bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Center for Microanalysis of Materials
Authors: Eades J.A. 
Published: June 2020

The main purpose of the Center for Microanalysis of Materials is to serve the 250 or so people, from the materials-science research community on the Urbana campus of the University of Illinois, who use its facilities each year. (This represents about 80% of all researchers in this field on campus.) However, there is also a continuing interest in working with scientists from other institutions via collaborative research programs.The Center houses a large number of state-of-the-art instruments in almost all aspects of microanalysis: electron microscopy, x-ray diffraction, backscattering spectroscopies and several techniques in surface microanalysis. This equipment is operated and maintained by a team of full-time professional staff. Staff members also train users and collaborate in their research.The virtue of having microanalytical resources organized this way is that each research group can call on a very broad range of techniques. It can use Auger spectroscopy this week, EXAFS next and a combination of SIMS and TEM the week after that. This possibility is not available in universities where each instrument is acquired and run by one particular group.
Geometry and formation of twins in YBa2Cu3O7-x
Authors: Sarikaya Mehmet , Kikuchi Ryoichi , Aksay I. A. 
Published: June 2020

Geometry and formation of twins in the orthorhombic YBa2Cu3O7-x phase are studied by transmission electron microscopy and modeling. Samples with bulk superconductivity at 90K are produced by heating the stoichiometric 1:2:3 proportions of metal oxides with a single heat treatment schedule involving a heating rate of 5°C/min to 950°C (1 hr) and 1°C/min cooling to room temperature. Powder mixtures were formed by colloidal mixing of oxide powders or by molecular mixing techniques.Twinned domains with {110} twin boundaries, parallel to [001] of the orthorhombic lattice, usually form with both variants occurring in a single grain (Fig. 1). The twin boundary separation λ (Fig. 2) is dictated by energetic and geometrical requirements which are both related to Δa = b — a, where b and a are lattice parameters of the orthorhombic phase. Geometrical requirements lead to the estimate that the stable values of λ are integer values of the basic distance d.
An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface
Authors: Loretto D. , Gibson J. M. , Yalisove S. M. , Tung R. T. 
Published: June 2020

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.
Computer systems in microscopy: The big, the small and the ugly
Authors: Rez Peter 
Published: June 2020

The transmission electron microscope has now reached a stage of maturity such that the differences between different models are in the details rather than the fundamental design. Although the early computer systems in microscopy appeared only as adjuncts to X-ray multichannel analyzers newer, more powerful systems have become available at relatively low cost and there is an increasing demand for image acquisition, processing and analysis. There is still no agreement as to what is the right design for a microscope computer system. The answer depends not only on the planned applications but also on the organization of the microscopy lab.For spectroscopy there is a need to acquire spectra both by multichannel scaling (EELS) and multichannel analysis (EDX) and process the results for quantitative analysis. In imaging the requirement can be for either capture of TV camera images or direct scanning of a focussed probe across the specimen with digitization of an appropriate signal (bright field, secondary electron).
Reflection monolayer scattering and RHEED diffraction conditions
Authors: Peng L.-M. , Cowley J.M. 
Published: June 2020

In an infinite crystal, when the fast electrons are transmitted through the crystal, the effects of the periodic potential distribution on the incident electron wave can be best described by expanding the electron wavefunction in terms of propagating Bloch waves having the same periodicity as that of the crystal. The requirement for a three dimensional translation symmetry excludes the existence of evanescent Bloch waves with imaginary component of wave vector. With the presence of external surfaces, as in the case of reflection high energy electron diffraction (RHEED), the translation symmetry in the surface normal direction is broken. Bloch waves which are confined to the surface region in the form of damping waves in the surface normal direction are then allowed.In an ideal two-beam case, when the Bragg reflection condition is exactly satisfied, the incident electrons are totally reflected back into the vacuum from the surfaces of crystal, giving rise to an evanescent wave in the crystal and a standing wave outside in the vacuum.
PC based diffraction pattern analysis programs
Authors: Jackson A. G. , Rowe M. 
Published: June 2020

