bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-fold astigmatism: An important TEM aberration
Authors: Krivanek O.L. , Leber M.L. 
Published: June 2020

Three-fold astigmatism resembles regular astigmatism, but it has 3-fold rather than 2-fold symmetry. Its contribution to the aberration function χ(q) can be written as:where A3 is the coefficient of 3-fold astigmatism, λ is the electron wavelength, q is the spatial frequency, ϕ the azimuthal angle (ϕ = tan-1 (qy/qx)), and ϕ3 the direction of the astigmatism.Three-fold astigmatism is responsible for the “star of Mercedes” aberration figure that one obtains from intermediate lenses once their two-fold astigmatism has been corrected. Its effects have been observed when the beam is tilted in a hollow cone over a wide range of angles, and there is evidence for it in high resolution images of a small probe obtained in a field emission gun TEM/STEM instrument. It was also expected to be a major aberration in sextupole-based Cs correctors, and ways were being developed for dealing with it on Cs-corrected STEMs.
Flux-line observation by electron Holography
Authors: Tonomura Akira 
Published: June 2020

In electron microscopy, the intensity of an electron beam transmitted through an object can be observed. While in electron holography, the phase of the electron beam can also be observed and displayed as an interference micrograph. Using a technique unique to holography, the precision of phase measurements can be increased to 1/100 of the electron wavelength. An interference micrograph of a magnetic object can be interpreted in a straightforward way: Contour fringes directly indicate projected magnetic flux lines and a constant magnetic flux of h/e (= 4 × 10-15 Wb) flows between two adjacent fringes (See Fig. 1).Examples of magnetic recordings are shown in Fig. 2. Flux lines inside and outside of the magnetic tapes, recorded in different ways, can directly and quantitatively be observed as interference micrographs. Figure 2 (a) shows an example of in-plane magnetic recording. Two magnetization streams, pointed in opposite directions, merge and produce vortices in the transition region similar to those produced by streams of water.
Microscopy of magnetic materials using an optimised FEG CTEM/STEM instrument
Authors: Chapman J N , Ferrier R P , Bormans B 
Published: June 2020

Modern magnetic materials, as well as being of major scientific interest, are being developed intensively for a wide range of technological applications To achieve superior properties great attention is devoted to the ways in which materials are produced in that many of the desirable attributes are induced by a particular growth process rather than being intrinsic to the material itself. Thus development of enhanced macroscopic properties requires that the magnetic microstructure be determined and its dependence on the physical microstructure understood. Furthermore, the information needed is not restricted to the materials in their as-grown state but on how they are affected by application of magnetic fields and changes in temperature.To satisfy all these requirements a highly modified electron microscope has been developed. The main criteria it had to fulfill were: (i) sufficient room around the specimen to house a small “micromagnetic laboratory” to allow a range of in-situ experiments to be undertaken
TEM examination of the magnetic domain boundaries in a duplex austenitic- ferritic stainless steel
Authors: Fourlaris G. , Gladman T. 
Published: June 2020

Duplex austenitic- ferritic stainless steels (DSS) offer significant advantages when compared to standard austenitic stainless steels, in several areas of industrial applications, due to their higher mechanical strength, superior resistance to corrosion and a lower price because of their lower nickel content. Despite the extensive research carried out so far in the area of DSS the characterisation of their magnetic properties, under stress or under a static field, has attracted significantly less attention. This is contrary to the fact that in certain naval constructions the suitability of a given type of steel is judged not only by its tensile, impact, and corrosion properties but also by its magnetic behaviour.A 2205 type austenitic- ferritic DSS has been cold rolled to different cold rolling reductions, with an aim of achieving a 0.2 % proof strength of at least 700 MPa with an elongation value of greater than 20%.
Study of cobalt oxide films deposited on single-crystal yttria-stabilized zirconia by pulsed-laser ablation
Authors: Ramamurthy Sundar , McKernan Stuart , Barry Carter C. 
Published: June 2020

