bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-resolution imaging of Σ=5 tilt boundaries in gold
Authors: Cosandey F. , Chan S.-W. , Stadelmann P. 
Published: June 2020

Until recently most of the information concerning the atomic structure of grain boundaries in metals has been obtained using molecular static and molecular dynamic computational techniques. With the recent developments of intermediate voltage microscope (300-400KV) this situation has changed and grain boundary atomic resolution is now possible for most metals. The purpose of this research is to examine the atomic structure of Σ=5 tilt boundaries in Au by high resolution microscopy and to compare the results to computational models.Thin film Au bicrystals containing Σ=5 (θ=36.5°±0.5) tilt grain boundaries were produced by epitaxial growth on NaCl bicrystalline substrates using a technique described in detail elsewhere. All high resolution images were obtained with a Philips 430 ST microscope using axial illumination and without objective aperture. All image simulations were obtained using the multislice formalism with EMS programs. All four {200} reflections from each crystal were used for the simulations with the following instrumental parameters; accelerating voltage V=300KV, spherical aberration constant Cs=1.1mm, defocus spread Δ=8nm and semi-angle beam divergence α=8mrad.
Clustering of coincident site lattice boundaries in polycrystals
Authors: fendle Valerie , Ralph Brian 
Published: June 2020

The distribution of coincident site lattice (CSL) and other geometrically special boundaries have been analysed in the form of “grain misorientation texture” (GMT) plots for several systems (pure nickel, a number of austenitic stainless steels and a complex superalloy, 1-5). Several heat treatment conditions have been investigated for each system. Principally, electron back scattering (EBS) in a scanning electron microscope has been used to collect the “microtexture” (i.e. grain specific) data which combines the considerable advantages of bulk specimen texture analysis, grain environment specification with semi-automatic operation. These data are currently being supplemented with thin foil transmission electron microscope (TEM) analyses which permit more detailed investigation of the grain boundary parameters (especially grain boundary planes).Conventional texture measurement shave akey role in assessing the overall changes which occur during thermomechanical processing. However, the very detailed orientation measurements give only a statistical picture and this means that neither the geometry of individual boundaries (the GMT) nor ary tendency for clustering of particular texture types or boundary types may be detected.
New imaging modes in STEM
Authors: Jones A.V. 
Published: June 2020

The most often quoted advantage of STEM over conventional TEM is the ability to produce multiple simultaneous images by the use of multiple detector systems. In practice, this postulated advantage has seldom been fully utilised, mainly because of the practical difficulties in designing such detector systems.Most STEMs to date have been constructed as two-channel instruments combining annular dark-field imaging with either filtered bright-freld or inelastic imaging. More complex forms of bright-field detector have been employed1, as have parallel-readout systems for energy-loss spectra but the ability of the spectrometer to produce multiple simultaneous images has not been fully utilised.The basis of the problem lies in the fact that the objective lens and the detector system(s) have in most cases been designed by the manufacturers as separate entities in order to simplify the later addition of user-specific detectors. Since the acceptance angle of even the best spectrometers is relatively small, additional post-specimen lenses [with their attendant aberrations] had to be added in order to make full use of the spectrometer.
Instrumentation for a corrected STEM
Authors: Crewe Albert V. 
Published: June 2020

In accepting an invitation to speak in this symposium all the speakers today are exposing themselves to great hazards, and none more so than me. The capabilities of computers, their variety, the associated instrumentation, are all expanding so rapidly and changes are taking place with such a frequency that we are all inevitably out of date. The mere fact of having to prepare an abstract in March for a meeting in August presents hazards. Who knows what revolution in the state of the art will be announced in the meantime?My own project was started four or five years ago so that we may be considerably behind the times. As time went along we were able to take advantage of some of the new developments in technology but in many cases we were simply too far along to make adjustments. As a result, if one were to ask whether our project should serve as a model or whether we would do it the same way again, the answer would have to be “no.” On the other hand, some of the features are good and may serve as examples for future projects. The reader will have to decide.
EELS parallel detection using 2-dimensional CCD array
Authors: Zaluzec N.J. , Strauss M. G. 
Published: June 2020

