bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of submicron particles in Al5Ti1B grain refining master alloys
Authors: Mayes C.D. , Tatlock G.J. , McCartney D.G. 
Published: June 2020

Al5%Ti1%B master alloys are frequently used in the grain refinement of aluminium alloys to induce heterogeneous nucleation during solidification and to promote an equiaxed grain structure. Boride particles are often observed in these alloys and could act as nucleation sites. However there are many more particles than nucleated grains in the samples and hence the precise role of the borides and other particles is not clear. We have therefore been undertaking a systematic TEM study of submicron particles extracted from master alloys using carbon extraction replication of fractured samples, with a view to investigating the nucleation mechanisms.Many of the particles analysed adopted a well defined hexagonal prism morphology (Fig.1) and varied in size from 5μm to 100 nm across the hexagonal face. A combination of EDX and EELS analysis plus electron diffraction was used to identify isolated particles as TiB2 containing little if any aluminium or potassium. These other elements are often detected in agglomerations of particles.
Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets
Authors: Chandramouli Mahesh 
Published: June 2020

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.
Structural changes in Pd electrodeposits during TEM sample preparation
Authors: Giannuzzi L. A. , Howell P. R. , Pickering H. W. , Bitler W. R. 
Published: June 2020

The small grain size and high dislocation density of electrodeposits make it necessary to employ TEM analysis for microstructural evaluation. It had been generally accepted that twinned microstructures of electrodeposits observed by TEM were annealing or growth twins, and subsequently inherent to the properties of the electrodeposit. However, in a recent study, deformation cross-twinning in Pd electrodeposits was unambiguously identified. The purpose of this paper is to report on the influence of TEM sample preparation on the structure of Pd electrodeposits.Electrodeposited Pd (courtesty J. Vanhumbeeck, Siemens NV, Belgium) TEM foils were thinned by the standard techniques of twin jet-electropolishing and ion beam milling. The Pd foils were examined in a Philips EM420T TEM with analytical capabilities operating at 120 kV.FIG. 1 is a series of three dark field micrographs from the same region showing deformation crosstwinning. The dislocation density increases with increasing foil thickness and decreasing deformation cross-twinning.
Morphologies of hypereutectic, rapidly solidified Nb-Ge alloys
Authors: Evans N. D. 
Published: June 2020

Rapid solidification of hypereutectic niobium-germanium alloys by splatting has been performed to compare the solidification paths of alloys having various amounts of overheat prior to rapid solidification processing (RSP). There is interest in this system because the superconducting A15 phase can achieve high critical magnetic fields and critical current densities. The processing technique, which has been described elsewhere, incorporated an electromagnetic levitation furnace to melt 500 mg masses of alloy in a containerless manner, and a pair of polished copper plates that acted as a double-hammer assembly.Scanning electron microscopy (SEM) was performed with either a Hitachi X-650 Scanning Electron Microanalyzer with a PGT System 4 X-Ray Analyzer energy dispersive spectroscopy (EDS) package, or a Hitachi S-800 High Resolution SEM. A Philips EM400T/FEG with an EDAX 9100/70 EDS system was used to perform analytical electron microscopy (AEM) at the Oak Ridge National Laboratory.
Electron diffraction detection of ordliking in annealed PbTe thin film
Authors: El-Sayed Karimat 
Published: June 2020

Lead telluride is an important semiconductor of many applications. Many Investigators showed that there are anamolous descripancies in most of the electrophysical properties of PbTe polycrystalline thin films on annealing. X-Ray and electron diffraction studies are being undertaken in the present work in order to explain the cause of this anamolous behaviour.Figures 1-3 show the electron diffraction of the unheated, heated in air at 100°C and heated in air at 250°C respectively of a 300°A polycrystalline PbTe thin film. It can be seen that Fig. 1 is a typical [100] projection of a face centered cubic with unmixed (hkl) indices. Fig. 2 shows the appearance of faint superlattice reflections having mixed (hkl) indices. Fig. 3 shows the disappearance of thf superlattice reflections and the appearance of polycrystalline PbO phase superimposed on the [l00] PbTe diffraction patterns. The mechanism of this three stage process can be explained on structural basis as follows :
Extraordinary mechanical bond between magnesium silicate ceramic coating and grain-oriented silicon steel
Authors: Gibbon Donald L. , Varsanik Richard G. 
Published: June 2020

