bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grain Boundary Engineering for Intergranular Fracture and Creep Resistance
Authors: Palumbo G. , Lehockey E.M. , Lin P. , Erb U. , Aust K.T. 
Published: June 2020

Previous studies (see review) have shown that grain boundaries crystallographically described by low Σ Coincidence Site Lattice (CSL) relationships can often display a high resistance to intergranular sliding, cavitation, and fracture; these boundaries satisfying Brandon’s criterion (Δθ≤15°Σ−1/2), for Σ≤29. Figure 1 summarizes the grain boundary structure-dependence of intergranular cracking on stressed C> rings (0.5% strain) of Alloy 600 (75Ni-15Cr-10Fe) following autoclave exposure to 10% NaOH at 350°C for 3000 hours. Grain boundaries connected to intergranular crack paths were characterized using electron backscattered diffraction (EBSD) in a SEM. As shown in Fig. 1, general grain boundaries (Σ≤29) are the preferred paths for intergranular cracking; ‘special’ grain boundaries (Σ>29) show a high resistance to intergranular attack.In quantifying the effect of ‘special’ grain boundary frequency on bulk intergranular cracking susceptibility, a geometric model has been formulated which considers that a propagating crack can arrest at a triple junction when both of the available intergranular paths for crack continuation are inaccessible owing to either (1) intrinsic resistance to cracking (e.g., low Σ CSL grain boundary) or (2) unfavourable orientation to the applied stress axis. Figure 2 summarizes the effect of ‘special’ grain boundary frequency on the probability of intergranular crack propagation as predicted by this model. Increasing the fraction of ‘special’ grain boundaries by only moderate amounts can considerably reduce the maximum attainable intergranular crack length in a material. For example, the probability of a crack propagating beyond 5 grain diameters is approximately 35% in a material having 15% special grain boundaries; the probability is reduced to approximately 1% in a material containing 45% ‘special’ grain boundaries, and to less than 0.001% in a material containing 75% special grain boundaries. These concepts have been recently applied in developing a proprietary thermomechanical processing methodology which serves to increase the frequency of special grain boundaries in austenitic stainless alloys to values in excess of 60%; such a treatment having been demonstrated to render Alloy 600 (see Fig. 1) immune to intergranular cracking.
Equilibrium Shapes of Pb Inclusions at 90° Tilt Grain Boundaries in Al
Authors: Johnson E. , Dahmen U. , Xiao S.-Q. , Johansen A. 
Published: June 2020

Ion implantation of lead in aluminum leads to spontaneous phase separation and formation of dense distributions of nanosized lead inclusions[1]. The inclusions have fee structure, and despite the large lattice mismatch (aA1 = 0.4048 nm and aPb = 0.495 nm) they grow in parallel-cube topotaxy with the matrix. Their shape is cuboctahedral with larger {111} facets and smaller {100} facets which is the minimum- energy shape for an fee crystal in equilibrium with its vapor, as calculated by considering only nearest neighbor bonds. Implantation of polycrystalline aluminum films is accompanied by preferential nucle- ation and enhanced growth of inclusions in the grain boundaries. In adapting their equilibrium shape, grain boundary inclusions will be subject to a larger number of constraints than inclusions in the bulk matrix. This may result in a variety of morphologies characteristic for different types of grain boundaries.In the present study we have used a well-defined bicrystal geometry to study the morphology and structure of lead grain boundary inclusions in mazed bicrystal aluminum films containing mainly 90°<110> tilt boundaries with fixed misorientation but variable inclination[2]. It was found that the shape, size and orientation of the inclusions in the grain boundaries depend on the inclination, i.e. the orientation of the grain boundary plane. Inclusions were all single crystalline and invariably faceted toward one aluminum grain and more rounded toward the other grain (fig.l). Independent of grain boundary inclination, the faceted side was a section of the cuboctahedral equilibrium shape of inclusions in parallel topotaxy with the bulk aluminum matrix. The rounded side, where the inclusions were rotated by 90° with respect to the aluminum lattice, approximated a spherical cap consisting partly of somewhat flatter segments with complex faceting, illustrating the lack of distinctly flat low-energy facets.
1/60 Sec Time-Resolved High-Resolution Electron Microscopy of Step-Diffusion of Tungsten Atoms on MgO (001) Surfaces
Authors: Tanaka N. , Kimata H. , Kizuka T. 
Published: June 2020

