bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low-Tc phase formation at the grain boundaries and electromagnetic granularity in (Bi,Pb)2Sr2Ca2Cu3Ox silver-sheathed tapes
Authors: Feng Yi , Umezawa A. , Edelman H. S. , Larbalestier D. C. 
Published: June 2020

High resolution transmission electron microscopy (HRTEM) was performed on progressively heat treated Ag-clad (Bi,Pb)2Sr2Ca2Cu3Ox (2223) tapes and was correlated with their transport critical current densities, DC magnetization and AC susceptibility. HRTEM reveals the presence of a small number of half layers of the low Tc Bi2Sr2CaCu2Ox (2212) phase clustered at the numerous (001) twist grain boundaries. This residual 2212 phase produces electromagnetic granularity in a temperature range around 77K and thus directly controls the critical current.The Bi(Pb)-Sr-Ca-Cu-0 (BSCCO) Ag-clad tapes with the stoichiometric 2:2:2:3 starting composition were prepared by a standard powder-in-tube method. Sample A was heat treated at 817°C for 5 hours only. Sample B was first heat treated at 817°C for 24 hours, and then heat treated for 100 hours at the same temperature after two intermediate pressings. Sample C was heat treated at 830°C for 72 hours, and then heat treated for additional 196 hours after one intermediate pressing.
The effect of time and temperature on the segregation of foreign ions to grain boundaries in growing α-Al2O3 scales
Authors: Pint B. A. , Garratt-Reed A. J. , Hobbs L. W. 
Published: June 2020

The addition of small quantities of certain oxygen-active or “reactive” elements (REs) such as Y, Zr, Hf and Ce produces a tremendous improvement in the oxidation behavior of both chromia and alumina-forming alloys. However, few of the hypotheses that have been put forth to explain this phenomenon have been confirmed by careful characterization of the oxidation process.The segregation theory emphasizes the role of RE segregation to oxide grain boundaries and has been successful in correlating the presence of Y and Zr segregants to changes in the oxidation mechanism (thus reducing the oxidation rate) of chromia and alumina scales. Improvements in oxide adhesion have been attributed to the segregation of REs to the metal-alumina interface on doped β-NiAl and FeCrAl alloys. All of these studies employed FEG-STEM equipped with XEDS in order to detect the interfacial segregation.The RE is also found in the scale as RE-rich particles which have been observed after high temperature oxidation using XEDS on SEM and FEG-STEM and detected using glancing-angle (0.5° incident angle) x ray diffraction.
New titanium oxide precipitates in Ti-doped sapphire
Authors: Xiao S. Q. , Phillips D. A. , Heuer A. H. 
Published: June 2020

When Ti-doped α-Al2O3 single crystals are annealed at 1400°C, needle-like rutile TiO2 precipitates form on the basal plane of α-Al2O3 and cause the asterism in star sapphire. Tetragonal rutile has a = 0.459 nm and c = 0.296 nm, and has the following orientation relationship with the α-Al2O3 matrix: (100)r // (0001)s and <011>r // <100>s, where the subscripts r and s refer to the rutile and sapphire, respectively. Moon and Phillips studied the precipitation in natural blue sapphire containing both Fe and Ti. They found that rutile precipitates formed after annealing at 1350°C but an orthorhombic α-TiO2 precipitate formed after annealing at 1150°C. In this study, Ti-doped α-Al2O3 single crystals were annealed at 1300°C. TEM specimens were prepared with their plane normals parallel to <110>s, <100>s and <0001>s, respectively, and ion beam thinned to electron transparency.Three different types of precipitates are present in the α-Al2O3 matrix. The first is the needlelike rutile precipitate lying on (0001)s, with the needle axes parallel to <100>s.
Contrasts of planar defects in reflection electron microscopy
Authors: Tsai Feng , Cowley J. M. 
Published: June 2020

