bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron beam-induced current imaging of antiphase domain boundaries in heteroepitaxial GaAs on group IV semiconductors
Authors: Malta D.P. , Posthill J.B. , Venkatasubramanian R. , Timmons M.L. , Humphreys T.P. , Das K. , Markunas R.J.
Published: June 2020

A viable GaAs heteroepitaxy technology is desirable in order to exploit the high mobility and direct band gap properties of GaAs while avoiding the high cost, defect density, and weight of bulk GaAs. Microstructural defects such as dislocations, microtwins, and stacking faults found in most heteroepitaxial GaAs films have thus far inhibited the achievement of device quality films. In addition, the formation of antiphase domain boundaries (APBs), at which As-As bonds and Ga-Ga bonds exist, is undesirable because they are electrically active. The APBs are believed to form due to the presence of single atomic steps on the underlying group IV substrate. Transmission electron microscopy investigations have previously reported the presence of APBs in GaAs heteroepitaxial films. Since the APBs act as electron-hole recombination sites, the electron beam-induced current. (EBIC) imaging mode of the scanning electron microscope (SEM) is ideally suited for straightforward and statistically significant. GaAs heteroepitaxial film evaluation.
Cathodoluminescence characterization of two-dimensional interface structure of quantum wells
Authors: Wada Kazumi
Published: June 2020

Exotic properties shown by quantum well structures, typical structures of future electron devices, are sensitive to interface roughness. Extensive studies are, thus, focused on characterization of interface structures. Recent improvement in quantum wire fabrication technology demands for characterizing not only perpendicular-interfaces to the growth direction but also parallel-ones (sidewall-interfaces). Such sophistication needs innovation in two-dimensional and nondestructive characterization technology.

In device structures, interfaces are generally located deep in bulk. STM which visualize surface atoms can not monitor such interface. It is, thus, difficult to two- dimensionally characterize the interfaces.

Interface steps induce well width fluctuation, which modulates optical transition energy between ground subbands in conduction and valence bands. Thus, interface step structures can be characterized by luminescence spectroscopy. Cathodoluminescence basically meets demand for nondestructive characterization of interface structures in two dimensions.
Image simulation as an aid for the interpretation of Electron Microscope images of magnetic structures
Authors: Zweck J. , Hoffmann H.
Published: June 2020

An electron wave that passes through a magnetic sample of constant thickness d0 suffers a phase shift Δϕ which is proportional to the magnetic flux inclosed:

where is a vector in the plane of the specimen. As is well known, this phase shift can be converted into an observable contrast by means of defocusing, quite similar as in the case of HREM imaging. However, realistic magnetic specimens are no ’weak phase objects’, therefore a complicated relationship between the experimentally observable contrast and the ’real’distribution of magnetization within the sample has to be expected. The approach to overcome these limitations in imaging of magnetic domains is closely related to the usual procedure well-known from HREM imaging: it is necessary to obtain an image under carefully controlled experimental conditions such as the amount of defocus and possible specimen tilt.
Electron radiation damage of natural zeolites at room and low temperature
Authors: Yokota Yasuhiro , Hashimoto Hatsujiro , Yamaguchi Terutoshi
Published: June 2020

Zeolites are easily changed to amorphous under electron beam irradiation. Bando reported that this phenomena take place at low temperature with 1/20 dose of room temperature. In the present work this phenomena was investigated using two kinds of specimens, by changing temperature, electron energy (100 kV-350 kV) and also by applying an electron energy loss spectrometer.

Mesolite is from Yaizu, Sizuoka Prefecture and Thomsonite is from Nishijima, Yamanasi Pref. , Japan. The specimen were ground to fine powder and dispersed on a microgrid. A Faraday gage which was installed in the observing chamber of the microscope was used for measure the dose rate. Decomposition was determined by measuring the current of a diffracted spot by the Faraday gage. Observation at low temperature was carried out using low temperature specimen holders fabricated to 200 kV and 400 kV electron microscopes.