Surface-diffusion process of atoms is one of the important factors for understanding various types of surface-related phenomena such as thin-film growth and catalysis reaction[l]. Development of field ion microscope (FIM) was a great breakthrough for the study of the process in atomic level. The diffusion process of Rh and Re atoms on tungsten surfaces was quantitatively studied, and the barrier potential (Ed) and the pre-exponential factor (D0) were successfully determined[2]. Recent development of scanning tunneling microscope (STM) has also enabled us to measure directly the moving of Pb and Sb-atoms on Ge and Si (111) surfaces[3, 4]. The time-resolution of these methods is, however, not sufficient to trace the diffusion process in detail.In previous papers, we reported the first experiment of tracing the diffusion process of tungsten(W)-atoms on terrace-regions of MgO (001) surfaces in the time-resolution of 1/60 s.using dynamic high resolution electron microscopy[5,6]. The values Ed=0.18 eV and Do=1.5x10−14 cm2/s were successfully determined from the video-tape images. In the present study, we have observed diffusing atoms along the surface-steps and studied the phenomena quantitatively.
Development of an SEM Digital Image Capture and Storage System and Associated Distributed Viewing Interface
Authors: Chu Benjamin R. , Moran Patrick B. , Schaedler Joseph B. 
Published: June 2020

The advent of cheaper and faster network, desktop and storage products coupled with maturing digital image capture technology for microscopy tools is allowing for innovative ways to enhance the way microscopy images are captured, stored and viewed. The SEM Laboratory at IBM’s Advanced Semiconductor Technology Center (ASTC) is trying to leverage the combination of networked computing power and image capture technology to reduce costs, improve productivity and provide our internal customers with a product that better fits into their overall data analysis and documentation strategy.ASTC's SEM Lab provides physical analysis support for over 200 semiconductor engineers working on advanced memory and logic process technologies. Over 15,000 requests (or jobs) are submitted annually to the SEM Lab which result in several hundred thousand images which are used to monitor in-line process lots, verify experimental lots and to aid in failure analysis. The original thrust of this project was to reduce the SEM Lab annual film budget (∼$400K), but changing customer needs necessitated a system that would also allow for storage, retrieval and viewing of captured SEM images.
A WWW Interface for Viewing and Searching Sets of Digital Images
Authors: Thompson Mary , Bastacky Jacob , Johnston William 
Published: June 2020

As microscope images are increasingly being created and stored digitally, researchers are in need of tools to help them organize and quickly search these collections. Because of the large amount of storage taken up by digital images they are frequently kept on bulk storage systems remote from the microscopist’s PC or workstation. The interface to these mass storage systems may be awkward and viewing large, remotely stored images can be very slow, making it difficult for the user to find a desired image.The LBNL Image Library was designed and implemented to provide a system to help researchers organize, browse and search through digital image collections, especially collections where the original images are stored off-line in a mass storage system. We also wanted to facilitate co-operative research by allowing access to the images by specified users at local and remote sites.
Virtual SEM 1.2 - Training in SEM
Authors: Griffin B.J. , Riessen A. van 
Published: June 2020

The greatest barrier to effective training in electron microscopy is the initial apprehension within students based on the complexity and cost of the instrumentation. A second, and today more real barrier, is the actual cost of hands-on training in courses, in terms of both instrument and staff resources. The software described below was developed to eliminate these barriers, to include a ‘fun’ component to relax students, to improve the effectiveness of short training courses and to act as a stand-alone resource for new SEM operators.A software package utilising multimedia components, “Virtual SEM 1.2”, has been developed to simulate the use and operation of a basic scanning electron microscope (SEM). Background SEM theory is provided through introductory tutorials and an automatic assessment section allows independent evaluation of student progress. The package is appropriate for entry level operator training and also as a reference for general operation.
Sub Surface Imaging Using a Toroidal Backscattered Electron Energy Spectrometer in a Scanning Electron Microscope
Authors: Rau E I , Robinson VNE 
Published: June 2020

