measurement of Mixing:Computer-Generated Morphologies and Impact-Modified Polymers
Authors: Tant M R , Calvert D B , Wehner P S 
Published: July 2020

Abstract
In this work we apply the Hayashi-Nishi method for quantitatively analyzing the state of mixing of a secondary component in a polymeric matrix. We (1) evaluate the method using computer-generated morphologies and (2) compare the state of mixing of a core-shell impact modifier in polymers having differing affinity for the impact modifier. In the Hayashi-Nishi method two numbers, related to dispersion and distribution, are required to quantify the state of mixing of a secondary phase in a polymeric matrix. The 5-parameter in the Hayashi-Nishi method is defined as

The Ai's are the areas of each individual secondary phase particle or aggregate and nis the number of such particles in the image. S is related to the size distribution of these aggregate areas and is a measure of dispersion of the secondary phase in that particular image.
Investigation of the Fracture of Resinated Single Wood Fibers in an Environmental Scanning Electron Microscope (Esem)
Authors: Egan A , Shaler S 
Published: July 2020

Abstract
Single fiber fracture is important in understanding the fundamental failure mechanisms in wood/polymer composite products such as medium density fiberboard (MDF). The mechanical properties and fracture behavior of individual wood fibers has only recently been observable using a combination of environmental scanning electron microscopy (ESEM), laser scanning confocal microscopy and digital image correlation (DIC). Previous work has shown that specific areas on the fiber such as microcompressions and pits acted as crack nucelators and induce a brash fracture across the surface of the fiber. Given the development of these procedures it is now possible to observe and measure the mechanical properties and fracture characteristics of the wood fiber/ polymer composite fibers.
Individual black spruce wood fibers were coated with diphenylmethane 4-4'diisocyanate resin containing Hostasol Red GG. The addition of the Hostasol Red flurochrome provided the option of quantifying resin coverage by fluorescence microscopy.
Mid-Infrared, Raman and NMR Imaging of Flax
Authors: Himmelsbach D S , Khalili S , Gamble G R , Akin D E 
Published: July 2020

Abstract
Multiple microspectroscopic imaging techniques have been employed to reveal the chemical and structural nature of flax (Linum usitatissimum L.) stem tissue, with the goal of finding the best technique by which to monitor retting processes for the production of linen fibers. Three of these techniques, which we have investigated for this purpose, are: mid-infrared (MIR), Raman and nuclear magnetic resonance (NMR) imaging. Initially, all three techniques were evaluated on the basis of their ability to reveal the nature of unretted flax stems. MIR imaging was found to be the most useful for this purpose. Thus, it was selected as the method of choice to follow retting processes to obtain flax fibers.
A Fourier transform (FT)-IR spectrometer equipped with microscope was used to acquire the MTR images. A FT-Raman spectrometer that was equipped with a Raman microprobe and utilizing a 1064 nm laser source was used to collect the Raman images.