One of the most common applications of pulsed-laser ablation (PLA) is the production of oxide films of almost any stoichiometry. In this work, thin films of cobalt oxide were grown onto single-crystal yttria-stabilized zirconia (YSZ) substrates of (100) orientation. Film morphology during the early stages of growth has been studied.Cobalt oxide films grown on suitable substrates have potential applications in electronic and magnetic devices. Like most transition metal oxides, cobalt oxide exists in more than one form, depending on the valence of the cations and their distribution . The transition from CoO to Co3O4 occurs at about 900°C in air, CoO being the high-temperature phase. However, by lowering the partial pressure of oxygen, the CoO stability region shifts down to much lower temperatures.The laser system used for the depositions was a Lambda Physik model 210i with KrF excimer laser (λ=248 nm) operating at an energy of 200 mJ per pulse. A Co3O4 pellet (96% dense) was fabricated as the target material.
Scanning tunneling microscopy of the topology of vapour-deposited and electro-deposited metal films
Authors: Liu J.B. , Clark Boyd , Duan J.Z. , Fisher R.M. 
Published: June 2020

The fracture and subsequent spontaneous delamination of thin metal films under the influence of excessive internal stresses, resulting from low temperature deposition and processing, can be extremely deleterious to the long term serviceability of IC devices. The conditions for fracture are determined by the magnitude of the residual stress, which can be measured by x-ray diffraction techniques, the fracture toughness of the thin film material and the size of any internal or sinface flaws that may be present.In order to establish the size and depth of microcracks at the surface, high resolution scanning (SEM) and transmission electron microscopy (TEM) and scanning tunneling microscopy (STM) are being used to define the topology of the surfaces of vapour-deposited films for comparison with electroplated films of the same metal. Direct knowledge of the surface relief is required to predict the onset of through-thickness cracking or to derive the fracture energy of the film material by detecting the critical conditions for cracking. Detailed knowledge of surface structures also is useful for understanding the mechanisms of film growth, including information on the crystallography of surface facets and growth steps.
Small, cool lenses
Authors: Crewe Albert V. 
Published: June 2020

The potential advantages of small magnetic lenses are well-known and obvious and many attempts have been made to make such lenses. Previous work has been adequately summarized in an excellent article by Mulvey who covered most of the ground. This paper can be considered to be just a small addendum to that publication. As often happens surprises occur when we combine two different concepts.If we consider an annular shaped coil (Fig. 1a) we can easily relate the power consumption to the ampere turns by a simple integration. Inserting some practical values, we obtainand we see that the power consumption does not depend upon the radius directly, only by virtue of the ratio r2/r1.We can make the coil into a lens very simply by wrapping it in iron (Fig. 1b). In the case of a thin lens (e.g. for an SEM) the focal length depends upon the value of s and the magnetic field and it is possible to combine these expressions to obtain
3-D reconstruction of biological material from serial section and stereo modeling
Authors: Mastronarde David , McDonald Kent , McIntosh J. Richard 
Published: June 2020

Stereo visualization of biological fine structure has long been useful for the appreciation of three-dimensional structure in high voltage electron micrographs of thick specimens. Quantification of specimen geometry by this method is difficult, however, since reproducible placement of a 3-D cursor in a gray-scale object with a single pair of stereo views is difficult. Serial thin sectioning and electron microscopy has been used to obtain quantitative three-dimensional information about biological structures, but when high resolution is required, serial section tracking can be problematic because distortions of as much as 5% between successive sections are common, impeding section alignment and reliable 3-D reconstruction.We are experimenting with computer image processing methods to overcome the above mentioned difficulties. A MicroVax III hosting a Parallax board set is being used to process images obtained from electron micrographs with a DAGE -81 video camera and displayed on a Mitsubishi high resolution color monitor.
Observation of the quantum size effect in the STEM
Authors: Ouyang F. , Isaacson M. 
Published: June 2020