The analysis of electron diffraction patterns can be done automatically using image techniques for collecting the diffraction pattern. This is useful if the material is well known. The alternative when the material is not well known is to do hand measurements on the plate and then enter that data into a program, or do the entire analysis by hand. We have developed a small software package called CRYSTAL, for a PC/AT which is an intermediate point between the fully automated approach and the approach by hand. These programs were written to be used in conjunction with the EMS programs in order to compare theoretical patterns with those obtained experimentally.The program menu is displayed by typing “CRYSTAL”. There are five choices available from the menu: 1) enter diffraction pattern data using the digitizer, 2) analysis of the zone and planes associated with the measured planes, 3) plot the theoretical diffraction pattern and/or the measured planes, either on the CRT or the plotter, 4) calculate x-ray planes and 20 angles, 5) return to DOS.
Development of a conical anode Fe-gun for low voltage SEM
Authors: Miyokawa T. , Norioka S. , Goto S. 
Published: June 2020

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.
Orientation relationships and morphologies in the MBE growth of CrSi2 films on (III) Si surfaces
Authors: Chang K.T. , Mazur J.H. , Fathauer R. 
Published: June 2020

Chromium disilicide is a semiconductor with a 0.3 eV bandgap. It has potential for applications in Si based infrared detectors. The CrSi2/Si system is a good candidate for epitaxy because of the low 0.1% lattice mismatch between the basal plane of CrSi2 and the (111) Si surface. Previous studies have reported that the growth of CrSi2 on (111) Si occurs as islands with orientation relationship. The work reported here is an extension of this previous study.In the present experiments, both (111) Si and 4°-off (111) Si were used as a substrates. After co-deposition of Cr and Si at room temperature in a MBE chamber, the deposited films was annealed in the same chamber at temperatures up to 720°C. Transmission electron microscopy diffraction and imaging were used to study the structure and morphology of the deposited films.
Transmission electron microscopy of composite materials
Authors: Lagerlof K.P.D. 
Published: June 2020

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.
Combined CTEM and STEM using a condenser-objective lens and 100kv LaB6 gun
Authors: Beaumont S.P. , Ahmed H. 
Published: June 2020

In order to study the differences in contrast that are observed in conventional and scanning transmission electron microscopy, a new microscope has been designed and constructed to examine the same area of a specimen in either mode of operation at a resolution of lnm or better.A schematic diagram of the instrument is shown in Fig.1 for each of its modes of operation. It operates at voltages of up to 100kV and uses an LaB6 gun that provides a 10 micron source which may be aligned using the coils marked A1. In the STEM mode this source is demagnified by two strong condenser lenses Cl & C2 (fp,min = 1.75mm) and finally by the prefield of a saturated condenser-objective lens (CO) in the centre of which the specimen is immersed. These lenses were designed with the aid of magnetic vector potential programs. A further program was written to calculate the characteristic trajectories and aberration coefficients of the condenser-objective.
A versatile spectrograph for a STEM
Authors: Engel W. 
Published: June 2020

Recently, spectrographs have been considered for the analysis of energy losses in a STEM [1,2]. Contrary to spectrometers, they permit simultaneous recording of the energy loss spectrum over a large range within which the resolution remains nearly constant. This yields two inherent advantages: First, during the recording of the entire spectrum in a spectrograph, the object is bombarded by less radiation. Second, for image formation several signals from the loss spectrum can be utilized in parallel by suitable detector electronics.Fig. 1 shows the set-up of the proposed spectrograph, which is under construction. It consists of a transfer lens, a sector magnet which is not double-focusing, and a projective. The projective has a system of interchangeable pole pieces to permit various enlargements of the spectrum, yet with minimum aberration.Table 1 contains the essential data of the spectrograph as they pertain to the various projective magnifications and also to the use without the projective (dashed optical path).
Hydrated form of some clay minerals observed using a film sealed environmental cell
Authors: Kohyama N. , Fukushima K. , Fukami A. 
Published: June 2020