Reflection electron microscopy (REM) has been used to study surface defects such as surface steps, dislocations emerging on crystal surfaces, and surface reconstructions. However, only a few REM studies have been reported about the planar defects emerging on surfaces. The interaction of planar defects with surfaces may be of considerable practical importance but so far there seems to be only one relatively simple theoretical treatment of the REM contrast and very little experimental evidence to support its predications. Recently, intersections of both 90° and 180° ferroelectric domain boundaries with BaTiO3 crystal surfaces have been investigated by Tsai and Cowley with REM.The REM observations of several planar defects, such as stacking faults and domain boundaries have been continued by the present authors. All REM observations are performed on a JEM-2000FX transmission electron microscope. The sample preparations may be seen somewhere else. In REM, the incident electron beam strikes the surface of a crystal with a small glancing angle.
Reflection electron microscopy of as-grown diamond surfaces
Authors: Wang Z.L. , Bentley J. , Clausing R.E. , Heatherly L. , Horton L.L. 
Published: June 2020

It has been found that the abrasion of diamond-on-diamond depends on the crystal orientation. For a {100} face, the friction coefficient for sliding along <011> is much higher than that along <001>. For a {111} face, the abrasion along <11> is different from that in the reverse direction <>. To interpret these effects, a microcleavage mechanism was proposed in which the {100} and {111} surfaces were assumed to be composed of square-based pyramids and trigonal protrusions, respectively. Reflection electron microscopy (REM) has been applied to image the microstructures of these diamond surfaces.{111} surfaces of synthetic diamond:The synthetic diamonds used in this study were obtained from the De Beers Company. They are in the as-grown condition with grain sizes of 0.5-1 mm without chemical treatment or mechanical polishing. By selecting a strong reflected beam in the reflection high-energy electron diffraction (RHEED) pattern, the dark-field REM image of the surface is formed (Fig. 1).
Microstructure and magnetic Structure of Co-based thin-film recording medium
Authors: Futamoto M. , Honda Y. , Inaba N. , Matsuda Y. , Suzuki M. 
Published: June 2020

Knowledge of the relationship between microstructure and microscopic magnetization configuration is strongly required to improve Co-based thin film media. The purpose of this paper is to report some of these properties measured for a thin film longitudinal recording medium and to discuss their inter-relationship.Figure 1 shows an SEM micrograph of fractured cross-section of CoCrPt/CoCrPtSi dual-layered medium which was used to demonstrate the feasibility of 2 Gb/in2 magnetic recording. The Cr underlayer is used to control the orientation, size, and distribution of magnetic crystals. Magnetic crystal grains, whose size ranges between 20-30nm, form chain-like clusters consisting of several crystals as shown in the plan-view TEM micrograph(Fig.2). Neighboring clusters are separated physically with an average distance of 3nm. Magnetic separation among magnetic crystals and/or clusters is important to reduce the medium noise which is related to magnetic coupling between crystals. The crystalline easy axes of the grains are randomly oriented in the film plane.
Magnetic domain wall movement in iron silicon
Authors: Wittig J.E. 
Published: June 2020

Lorentz microscopy in the transmission electron microscope directly images magnetic domains. By changing the magnetic field of the electromagnetic lenses relative to the specimen plane, the movement of the magnetic domain walls and their interaction with microstructural features can be observed in situ. This type of experiment has successfully analyzed the microstructure-domain wall interactions in spinel ferrites and iron-rare-earth-boron magnetic materials. The domain wall motion reveals the qualitative pinning potential of grain boundaries, precipitates, inclusions, stacking faults, and cracks. In addition, these in situ experiments display the dynamics of magnetic domain nucleation. The current study investigates the magnetic domain wall movement in iron silicon alloys. Since magnetic properties such as intrinsic coercivity and permeability are structure sensitive, the influence of microstructure on domain wall movement dictates the soft magnetic behavior.Thin foils of iron-6.5 wt% silicon were prepared by electropolishing ribbons produced by melt spinning techniques. The magnetic domain walls were imaged in the defocused (Fresnel) mode with a Philips CM20T operated at 200 kV.
Real-time observation of vortex lattices in a superconductor
Authors: Harada K. , Matsuda T. , Bonevich J.E. , Igarashi M. , Kondo S. , Kasai H. , Yoshida T. , Pozzi G. , Kawabe U. , Tonomura A. 
Published: June 2020

