bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Structures of Shape-Controlled Platinum Nanoparticles
Authors: Wang ZL , Ahmadi TS , Petroski JM , El-Sayed MA 
Published: July 2020

Abstract
The selectivity and activities of platinum (Pt) particles strongly depend on their sizes and shapes. A technique has been recently reported for controlling the shapes and sizes of Pt particles [1]. Pt particles were prepared by bubbling Ar gas through the solution of K2PtCl4, and the Pt ions were reduced by flowing H2 gas through the solution. The shape control was performed by changing the ratio of the concentration of the capping polymer material to that of the platinum cations used in the reductive synthesis of colloidal particles in solution at room temperature [2]. High percentage of cubic, tetrahedral and octahedral particles have been prepared at room temperature, making it possible for studying the chemical activities of particles with different shapes and facets. This paper aims to study the surface structures of Pt particles prepared by the shape-controlling synthesis technique using high-resolution transmission electron microscopy (HRTEM).
Graphitic Cones
Authors: Krishnan A , Dujardin E , Bisher M E , Treacy M M J , Hugdahl J , Lynuir S , Ebbesen TW 
Published: July 2020

Abstract
New structural forms of carbon have been discovered in recent years, the most notable being the fullerenes and nanotubes. The notion that curvature is readily accommodated by graphite sheets has led to speculation about other possible topologies that incorporate pentagons or heptagons in hexagonal graphite nets. by consideration of Euler’s theorem and the symmetry of a graphite sheet, five conical structures can be predicted. If pentagonal defects only are present, cone angles are completely determined by the total number of pentagons, n, where 0≤n≤6 for open structures. In the absence of heptagons, growth of any graphitic structure containing more than 6 pentagons leads inevitably to the closed n =12 form. Consequently, five cone angles are possible, with disk (n=0) and tubular (n=6) forms representing the end-members of the topological series. Ge and Sattler1 have observed the smallest-angle member of this series with a cone angle of 19.2° (n=5).
Identification of Metal-Impurity Gettering Sites in Silicon Formed by Supersaturation Boron Implantation and Annealing Using HRTEM and STEM Micro Analysis
Authors: Headley T J , Michael J R , Myers S M , Petersen G A , Aselage T L , Bruley J 
Published: July 2020

Abstract
Future Si microelectronic devices will require increasingly stringent limits on transition-metal impurities. There is thus a need to develop new methods for impurity gettering that rely on gettering sites that are active for arbitrarily small impurity concentrations, below the characteristic solid solubility at which metal suicides precipitate. These sites must also be highly preferred relative to solution sites in the Si matrix even at elevated temperatures. One such method has been developed that is also expected to be compatible with front (device) side gettering enabling smaller diffusion lengths for lower processing temperatures. This method involves boron implantion in the front side to levels above the boron-saturation limit and annealing to generate the gettering sites. The gettering layer is introduced at a depth beneath the device zone through appropriate choice of implantation energy. SIMS compositional profiling shows transition metals are strongly gettered within the boron-supersaturated layer. The purpose of this study was to identify the structure and composition of the gettering sites within the boron-supersaturated layer.
The Microstructure of GaAs Grown on Glass Substrates by Molecular Beam Deposition
Authors: Jones Kim M , Friedman Dan J , Al-Jassim MM 
Published: July 2020

Abstract
In the mid to late 80's there was considerable effort directed at the hetroepitaxial growth of III-V's (GaAs, GaP and InP) on Si substrates for solar cell applications. The primary incentive for this work was the cost reduction of expensive substrate materials. This is particularly important when considering large scale production of terrestrial photovoltaic modules. In the U.S. these efforts produced cell efficiencies up to 21% and continued development of this solar cell structure is currently being pursued in Japan. Similar cost effective structures are being investigated at NREL such as the growth of polycrystalline GaAs films on inexpensive glass substrates for solar cell applications. Polycrystalline films, however, tend to contain a high density of grain boundaries which are regions for carrier recombination and enhanced dopant diffusion which can limit cell performance. In order to reduce the detrimental effects of grain boundaries, the growth of large grain (hence low boundary area) GaAs is being investigated
TEM Observation of Delamination Behavior of c-BN Thin Film
Authors: Kim Ig-Hyeon , Sung Changmo , Lee Sang-Ro 
Published: July 2020