Since the interlayer or adsorbed water of some clay minerals are quite easily dehydrated in dried air, in vacuum, or at moderate temperatures even in the atmosphere, the hydrated forms have not been observed by a conventional electron microscope(TEM). Recently, specific specimen chambers, “environmental cells(E.C.),” have been developed and confirmed to be effective for electron microscopic observation of wet specimen without dehydration. we observed hydrated forms of some clay minerals and their morphological changes by dehydration using a TEM equipped with an E.C..The E.C., equipped with a single hole copper-microgrid sealed by thin carbon-film, attaches to a TEM(JEM 7A) with an accelerating voltage 100KV and both gas pressure (from 760 Torr to vacuum) and relative humidity can be controlled. The samples collected from various localities in Japan were; tubular halloysite (l0Å) from Gumma Prefecture, sperical halloysite (l0Å) from Tochigi Pref., and intermediate halloysite containing both tubular and spherical types from Fukushima Pref..
The theory of improved resolution in stroboscopic SEM for EBIC-mode
Authors: Komolova L.F. , Obyden S.K. , Saparin G.V. , Spivak G.V. 
Published: June 2020

Idea of istrohoscopic principle in electron microscopy for the first time was described by ref. Now that is widely used in scanning electron microscopy(SEM)for the studies of dynamical effects caused by exciting electron beam in real materials. It was shown that the stroboscopic principle can be also used to improve the, spatial resolution in the SEM. This possibility was realized for CL-mode. In the present work the quantitative account of resolution inhancement of the EBIC SEM is given.Physical consideration of EBIC-processes in the material demonstrates the time-inertial properties of this processes. The above fact obliges to, work in the conventional scan case at bad resolution. Real method supposes the usage as a videosignal under pulse excitation of specimen by electron beam only the initial phase of rising induced current into the material. To solve this problem the induced current must be determined as a function of time at the condition of nonstationary excitation.
TEM examination of dislocations generated in GaAS photocathode structures
Authors: Fletcher J. , Titchmarsh J.M. , Booker G.R. 
Published: June 2020

Basic studies have been performed on GaAs epitaxial multilayer structures of the type used for transmission photocathodes. The substrates were horizontal Bridgman (100)GaAs, and the layers either GaAs or GaAlAs grown by the LPE method and Zn-doped. TEM examinations were made to determine the nature and distribution of dislocations present in the structures, deduce how they were formed and suggest how they might be eliminated. Special attention was given to those dislocations formed by surface stresses generating 60° dislocations with at the specimen surface and moving down on inclined {1ll} slip planes to form a network at an underlying interface. One feature of the work was the TEM examination of ∽ 1° angle-lap and 90° cross-section thinned specimens to determine the three-dimensional distribution of the dislocations. Results are reported for three different aspects of the work.First, when GaAs layers are grown by the LPE method.
Representation of information in SEM by equal signal lines
Authors: Rau E. , Karelin N. , Dukov V. , Kolomeytsev M. , Gavrikov S. , Sedov N. 
Published: June 2020

There are different methods and devices for the increase of the videosignal information in SEM. For example, with the help of special pure electronic [1] and opto-electronic [2] systems equipotential areas on the specimen surface in SEM were obtained. This report generalizes quantitative universal method for space distribution representation of research specimen parameter by contour equal signal lines. The method is based on principle of comparison of information signal value with the fixed levels.Transformation image system for obtaining equal signal lines maps was developed in two versions:1)In pure electronic system [3] it is necessary to compare signal U (see Fig.1-a), which gives potential distribution on specimen surface along each scanning line with fixed base level signals εifor obtaining quantitative equipotential information on solid state surface. The amplitude analyzer-comparator gives flare sport videopulses at any fixed coordinate and any instant time when initial signal U is equal to one of the base level signals ε.
Morphology and coalescence growth of metal oxide smoke particles prepared by gas evaporation technique
Authors: Shiojiri M. , Kaito C. , Sasaki H. , Fujita K. 
Published: June 2020

The crystal habit and growth of metal oxide smoke particles which were prepared by burning component metals in a mixture gas of 80 % Ar and 20 % O2 at a pressure of 100 Torr are studied by electron microscopy.Figure 1 shows SEM and TEM images and ED patterns of a single-crystal In2O3 particle, which grew in an octahedron bounded by eight {111} planes of the cubic bixbyite structure. The particle in (a) and (b) is oriented with the [001] and directions parallel to the incident electron beam, respectively. The determination of crystal habit has so far been done only by TEM observations of a single particle which is placed in different orientations with a tilting goniometer stage, considering thickness contours in the images and fine structures due to double refraction effect as shown in the ED patterns. It is, however, laboursome and sometimes ambiguous. Since the SEM images reveal not only the crystal external form but also surface structure, SEM observations are very useful for the study of fine particles whose sizes are several tens of nanometers or less.
Analytical contrast calculations in the two-beam case
Authors: Katerbau K.-H. 
Published: June 2020

