bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure and magneto-optic properties of unannealed and annealed Fe/Pt and Co/Pt multilayers
Authors: Visokay Mark R. 
Published: June 2020

Two requirements for magneto-optical storage media are remanent perpendicular magnetization and large magneto-optic Kerr rotations. Several film structures and material systems have been proposed for this purpose, including amorphous rare earth-transition metal alloys, Co/Pt multilayer films and Co/Pt alloys. Another structure that has potential for magneto-optic applications are thin films of ordered alloys based on the Llo structure, with two possible materials systems being Fe/Pt and Co/Pt. Ordered CoPt and FePt both adopt the Llo crystal structure, are ferromagnetic, and are magnetically easy along the unique axis. Thin films oriented such that the c axis is out of the film plane are expected to have large perpendicular anisotropy, and both FePt and CoPt are known to have large Ken-rotations, so both of the requirements mentioned above can be met with these materials.In order to produce the ordered structures oriented with the c axis out of the plane epitaxial multilayers of the two constituents were produced by magnetron sputtering onto epitaxial Pt [001] seed layers deposited onto MgO [001], resulting in multilayers stacked along Pt [001].
High-resolution imaging with the schottky emitter FEG TEM
Authors: Otten Max T. 
Published: June 2020

The Philips CM-series Field Emission TEMs, equipped with the Schottky field emitter and operating at 200 kV (CM20 FEG and the newer CM200 FEG) and 300 kV (CM30 FEG) have a dramatically improved performance in HRTEM imaging relative to their LaB6 equivalents (Table 1). The spatial and temporal coherence of these microscopes far exceeds that of similar microscopes equipped with LaB6 filaments. As a result, the information in the HRTEM images proceeds well beyond the point resolution (the information limit for the 200 kV microscopes typically lies around 0.6× their point resolution) (Fig. 1).The information limit is determined by brightness (controlling the illumination semi-angle α and thus the spatial coherence) and the energy spread (controlling the temporal coherence). These two factors are inversely related — if one goes up, the other goes down. The energy spread under HRTEM conditions is ∼0.8 eV, a value that is not inherent to the Schottky emitter but is due to the total system including the emitter and high-tension tank and accelerator.
Quantitative electron holography applied to crystal wedges and interfaces
Authors: Gajdardziska-Josifovska M. 
Published: June 2020

Electron holography is unique among transmission electron microscopy techniques in that it allows retrieval of phase of the electron wave, information which is lost with other imaging techniques. With access to the phase, interactions of the incident electron wave with the electrostatic and magnetic potentials of the specimen can be studied directly with high spatial resolution. Besides resolution enhancement, the original goal for electron holography, applications to wide range of materials problems are currently under investigation. This work will address applications to measurements of mean inner potential of crystals and to epitaxial crystal interfaces.In non-magnetic materials, in the absence of external electrical fields and/or charge layers, the electrostatic potential which alters the phase of the exit surface wave results from the atomic potentials. For amorphous and polycrystalline samples of known thickness, the phase change depends on the volume average of the atomic potentials, i.e. the mean inner potential V0.
Application of electron holography to ferroelectric study
Authors: Zhang X. , Joy D. C. , Allard L. F. , Nolan T. A. 
Published: June 2020

With the development of FE TEM, electron holography becomes a reality to materials scientists, which opens a new window for materials study. Weak phase objects, such as a thin transparent specimen or an electric or a magnetic field, which have little or no effect on the intensity of the transmitted wave, can readily be observed via holography because of the phase shift that they produce. Application of the electron holographic method has been extended to the study of ferroelectric domain wall structures. This work presents the most recent results in this area.Polarization gradients within domain walls are extremely important for the understanding of the extrinsic elastio-dielectric properties of ferroelectrics. Electron holographic studies of the local domain wall profiles provide essential input parameters for phenomenological theories of domain structure and of the macroscopic properties derived from the theories. Figure 1(a) is an electron hologram of the ferroelectric (BaTiO3) 90° domain wall area.
Direct observation of Fe-Al-Zn ternary intermetallic compound and its transformation during the early stage of hot-dip galvanizing
Authors: Lin C. S. , Chiou W. A. , Meshii M. 
Published: June 2020