Conventional parallel detectors for Electron Energy Loss Spectroscopy (EELS) have been mainly based upon systems using linear photodiode arrays in a conjugate image plane of an electron spectrometer. We have developed a unique two dimensional charge coupled device (CCD) camera system which can be used as a detector for EEL spectroscopy and imaging, utilizing high sensitivity, high resolution CCD's, which are typically used in medial or astronomic imaging.The present detector system is based upon a Tektronics TK512M 512 x 512 pixel CCD array, (figure 1) which is optically coupled to a YAG:Ce single crystal scintillator. This CCD imaging system views an electron energy loss spectrum which is magnified by a quadrupole doublet lens attached to a Gatan 607 electron spectrometer on a Philips EM420 TEM as is illustrated in figure 2. The CCD controller, detector head electronics and electron optics were developed at Argonne specifically for high speed data acquisition and allow the recording of complete spectra in as short a time as 10 μsec or approximately 103times faster than the typical 1024 pixel photodiode arrays’ thus allowing the potential for time resolved spectroscopy.
Recent developments in EDS for TEM/STEM
Authors: McCarthy J.J. 
Published: June 2020

The development of TEM and STEM in the 100 keV to 400 keV range has prompted the increased use of energy dispersive spectrometers (EDS) for analytical studies on these instruments. The TEM/STEM environment is a harsh one for the EDS in comparison to the SEM. In response to this special environment, spectrometers specifically for TEM/STEM have been developed. This paper will provide a general review of these developments and indicate future directions.Space near the specimen holder is at a premium in most TEMs. This reduces the solid angle subtended by the Si(Li) detector. Increased cooperation between EM and EDS manufacturers, and the use of new materials for shielding, collimation, and internal detector parts have improved this situation. The use of graded material collimators, removable ultra thin windows (UTW), and compact gate valve arrangements can reduce detector size. The routine use of computer aided design (CAD) systems and computer controlled machining allow extremely close tolerances to be incorporated in the latest designs.
Characterization of double contours and twin images in REM
Authors: Yao N. , Cowley J. M. 
Published: June 2020

The REM technique may be used to reveal detail on the surfaces of large crystals. The single-atom-height steps on certain single crystal surfaces can be seen with high contrast. The observations of double contours of atomic steps on single crystal surfaces have been reported recently. The doubling has been interpreted as Fresnel diffraction contrast or as effects caused by the distortion field around the surface steps. However, due to the foreshortening and other effects, the resolution in the observation direction is limited and details of the surface structure can be obscured by imaging and diffraction artefacts.The InP(110) surface was obtained by cleavage of a (100) wafer in air. In order to reduce the contamination effects, a nitrogen cooling holder was employed during the observation. The Pt (111) surface was prepared and observed under the conditions described by Hsu and Cowley.
HREM studies on interfaces in internally oxidized alloys
Authors: Mader W. 
Published: June 2020

Precipitation of metal oxides by internal oxidation of metal alloys has been widely used for dispersion strengthening of materials in electrical contact applications. Like in other precipitate systems, the oxide precipitates have the freedom to form with any shape and relative orientation with respect to the metal matrix. It is expected that natural, low energy interfaces which are perfectly flat at an atomic scale can be produced by this technique. For these reasons, such interfaces are ideal objects for HREM studies. Interfaces between Nb and Al2O3 and between Ag and CdO, produced using internal oxidation were investigated by HREM techniques in order to extract structural and chemical information at the atomic level.Specimens of Nb containing 3.5 at% A1 were oxidized at 1500°C in a controlled atmosphere with a low oxygen pressure in order to avoid external oxidation. Small plate-like Al2O3 precipitates 15-30 nm thick and 200-800 nm wide were observed.
Fractographic study of an Al2O3/Al composite
Authors: Flinn B. D. 
Published: June 2020

