bluuebunny/crossref_metadata_2025 huggingface dataset:
The New Form Of The Zeta-Factor Method For Quantitative Microanalysis In Aem-Xeds And Its Evaluation
Authors: Watanabe M , Williams D B
Published: July 2020

For quantitative thin-film microanalysis using X-ray energy dispersive spectrometry (XEDS) in analytical electron microscopy (AEM) the Cliff-Lorimer ratio technique is widely applied. One of the critical steps in the ratio technique is to determine the aiff-Lorimer k factor relating the characteristic X-ray intensities to the compositions. The k factor can be determined experimentally with the relative error of ˜ ± 1%. So, the most accurate quantification can be performed using the experimental k factors. To determine the k factors experimentally, standard thin-filrns with known composition are required. Unfortunately, this is not always possible because such the standards may not be available. Even if all standards are available, many k factors should be determined in multi-component system. This is time consuming. These limitations in k-factor determination make thin-film quantification harder. This paper presents a new quantitative procedure for thin specimens to overcome these limitations.
Multiprobe Studies Of Interfaces In Complex Crystals Using Advanced Electron Microscopy
Authors: Zhu Yimei , Wu L , Volkov VV
Published: July 2020

The small probe size and high spatial resolution of TEM offer unique capabilities for studying interfaces of materials. Compared with neutron and x-ray diffraction, TEM is often considered nonquantitative. In HREM, especially, atomic images can alter significantly with imaging parameters that are often difficult to determine experimentally. The weakness of the HREM can be circumvented by a multiprobe approach, i.e., the combined use of a wide range of TEM techniques, such as B-F/D-F imaging, nano-probe EDS and EELS, electron diffraction, and strain-field characterization. Quantitative analysis, based on the calculations and experimental TEM data, is often necessary to correctly derive the crystal-, chemical-, and electronic-structure of an interface.

We review our multiprobe approach in studying interfaces in complex systems of superconductors, starting with the simplest interface, twin boundary, in YBa2Cu3O7-δ. Although HREM suggested that there are two types of twin boundaries, with and without a ˜d110 lattice translation at the boundaries, the structural characteristics of the interfaces were determined by analyses of the interfacial δ-α fringe and the associated diffuse scattering, while EELS revealed their association with the local oxygen/hole concentration.
Dynamics Of Grain Boundary Space-Charge Potential In Electroceramics
Authors: Johnson Kevin D , Dravid Vinayak P
Published: July 2020

A large number of bulk and thin-film electroceramic systems contain electrically active interfaces which dictate the various useful electronic properties of these devices. The electrical activity of these interfaces stems from a complex interplay among various interfacial attribute but often involves formation of some form of electrostatic potential at the interfaces which is modified under applied bias of current and/or voltage.

Figure la schematically shows charge distribution at a model grain boundary (GB), while Figure 1(b) shows its corresponding potential distribution. As shown in Figure 1(c), the energy band structure bends opposite to this built-in potential, causing a downward shift at the grain boundary. The difficulty with evaluating the Schottky barrier model, which is often invoked to explain GB electrical activity, is that the charge density distribution and therefore the band bending is expected to dynamically alter as bias is applied across the grain boundary. This variation adds another level of complexity to theoretical descriptions of the barrier behavior
Hrem Of General And Twist Grain Boundaries
Authors: Merkle K L , Thompson L J
Published: July 2020

The observation of atomic-scale structures of grain boundaries (GBs) via axial illumination HREM has been largely restricted to tilt GBs, due to the requirement that the electron beam be parallel to a low-index zone axis on both sides of the interface. This condition can be fulfilled for all tilt GBs with misorientation about a low-index direction. The information obtained through HREM studies in many materials has brought important insights concerning the atomic-scale structure of such boundaries. However, it is well known that tilt GBs occupy only an infinitesimally small fraction of the 5-dimensional phase space which describes the macroscopic geometry of all GBs. Therefore, although tilt GBs are very important due to their low energy, it would be usefulto also study twist GBs and general GBs that contain twist and tilt components.