Abstract
Cubic boron nitride films were prepared by helicon wave plasma CVD process on (100) Si. The film deposited under the intense impact of energetic ions is usually delaminated from the substrate after deposition. The delamination behavior of c-BN film was investigated with transmission electron microscopy. It is found that moisture in the air, surface roughness of the film and substrate, as well as severe compressive stresses in the film are the primary contributors to film delamination. An aqueous oxidation was verified by EDXS analysis, which generate local stress by volume expansion at the crack region in the c-BN layer.
The cross-sectional TEM micrograph of c-BN film in Fig. 1 shows that a very thin layer of h-BN is deposited before the c-BN layer starts to grow at an early stage of film growth. A columnar structured thin h-BN layer about 20 nm thickness at the interface is clearly separated from the c-BN layer in an aspect of microstructure.
Characterization of Crystal Polarity Across Twin Boundaries in GaP
Authors: Cohen Dov , McKernan Stuart , Barry Carter C 
Published: July 2020

Abstract
The measurement of the absolute crystal polarity is crucial to understanding the structural properties of planar defects in the sphalerite structure. Due to the directionality of the chemical bond between cations and anions in this lattice, grain boundaries in sphalerite can be described by two distinct structural models. Each model is distinguished by the relative orientation of the polar axis in the grains adjoining the interface. In order to evaluate the polarity of twinned grains in GaP, a dynamical diffraction technique is used to determine the Ga to P bond direction across a coherent twin boundary.
The characterization of the polarity in GaP was performed using a convergent-beam electron diffraction technique developed by Tafto and Spence.CBED can be used to identify the direction of the crystal polarity by observing asymmetries in dynamical diffraction contrast in reflections from crystal planes of opposite polarity. Such contrast arises when the Ewald sphere intercepts a weak {002} reflection plus two or more higher order, odd indexed reflections.
Visualizing Sub-Micron Burried Metal Line in VLSI Devices using a SEM
Authors: Drouin D , Hovington P , Gauvin R , Beauvais J 
Published: July 2020

Abstract
In recent years, the critical dimension in “Very Large Scale Integrated” devices has dramatically decreased. The microelectronics industry road map predicts that by the year 2000 the critical dimension will be below 250 nm. This reduction in scale will imply the development of new techniques to control the fabrication of such devices. This paper presents a novel approach to characterize VLSI devices based on Monte Carlo calculations. The principle of this technique is to use information from backscattered electrons (BE). The energies of those electrons are related to their maximum range within the structure. Thus it is possible to distinguish the layer from which they are backscattered. In order to collect this information an energy filtered backscattered electron detector must be used.
Figure 1 shows a cross section of a structure produces using a typical VLSI process. The two metal layers are usually patterned to define small lines and contacts.
On the Influence of Specimen Thickness in TEM Images of Super-Conducting Vortices: II
Authors: Bonevich J , Capacci D , Patti R , Pozzi G , Harada K , Kasai H , Matsuda T , Tonomura A 
Published: July 2020

Abstract
In our previous papers on the same topic we have shown how the finite thickness of the specimen influences the magnetic field distribution associated to a single superconducting vortex. Fortunately, Clem found an approximate, but analytical, solution for this problem predicting that the field lines are bent within the specimen and fan out near the surfaces, giving an external field topography broader than the bulk one. This is shown in Figure 1 (a) which reports the projected phase maps of the magnetic field, i.e., the phase shift experienced by a coherent electron plane wave in an ideal experiment where the beam direction is parallel to the specimen surface and the apparent infinite thickness of the specimen is overlooked. The specimen thickness has been taken equal to 2 λL, the bulk London penetration depth. Figure 1 (b) shows the trends of the z-component of the magnetic field calculated up to a distance from the core of 5 λL at the film surface (lower curve), at the film center (intermediate curve) and, for reference, the bulk Clem model (upper curve).
Theoretical Foucault Images of Superconducting Fluxons
Authors: Beleggia M , Pozzi G , Harada K , Kasai H , Matsuda T , Yoshida T , Tonomura A 
Published: July 2020