Fig. 1 (a), (b) are high resolution lattice images of Mesolite by 200 kV TEM operated in room temperature, (b) was taken 20 second after the same part of (a). The thickness of amorphous region in (a) is 8 nm, in (b) the amorphous region increased to 30 nm.
Dynamic observation on deformation and fracture of wool fibers
Authors: Dong Xuexi
Published: June 2020

It’s no doubt that the investigation on the regularity of deformation and fracture of textile materials under tensile force has practical significance for determining their processing parameters and using conditions rationally. Particularly in recent years, textile materials have been increasingly applied to engineering fields of such as building and spaceflight etc. So people pay more and more attention to the study of deformation and fracture of them. SEM is one of important means for this study.

Much information has been furnished which concerned with the behavior of fibers in deformation and fracture by studying the fracture morphology of materials with SEM. Some workers have observed the tensile courses and the fracture ends of fibers and obtained a lot of interesting results and important conclusions. But, so far, it hasn't been reported that how to measure the forces quantitively when deformation, lines and cracks emerging on materials . If the state of forces in fibers could be known during deformation and fracture, important advances would be achieved in this field.
Correlation of shearing properties with the structure of garment leathers
Authors: Lokanadam B. , Subramaniam V. , Ramasami T.
Published: June 2020

Shearing property is of fundamental importance in influencing the complex deformations of a garment leather during use. The properties such as stretch, shape retention etc., are closely related to the shearing behaviour of garment leather. Although, textile fabrics have been investigated extensively for their shearing properties(1-3), the studies on leather have been limited. It is logical to expect the three-dimensional structure of leather and the intrinsic properties of collagenous fibre would be markedly different from those of other textile fabrics. The shearing property of a fabric can be expected to be influenced by its weave and matrix structure. An attempt has now been made to correlate the ultra and micro structural details of a garment leather with its shearing properties.

A simple instrument has now been developed to assess the shearing behaviour of a soft fabric like garment leather. The shear test on garment leather involves the radial deformation of a sample piece by small degrees and measurement of the resultant shear stress and strain levels. Full chrome grain garment and suede garment leathers obtained from sheep skins were used for measurement of shearing properties.
EM observation on poly(β-alanine) crystal formed by the thermal solid State polymerization
Authors: Kimura Hirokazu , Sakabe Hiroshi , Morita Hitoshi , Itoh Takashi , Konishi Takashi
Published: June 2020

It is well known that several ω-amino acids are polymerized in the solid state. A single crystal of ε-aminocaproic acid has been reported to be polymerized in the solid state to be the biaxially oriented nylon 6. We also reported in the previous paper that the thermal solid state polymerization of glycine single crystal produced poly(glycine-I) crystal.

In this paper,structure of poly(β-alanine) polymerized in the solid state is investigated by means of scanning electron microscopy (SEM).transmission electron microscopy (TEM) and X-ray diffraction.

Commercial β-alanine (Nakarai Tesque,Inc.,Kyoto) was recrystallized three times from the distilled-water solution (lg/ml) at 80°C. The single crystal continued to grow gradually during 24 hr. The obtained single crystals with rhombic habit had clear cleavage planes. These single crystals about 10 mm in size were used as the original specimens. The polymerization procedure was carried out on the single crystals at temperatures between 140 and 170°C in an evacuated and subsequently sealed tube.
Surface evaluation of titanium and vitallium dental implants using SEM
Authors: Krizan K. E. , Laffoon J. E. , Zeitler D. L. , Madison S.
Published: June 2020