Previous observations of magnetic flux-lines (vortex lattices) in superconductors, such as the field distribution of a flux-line, and flux-line dynamics activated by heat and current, have employed the high spatial resolution and magnetic sensitivity of electron holography. And recently, the 2-D static distribution of vortices was also observed by this technique. However, real-time observations of the vortex lattice, in spite of scientific and technological interest, have not been possible due to experimental difficulties. Here, we report the real-time observation of vortex lattices in a thin superconductor, by means of Lorentz microscopy using a 300 kV field emission electron microscope. This technique allows us to observe the dynamic motion of individual vortices and record the events on a VTR system.The experimental arrangement is shown in Fig. 1. A Nb thin film for transmission observation was prepared by chemical etching. The grain size of the film was increased by annealing, and single crystals were observed with a thickness of 50∼90 nm.
Exploratory work on coherent diffraction and electron holography using a hitachi Hf 2000
Authors: Steeds J W , Vincent R , Spellward P , Deng X F 
Published: June 2020

Now that coherent electron diffraction can be performed routinely on appropriately chosen specimens in a standard commercial instrument there are a number of applications of the technique which are in progress.One of these is in crystal structure determination. For sufficiently thin crystals, the fringes in the overlap between adjoining reflections n and n+1 give the relative phases (ϕn + 1 - ϕn+δ) of their complex structure factors, apart from an unknown phase factor, δ, which depends on the probe position. In a systematic row of reflections, the next overlap between reflections n + 1 and n + 2 gives (ϕn + 2 - ϕn + 1+δ) and so the difference between these two phasings becomes (2ϕn + 1 - ϕn - ϕn + 2), eliminating the unknown factor δ. Now that coherent diffraction has been achieved in the zero order Laue zone of a zone axis pattern it is possible to phase the whole two dimensional mesh relative to the central beam (Figure 1).
High-resolution coherent imaging in STEM
Authors: Cowley J.M. , Gribelyuk M.A. 
Published: June 2020

The ultimate aim of high resolution electron microscopy is the accurate determination of the positions and types of the atoms in a specimen. The coherent imaging theory for STEM is reviewed with the emphasis on its potential for achieving this aim by holographic methods. The STEM modes of holography are in many respects equivalent to the corresponding TEM modes, but have the advantage that, because with a FEG electron source the focussed probes have sub-nanometer diameter, a strong signal is obtained from the illuminated region and the problem of shot-noise is much less important.The original proposal for holography by Gabor envisaged the use of a reconstruction process on the recorded hologram to correct for the lens aberrations and hence improve the image resolution. The more general and more challenging problem is to reconstruct the aberration-free wave function at the exit face of the specimen (with its real and imaginary, or amplitude and phase, components) and then to invert the dynamical diffraction process and derive the projected potential distribution of the object.
Electron holography of interfaces in electroceramics
Authors: Dravid Vinayak P. , Ravikumar V. , Plass Richard 
Published: June 2020

With the advent of coherent electron sources with cold field emission guns (cFEGs), it has become possible to utilize the coherent interference phenomenon and perform “practical” electron holography. Historically, holography was envisioned to extent the resolution limit by compensating coherent aberrations. Indeed such work has been done with reasonable success in a few laboratories around the world. However, it is the ability of electron holography to map electrical and magnetic fields which has caught considerable attention of materials science community.There has been considerable theoretical work on formation of space charge on surfaces and internal interfaces. In particular, formation and nature of space charge have important implications for the performance of numerous electroceramics which derive their useful properties from electrically active grain boundaries. Bonnell and coworkers, in their elegant STM experiments provided the direct evidence for GB space charge and its sign, while Chiang et al. used the indirect but powerful technique of x-ray microchemical profiling across GBs to infer the nature of space charge.
HRTEM study of heavy ion irradiation damage in Ca2La8(SiO4)6O2
Authors: Wang L.M. , Weber W.J. 
Published: June 2020

Radiation effects in complex ceramic materials, including the crystalline phases with the apatite structure are of interest to the materials science, geoscience and biomedical communities. It has been shown by in situ TEM experiments that these materials can easily be rendered amorphous under heavy ion irradiations. Detailed study at atomic level using HRTEM on this crystalline to aperiodic transition is necessary for the fundamental understanding of the process. The results reported below are from a systematic HRTEM study on 1.5 MeV Kr ion irradiated synthetic Ca2La8(SiO4)6O2.The TEM samples were prepared from (0001) thin foils by Ar ion-milling which was finished at 3.5 kV and 13°. As shown in fig. 1, the width of the amorphous rim at the sample edge after ion milling is less than 2 nanometers. The pre-thinned TEM samples were irradiated at room temperature with 1.5 MeV Kr ions in the HVEM-Tandem Facility at Argonne National Laboratory.
Elemental analysis of single atmospheric particles influencing visibility at the grand canyon
Authors: Turpin Barbara J. , Huang Po-Fu , Roos Amy , McMurry Peter H. 
Published: June 2020