Abstract
Individual flux lines in superconducting specimens have been recently observed using a 300kV holography electron microscope equipped with a cold field emission gun in the transmission mode by means of the out-of-focus method. In this way it has been possible to observe the dynamic behaviour of fluxons depending upon the variations of the temperature and/or the applied magnetic field or current. The main disadvantage of this method is that correlation with structural defects is troublesome owing to the large defocus distance (of the order of 1 cm for conventional superconductors) necessary for the detection of flux lines.
This drawback is not present in the Foucault technique, where the contrast is generated in the focused image by masking part of the transmitted beam by means of an aperture. Therefore, some preliminary calculations have been made recently using one-dimensional models, which allow for a quick and easy simulation of the factors affecting the experimental conditions.
Differential Microscopy by Electron Holography With an Electron Trapezoidal Prism
Authors: Tanji T , Manabe S 
Published: July 2020

Abstract
Electron holography has been successfully used in the observation of phase objects such as magnetic fields and electrostatic potentials. Electron holograms are constructed by the interference of a modulated object wave and a well-defined reference wave and in most cases the reference wave is required to be a plane wave. Frequently, however, the magnetic or electric field extends beyond the interference region, resulting in a distorted reference wave. The reconstructed wave from a hologram made with a distorted reference wave does not accurately express the object wave but the difference from the reference wave.
Differential interferometry is a useful technique in the absence of a well-defined reference wave. Some electron holography techniques using two-beam illumination for differential interferometry have been proposed. We have also proposed a new technique for differential microscopy by conventional electron off-axis holography, which utilizes an electron biprism to shear the object wave. Shearing of the object wave is essential for differential interferometry.
Magnetic and Crystallographic Microstructure of SrRuO3 Studied by Lorentz Transmission Electron Microscopy
Authors: Marshall AF , Klein L , Dodge JS , Ahn CH , Reiner JW , Mieville L , Geballe TH , Beasely MR , Kapitulnik A 
Published: July 2020

Abstract
SrRuO3 is a low temperature ferromagnet (Tc ≌ 150K) which has recently been investigated in thin film form due to its structural compatibility with other thin film perovskites materials of practical interest, including high-temperature superconductors. Magnetization studies of thin films of SrRuO3 deposited on cubic SrTiO3 indicate strong uniaxial anisotropy with the easy direction approximately along either the a or b axis, which are difficult to distinguish. The orthorhombic structure of SrRuO3 (a = 5.53, b = 5.57, c = 7.84 Å) has six symmetry-related orientations on the cubic substrate (a = 3.9Å). Using Lorentz transmission electron microscopy both the magnetic and the crystallographic domain microstructure are characterized.
For TEM imaging the films are readily removed from the substrate by chemical etching, using a HF:HNO3:H2O etch of approximately 1:1:1 dilution. Free-floating SrRuO3 films of 300-1000Å in thickness are then supported on standard carbon/formvar films on Cu substrates.
Magnetic Contrast in the cFEG SEM Using the Upper (Above-the-Lens) Detector
Authors: Brewer LN , Dravid VP 
Published: July 2020

Abstract
An unconventional and important use of the SEM is in the study of magnetic phenomena of materials. Many magnetic phenomena occur on the surfaces of materials as is the case for magnetic recording in computer memory and audio tapes. The “above-the-lens” or “upper” detector of the cFEG SEM(Hitachi S4500) is especially suited to probing surface phenomena (Fig. 1). The upper detector is used in combination with a magnetic “snorkel” lens which pulls secondary electrons (SE) up to the detector, resulting in an extremely high and pure SE yield. While magnetic imaging in a standard, side-mounted Everhart-Thornley (lower) detector is well understood, the image contrast mechanism for the upper detector is not presently known. We tested both energy filtering and trajectory contrast as possible magnetic contrast mechanisms using a cassette recording tape (Fe2O3 based) and barium hexaferrite ceramic magnets.
Two sets of experiments were performed to explore the magnetic contrast.
Segregation at Adherend Interphases in Fiber-Reinforced Epoxies
Authors: Arayasantiparb D , Siangchaew K , Libera M , McKnight S 
Published: July 2020