In recent years Titanium (Ti) has been the metal of choice for use as a dental implant material. Vitallium (Vi, and alloy composed of Co, Cr, Ni, and Fe) was considered in the past as an ideal implant material, but current studies show Ti is perhaps better tolerated by tissues in the oral cavity. The purpose of this study is to evaluate the surfaces of Ti and Vi endodontic endosseous implants (EEI) placed in a primate model for one year. In human clinical situations this type of dental implant is sometimes used to stabilize compromised teeth. Under intravenous general anestheisia four cynomolgus monkeys had root canal instrumentation in all central incisors. Placement of the EEI followed a pulpectomy and hand drilling to the proper depth and size for the solid rods to use the bore as a pathway to supporting bone. A total of eight Ti and eight Vi, tapered, size 50, EEI were cleanned, sterilized, and cut to length. Two EEI were inserted in the maxillary (Mx) incisors and two in the mandibular (Md) incisors of each animal. One year after placement animals were perfused via carotid cannulation with an aldehyde fixative. The jaws were retrieved, decalcified, EEI separated from tissue, and processed for scanning electron microscopy (SEM). These experimental EEI samples were critical point dried, mounted on stubs, coated with gold palladium, examined, and photographed with an Amray 1820D SEM. Non-operative control EEI samples were treated, processed the same as the experimentals and photographed with a JEOL JSM 35C SEM. Evaluation of the SEM photomicrographs suggest surfaces of EEI change during: 1) handling to implantation, 2) one year in vivo, and 3) processing. Nonoperative Ti control surfaces (Figs. 1 & 2) appear smooth with crater-like concavities of many sizes, subtle valleying, and crisscrossing machine mark (arrow) [Angle measurements of the crisscross marks compared to the long axis were significantly near 40° for both Ti experimental & control]; Vi control surfaces (Figs. 3 & 4) appear rougher with crevasse-like pits and a machine mark (arrow). Md Ti EEI (Fig. 5) has a prominent insertion gouge (⋆), smoother edged concavities than the control, and pre-operative machine marks like those in Fig. 1 (arrow). Mx Vi EEI surface (Fig. 6) has rounder edged pits and a right side smooth surface blemish (⋆). In conclusion these data suggest that Ti EEI surfaces change less than Vi counterparts. This gathering of information is being correlated with concurrent tissue studies indicating Ti may be better tolerated than Vi EEI which supports the premise that Ti is the material of choice for some dental implants in the tissues of the oral cavity.
An EM Study of silicone hydrophobicity in commercial gypsum wallboard
Authors: Freeman H. A. , Peters Y. A.
Published: June 2020

Considerably improved performance is provided by gypsum construction wallboard which has been formulated to enhance durability and water resistance in applications that are susceptible to high humidity and moisture. One ingredient that is economically added in small amounts for this purpose is a low viscosity methyl hydrogen silicone fluid. The silicone was found to provide the necessary hydrophobic character and strength improvement when it was incorporated with the gypsum slurry in early stages of wallboard manufacture. However, it remained unknown where the silicone became localized to achieve this effect. Microanalyses were therefore performed in the analytical electron microscope to define the distribution of silicone in commercial gypsum wallboard samples.

Gypsum samples were obtained which included those containing silicone and others to which no silicone had been added during manufacture. Analyses were performed in a JEM 2000FX analytical electron microscope operated at 200 keV and equipped with Tracor Northern Micro-ZHV and Microtrace energy dispersive x-ray spectrometers. Scanning (SEM), transmission (TEM), and scanning transmission (STEM) images were correlated with the mapped distributions of as many as six different elements acquired simultaneously. Low Z substrates and tilting specimen holders effectively minimized incorporation of spurious x rays in the final spectra.
A new equation to estimate trace rotation of planar features caused by double tilting of TEM specimen stage
Authors: Bande Hong , Qingchang Meng , Qing Liu
Published: June 2020

Hirsch et al present an equation attributed to Presland and Pashley, which they infer can be employed to calculate the trace rotations of planar features during tilting. However, it is inapplicable due to the imperfection in theoretical consideration and it gives different results comparing to experiment as discussed in author’s paper.

A new equation has been derived as shown in Figure 1. X and Y are the projectioas of tilt axes of double tilt stage on screen. OA is the intersection line of a planar feature intersecting with the foil surface, ψois the angle between OA and OX, it can be measured on screen (or on negatives) at foil normal orientation. To tilt a specimen to a new orientation [UVW] from [U0V0W0] , the tilt angle α and β can be calculated using the equations derived by the author’s, or read from the goniometer stage ia the light of diffractioa pattern. Suppose tilt the specimen around axis Y for β at first,the intersection line goes to OB, aad the trace on screen is OB’; then tilt the specimen around X for α, the spesimen attains its new orientation [UVW] and the intersection line goes to its final position OC. OD is the projection of OC, and the angle between OD and OX is ψ.
Nanoscale compositional changes in Cr-Mn steels α-bombarded at 773 K
Authors: Ruedl Erico , Valdrè Giovanni
Published: June 2020

The structural materials for nearer-term fusion reactors such as ITER and DEMO will likely be steels. During their operation, the radiation damage in the structural components made of steels will become very complex since the damage is produced simultaneously by high energy neutrons, protons, α-particles and other particles. As long as no fusion device for material testing exists, data about the formation of radiation damage in candidate steels can only be obtained by simpler irradiating condition such as by neutrons with mixed energy spectra, protons and/or α-particles. The present work deals with a study of Cr-Mn austenitic steels, a category of materials of current interest in fusion technology because it is expected to produce less long term waste than Cr-Ni steels.