We have prepared thin-film Au samples by an epitaxy technique in which (01l) and (001) grains are grown side by side.
Structural Determination Of A Novel Defect In SrBi2Ta2O9 Using Atomic-Resolution Z-Contrast Imaging
Authors: Yan Y , Xu Z , Lu X , Viehland D , Al-Jassim MM , Pennycook S J
Published: July 2020

Ferroelectric thin films have received much attention because of their nonvolatile ferroelectric random access memory (NVFRAM) applications. Recently SrBi2Ta2O9 (SBT), a bismuth-layered ferroelectric compound, has been recognized as a leading candidate for the NVFRAM applications because of its negligible fatigue, low leakage currents and ability to maintain bulk characteristics when fabricated in very thin films. While most work up to date has been focused on its thin film forms for nonvolatile memory applications, its intrinsic properties, basic structure and the effects of defects on the properties are not well understood, mainly due to the lack of sizable single crystals and the details of defects. In this paper we report the first direct determination of a novel planar defect structure in SrBi2Ta2O9, using high-resolution Z-contrast imaging.
Atomic Structure Of Epitaxial Thin Films Of The Srn+1tinO3n+1 Ruddlesden-Popper Homologous Series
Authors: Tian W , Jiang J C , Pan X Q , Haeni J H , Schlom D G
Published: July 2020

The n+1TinO3n+1 Ruddlesden-Popper homologous series are promising candidates in the search for low loss tunable dielectric materials. SrTiO3 (n=∞) has the perovskite structure with alternating TiO2 and SrO layers. However, those members of the n+1TinO3n+1 series with n≠∞ have tetragonal symmetry and space group 14/mmm. These phases are formed by inserting a rock-salt SrO layer every n SrTiO3 perovskites, resulting in a successive perovskite blocks being mutually sheared by [1/2,1/2,0] (Fig. 1).

Previously, the n = 1 - 3 members of this series have been made in polycrystalline form using solid state synthesis methods. Attempts to synthesize intermediate members (4≤n<∞) have been unsuccessful and resulted in mixed phase samples. Fortunately, significant advancement in epitaxial growth techniques makes it possible to control the synthesis of a wide variety of homologous oxide crystal systems. In the present work, thin films of the Srn+1TinO3n+1, RP series with n = 1 - 5 have been synthesized using reactive molecular beam epitaxy (MBE).
3d Mapping Of Light-Element Segregation In 316 Stainless Steel By Atom Probe
Authors: Kelly T F , Larson D J , Miller M K , Flinn J E
Published: July 2020

A vanadium-bearing variant of 316 stainless steel that was rapid solidification processed (RSP) by gas atomization and hot extrusion of the powder (10:1 extrusion ratio at 900°C) has been studied previously by conventional atom probe field ion microscopy (APFIM). The mechanical properties of this steel were markedly improved by RSP and aging (600°C for 1000 hours). High nitrogen (0.45 at% (0.2 wt%)) and oxygen (0.16 at% (0.05 wt%)) contents were intentionally introduced by melting under 80% nitrogen/20% oxygen gas and atomizing in nitrogen gas. A nominal boron concentration of 0.04 at% (0.01 wt%)) is present as a tramp element. As a result, a large number density (˜ 2 × 1021 m-3) of 25 nm plate-like vanadium-rich nitrides precipitate during aging of the alloy and these precipitates contribute a major portion of the strengthening. Previous efforts to locate the oxygen in the structure using APFIM were inconclusive largely due to poor counting statistics.
How Small Is Too Small ? Understanding The Electronic Structure Of Atomic-Scale Transistors
Authors: D. A. Muller  , Sorsch T , Moccio S , Baumann F H , Evans-Lutterodt K , Timp G
Published: July 2020

The transistors planned for commercial use ten years from now in many electronic devices will have gate lengths shorter than 130 atoms, gate oxides thinner than 1.2 nm of SiO2 and clock speeds in excess of 10 GHz. It is now technologically possible to produce such transistors with gate oxides only 5 silicon atoms thick[l]. Since at least two of those 5 atoms are not in a local environment similar to either bulk Si or bulk SiO2, the properties of the interface are responsible for a significant fraction of the “bulk” properties of the gate oxide. However the physical (and especially their electrical) properties of the interfacial atoms are very different from.bulk Si or bulk SiO2. Further, roughness on an atomic scale can alter the leakage current by orders of magnitude.

In our studies of such devices, we found that thermal oxidation tends to produce Si/SiO2 interfaces with 0.1-0.2 nm rms roughness.
The Si/SiO2 Interface: Atomic Structures, Composition, Strain And Energetics
Authors: Pennycook S J , Duscher G , Buczko R , Pantelides S T
Published: July 2020

A number of recent studies of grain boundaries and heterophase interfaces have demonstrated the power of combining Z-contrast STEM imaging, EELS and first-principles theoretical modeling to give an essentially complete atomic scale description of structure, bonding and energetics. Impurity sites and valence can be determined experimentally and configurations determined through calculations.