The study of small particles or microclusters has been very active in recent years. When the particle size becomes smaller, its electronic properties deviate from those of bulk material and become size dependent. This phenomenon is refered to as the quantum size effect.One of the frequently used probes for studying the electronic states of small particles is the surface plasmon (SP) excitation. Genzel et al. studied the optical absorption peaks from silver particles in glass. They found a blue shift of the SP peak when the particle size becomes smaller (see Fig 2). Electron energy loss spectroscopy (EELS) studies have also been performed. Recently vom Felde et al. reported broad beam EELS with large momentum transfer from potassium particles embedded in a MgO matrix. They observed that the surface plasmon energy increases when particle size becomes smaller, and there is a positive dispersion for particles of size 40 Å.
Elemental analysis of human erythrocytes
Authors: Livesey S. A. , del Campo A. A. , Griffey E. S. , Ohlmer D. , Schifani T. , Chiovetti R. 
Published: June 2020

The aim of this study is to compare methods of sample preparation for elemental analysis. The model system which is used is the human erythrocyte. Energy dispersive spectroscopic analysis has been previously reported for cryofixed and cryosectioned erythrocytes. Such work represents the reference point for this study. The use of plastic embedded samples for elemental analysis has also been documented. The work which is presented here is based on human erythrocytes which have been either chemically fixed and embedded or cryofixed and subsequently processed by a variety of techniques which culminated in plastic embedded samples.Heparinized and washed erythrocytes were prepared by the following methods for this study :(1). Chemical fixation in 4% paraformaldehyde/0.25% glutaraldehyde/0.2 M sucrose in 0.1 M Na cacodylate, pH 7.3 for 30 min, followed by ethanol dehydration, infiltration and embedding in Lowicryl K4M at -20° C.
Structural analysis of faceted grain boundaries in Bi-doped Cu
Authors: Luzzi D. E. , Blum B. , Inui H. 
Published: June 2020

Conventional(CTEM)and high-resoIution(HREM) transmission electron microscopy have been used to investigate the structure of faceted grain boundaries in Cu doped with Bi. The solubility of Bi in Cu exhibits retrograde behavior with a maximum of 160 at. ppm. at 850 ° C and decreasing above and below this temperature (eg. to < 3 at. ppm. at 600 ° C). When aged at temperatures below this retrograde region, Blis known to segregate tothe grain boundaries. In addition to this segregation, these materials exhibit a reversible faceting-de-faceting transition at 710 ° C which has been postulated asarising from a two-dimensional phase transformation at the grain boundaries. Until the present time, little experimental work has been doneto characterize the structures of these faceted boundaries.In the present experiments, Kikuchi pattern analysis and edge-on imaging have been used to characterize the five macroscopic degrees of freedom of individual facets. Bulk Cu specimens with 50 at.ppm.
Effect of electrolyte on thin-foil precipitate artifacts in copper-bearing steels
Authors: Thompson S.W. , Krauss G. 
Published: June 2020

Copper additions to steel produce significant precipitation strengthening. Transmission electron microscopy (TEM) of aged copper-bearing steels reveals the presence of fine (usually 10 nm or larger), fcc, ε-copper particles. Additionally, very fine (less than 5 nm), Cu-rich bcc clusters or precipitates have been detected. The former particles are easily imaged via TEM, whereas the latter are difficult to detect by conventional TEM. Considerable variability in TEM observations causes concern about artifacts which may be produced during jet polishing. This note describes experiments which demonstrate that the true documentation of Cu-precipitate distributions is sensitive to the electrolyte used to prepare thin foils for TEM examination.Hot-rolled and quenched 32mm-thick steel plates (provided by Lukens Steel) contained (in wt pct) 0.05C, 1.12Cu, 0.88Ni, 0.50Mn, 0.20Mo, 0.71Cr, 0.28Si, 0.04Nb 0.02Al, 0.0lP, and 0.002S. All specimens were aged at 675°C for one hour. Foils were produced by conventional thinning methods and jet polished with three electrolytes:
High-resolution Electron Microscopy of defects in Ni3Al
Authors: Mills M. J. 
Published: June 2020