The galvannealed steel sheets have received ever increased attention because of their excellent post-painting corrosion resistance and good weldability. However, its powdering and flaking tendency during press forming processes strongly impairs its performance. In order to optimize the properties of galvanneal coatings, it is critical to control the reaction rate between solid iron and molten zinc.In commercial galvannealing line, aluminum is added to zinc bath to retard the diffusion rate between iron and zinc by the formation of a thin layer of Al intermetallic compound on the surface of steel at initial hot-dip galvanizing. However, the form of this compound and its transformation are still speculated. In this paper, we report the direct observations of this compound and its transformation.The specimens were prepared in a hot-dip simulator in which the steel was galvanized in the zinc bath containing 0.14 wt% of Al at a temperature of 480 °C for 5 seconds and was quenched by liquid nitrogen.
TEM sample preparation of wear-tested room-temperature pulsed-laser-deposited thin films of MoS2 by ultramicrotomy
Authors: Lloyd Pamela F. , Walck Scott D. 
Published: June 2020

Pulsed laser deposition (PLD) is a novel technique for the deposition of tribological thin films. MoS2 is the archetypical solid lubricant material for aerospace applications. It provides a low coefficient of friction from cryogenic temperatures to about 350°C and can be used in ultra high vacuum environments. The TEM is ideally suited for studying the microstructural and tribo-chemical changes that occur during wear. The normal cross sectional TEM sample preparation method does not work well because the material’s lubricity causes the sandwich to separate. Walck et al. deposited MoS2 through a mesh mask which gave suitable results for as-deposited films, but the discontinuous nature of the film is unsuitable for wear-testing. To investigate wear-tested, room temperature (RT) PLD MoS2 films, the sample preparation technique of Heuer and Howitt was adapted.Two 300 run thick films were deposited on single crystal NaCl substrates. One was wear-tested on a ball-on-disk tribometer using a 30 gm load at 150 rpm for one minute, and subsequently coated with a heavy layer of evaporated gold.
Interfacial study of nanophase Pt or Pd particles on the surface of nanophase WO3 or TiO2 particles
Authors: Hsu Chi-Ming , Lin Hong-Ming , Tung Chiun-Yen , Hsu Teh-Yu , Yang Chao-Cheng 
Published: June 2020

Nanocrystalline (NC) metals are a subdivision of the family of nanostructural materials. Nanostructural materials are single phase or multi-phase polycrystals, the crystal size of which is of the order of a few (typically 1-100) nanometers in at least one dimension. Nanocrystalline materials have many interesting physical and chemical properties which attract researchers. Particularly in catalyst’s utility, it can provide a large specific surface area and active sites. Its size efficiency (Kubo efficiency) may create different electron energy gap which permits us to do other functional designs. Some phenomenons contribute to attractiveness of nanocrystalline material as catalysts or sensors. The interfacial study between NC metal and oxides became an important issue to evaluate the performance of the these applications.Gas-condensation technique is used to produce the nanophase WO3 or TiO2 by evaporating the tungsten in 10 mbar O2 atmosphere or pure titanium in (10 mbar O2/90 mbar He) atmosphere, respectively.
Electons' eyeview of buckytubes and friends
Authors: Lin Xiwei , Wang Yun-Yu , Wang X.K. , Yee A. , Dravid Vinayak P. , Chang R.P.H. , Ketterson J.B. 
Published: June 2020

Synthesis, characterization and properties of various all-carbon molecules, the fullerene family (buckyballs), have been on the research forefront since the large scale production scheme developed by Krätschmer et al. Recently, Iijima and coworkers have reported TEM observations of hollow graphitic tubules of nanometer scale (buckytubes). In particular, the large scale buckytube synthesis method of Ebbesen and Ajayan has stirred considerable interest similar to that after the Krätschmer et al. discovery of large scale buckyball synthesis.We have synthesized gram-scale quantities of buckytubes and their derivatives based on an arc method similar to that of Ebbesen and Ajayan. The arc was formed between a 1” and a 1/2 “ diameter graphite rods under 100 torr atmosphere of helium at a current of 180-200 Amps and a voltage of 20-30 V. The cross section of the resulting build-up rod consists of a gray core, followed by a black ring and another gray shell.
Microstructural characterization of a cast RENi5-based alloy
Authors: Micha G. M. , Zhang L. 
Published: June 2020