In a SEM, an object under examination is scanned by a focused electron beam, of energy typically 2-30 keV. Some of the incident electrons are scattered out of the sample, carrying with them depth information from the internal structure of the sample. By detecting BSEs in a definite energy range, it is theoretically possible to separate images of individual layers of a three-dimensional sample, ie, perform a kind of instrumental tomography. Additionally, detecting BSEs on an energy separation basis gives another degree of freedom to microscopists to determine greater specimen information. To do this, a suitable BSE energy filter or spectrometer is required.To be effective and produce high quality images, a BSE spectrometer should have a working distance of less than 40 mm. It should be axially symmetric with the electron beam passing through the center of the analyser, impinging on the specimen normal to its surface. The specimen being scanned must be placed in the space free from the analysing field of the spectrometer, which should not introduce any magnetic fields. Using these criteria, computer simulations were performed to determine the equipotentials and trajectories of electrons in cylindrical, hyperbolic, sector spherical and sector toroidal electrostatic energy analysers. The results showed that the above requirements could be satisfied by a toroidal energy analyser, which also has the advantage over the others as to the coupling coefficient, relative aperture dimensions and energy resolution capabilities.
Stem Dark-Field Image Using A 200-kV AEM
Authors: Tomita T. , Honda T. , Kersker M. 
Published: June 2020

Interpretation of the high resolution transmission image typically requires simulation since the contrast changes in a complicated way due to changes in focus and specimen thickness. The contrast in images formed by collecting high angle forward scattered electrons in STEM does not change with changes in thickness or defocus.Until recently, high angle annular dark field (HADF) images were obtained only from instruments using cold field emission guns. Recently we have attempted to obtain HADF images using Schottky (ZrO/W(100)) thermal field emission and using a 200kV instrument designed as a comprehensive TEM/STEM. Advantages of the ZrO/W emitter are easy operation, very good short and long term stability, high brightness, and narrow energy spread. This microscope, The JEM2010F with thermal field emission, allows subnanometer analysis with EDS(spot, line, and mapping), EELS, holograms, etc, and has a standard TEM imaging system for high resolution imaging and for various diffraction modes, viz., CBED, selected area, Tanaka, etc.
The limitations of quantitative EDS analysis at low voltage
Authors: Nockolds C. E. 
Published: June 2020

There are several reasons for carrying out x-ray microanalysis at low beam energies. In conventional electron probe microanalysis with wavelength dispersive spectrometers (WDS) there has been a considerable effort in recent years to improve the accuracy of quantitative analysis of the “light” elements B, C, N and O. The shapes of the low energy K x-rays and the L x-rays of the first transition series metals are also being studied with the aim of determining the chemical environments of the atoms in a sample. In most materials these soft x-rays suffer from very high absorption, and reducing the depth of the interaction volume by lowering the beam voltage to 5kV or below leads to a much reduced absorption correction. In scanning electron microscopy the introduction of thin window energy dispersive spectrometers (EDS) has made it possible to look at low energy x-rays and here the main interest in working at low voltages is in the improvement of the resolution of analysis.In this paper the limitations of SEM/EDS low voltage analysis will be examined, and possible solutions to some of the problems explored. It will be assumed that the aims are to achieve quantitative analysis at the best possible spatial resolution.
A simulation program for quantitative procedure in EPMA
Authors: Merlet Claude 
Published: June 2020