The improved resolution of the latest generation of intermediate voltage electron microscopes makes possible the direct study of the atomic structure of defects in close-packed metals and alloys. Of particular technological interest are several classes of intermetallic compounds which exhibit desirable mechanical properties at higher temperatures. This paper demonstrates the current application of high resolution transmission electron microscopy (HRTEM) to the study of dislocation cores and interfaces in nickel-based alloys, and the implications of the observations in terms of models of deformation and fracture.Several intermetallic alloys with the L12 (Cu3Au) structure exhibit an anomalous increase in the flow stress as a function of temperature. The theoretical models that have been proposed to explain this behavior are based upon consideration of a thermally activated cross slip of screw dislocations from {111} to {010}. These models assume that the dissociation of the a superlattice (SL) dislocation occurs by the formation of an anti-phase boundary (ABP) which is bounded by two a/2 superpartial (SP) dislocations with parallel Burgers vectors.
Dislocation structures in deformed Ni3Al
Authors: Subramanian Raja , Robertson I.M. , Birnbaum H.K. 
Published: June 2020

The improvement of the ductility of Ni3Al by the addition of boron has revived interest in intermetallic alloys. Addition of up to about 500 wt. ppm of boron increases the ductility of Ni3Al by as much as 50%. This improvement is dependent on the deviation from stoichiometry with optimum effect being obtained for the Ni-rich composition. The ductility enhancement has been attributed to the boron increasing the cohesive energy of the grain boundary and to a disordered boundary layer easing the slip process through the grain boundary.The dislocation structures produced in deformed Ni3Al with and without boron has been examined in the transmission electron microscope . Samples were deformed to a 3 % strain in bulk form while others were deformed in situ in the transmission electron microscope. (Details of the in situ TEM straining technique can be found in ref.)
A Transmission Electron Microscope study of APB in TiAl
Authors: Feng C. R. , Michel D. J. , Crowe C. R. 
Published: June 2020

Antiphase domains are usually observed in materials with an ordered superlattice structure and the domain boundaries are termed antiphase boundaries (APB). For the Ll0 structure of TiAl, no micrographs have been presented to confirm the existence of an APB. The primary reason for this is the high APB energy which is associated with the separation of the superdislocations. However, APB also could be formed thermally. The purpose of this paper is to report the observation of a thermally formed APB in TiAl and to describe the character of this APB.The TEM foils were prepared from a 7.5v% TiB2 particle reinforced Ti-45at% Al alloy, initially produced by Martin Marietta Laboratories through XD™ processing followed by casting. Thin sections were sliced from the block alloy and 3mm discs were cut from the thin sections.
Approaches for TEM imaging of cavitation in toughened nylon
Authors: Wood Barbara A. 
Published: June 2020

A controversial topic in the study of structure-property relationships of toughened polymer systems is the internal cavitation of toughener particles resulting from damage on impact or tensile deformation.Detailed observations of the influence of morphological characteristics such as particle size distribution on deformation mechanisms such as shear yield and cavitation could provide valuable guidance for selection of processing conditions, but TEM observation of damaged zones presents some experimental difficulties.Previously published TEM images of impact fractured toughened nylon show holes but contrast between matrix and toughener is lacking; other systems investigated have clearly shown cavitated impact modifier particles. In rubber toughened nylon, the physical characteristics of cavitated material differ from undamaged material to the extent that sectioning of heavily damaged regions by cryoultramicrotomy with a diamond knife results in sections of greater than optimum thickness (Figure 1). The detailed morphology is obscured despite selective staining of the rubber phase using the ruthenium trichloride route to ruthenium tetroxide.
Morphology study of polyvinyl acetate latex by etching with PTA
Authors: Shaffer O.L. , Dimonie V. , El-Aasser M.S. , Vanderhoff J.W. 
Published: June 2020