Ceramics have limited engineering applications due mainly to inherent brittleness and catastrophic failure. However the fracture toughness of ceramics has been increased significantly by incorporating ductile second phases into the ceramic matrix. The exact toughening mechanism(s) have not been clearly determined, although several likely models have been proposed. In particular, the ductile phase is thought to contribute to the toughness of the composite if intact particles remain in the crack wake. The intact particles deform plastically and exert tractions on the crack surfaces which inhibit crack opening and hence increase toughness. In order to further enhance understanding of ductile dispersion toughened ceramics, the fracture behavior of an innovative composite composed of co-continuous Al2O3 and A1 (20 vol. %) phases is described.The fracture behavior was investigated by examining indentation induced cracks and mode I fracture surfaces with a JEOL 840A SEM.
The coprecipitation of Cr3P and Cr in Cu
Authors: Witcomb M.J. , Dahmen U. , Westmacott K.H. 
Published: June 2020

Cu-Cr age-hardening alloys are of interest as a model system for the investigation of fcc/bcc interface structures. Several past studies have investigated the morphology and interface structure of Cr precipitates in a Cu matrix (1-3) and good success has been achieved in understanding the crystallography and strain contrast of small needle-shaped precipitates. The present study investigates the effect of small amounts of phosphorous on the precipitation behavior of Cu-Cr alloys.The same Cu-0.3% Cr alloy as was used in earlier work was rolled to a thickness of 150 μm, solution treated in vacuum at 1050°C for 1h followed by quenching and annealing for various times at 820 and 863°C.Two laths and their corresponding diffraction patterns in an alloy aged 2h at 820°C are shown in correct relative orientation in Fig. 1. To within the limit of accuracy of the diffraction patterns the orientation relationship was that of Kurdjumov-Sachs (KS), i.e. parallel close-packed planes and directions.
Identification of Cr and Cr2Nb precipitates in as-melt-spun Cu-Cr-Nb ribbons
Authors: Ellis D. L. , Michal G. M. 
Published: June 2020

A material with high thermal conductivity and mechanical strength at elevated temperatures is required for certain aerospace applications. Copper based alloys precipitation hardened with near zero solubility phases are candidate materials. Utilizing rapid solidification technology, elements such as Cr and Nb can be dissolved into liquid copper and fully precipitated out in the solid state. However, such elemental precipitates readily coarsen at elevated temperatures. The aim of this work was to create a more stable refractory metal intermetallic phase, C2Nb, in an essentially pure copper matrix via melt spinning.Ribbon was produced by induction melting a master alloy in an alumina crucible with a hole diameter of 1 mm (0.040-inch) using a graphite susceptor under an argon atmosphere. The alloy was heated to 1593°C (2900°F)and ejected onto a Cu wheel with a surface velocity of 20 m/s using a pressure of 0.07 MPa (10 psi). The resulting composition of the ribbon was 1.95 a/o Cr and 0.48 a/o Nb as determined by bulk spectrographic analysis.
Multislice calculations: “Slicing” and those upper Laue layer interactions
Authors: Kilaas Roar 
Published: June 2020

Scattering involving reflections outside the zero'th order Laue zone has generally been ignored in multislice calculation. It can be argued that in most cases the contribution from higher zones are negligible and can safely be ignored, but a more accurate description of the problem of including ULL effects is given by the following two statements:i) the multislice program in question lacks the facility to include ULL layer interactionsii) the calculation takes too long to be practicalGiven the fact that computers are becoming cheaper and faster, ii) will at one point no longer be valid and we are left with i). With few exceptions, multislice programs were not written with ULL interactions in mind. To understand why this is the case, it is necessary to understand why certain scattering angles are included in the calculation and why others are not. As one will see below, the “inclusion” of ULL interactions are directly related to the slice thickness used in multislice calculation and the method of determining a “projected” potential for that slice.
Revealing depth information by processing EBIC images
Authors: Radzimski Z. , Humphreys T. , Russ J. 
Published: June 2020