Abstract
The fact that there is a region at the epoxy/adherend interface known as the interphase whose chemistry and structure are different from that of bulk epoxy is well established (1-2). The specific nature of the interphase depends on the resin and curing agent, the adherend surface-chemical properties, and the adherend sizing treatment if any, among other possible variables. The interphase is critically important, since it is responsible for stress transfer between the matrix and reinforcing fibers. While it has been studied by a variety of analytical methods (eg. 3-5), none have had sufficient spatial or spectral resolution to establish the physical extent of the interphase or its compositional deviation from bulk epoxy. This research exploits high-spatial-resolution analysis in a field-emission STEM to study the interphase in epoxy/adherend systems using high-angle electron scattering (HAADF-STEM) and energy-loss spectroscopy (PEELS).
Thin specimens were cut by ultramicrotomy using a diamond knife from single-fiber tensile bars consisting of anodized aluminum wire embedded in an epoxy matrix (Fig 1.)
Interfacial Segregation in Al-Cu-Mg Alloys
Authors: Ford RG , Carpenter RW , Kim MJ , Sieradzki K 
Published: July 2020

Abstract
The corrosion behavior of Al-Cu-Mg alloys, specifically 2024 alloy (nominally, in weight %, 4.4 Cu, 1.5 Mg, 0.6 Mn), is thought to depend on heterogeneous Cu and Mg distribution through the existence of segregation-dependent local electrochemical cells at the corrosion interface. Few nanospectroscopy measurements of segregation have been made for this or similar alloys. These alloys are precipitation hardenable. The primary precipitating phases are S and the well known Θ(CuAl2) and their metastable intermediates. TEM analysis of aged alloys in this subgroup showed that the orthorhombic S phase (a=4.0Å, b=9.25Å, c=7.15Å) occurred as a thin plate type variant, called S´, within matrix grains and as larger monolithic particles on grain boundaries. Intragranular pricipitate particle densities were heterogeneous particularly near grain boundaries, indicating that strong segregation was present that would result in local electrochemical cells where grain boundaries and large precipitates intersected the alloy surface.
HRTEM and nanospectroscopy are used to analyze the structure and chemistry of heterophase interfaces and grain boundaries.
AEM Analysis of Grain Boundary Segregation and Precipitation in Al-Mg Alloys
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Vetrano JS , Bruemmer SM 
Published: July 2020

Abstract
Magnesium is an important and common solid solution strengthening agent for aluminum alloys. It has been known for many years that Mg segregation to grain boundaries (GBs) and other structural inhomogeneities can lead to precipitation of the ² (Al3Mg2) phase during low-temperature aging. This phase is anodic with respect to the matrix so its presence degrades the stress corrosion cracking (SCC) resistance of the alloy. The details of P-phase precipitation have been studied in detail in binary Al-Mg alloys [3-5] but there is some indication that ternary elements can alter the precipitation kinetics and spatial distribution which in turn will affect SCC. Therefore we are studying the segregation and precipitation of Mg in a commercially important Al-Mg alloy which contains Mn and Cr as grain refining particles.
Specimens were prepared from a commercial 5083 heat with the composition 4.47% Mg, 0.61% Mn, 0.08% Cr, 0.09% Si, 0.21% Fe, 0.05% Cu, bal. Al (all compositions in weight percent). Following cold rolling they were given a recrystallization anneal of 10 min. @ 500°C and air cooled.
Electron Backscattered Diffraction (EBSD) with a Cold Held Emission Gun (cFEG) SEM: Resolution, Sensitivity and Applications
Authors: Isabell Thomas C , Dravid Vinayak P 
Published: July 2020