Transmission electron microscopy has been used extensively for studying the morphology of latex particles. Special techniques have been developed such as preferential staining with osmium tetroxide (OsO4), ruthenium tetroxide (RuO4), freeze fracturing, microtoming and negative staining with phosphotungstic acid (PTA). The purpose of this study is to develop a new technique using PTA as an etching agent for poly(vinyl acetate)(PVAc) latex.Several latexes were prepared by both batch and semicontinuous emulsion polymerization with poly(vinyl alcohol)(PVA) as a stabilizer. Three types of PVA were used, high molecular weight Elvanol 52-40(DuPont) and Vinol 540(Air Products), and low molecular weight Vinol 205(Air Products). All the alcohols were partially hydrolyzed. A PVAc soap free(no PVA) latex was also prepared. To etch the particles one drop of latex was diluted in approximately one ml of 2% aqueous PTA. The volume of latex used depended upon the solids content of the latex and the size of the particles. The PTA latex dispersions were sampled at several intervals.
Two-stage self-seeding method for preparation of single crystals of poly(phenylene sulfide)
Authors: Chung Sengshiu , Cebe Peggy 
Published: June 2020

We are studying the crystallization and annealing behavior of high performance polymers, like poly(p-pheny1ene sulfide) PPS, and poly-(etheretherketone), PEEK. Our purpose is to determine whether PPS, which is similar in many ways to PEEK, undergoes reorganization during annealing. In an effort to address the issue of reorganization, we are studying solution grown single crystals of PPS as model materials.Observation of solution grown PPS crystals has been reported. Even from dilute solution, embrionic spherulites and aggregates were formed. We observe that these morphologies result when solutions containing uncrystallized polymer are cooled. To obtain samples of uniform single crystals, we have used two-stage self seeding and solution replacement techniques.
Computer-aided parallel EELS techniques: acquisition, processing, & imaging
Authors: Hunt John A. 
Published: June 2020

The recent commercial introduction of the parallel detection electron energy-loss spectrometer has undoubtedly made electron energy-loss spectroscopy (EELS) more viable as a technique for routine microanalysis. Additionally, the increased recording efficiency of parallel EELS (PEELS) warrants the use of more involved acquisition and processing techniques than was necessary, or even possible with serial EELS. This increased complexity places greater demands on the computer systems controlling data acquisition. Multichannel analyzers systems with small resources and limited programming facilities are not capable of exploiting the full capabilities of the PEELS spectrometer.Preliminary efforts of the author with the Gatan PEELS spectrometer were concentrated on development of a flexible acquisition system at National Institutes of Health. Hardware control is performed through machine-language drivers called from high-level languages (HLL) such as FORTRAN and C. The software drivers and hardware were designed to minimize processor involvement in the data collection process, resulting in the capability to collect data while processing continues within the parent HLL. This design simplifies the HLL program structure and minimizes data collection dead time.
Electron spectroscopic imaging of thick crystalline specimens
Authors: Reimer L. , Rennekamp R. , Bakenfelder A. 
Published: June 2020

Electron spectroscopic imaging (ESI) by an energy-filtering electron microscope (EFEM, Zeiss EM902) shows the following advantages when compared with the unfiltered bright-field mode:1.The zero-loss image does not contain the contribution of inelastically scattered electrons. Though plasmon scattering shows a conversation of Bragg contrast - edge and bent contours and lattice defect images -, the angular distribution of inelastically scattered electrons results in a broader spectrum of excitation errors and a blurring of Bragg contrast.2.The zero-loss image avoids the chromatic aberration of inelastically scattered electrons for medium specimen thicknesses and can be applied so long as the intensity of the zero-loss peak in the electron energy-loss spectrum (EELS) is high enough for an exposure in a reasonable time (<100 s).3.Thick specimens with negligible zero-loss intensity can be imaged with an energy window at the highest multiple plasmon loss of the Poisson distribution or at the most probable energy of a Landau distribution. The angular distribution of electrons with these energy losses is so broad that the Bragg contrast is blurred, and the contrast is only caused by anomalous absorption effects similar to multi-beam images in the STEM mode when using a large probe aperture.