Collection and preservation strategies and a routine analysis procedure were developed for elemental analysis of individual atmospheric particles using a scanning-transmission electron microscope (STEM) equipped with a super ultra-thin window energy dispersive x-ray detector. These techniques were applied to airborne particles collected at Meadview, AZ, a remote site just downriver of the Grand Canyon. Collection, preservation and beam damage issues of concern in electron microscopic analysis of atmospheric particles will be discussed. Aerosol compositions are usually determined from bulk particle measurements, and it is assumed that compounds are either internally mixed (all present in each particle) or externally mixed (particles each contain a single compound). Insight into the microscopic mixing characteristics of atmospheric aerosols will ultimately further the understanding of atmospheric particle transformation, visibility degradation, and the fate of airborne pollutants.Particles were collected in the summer of 1992 in three size fractions (1.0-0.5 μm, 0.5-0.26 μm, 0.26-0.12 μm in diameter) using a Hering Low Pressure Impactor and a 250 Å thick silver film substrate supported by a silver TEM grid.
Microstructure of fly ash containing concrete, with emphasis on the aggregate-paste boundary
Authors: Gillott Marcelle A. , Naik Tarun R. , Singh Shiw S. 
Published: June 2020

Concrete is a highly heterogeneous structural material that is subjected to complex stresses. It has been well established that concrete is weakest in the interfacial region between coarse aggregates and the hydrated cement paste. Although there have been several studies on the microstructure of fly ash containing cement pastes, relatively less is known about the effect of fly ash on the aggregate-paste boundary in concrete.Air entrained plain portland cement concrete mixtures were prepared to produce a design strength of 6000 psi at the 28-day age. The air and H2O-cementitious ratios were held approximately constant for both the control and fly ash containing preparations. ASTM Class C fly ash replaced 15% to 70% of the cement in various samples. Measurement of mechanical properties indicated compressive strength increased for concrete with up to 30% fly ash; only slight differences in tensile strength were observed among the control, 15% and 30% fly ash replacements.
Electron microprobe and electron diffraction study of a new ferric iron sanidine from the leucite hills, wyoming
Authors: Kuehner S.M. , Joswiak D.J. 
Published: June 2020

The group of minerals classified as feldspars are among the most common rock-forming minerals in the earth’s crust. The majority of feldspar compositions fall within the ternary system NaAlSi3O8-KAlSi3O8-CaAl2Si2O8, though substitution of other elements, usually in minor amounts, is common. Described here is a naturally occurring ferric iron sanidine feldspar composition in which up to ∼70 mole% of the KAlSi3O8 molecule is replaced by KFe3+	Si3O8. It thus constitutes a new end-member feldspar composition and the data have been submitted to the Commission on New Mineral Names for evaluation.The ferric iron sanidine is found in the 1.1ma volcanic rocks of the Leucite Hills, Wyo. The composition of these lavas and plugs is unusually rich in K and Fe3+, and depleted in Al compared to typical basaltic rocks. Sanidine grains are among the last phase to crystallize in the groundmass of the rocks classified as orendites, and rarely exceed 150um in length.
Comments on the use of the relativistic schrödinger equation in high-electron diffraction
Authors: Op de Beeck Marc 
Published: June 2020

1.IntroductionIn high energy electron diffraction the electrons are accelerated to a velocity which becomes comparable to the velocity of light. It is therefore obvious that in principle the Relativistic Dirac Equation (RDE) should be used to describe the diffraction process. However, in 1961, Fujiwara published his famous paper in which he derived that the transition probabilities calculated with the RDE agreed, up to a very good approximation, with these of the Schrödinger equation, provided the relativistic corrections to the values for the electron mass and wavelength are taken into account. As this Relativistic Schrödinger Equation (RSE) is much easier to handle, it became the fundament of all theoretical developments in electron microscopy and of all commercially available simulation packages. It is our believe however that the results of Fujiwara have been misinterpreted. The correct interpretation will lead to a correction of more than 15% on the kinetic energy of the electron.
Scanning tunneling microscope images of doped polypyrrole on ITO glass
Authors: Bilger R. , Cantow H.-J. , Heinze J. , Magonov S. 
Published: June 2020