In the last ten years the development of new X-ray depth distribution models in electron probe microanalysis (EPMA), has allowed to obtain accurate quantitative programs for stratified and massive samples. With these new quantitative methods, for the energy lines greater than 1keV and for massive samples, the results of the quantification are independent of the accelerating voltage (for an excited line). Nevertheless, for light elements, and for soft X-ray emission in complexe compounds, the choice of these optimum experimental conditions is not trivial. Moreover, the physical parameters and boundary conditions of the measurements are not well known.In an attempt to choose the optimum accelerating voltage, and to solve some difficulties in the quantification of low energy lines, a software (freeware) has been developed on PC and under the WINDOWS operating system. The calculation procedure is based upon the double partial gaussian profile ϕ(ρz) (recently developed for massive compounds). This description, flexible, precise and mathematically simple allows to compute rapidly the X-ray intensities. The program, which has been designed mainly for WDS electron probe, uses graphic simulations, and includes two sections:
Chemical Effects of Lanthanides and Actinides in Glasses Determined with Electron Energy Loss Spectroscopy
Authors: Fortner Jeffrey A. , Buck Edgar C. , Ellison Adam J. G. , Bates John K. 
Published: June 2020

The chemical and structural environments of f-electron elements in glasses are the origin of many of the important optical, electronic, and magnetic properties of materials incorporating these elements. Thus, the oxidation state and chemical coordination of lanthanides and actinides in host materials is an important design consideration in optically active glasses, magnetic materials, perovskite superconductors, and nuclear waste materials.The energy loss spectra of the lanthanides are characterized by sharp 3d3/2→4f5/2 (M4) and 3d5/2→4f7/2 (M5) lines, the relative intensities of which are determined by the 4f-shell occupancy of the excited ion. For the light lanthanides, the dependence of these relative peak heights on 4f-shell occupancy is quite pronounced. In particular, the ratio of the M4 to M5 peak areas in the second derivative spectra is extremely sensitive to the formal valence of the multivalent elements Ce and Pr. In figure 1, the EELS spectra are presented for Ce(III) and Ce(IV) in well-characterized reference materials.
Determination of local dielectric function in donor-doped barium titanate
Authors: Katti Kalpana S. , Qian Maoxu , Sarikaya Mehmet 
Published: June 2020

Barium titanate (BaTiO3) is one of the basic materials for electroceramic components and is also used for electrooptic applications. When certain donor dopants such as Nb are introduced, it exhibits the property of positive temperature coefficient of resistance (PTCR) wherein there is a jump in resistance of several orders of magnitude at the transition temperature (∼ 120°C). Although considerable work has been done to understand the influence of dopants on bulk samples, it is not clearly known what the detailed distribution of the dopant is and how it affects local properties.This paper addresses the problem of how the addition of Nb affects local properties of BaTiO3. This is done by using electron energy loss (EEL) spectroscopy which probes the local electronic structure. We use the Kramers-Kronig (KK) analysis to compute the local dielectric function from the low loss electron energy loss data.
Integrated computer data acquisition and control in analytical electron microscopy
Authors: Weiss J. K. , de Ruijter W.J. , Cosart Douglas. W. 
Published: June 2020

Computers were considered to be mainly “add-on” equipment for analytical electron microscopes until only the last several years. Before that time, although most microscopes had been microprocessor-controlled for at least five years, the only use of more conventional computers was for controlling spectrometers connected to the microscope. The fundamental limitation of computers for scanned imaging was mostly one of speed. Spectra could be acquired and displayed in real time even by computers of early 1980’s vintage, whereas only modern computers are capable of acquiring and displaying video rate digital scanned images.The result of this fundamental difference in signal rates between imaging and spectroscopy is that separate computer systems have been developed for imaging and spectroscopy. Even in the cases where spectroscopy systems (most notably EDX systems) have integrated some image acquisition capabilities, or where imaging systems have integrated some spectroscopy, the design of the systems is virtually always centered around either imaging or spectroscopy.
Extracting 3-D information from SEM and TEM images: approches and applications in the physical sciences
Authors: L’Espéranee Gilles , Dionne Martin , Jeulin D. , Demarty C. H. , Tremblay S. , Perrier E. 
Published: June 2020