The conventional use and interpretation of electron beam induced current (EBIC) images in the SEM suffer from several inherent problems. One such problem is the superposition of topographic details, e.g., scratches, dust, contact damage, on the subsurface EBIC signal. Moreover, the use of an accelerating voltage to select depth may not distinguish information from regions close in depth. This exists in depth dependent defect imaging in multi-layer heteroepitaxial structures where two or more defect layers may overlap in the EBIC image.To alleviate these problems, techniques of image processing may be employed. By digitizing and storing several images, for example in the first problem EBIC and secondary electron image and in the second problem EBIC images obtained at different accelerating voltages, it is possible to use image differencing to extract a more selective image that reveals the desired information. In principle, image differencing requires simple subtraction (or division) of the brightness of each pixel in one image from that in the second.
Electron microscopy of superconducting and related oxides
Authors: Morrissey K. J. , Subramanian M. A. , Torardi C. C. , McCarron E. M. , Calabrese J. C. , Gopalakrishnan J. , Horowitz H. S. , Michel J. B. , Askew T. R. , Flippen R.B. , Chowdhry U. , Sleight A. W. 
Published: June 2020

It is important to combine characterization techniques such as electron microscopy with novel materials synthesis in the study of high Tc superconducting phases. Results from electron microscopy studies have been correlated with structure determinations made using x-ray and neutron diffraction (1.2,3.4). Superconducting phases studied to date include YBa2Cu3O7-x, La1.25Ba1.75Cu3O7, Bi2Sr2CuO6, Bi2Sr2CaCu2O8, Tl2Ba2CuO6 Tl2Ba2CaCu2O8, and Tl2Ba2Ca2Cu3O8. A comparison between structures and defect populations suggests that structural defects, which modify the Cu-O arrangement (sheets or chains) intergrowths and grain boundaries, will affect superconductivity. Techniques used in this investigation include HREM, CBED, AEM, SAD and conventional imaging techniques.Samples characterized in this study were prepared in our laboratory, using both conventional and novel synthesis routes. Powder samples in the Tl-Ba-Cu-O system were prepared by heating mixtures of high purity BaO2, Tl2O2 and CuO to 850-900°C in sealed gold tubes for 1-6 hours (3,4). Similar procedures were followed in the Bi2Sr2CaCu2O8 system using Bi2O3, CaCO3, SrO2/Sr(NO3)2 and CuO. heating the mixtures in air at 700-900°C for 12-36 hours (2.4).
High resolution electron microscopy of bismuth and thallium superconductors
Authors: Zhang J. P. , Li D. J. , Shibahara H. , Marks L. D. 
Published: June 2020

A new frontier has opened up in the field of superconductivity with the very recent discovery of compounds of bismuth and thallium which appear to superconduct above 100 K. Both of these compounds appear to be perovskite derivatives with intergrowth of the basic perovskite with bismuth double-layers and perhaps thallium double layers. The structure of these compounds, however, is not as yet completely established, particularly the thallium material which to date has only been produced in very small quantities due to the toxic nature of thallium.We have very recently been studying both the bismuth and thallium superconductors by high resolution electron microscopy. The bismuth material appears to be an intergrowth of a five layer perovskite with a buckling of the structure along the b axis (see Figure 1) which preliminary image simulations suggest is in the form of a shear wave of amplitude in the region of 0.25 Angstroms.
Microstructure of the superconducting phase (85K) in the Bi-Sr-Ca-Cu-O System
Authors: Sung C. M. , Harmer M. P. , Smyth D. M. , Williams D. B. 
Published: June 2020

The discovery of high temperature superconductivity by Bednorz and Muller in a cuprate-based system generated an extensive search for new superconducting oxide phases. Superconductivity at 90K was observed by Wu et al. in the Y-Ba-Cu-O system and this temperature, until recently, had not been exceeded reproducibly. Superconductivity at 20K was reported in another cuprate system containing bismuth instead of yttrium, and recently superconductivity at 85K and 110K was reported by Maeda et al. in a Bi-Sr-Ca-Cu-O system. A Bi2Sr2CaCu2O8.2 phase has been found to be the origin of the 85K superconducting transition, and its crystal structure was determined by x-ray diffraction. In this paper, we comment on the microstructure and chemistry of the new superconducting phase using selected-area electron diffraction (SAED), convergent beam electron diffraction (CBED), and x-ray energy dispersive spectroscopy (EDS) experiments.The superconducting Bi2Sr2CaCu2O8+x samples investigated were synthesized in air by standard solid-state reaction techniques from appropriate amounts of Bi2O3, CuO, SrCO3, and CaCO3.
Spectraplot: A PC-based spectrum translation and display program
Authors: Colijn H. O. 
Published: June 2020