Routine observation of magnesium silicate coatings on transformer steel showed them to have a remarkable ability to withstand deformation without delaminating, contrary to experience with other glassy or crystalline coatings on steel. Out-of-specification materials may produce poorly bonded coatings. A full-scale examination of the steel-coating process was undertaken to discover the keys to this difference and to contribute to the design of improved magnesium oxides.These observations have been made possible by the development of a Br-methanol solution technique by which the steel may be dissolved away from the oxide or silicate coating. Observations have been carried out by TEM, AEM, SEM, and EDS.Before decarburization, the cold-rolled silicon steel has a thin (0.5 to 1.0 micrometter) silicon-rich coating, comprised of amorphous silica with minor fayalite (Fe2SiO4) (see Fig. 1).
Microstructure of polycrystalline near epitaxial (100) and (111) pyrochlore on A (100) MgO Substrate
Authors: Rou Shang Hsien 
Published: June 2020

New and interesting physical phenomena are being observed via thin film depositions using a variety of processing techniques in different material systems. The present study describes Pb-Zr-Ti-O pyrochlore thin films which were deposited onto (100) MgO substrates using an ion beam sputtering technique. These films are of interest because of their unique microstructure which may provide valuable information in better understanding the epitaxial growth of thin films. Characterization were performed using conventional transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Special TEM sample preparation procedures have been developed, which will be reported elsewhere.The as-deposited pyrochlore thin film is near epitaxial and is oriented with both (100) and (111) parallel
to the (100) of the MgO substrate. Figure 1(a) shows the selected area diffraction pattern (SADP) of the pyrochlore thin film taken parallel to the [100] zone axis of the substrate.
An Analytical Electron Microscopy and surface analysis study of diamond films
Authors: Henderson A.E. , Fitzgerald A.G. , Potrous S.M. , Storey B.E. 
Published: June 2020

The formation of diamond films by plasma assisted chemical vapour deposition (PACVD) techniques has become an area of intense interest over the past few years. These films have potential applications in optical devices, microelectronics and as wear resistant coatings. To exploit the unique properties of these diamond coatings they must be fully characterized.In this investigation polycrystalline diamond films produced by PACVD, on single crystal silicon substrates have been studied by a range of microbeam analytical techniques. Surface analyses have been made in a VG Microscopes HB100 UHV SEM by Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Depth composition profiles have been made by Auger electron spectroscopy. The silicon-diamond interface region has been investigated by x-ray microanalysis in a JEOL T300 SEM. The diamond films were prepared for transmission electron microscopy by dissolving away the silicon substrate in an HF/nitric acid solution. The resulting free standing diamond film was ion thinned to produce electron transparent areas. The thinned film was then sandwiched in a folding electron microscope grid for analysis in a JEOL 100C STEM.
The skin-core morphology of injection-molded syndiotactic polystyrene
Authors: Cieslinski R.C. , Lopez L.C. , Wesson R.D. 
Published: June 2020

Injection molding is an important fabrication process for the molding of thermoplastics. It is generally recognized that the final properties of the injection molded part are strongly dependent upon morphology, orientation, and stress. These effects are particularly evident in a semicrystalline polymer such as syndiotactic polystyrene where the melt orientation and cooling rates can vary appreciably from point to point within the mold cavity leading to pronounced morphological and crystallinity inhomogeneities.This paper describes the effects of polymer mold temperature on the overall morphology of syndiotactic polystyrene in an injection molded tensile bar specimen. The morphology was examined in samples molded at 50°C and 160°C using polarized optical microscopy, transmission electron microscopy, and Fourier transform infrared micro-spectroscopy.A skin-core effect was found and significant structural differences existed in the skins of the samples molded at the two temperatures. Bars molded at 50°C had a shish kebab morphology at the surface (Figure 1)
Contributions of Electron Microscopy to Biology and Medicine
Authors: Weibel Ewald. R. 
Published: June 2020

In the development of the biological and medical sciences, morphology has traditionally served as pacemaker, from the Renaissance on when Vesalius founded Anatomy as a science.The invention of the microscope brought observation into the range of invisible structures. This ended around the middle of the last century when the cell was discovered as the fundamental unit of living matter, and also as the site of disease, causing “numoral” pathology to be replaced by cellular pathology (Virchow).At the same time, microscopic methods had reached their limit. The chemical revolution stepped in and biochemistry became the pacemaker in biology and medicine; we seemed to move back to “humoral pathology”.When electron microscopy was applied in biological studies after 1950 a new “invisible world” was discovered: the power of morphological observation was extended to the molecular level. Membranes were discovered as boundaries of the cell and as barriers between compartments: cell function was seen as a highly ordered process. Step by step with ever more refined techniques, cellular organization was unravelled. Today's picture is that of a totally ordered cell with precise relationships to its neighbors. The structure of bacteria and viruses and the pattern of their interaction with cells and tissues was revealed. The diversity of cells became reduced to variations over a common basic scheme.
HREM Studies of Structural Changes Induced by Phase Transformations in Zirconia Powders
Authors: Blanchin M.G. , Nihoul G. , Bernstein E. 
Published: June 2020