The image of a lattice defect in a crystalline specimen depends on a variety of different parameters, describing the material, the experimental conditions and the lattice defect itself. In a two-beam case the material parameters are the extinction length ξg and the anomalous absorption length ξ'g, the experimental parameters are the specimen thickness t, the depth zo of the defect in the foil and the excitation error w (as usual w = s.ξg). Till now, most calculations of the diffraction contrast of lattice defects were done numerically. Analytical calculations can be performed, however, and lead to a much better insight into the dependence of the contrast on the different parameters.We consider the two-beam case and use the column approximation. A coordinate system (x,y,z) is introduced with its origin in the centre of the lattice defect and the z- axis parallel to the electron beam. x,y are the column coordinates.
Electron beam scattering in an organic specimen
Authors: Adesida Ilesanmi 
Published: June 2020

The understanding of electron-solid interactions is of prime importance to both conventional transmission and scanning electron microscopists. Monte Carlo simulation of electron beam scattering in various target samples has made fundamental contributions to this understanding, especially in scanning electron microscopy where primary electron beams of a few to many kilovolts are utilized. A significant example is the understanding of energy dissipation patterns of incident electrons in an organic sample (polymethylmethacrylate-PMMA) which is very useful in electron beam lithography (1). Furthermore, with the close similarity between the organic sample and a biological specimen, a Monte Carlo approach is also very useful for the study of energy dissipation in biological specimens (2).To enhance our knowledge of these dissipation processes, a more comprehensive Monte Carlo simulation program has been developed. The program is based on the semi-direct technique of simulating individual inelastic scattering and elastic scattering with probabilistic weightings.
Surface structure of (001) Au films by high resolution transmission electron microscopy
Authors: Krakow William 
Published: June 2020

In nonprimitive lattices, surface layers corresponding to partially filled unit cells give rise to reflections forbidden in the bulk structure. These reflections allow detailed studies of the surface layer by high resolution transmission electron microscopy and computer modeling experiments.The occurrence of fractional unit cells at the surface of (001) oriented Au films can be demonstrated by assembling the fcc lattice by the alternate stacking of planar {100} type layers such that the atoms of,each atomic layer are embedded in the depressions of neighboring planes above and below. The stacking sequence is of the ABABAB….type with the B layers shifted an amount ao/2 in the [100] direction (Fig. 1a). The presence of an excess A or B layer gives rise to additional reflections with mixed odd and even Miller indices which are forbidden in the fcc lattice, e.g., (110). In obtaining diffraction patterns from ∼100Å thick Au films the forbidden reflections were approximately 2% of the corresponding bulk lattice reflections and easily identified (see Fig. 1b).
Long period structure in the Cu-Sn system
Authors: Van Sande M. , De Ridder R. , Van Tendeloo G. , Van Landuyt J. , Amelinckx S. 
Published: June 2020

High resolution electron microscopy and electron diffraction were used to study the Cu-Sn system in the composition range 3:1. Two different long period superstructures have been reported before as ordening phases with respect to the HCP structure. It was the purpose of this study to eliminate this ambiguity and investigate the influence of slight additions of a third element with respect to the Cu3Sn composition.Molten alloys were homogenized, quenched and annealed prior to electrolytical thinning of trepanned discs by jet polishing. The Cu3Sn-structures as described in the literature are derived from the Cu3Ti-orthorhombic basic structure which itself is a superstructure of the hexagonal close packed structure. As a confirmation of the structure model the derived phases should present the orientation and translation variants associated with the symmetry reduction fromfor the HCP structure tofor the Cu3Ti. From group theoretical considerations one expects three orientation variants and four translation variants;_the latter are then related by the three displacement vectors[100],[120] and[120].Our electron diffraction data and structure images confirm the structure proposal of Schubert and his description as a long period antiphase boundary structure with a periodicity of 10 times the b spacing of the orthorhombic cell.