The materials examined were: AMCR 0033 composed of ∼71wt% Fe, 17.5 Cr, 10.4 Mn, 0.53 Si, 0.2 N, 0.1 C; Nitronic 32 composed of ∼66.5 Fe, 12.3 Cr, 18 Mn, 1.5 Ni, 0.55 Si, 0.18 Cu, 0.35 N 0.1 C; AMCR composed of ∼71 Fe, 10 Cr, 17.5 Mn, 0.57 Si, 0.25 Cu, 0.2 C, 0.06 N.
High resolution TEM observation of shape memory alloy Ni-Ti at room temperature to high temperature
Authors: Li Yan , Hashimoto Hatsujiro , Sukedai Eiichi , Yokota Yasuhiro , Song Minghui
Published: June 2020

Many investigations and applications of the reversible shape memory (RSM) alloys have been carried out since they were found in 1960 and the mechanism have been discussed extensively.

In order to see the structure change of RMS-alloys in atomic scale on either side of the temperature of phase transformation, Ni-Ti alloy whose transformation temperature is 74 C has been heated inside of the 400kV (JEOL) electron microscope from room temperature to 230 C and atomic structure change has been recorded in TV and photographic films.

Fig. 1(a) shows a structure of the electro-polished thin film of Ni-Ti alloy in (001) projection at room temperature, in which a martensitic structure is seen. As indicated in the figure, repeating twin structure whose twin boundary (T.B) is (100) and periodic black and white (B-W) contrast anomaly parallel to (110) in each twin bands are seen.Fig.1(b) is the enlargement of a region S in (a), in which the lattice fringes of (010) are seen on either side of T.B and B-W. Very small fringe shift is seen between B-W bands.
Microdiffraction analysis of precipitate crystallography and morphology in Al alloys
Authors: Muddle B.C. , Hugo G.R.
Published: June 2020

Electron microdiffraction has been used to determine the crystallography of precipitation in Al-Cu-Mg-Ag and Al-Ge alloys for individual precipitates with dimensions down to 10 nm. The crystallography has been related to the morphology of the precipitates using an analysis based on the intersection point symmetry. This analysis requires that the precipitate form be consistent with the intersection point group, defined as those point symmetry elements common to precipitate and matrix crystals when the precipitate crystal is in its observed orientation relationship with the matrix.

In Al-Cu-Mg-Ag alloys with high Cu:Mg ratios and containing trace amounts of silver, a phase designated Ω readily precipitates as thin, hexagonal-shaped plates on matrix {111}α planes. Examples of these precipitates are shown in Fig. 1. The structure of this phase has been the subject of some controversy. An SAED pattern, Fig. 2, recorded from matrix and precipitates parallel to a <11l>α axis is suggestive of hexagonal symmetry and a hexagonal lattice has been proposed on the basis of such patterns.
Microstructure of a solidified Al-Si-Fe-Cu alloy
Authors: Hidalgo-Prada B. , Maldonado E.
Published: June 2020

Basic aspects of solidification can be examined by experimentation with the solidification processing followed by analysis of microstructural morphologies. The resultant structure depends on parameters such as the cooling rate, degree of undercooling, heat flow and growth rate.

In this work, a commercial aluminum alloy of Al - 5.98Si - 0.50Fe - 3.00Cu - 0.06Mn wt%, have been solidified at intermediate cooling rate.