Techniques for extracting 3-D information from TEM samples in life sciences have considerably progressed in recent years. One approach has been the use of serial sections prepared by ultramicrotomy from which the volume of the sample and of various constituents can be reconstructed.In the case of engineering materials, however, ultramicrotomy generally induces severe deformation resulting in a large density of structural defects (dislocations, stacking faults etc.). This leads to significant diffraction contrast effects which mask microstructural features such as second phase particles, precipitates etc. Recently, a series of TEM bright field images taken at different tilts have been used in combination with image analysis to determine the volume fraction (Vf) of second phase particles in thin foils of aluminum alloys. Although the technique was successful to remove most of the diffraction contrast effects and to make the particles visible, the need to acquire and process a large number of images makes the technique laborious and can lead to artefacts.
Role of microstructure in determining the tribological properties of ceramic materials
Authors: Doğan C.P. , Hawk J.A. 
Published: June 2020

It is well known that experimentally-determined values of wear resistance are not materials’ constants, but rather measured responses to a particular set of conditions imposed by a specific wear environment. Nonetheless, a material’s tribological performance is often estimated based on its bulk material properties. For applications requiring abrasive wear resistance, for example, ceramic materials are traditionally selected based on their hardness and fracture toughness, which are assumed to be proportional to the wear resistance. However, recent studies have indicated that for many commercially-important ceramic materials, subtle differences in the microstructure (not always reflected in measured values of bulk hardness and fracture toughness), can lead to large variations in the abrasive wear resistance.A number of microstructural variables can influence the tribological properties of a ceramic material: matrix grain size, matrix grain shape, the presence of intra-and inter-granular second phases, and the presence of transforming second phases (in zirconias and zirconia-toughened ceramics, for example).
TEM/AEM characterization of fine-grained clay minerals in very-low-grade rocks: Evaluation of contamination by empa involving celadonite family minerals
Authors: Li Gejing , Peacor D. R. , Coombs D. S. , Kawachi Y. 
Published: June 2020

Recent advances in transmission electron microscopy (TEM) and analytical electron microscopy (AEM) have led to many new insights into the structural and chemical characteristics of very finegrained, optically homogeneous mineral aggregates in sedimentary and very low-grade metamorphic rocks. Chemical compositions obtained by electron microprobe analysis (EMPA) on such materials have been shown by TEM/AEM to result from beam overlap on contaminant phases on a scale below resolution of EMPA, which in turn can lead to errors in interpretation and determination of formation conditions. Here we present an in-depth analysis of the relation between AEM and EMPA data, which leads also to the definition of new mineral phases, and demonstrate the resolution power of AEM relative to EMPA in investigations of very fine-grained mineral aggregates in sedimentary and very low-grade metamorphic rocks.Celadonite, having end-member composition KMgFe3+Si4O10(OH)2, and with minor substitution of Fe2+ for Mg and Al for Fe3+ on octahedral sites, is a fine-grained mica widespread in volcanic rocks and volcaniclastic sediments which have undergone low-temperature alteration in the oceanic crust and in burial metamorphic sequences.
Transmission electron microscope observation of diamond / WC interface
Authors: Kim Geun-Hong , Chun Chang-Hwan 
Published: June 2020

Commercial diamond coated WC-Co cutting tool has been investigated by transmission electron microscope (TEM) to understand the nucleation and growth of diamond on WC substrate. Cross-sectional specimens have been prepared by mechanical polishing followed by ion milling. TEM observations have been performed using analytical TEM, JEM 4000FX (JEOL Ltd.).The surface of the coated diamond is composed of grains of 2 - 5 μm in diameter. Each main grain is formed by columnar subgrains of 10 - 50 nm in diameter with similar orientations. Cobalt, a binder in cemented carbide, within 5 μm in depth from the carbide surface has been found to be removed to increase the adhesion of diamond.One of diamond subgrains, which has been grown large in [001] orientation on WC grains is shown in Fig. 1. High density of twins are found on (111) plane starting from WC grain boundaries. It is thought that the interfacial stress between diamond layer and WC grains is accommodated by these twins.