Many labs today wish to transfer data between their EDS systems and their existing PCs and minicomputers. Our lab has implemented SpectraPlot, a low- cost PC-based system to allow offline examination and plotting of spectra. We adopted this system in order to make more efficient use of our microscopes and EDS consoles, to provide hardcopy output for an older EDS system, and to allow students to access their data after leaving the university.As shown in Fig. 1, we have three EDS systems (one of which is located in another building) which can store data on 8 inch RT-11 floppy disks. We transfer data from these systems to a DEC MINC computer using “SneakerNet”, which consists of putting on a pair of sneakers and running down the hall. We then use the Hermit file transfer program to download the data files with error checking from the MINC to the PC.
Microstructure of a Y2Ba2Cu3O7-Σ superconductor pellet prepared by shock consolidation
Authors: Antrim R. F. , Marti J. , Iqbal Z. 
Published: June 2020

R&D in high Tc superconductors encompasses two broad areas, namely, 1) synthesis and characterization of high Tc superconducting powders and 2) consolidation of the powders into useful parts. In the latter area, techniques such as thin film deposition, high temperature sintering of the powders and continuous casting are being pursued by various groups. Another technique which could prove useful in the fabrication of larger pieces is that of shock compaction. In this approach, explosives are used to propel a piston, resulting in a shock wave which leads to high pressure- high temperature consolidation of the powder. In this report we examine the microstructure that results when a superconducting powder was consolidated into a pellet using the shock-loading technique.The nominal composition of the starting powder was Y1Ba2Cu3O7δ (“123”). Explosives were used to create a shock-wave with an estimated peak pressure of 60 GPa and temperatures of about 800°C.
Transmission electron microscope characterization of dislocation structure in BiSrCaCu superconducting oxide
Authors: Liang J.M. , Chang L. , Chen Y.C. , Tang S.F. , Chiao Y.S. , Wu P.T. , Chen L.J. 
Published: June 2020

The recently discovered new class of BiSrCaCu superconducting oxide with Tc as high as 120 K has generated a new wave of intense research on the high Tc superconducting systems. in this presentation, we report the results of a transmission electron microscope (TEM) study of dislocation structure in a superconducting BiSrCaCuO compound.The superconducting oxide with nominal composition of Bi2Sr2CaCu2Oy was prepared by quenching or slow cooling the solid-state-reaction sintered specimens which had been calcined from mixed Bi2O3, CaCo3, CuO, and SrCO3 powders. Thin foils for TEM examinations were generally prepared by grinding in a pestle and mortar. A JEOL-2000FX transmission electron microscope operating at 200 keV was used.The quencehed specimens exhibited Tc-onset at 120 K and Tc-zero at 90 K, whereas the slowly cooled specimens showed Tc-onset at 104 K and Tc-zero at 75 K. X-ray diffraction and TEM/EDS data showed that the sintered samples were mainly of a phase with nominal composition Bi2Sr2CaCu2Oy, XRD, SAD and CBED identified that the crystal structure is orthorhombic with a=0.541 nm, b=2.69 nm, and c=3.07 nm.
Field emission SEM with wide operating voltage range
Authors: Norioka S. , Miyokawa T. , Goto S. , Niikura T. , Sakurai S. 
Published: June 2020

A newly developed conical anode field emission electron gun (FE-GUN)has been installed on the JSM-840F Scanning Electron Microscope (SEM). The cross sectional view of the column is shown in Fig. 1. The gun is usable at a wide accelerating voltage range from 0.5 kV to 40 kV, and is suitable for general purpose SEMs. The gun can be used within the virtual source range even at an extract voltage as high as 7 kV and an accelerating voltage as low as 0.5 kV. The extract voltage can be raised up to 7 kV even when the emitter tip radius becomes larger after repeated flashing for smoothing the emitter tip surface. This allows elongation of the emitter life.With the FE-GUN, since the electron source (virtual source) moves with accelerating voltage change, an image may disappear due to the deviation of the electron probe from the optical axis when the accelerating voltage is changed.