Cylindrical specimens of 50 mm in diameter and 165 mm long were solidified from a superheating of 80 °C, by pouring the melt into steady state water-cooled metallic moulds. For microstructural analysis, small slices were cut from the ingot and prepared by polishing and etching using a solution of NaOH a t 70 °C by inmmersion for 5 minutes. The specimens were then cleaned in concentrated HNO3.The microstructural observations and x-ray microanalysis were done using an ISI-60 SEM.
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 HREM study of superstructures in Ca4Al6SO16
Authors: Wang Y.G. , Ye H.Q. , Kuo K.H.
Published: June 2020

A synthetic compound Ca4Al6SO16 (usually abbreviated as C4A3S) obtained by mixing CaO, A12O3 and CaSO4 powders and finally sintered at 1380°C is a cement with excellent hydraulicity and greatly expanding in application. It is hydralysed rapidly by water to form predominatly calcium aluminate hydrates and therefore unlikly to occur naturally, although structurally it may be regarded as an end member of the sodalite-hauynite series of naturally occuring minerals. C4A3S has a cubic structure with ao=9.19Å and space group . Fig.1 is the projection viewed down axis, in which there are two sets of 8C position in , namely CaI and CaII, occupied by the calcium atoms, respectively, and the ratio of occupations in these two sets of positions is about 3:1. This suggests that the calcium atoms can freely occupy these sites in various degrees and usually they almost locates on the CaI positions. A through-focus series of the lattice images were found in good agreement with the simulated ones. Each bright spot in the image taken at Scherzer defocus correspounds to a colunm of sulphur atom in the structural model (Fig.1).
Microstructure and microanalysis of silicon nitride ceramics in the Y-Si-Al-O-N and Y-Si-O-N systems
Authors: Cinibulk Michael K.
Published: June 2020

Silicon nitride ceramics are among the leading candidate materials for use in structural applications at high temperatures. Due to the highly covalent nature of the Si-N bond and therefore low self-diffusivity, processing Si3N4 to full density requires the use of additives to provide a medium for liquid-phase sintering. When exposed to temperatures above ∼1000°C the resulting amorphous grain-boundary phases soften, leading to grain-boundary sliding and the eventual failure of the ceramic. The objectives of this work were to modify the grain-boundary phase composition and then attempt to devitrify the resulting intergranular phase to a refractory crystalline phase, producing a sintered Si3N4 with improved high-temperature strength and oxidation resistance. Transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDS) were used to characterize these materials. This paper describes these results.
Quantitative stereological analysis of the pore-size distribution in a colloidal silica sol-gel
Authors: Kerch Helen M. , Gerhardt Rosario
Published: June 2020

The pore size distribution of an unsintered colloidal gel has been determined by stereological analysis of ultramicrotomed thin sections (70 nm) of the gel. This is a novel use of the ultramicrotomy technique as the epoxy represents the porous phase of the microstructure rather than just the medium used to maintain a coherent structure during thinning. In order to obtain statistically significant pore size information a nested sampling scheme was carried out, and a total of 36 two-dimensional fields taken at 19,000 X were examined. Pore diameters were measured with a digital image analyzer which measured 15 projected diameters every 12° from the center of the feature. Stereological quantities obtained were average pore diameter (Davg), number of pores per unit area (NA), and number of pores per unit volume (NV).
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.
Electron Microscopy and the Electronics Industry: Partners in Development
Authors: Brinkman W. F.
Published: June 2020

Since the invention of the transistor and the birth of the solid-state electronics industry, electron microscopy has been an integral part of the boom in the science and technology of semiconductors. The relationship has been symbiotic: the technique of microscopy has probably gained almost as much as the electronics industry from innovations. Historically, semiconductor research has always come down to a question of the growth of perfect materials with perfect interfaces, and microscopic analysis below the optical level has been essential to improvements. When applications for the semiconductors germanium and silicon were discovered in solid-state devices, its became necessary to grow high-quality single crystals free of defects. A lot of work at Bell Labs and other institutions was directed at understanding the behavior of dislocations in crystals. Bill Schockley, a co-inventor of the transistor, is well-known for his contributions to dislocation theory, particularly dislocation dissociation in semiconductors. Bob Heidenreich, from Bell Labs, contributed much to the early stages of microscopy of defects and dislocations. The need for dislocation-free material generated extensive efforts around the world which led to the growth of high-purity single-crystal silicon in the 1960’s. Silicon is now the highest quality and purest material available, and also the cheapest in single-crystal form.
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.