Abstract
A thorough and complete assessment of microstructure of materials requires a wide variety of analytical techniques, which should be sensitive to at all length scales - from mms to atomic scale. While there have been rapid advances in imaging and spectroscopy techniques for microstructural analysis - at all length scales, techniques for crystallographic analysis of microstructure have primarily relied on bulk x-ray/neutron diffraction and TEM. X-ray and neutron diffraction techniques, though very powerful, are primarily bulk techniques and extraction of local crystallography is formidable if not impossible. On the other hand, TEM diffraction techniques provide precise crystallographic information, but at a much smaller length-scale and suffer from poor statistics and tedious specimen preparation procedures. With the advent of commercially available electron backscattered diffraction (EBSD) and orientational imaging (OIM) systems for SEM, and sophisticated pattern recognition procedures, it is now possible to bridge the length-scale gap between bulk and TEM diffraction techniques.
Analysis of Multiphase Materials Using Electron Backscatter Diffraction
Authors: Wright SI , Field DP 
Published: July 2020

Abstract
Image analysis techniques coupled with crystallography computer codes have been used to index electron backscatter diffraction patterns (EBSPs). The ability to automatically obtain the crystallographic orientation from EBSPs coupled with computer control of the electron beam (or stage) in a scanning electron microscope (SEM) provides a much more complete description of the spatial distribution of crystallographic orientation in polycrystalline materials than has been previously attainable using conventional metallography techniques. Orientation data obtained using this technique can be used to form images reflecting the spatial arrangement of crystallographic orientation in a microstructure. Such images enable the topological features of a microstructure to be linked with the orientation characteristics. The formation of these images, as well as the data collection technique, is sometimes termed Orientation Imaging Microscopy (OIM). The utility of this technique for exploring the property/structure relationship in polycrystalline material has been demonstrated by numerous researchers. However, as yet, this technique has almost exclusively been applied to single phase materials.
The Influence of Microtexture on Fatigue Behavior in Titanium Alloys
Authors: Woodfield A P , Sutliff J A 
Published: July 2020

Abstract
Automated electron backscatter diffraction pattern (EBSP) measurements were conducted in an attempt to relate low cycle fatigue (LCF) behavior to underlying microtexture in alpha-beta forged and heat treated Ti-6242 materials. Conventional load control, R=0 LCF tests were conducted with two wave forms, 30 cycles per minute (30 cpm), and 2 minute hold at peak stress, (dwell). The fracture surfaces and adjacent microstructures of the LCF specimens were examined using light microscopy, scanning electron microscopy (SEM), and orientation imaging using automated EBSP.
Fracture surfaces of dwell LCF specimens frequently contained large macroscopically flat, shiny facets, while 30 cpm specimens showed no such evidence of facets. Additionally, the dwell LCF specimens that contained facets had very low lives, typically around 1000 cycles at 126 ksi maximum stress. EBSP measurements directly on the facets, and on cross-sections through the facets revealed that the facet fracture plane was on, or close to (0001) of the primary alpha grains, Fig. 1, and was approximately perpendicular to the stress axis.
Controlled Environment (ECELL) HREM
Authors: Boyes Ed 
Published: July 2020

Abstract
The ability to control the environment inside the electron microscope is a very desirable general capability and one long pursued for higher vacuum or chemical reactions (1,2) Here we are primarily concerned with providing the essential facilities for realistic in-situ dynamic studies of chemical reactions between gases or vapors and solids. The compromises with microscope performance have been reduced substantially compared with previous gas experiments (2,3).
The primary applications for the present instrument are to reaction catalysts and the products of reactions where they are solid state materials of commercial value. Firstly, the catalyst may have to be (re)processed after transfer through the air or other hostile (i.e. non-reactor) environment. Secondly, the high vacuum atmosphere in a typical TEM may not be a compatible environment for the catalyst or other material (e.g. if it is solvated). Thirdly, the sequence of events in changes in the microstructure of a chemically active species will likely depend on the atmosphere in which those changes take place or are promoted (e.g. by heating).