The use of microcrystalline (submicron) and nanocrystalline (≤10nm) particles as powder materials for sintering of advanced ceramics like oxide-based ceramics or high-Tc superconductors , requires new techniques for characterization. Thus classical optical microscopy or even scanning electron microscopy are no longer effective for examination of 1-10 nm particles. In previous work we developed quantitative analysis of transmission electron microscopy (TEM) observations at medium resolution (0.4-1 nm, typically) to study morphology, size distribution, agglomeration and/or aggregation state of elementary powder particles characterized by bright- and dark - field imaging as well as diffraction TEM techniques.Here the high resolution TEM (HREM) techniques (at 200 kV) have been used to investigate phase transformations occuring in ultrafine zirconia powders processed by calcination of an amorphous hydrated zirconium oxide prepared at low temperature. X-ray examination showed the sequence : amorphous , cubic (C) or tetragonal (T) , monoclinic (M), at increasing temperatures.
Structure of Octacyanophthalocyanine Derivatives Prepared by CVD
Authors: Ueda Y. , Ashida M. 
Published: June 2020

Phthalocyanine compounds have been attracting a good deal of attention as semiconductors and photoconductors. We have studied the crystal structure of octacyanophthalocyanine(2a)-metal complex crystal prepared by CVD reaction of 1,2,4,5-tetracyanobenzene (TCNB:1a) with metal films by HREM. In the case of 2a-K complex crystal, the high resolution image of the crystal showed a grid pattern with a spacing of 1.57nm, as is shown in Fig.1. The planar molecules of 2a stacked along a column to coordinate with the intercalated potassium atoms in the complex crystal. In this study, we examined the structure of the films prepared by CVD reaction of TCNB derivatives, which were introduced iodides(1b) or chlorines(1c) into 3 and 6 positions of TCNB, with KCl.The films were prepared on a cleavage face of KCl single crystal by heating with the powders of 1b and 1c in an evacuated sealed tube at 350 C for 12h. The specimens were examined in a JEOL-200CX microscope equipped with a minimum dose system.
Determination of Intensity Distribution of Effective Source by Means of PIXsysTEM
Authors: Hosokawa F. , Osuna T. , Suzuki M. , Oikawa T. 
Published: June 2020

The resolution of the transmission electron microscope is discussed considering its phase contrast transfer function (PCTF). Usually, as the envelope function for PCTF, the defocus due to the chromatic aberration (ED) and the reduction of the interference (EJ) due to the incidence angle of the electron beam upon the specimen are considered. It was shown by Frank that the latter is given by the Fourier transformation of the effective source. In the present study, the author shows that EJ can be calculated from the intensity distribution of a filament image formed near the back focal plane of the objective lens. This means that we can virtually get the profile of the effective source without focusing the exact back focal plane on the fluorescent screen, in the diffraction mood. Using the PIXsysTEM, the author also investigated the profile function of the effective electron source and calculated EJ values under various illumination conditions.Assume that the specimen is thin enough to be approximated as a weak phase object. In Fig. 1, consider A and B as filament images formed near the back focal plane of the objective lens by transmitted wave and scattered wave, respectively. They act as emitting sources for the image plane.
Projected Structure of the Surface Protein of Sulfolobus Spec. B12 Determined to a Resolution of 1.0 NM by Cryo-Electronmicroscopy
Authors: Lembcke G. , Zemlin F. 
Published: June 2020

The thermoacidophilic archaebacterium Sulfolobus spec. B12 , which is closely related to Sulfolobus solfataricus , possesses a regularly arrayed surface protein (S-layer), which is linked to the plasma membrane via spacer elements spanning a distinct interspace of approximately 18 nm. The S-layer has p3-Symmetry and a lattice constant of 21 nm; three-dimensional reconstructions of negatively stained fragments yield a layer thickness of approximately 6-7 nm.For analysing the molecular architecture of Sulfolobus surface protein in greater detail we use aurothioglucose(ATG)-embedding for specimen preparation. Like glucose, ATG, is supposed to mimic the effect of water, but has the advantage of being less volatile. ATG has advantages over glucose when working with specimens composed exclusively of protein because of its higher density of 2.92 g cm-3. Because of its high radiation sensitivity electromicrographs has to be recorded under strict low-dose conditions. We have recorded electromicrographs with a liquid helium-cooled superconducting electron microscope (the socalled SULEIKA at the Fritz-Haber-lnstitut) with a specimen temperature of 4.5 K and with a maximum dose of 2000 e nm-2 avoiding any pre-irradiation of the specimen.
Fast and Accurate Autotuning of a TEM for High-Resolution and Low Dose Electron Microscopy
Authors: Koster A.J. , Typke D. , de Jong M.J.C. 
Published: June 2020