RENi5 (RE: rare earth) based alloys have been extensively evaluated for use as an electrode material for nickel-metal hydride batteries. A variety of alloys have been developed from the prototype intermetallic compound LaNi5. The use of mischmetal as a source of rare earth combined with transition metal and Al substitutions for Ni has caused the evolution of the alloy from a binary compound to one containing eight or more elements. This study evaluated the microstructural features of a complex commercial RENi5 based alloy using scanning and transmission electron microscopy.The alloy was evaluated in the as-cast condition. Its chemistry in at. pct. determined by bulk techniques was 12.1 La, 3.2 Ce, 1.5 Pr, 4.9 Nd, 50.2 Ni, 10.4 Co, 5.3 Mn and 2.0 Al. The as-cast material was of low strength, very brittle and contained a multitude of internal cracks. TEM foils could only be prepared by first embedding pieces of the alloy in epoxy.
Characterization of laser-irradiated C60 solution and cell damage by SEM,TEM and atomic-force microscopy
Authors: Brandelik Donna M. , Sutherland Richard L. , Jiang Hao , Lloyd Pamela , Wade Adams W. 
Published: June 2020

Investigation of laser irradiated purple C60/toluene solutions revealed a photochemical change of the solution at high incident laser fluences. The initial purple solution turned pink and a black precipitate formed which was insoluble in toluene. Interaction at the cell surface was indicated as cell damage occurred before the solution changes were seen. Subsequent chemical analysis by Mass Spectroscopy showed that the pink solution contained C60 and adducts. The black precipitate was found to contain no C60, but instead contained only adducts and lower fuller-enes NMR on the pink solution revealed a SiCHx peak as evidence of glass etching.Scanning electron microscopy revealed needle crystals from a pure C60 sample, in figure 1. Figure 2 shows the crystals from the pink solution. The black precipitate appears to have a porous,very grainy texture and lacks the crystalline structure of the other samples (figure 3). All three samples were deposited on carbon coated grids. The pyrex glass cell was damaged by the laser and showed an etching pattern (figure 4).
Structure determination of inorganic structures by HREM, Cip, and electron diffraction
Authors: Zou Xiaodong , Zubkov V.G. , Svensson Gunnar , Hovmöller Sven 
Published: June 2020

High resolution electron microscopy (HREM) combined with crystallographic image processing (CIP) is becoming a powerful technique for solving inorganic structures. With the image processing systems CRISP and ELD, running on a personal computer, this technique can be easily established in other laboratories. HREM images and electron diffraction patterns are digitized by a CCD camera and transferred into a PC. Phases and amplitudes are extracted from the Fourier transform of the HREM images. For thin crystals of metal oxides, the phases obtained by HREM and CIP inside the Scherzer resolution of the microscope are identical to the x-ray structure factor phases.Electron diffraction extends to much higher resolution than EM images (beyond 1 Å). The quality of the amplitudes is also higher than that from images, since ED data is not affected by the contract transfer function (CTF). Amplitudes extracted by ELD are close to x-ray diffraction amplitudes (within 30%).
Design and application of a scanning tunneling microscope for the observation of large machined surfaces
Authors: Grigg D.A. , Dow T. A. , Russell P. E. 
Published: June 2020

The scanning tunneling microscope is an instrument which can be used to image conductive surfaces with angstrom resolution. This makes the STM an ideal instrument for microscopic studies on machined metals and semiconductors. Several papers have been published showing the effectiveness of the scanning tunneling microscope (STM) to image single point diamond turned metal surfaces such as gold and aluminum.A large sample STM has been constructed specifically to handle machined samples as large as 76 mm in diameter (Fig. 1). A tube scanner has been implimented which allows scan lengths of up to 10 μm. The STM has been designed for quick and easy sample/tip exchange.STM studies have been made on single point diamond turned metals and semiconductor materials. Two forms of copper were diamond turned and studied using the large sample STM;
Accuracy and precision in data analysis
Authors: Trebbia P. 
Published: June 2020