Here we present an investigation of the Si/SiO2 interface. The Z-contrast image in Fig. la, taken with the VG Microscopes HB603U STEM, shows that the atomic structure of Si is maintained up to the last layers visible. The decrease in intensity near the interface could originate from interfacial roughness of around one unit cell (∼0.5 nm), or may represent dechanneling in the slightly buckled columns induced by the oxide. Fig. lb, taken from a sample with ∼1 nm interface roughness, shows a band of bright contrast near the interface. This is not due to impurities or thickness variation since it disappears on increasing the detector angle from 25 mrad to 45 mrad (Fig. lc), and is therefore due to induced strain.
Characterization Of SiO2/Si Interface Using Secondary Ion Mass Spectrometry(Sims) And Laser Post-Ionization Sputtered Neutral Mass Spectrometry(Snms)
Authors: Hayashi S , Yanagihara K
Published: July 2020

SIMS has inherent difficulties with quantification because of the so called “matrix effect”. Many factors contribute to the matrix effect, e.g. differing concentration of oxygen, sputtering rate differences in the hetero-layers, etc. In the case of MOS(metal-oxide-semiconductor) structures, the oxide layer gives rise to a large matrix effect. It is thus very difficult to use SIMS to evaluate the relationship between the electrical properties of the LSI devices and the impurity profiles present in such systems.

So we have been studying laser post-ionization SNMS, which consists of TOF-SIMS apparatus and excimer laser, in order to quantify the impurity profiles around SiO2/Si interface. Depth profiles of implanted Cu with 1×1015 atoms/cm2 in SiO2(100 nm)/Si system taken by Monte-Carlo simulation,SIMS and laser post-ionization SNMS are shown in Fig.l. In this implantation condition the Cu+:Cu2+:Cu3+ percentage ratios of the charge distributions were 44:42:14. Fig. 1(a) shows the theoretical depth profiles expetted from this implantation condition by Monte-Cairo simulation.
Study Of Single-Wall Carbon Nanotube-Supported Platinum Catalyst For Selective Hydrogenation Of The Carbonyl Function On An (α,β-Unsaturated Aldehyde
Authors: Lordi V , Yao N , Wei J
Published: July 2020

Supported Pt-metal catalysts are of immense commercial importance for hydrogenation reactions. The fine chemicals industry relies on special catalysts that selectively hydrogenate specific bonds or chemical functions on molecules. The activity, selectivity, lifetime, etc. of a supported hydrogenation catalyst is wellknown to depend strongly on the chosen support, but systematic studies of the role of the support and of support-metal interactions are lacking in the literature. The purpose of this work is to examine in detail the function of single-wall carbon nanotubes (SWNT) as support for a Pt catalyst, in the context of a selective hydrogenation reaction. The test reaction consists of the hydrogenation of the carbonyl group on 3-methyl-2- butenal, a reaction extensively studied on well-characterized Pt surfaces and also unsupported polycrystalline Pt. This reaction, which follows a parallel/consecutive reaction network (Fig. 1), represents a class of selective hydrogenation reactions of α,β-unsaturated aldehydes that are important in the fine chemicals industry for flavorings, fragrances, and some pharmaceuticals.
Conservation of superstructure at Ag/Si(l1l)--R30-Ag Interface observed by UHV-TEM
Authors: Oshima Y , Sigeki S , Hirayama H , Takayanagi K
Published: July 2020

A lot of efforts have been devoted to understanding an interfacial structure. But, there are some difficulties about it as follows: An interfacial structure depends on a surface structure of a substrate and its temperature. Also, an interfacial structure is not homogeneous in general because of a lattice mismatch between a substrate and an overlayer thin film.

Ultrahigh vacuum transmission electron microscope (UHV-TEM) is very powerful to observe clean surface and the fabrication during deposition on the surface. Since structural information can be obtained from 10 nm-sized area to a few μm area using TEM, UHVTEM is very appropriate to investigate interfacial structure in detail.