The application of transmission electron microscopy (TEM) for the research on biological and inorganic structures is restricted by the radiation sensitivity of the specimens and the deviations from the optimal setting of the TEM parameters. The three most important optical parameters that require extensive fine tuning are the defocus, astigmatism and beam tilt misalignment. Autotuning, i.e. automatic optimization of these three parameters, can help to optimize microscope settings using a minimum amount of electron irradiation.Until recently, the practical applications of the autotuning methods proposed in literature were limited due to insufficient computational power and the lack of commercially available computer interfaces to TEM. These instrumental limitations can now be overcome be a fully remote controllable TEM, a highly sensitive video camera system, and a fast image processing system.
The Electron Microscope and the Computer: Present Trends and Future Prospects
Authors: Rez Peter , de Ruijter W.J. 
Published: June 2020

In the present generation of electron microscopes the roles of computers or microprocessors can be divided into control, acquisition and analysis of both spectral and image data. Not much, however, has been done to realise the full power of computer based systems and integrate all these functions with the electron optics. The control of practically all microscope columns is performed by an 8-bit or 16-bit processor usually running a program that repeatedly scans for user inputs and changes lens currents or alignment settings if necessary. External control for special experiments can either be implemented by scanning an additional user input from a serial port or by allowing external analog signals to replace those generated by the microscope control scheme. As the program loop typically takes 0.1 sec to complete it is preferable to implement some functions such as external beam scanning by providing analog ramps (even if generated by another computer).Computer acquistion of data was introduced to electron microscopy with analytical techniques, such as EDX, in which the computer was the basis of a multi channel analyser. In the case of energy loss and Auger spectroscopy, computer scanning of the spectrometer and acquisition of single electron pulse-counted data quickly displaced chart recorders as a means of collecting data. A computer based system not only could perform acquisition more efficiently, it could also provide a convenient means for processing the results and doing quantitative analysis. Furthermore digitally stored data could easily be transferred to other systems on disks or by direct link (such as ethernet) and analysed elsewhere. However for image acquisition there has been very little use of computers in acquiring data. Although microscopists are happy to consider a spectrum as an array of numbers they still prefer to deal with images as pictures rather than digital data sets. The problems are not entirely psychological since a major barrier to the widespread use of image processing in microscopy is the lack of a suitable detection system. TV cameras compare unfavourably with photographic plates in terms of both dynamic range and "resolution" as defined loosely in terms of pixel size or lines/mm. This argument does not apply to scanning microscopes but, even in scanning systems, frame buffers and powerful computer systems have only been integrated as part of the microscope electronics in the last few years. Microscopists still prefer to measure quantities from exposed photographs rather than work with digitized data in a workstation environment using high level image processing software. Until recently cost may have been a consideration but now computing platforms of sufficient capability are less than 1/5 of the cost of an average SEM.
Temperature Measurement on Micro-Area of Polycrystalline Film with TEM
Authors: Takaoka Akio , Hiroshi Taoka , Katsumi Ura 
Published: June 2020

With a focused laser beam, we can heat a specimen in TEM locally (∼5 μm), and rapidly (∼10 μs) and also at a high temperature (>1000°C)[1]. For such heating, a new method for temperature measurement is necessary. By using the thermal diffuse scattering in the TEM specimen, the temperature in a local area (∼1 μm) can be measured rapidly (<10 μs)[2]. Figure 1 is the schematic diagram of the local heating system by a laser diode and the temperature measuring system.The intensity of transmission beam through a specimen depends on (1) temperature T, (2) thickness d, (3) material of specimen, (4) Bragg condition, (5) accelerating voltage and (6) detection angle at the detector. If the conditions for (3)-(6) are fixed, the transmission is represented by τ(T,d). With two wave approximation, the transmission through a thin crystal is theoretically shown by Hall, Hirsch[3] and Kamiya. In the case of polycrystal, the transmission is given by the statistical average of transmission for each crystallite. In Fig.2(a), the solid lines are the calculated values for polycrystalline Al films, while the circles are the measured values for evaporated Al films with a heating specimen holder. Here, the transmission is normalized with the value at room temperature. Some disagreement exists in both values, because the some assumed conditions are not valid in the experiment.
An Ultra-High-Resolution Objective Lens for a 200-kV TEM
Authors: Bakker J.G. , Asselbergs P.E.S. 
Published: June 2020

High resolution TEM imaging has been well established as superb technique for obtaining structural information about materials on an atomic scale. Trends in equipment for high resolution imaging have progressed to the stage where point resolutions below 2 Å can be obtained at 200 kV. This paper describes such a new objective lens for the Philips CM20 Transmission Electron Microscope.In designing a new objective lens, several parameters have to be taken into account. Not only should the coefficient of spherical aberration of the objective lens be minimised, the lens should also allow considerable tilting of the specimen in two directions. The lens should be compatible with X-ray analysis. And last but not least, the design of lens must ensure that the heat transfer of the lens to the specimen environment is minimised.