Scanning tunneling microscopy (STM) becomes an excellent tool for surface structure studies in the case of conductive and semiconductive materials. The STM has advantage of extending the range of SEM and TEM studies to topography measurements in the angstrom scale. This method also does not require special sample preparations and can be used in air. The polymers with electronic conductivity are among compounds to be studied by STM. Recently the STM images of doped polypyrrole were obtained for polymer molecules deposited on graphite. The authors claimed the observation of single polypyrrole chains with helical structure and diameter approximately 1.2 nm. We had tried the electrochemical deposition of conductive polymers on ITO for preparing structured polypyrrole layers on a smooth conductive glass surface. These samples were studied by STM.The STM images of the surface of polypyrrole samples were obtained in air with the Nanoscope II).
Imaging polymers, proteins and dna in aqueous solutions with the atomic force microscope
Authors: Gould S.A.C. , Drake B. , Prater C.B. , Weisenhorn A.L. , Lindsay S.M. , Hansma P.K. 
Published: June 2020

The atomic force microscope (AFM) is an instrument that can be used to image many samples of interest in biology and medicine. Images of polymerized amino acids, polyalanine and polyphenylalanine demonstrate the potential of the AFM for revealing the structure of molecules. Images of the protein fibrinogen which agree with TEM images demonstrate that the AFM can provide topographical data on larger molecules. Finally, images of DNA suggest the AFM may soon provide an easier and faster technique for DNA sequencing.The AFM consists of a microfabricated SiO2 triangular shaped cantilever with a diamond tip affixed at the elbow to act as a probe. The sample is mounted on a electronically driven piezoelectric crystal. It is then placed in contact with the tip and scanned. The topography of the surface causes minute deflections in the 100 μm long cantilever which are detected using an optical lever.
Scanning tunneling microscopy of the enzymes of muscle glycogenolysis
Authors: Edstrom R. D. , Meinke Marilyn H. , Yang R. , Yang X. , Evans D. F. 
Published: June 2020

In skeletal muscle, glycogen metabolism occurs in particulate complexes consisting of glycogen and the enzymes responsible for its synthesis and degradation and the enzymes and other factors which regulate those processes. Glycogenolysis is the result of phosphorylase a acting on glycogen to form glucose 1-phosphate which is then metabolized for energy production. The activity of phosphorylase is regulated by a network of kinases and phosphatases which respond to hormonal and neuronal stimuli. The enzymes phosphorylase and phosphorylase kinase have been examined by scanning tunneling microscopy.Phosphorylase b and phosphorylase kinase were prepared from rabbit muscle and dialyzed vs. pH 7.0, 10 mM imidazole buffer containing 100 μM CaC12and 100 μM MgCl2. The final concentration of each protein solution was adjusted to 1 mg/ml and two 0.5 μl portions were applied to the atomically flat graphite surface and the solutions dried under a stream of filtered nitrogen for a few moments.
A five-axis computer-controlled stage for the Transmission Electron Microscope
Authors: Mackenzie J. M. , Bergensten R. W. 
Published: June 2020

A new five axis computer controlled stage system for the transmission electron microscope has been developed. The current design uses the existing stage of a Philips 400T without internal modification. The motors are all synchronous and employ feedback control from shaft encoders rather than “steps”.The X and Y translation controls have an increment of 15 nm and are engaged by electronic clutches. The alpha tilt control can be incremented in 0.0625 degree units which allows 16 “steps” per degree. The beta tilt has an increment of 0.0017 degrees (approximately 500 counts per degree). The Z axis control has a 3 nm increment and can be controlled by a set of manual override switches. The position of the stage is monitored by shaft encoders in such a way that manual positioning does not effect motorized repositioning.All five axes are calibrated for speed to determine the log/linear range of movement (Figs. 1-4). From the graphs, three speeds are chosen.