Every time an experiment is carried out within an Analytical Electron Microscope (AEM) or any other instrument, the measurement contains information related not only to the object under study, but also to the instrument itself.Let O be an object (a precipitate in an alloy or a protein in a membrane). This object is usually supported by a background B1 (the alloy prepared as a thin specimen, the embedding material in biological sections). The specimen (O + B1) is then sampled by an interacting probe (visible light in optical microscopy, electrons in AEM) which gives an image I1 of the specimen, defined by : I1 = f(O + B1). The function f, called the transfer function of the instrument, is probably not linear over all the spatial frequencies exhibited by the specimen and does not transmit all the information contained in O. For example, in AEM, the image obtained on a screen does not contain in a direct form the information about the phase. Moreover, the instrument adds its own background B2 (parallel detectors such as photographic plates,
Computers and diffraction analysis
Authors: Eades J. A. 
Published: June 2020

For well over two decades computers have played an important role in electron microscopy; they now pervade the whole field - as indeed they do in so many other aspects of our lives. The initial use of computers was mainly for large (as it seemed then) off-line calculations for image simulations; for example, of dislocation images.Image simulation has continued to be one of the most notable uses of computers particularly since it is essential to the correct interpretation of high resolution images. In microanalysis, too, the computer has had a rather high profile. In this case because it has been a necessary part of the equipment delivered by manufacturers. By contrast the use of computers for electron diffraction analysis has been slow to prominence. This is not to say that there has been no activity, quite the contrary; however it has not had such a great impact on the field.
Low-voltage high-resolution SEM of biological samples
Authors: Pawley James B. 
Published: June 2020

There are three reasons for the recent upsurge of interest in using the SEM at a beam voltage (Vo) around 1 kV (LVSEM). The most common one arises from applications in the semiconductor industry and emphasizes the reduction in charging artifacts and in subsurface beam damage obtainable at low VoThe second reason derives from the belief that, given instrumentation capable of producing a sufficiently small probe, the increased contrast in the topographic component of the secondary electron signal will permit an important improvement in real topographic spatial resolution.The third reason is that recent developments in instrumentation have shown that by coupling a cold field-emission source with a short focal length lens, it is indeed possible to obtain small probe diameters at low voltage. Although they are considerably larger than probes obtained at higher voltage, they are nonetheless smaller than the smallest topographical feature yet imaged in the secondary electron (SE) mode. (Fig 1)
High resolution at low voltage: A new approach
Authors: Jones Arthur V. 
Published: June 2020

With the introduction of field-emission sources and “immersion-type” objective lenses, the resolution obtainable with modern scanning electron microscopes is approaching that obtainable in STEM and TEM-but only with specific types of specimens. Bulk specimens still suffer from the restrictions imposed by internal scattering and the need to be conducting. Advances in coating techniques have largely overcome these problems but for a sizeable body of specimens, the restrictions imposed by coating are unacceptable.For such specimens, low voltage operation, with its low beam penetration and freedom from charging artifacts, is the method of choice.Unfortunately the technical dificulties in producing an electron beam sufficiently small and of sufficient intensity are considerably greater at low beam energies — so much so that a radical reevaluation of convential design concepts is needed.The probe diameter is usually given by
Development of imaging plate system for a TEM
Authors: Oikawa T. , Mori N. , Ichikawa R. , Ohnishi M. , Kawasaki M. 
Published: June 2020

The superior characteristics of the “Imaging Plate” (IP) for electrons have already been ascertained, and its fundamental characteristics and application data reported. Conventionally, however, the IP, which was developed for X-ray radiography was applied to TEM image recording. So, its superior characteristics had not been given full play and it had been necessary to optimally redesign the IP for TEM. This report introduces our newly developed Imaging Plate System for TEM (TEM-IP System), which includes processes of taking, reading, processing and printing images.Fig.l shows the block diagram of the TEM- IP system. The newly developed devices are as follows:1.IP for TEM2.Camera chamber of TEM3.Image reader (including eraser)4.Image processor5.Printer.<Magazine-to-magazine form> The IP exposed in the camera chamber, can be loaded in the image reader together with its magazine, Lo carry out image reading. After completion of image reading and erasing in the image reader, the IP can be reloaded in the camera chamber, for repeated exposure.
Structural imaging of polytypoids in high Tc oxide superconductors
Authors: Ramesh R. , Wang E. , Tarascon J.M. , Thomas G. 
Published: June 2020

The structure of the superconducting polytypoid in the newly discovered high Tc super conducting system, Pb2Sr2Cu2Oy has been examined by high resolution electron microscopy, electron diffraction and xray microanalysis. High resolution imaging has shown the presence of the Pb2Sr2Cu2Oy at the grain boundaries. In analogy to the Bi-Ca-Sr-Cu-O(BCSCO)system, it is suggested that this polytypoid could have a lower transition temperature compared to the matrix. This may explain the steps in the resistivity plot. It is also shown that complex cationic ordering, such as replacement of Sr by Ca and/or Y, could lead to extra reflections in the diffraction patterns.Pb-Sr-(Ca-RE)-Cu-O sintered samples were prepared by standard solid state processing techniques. Samples were prepared under 1% flowing oxygen. Samples for electron microscopy were prepared by argon ion milling at liquid nitrogen temperature at 6kV. High resolution electron microscopy was carried out in the Berkeley Atomic Resolution Microscope at 800kV.
Scanning probe parallel EELS analysis of interfaces in ceramics and ceramic composites
Authors: Weiss J. K. , Carpenter R. W. , Braue W. , Higgs A. A. 
Published: June 2020

Much recent work has centered on the structure of interfaces in polycrystalline sintered ceramic and ceramic composite materials. The suggestion that most interfaces are wetted by a thin (1-10 nm) amorphous layer has been tested by the use of high resolution imaging, along with some work being done using microanalytical techniques. This study utilizes a system developed to acquire numerous electron energy loss spectra with a parallel detector while scanning a small electron probe across the various interfaces.The work was performed on a Philips EM400ST equipped with a high-intensity field emission gun capable of producing a probe with a “diameter” of 2±.5 nm and a current of up to 5 nA . The parallel EELS spectrometer was a Galan 666 equipped with a 1024-channel photodiode array coupled to a YAG scintillator, capable of full spectrum acquisition in as little as 25 msec with an energy resolution of < 1 eV. The PEELS was controlled byan MCA microcomputer designed at ASU, which also controls the probe scan sychronously with the multiple spectrum acquisition by an external voltage added to the beam deflection circuit from a set of DACs.
EDS analysis of .04% Zn in GaAs using x-ray filters
Authors: Christenson K. K. , Eades J. A. , Whitehead M. E. 
Published: June 2020

The x-ray Mass Absorption Coefficient (MAC) of an element varies with the energy of the x-ray. Absorption is strong for low energy x-rays and drops with increasing energy until the x-ray has sufficient energy to excite an inner shell electron. At this point there is a large jump in absorption referred to as an “absorption edge” followed by another steady decline with increasing energy (Fig. 1). This variation in transmission can be used either to eliminate x-rays from a low z matrix (a “high pass” filter) or, by utilizing the absorption edge, to eliminate x-rays with an energy above the desired signal (“band pass” filtering).While the use of such filters in XRF analysis is an established practice, their use in EDS analysis has only been suggested recently. In this experiment a Cu foil placed over the outer face of the x-ray collimator was used as a band pass filter to suppress the Ga and As matrix signals which allowed the quantification of .04% Zn in GaAs. This work was carried out at 120 keV in a Philips EM420 with an EDAX 9900 x-ray detector system (standard detector with a 15 mm WD and 30 mm2 area).