In this study, structure of Ag/Si(111)--R30-Ag interface was observed by UHVTEM. Especially, it is interesting whether the superstructure is conserved at this interface or not. The Si(l11)- as the substrate surface was obtained by Ag 1ML deposition on Si(l11) 7×7 surface at 673 K.
Transmission Electron Microscopic Study Of Heteroepitaxial Mechanism Of Cvd-Dlamond Grown On Pt(Lll) Substrate.
Authors: Zhou Guofu , Takai Yoshizo , Shimizu Ryuichi
Published: July 2020

Owing to its unique and outstanding physical-chemical properties, diamond is considered to be one of the most important potential materials for applications such as in mechanical, optical, thermal, and electronic devices. Among them, the most attractive application of diamond would be a semiconductor for high temperature and high power electronic devices. To realize such novel devices, a high quality of defect-free single-crystal diamond film is required. Recently, continuous diamond films are found to be able to grow on Pt(lll) substrate. Since the diamond film synthesized on Pt shows a high degree of epitaxy, this approach has drawn the attention of reseafchers in this field and some research results have been reported. However, the heteroepitaxial mechanism is still to be elucidated; in particular, why does diamond grow heteroepitaxially on the Pt substrate and how do the atoms align in the interface between diamond and the Pt substrate? In order to solve those problems, it is very necessary to study the diamond growth mechanism on an atomic scale.
Statistical Assessment Of Experimental Uncertainty In The Quantitative Analysis Of Strong-Beam A-Fringe Contrast.
Authors: Cohen Dov , Barry Carter C
Published: July 2020

Grain boundaries and related planar defects in crystalline materials are often characterized by relaxations from geometric lattice constructions in order to lower the interfacial energy. Grain boundaries may relax by local reconstructions of the atomic structure along the interface and/or rigid-body lattice translations that perturb the relative positions of the grains far from the interface. Rigid-body lattice translations can by studied using α-fringe contrast along planar interfaces in strong-beam transmission electron microscopy (TEM) images.[l-3] Oscillatory fringe contrast may appear along an interface between two grains which are related by a translation vector, R, when the interface lies inclined to the incident electron beam and imaged with a diffraction vector, g  c, common to both grains.[4] The fringe contrast is due to an interference between the direct and scattered electron beams when the diffracted electron beams undergo a phase shift propagating across the interface. The phase shift, α, is proportional to the projection of R onto g  c (i.e. α = Rg  c) and the fringe contrast is known as α-fringe.
400 Kv Electron Cryo-Microscopic Imaging Of Large Icosahedral Viruses Towards Atomic Resolution
Authors: Jakarta Joanita , Chiu Wah
Published: July 2020

Three-dimensional structure studies provide important information about the organization of macromolecules, often revealing biological mechanisms and protein structure-function relationships. 400 KV electron cryo-microscopy is an emerging technology that is proving to be a powerful tool for studying the structures of large macromolecular assemblies that are often not tractable using other techniques. Its large depth of field makes it well-suited for imaging large objects to high resolution. In addition, a high accelerating voltage minimizes chromatic aberration yielding images of higher contrast. Recently a 400 KV electron cryo-microscope has been used to image periodic arrays of tubulin to 3.5 Å and single particles at somewhat lower resolutions (13 Å) providing practical demonstrations of its usefulness in modern structural biology. In this paper we present high resolution image data of two large icosahedral viruses: herpes simplex virus IB nucleocapsid (HSV IB) and rice dwarf virus (RDV). Human herpes virus (HSV) is associated with a spectrum of diseases ranging from cold sores to more severe clinical manifestations such as mental retardation.
Atomic-Resolution Z-Contrast Imaging Of Decagonal Quasicrystals: A Nucleation And Growth Mechanism
Authors: Yan Y , Pennycook S J
Published: July 2020

Though quasicrystals were discovered more than a decade ago, the fundamental questions of why and how quasicrystals form are still unanswered. Knowledge of atomic positions, for all species present, is the most important factor in trying to answer this question, and we have therefore applied Z-contrast imaging to this problem. The quasicrystalline structure, a state with long-range order, but no periodic translation symmetry, has been commonly described by the Penrose tiling model, in which two types of tile are connected according to strict matching rules. However, such a mathematical description does not provide any physical insight into how and why quasicrystals arise. An alternative description of the ideal quasicrystal has been given by Gummelt, who showed that the ideal quasicrystalline arrangement can be obtained with a single type of tile which is allowed to overlap so as to cover the surface. The equivalence of these two descriptions was proved by Steinhardt and Jeong.
Self-Assembling Of Ordered Mesoporous Titania Nanostructures
Authors: Yin JS , Wang ZL
Published: July 2020

Ordered self-assembly of nanocrystals is scientifically interesting due to not only the unique properties of the nanocrystals, but also the collective properties of the assembly. Compared to lithography method, self-assembly is limited by a lack of control over the sizes of the ordered arrays, resulting in difficulties in characterizing their physical and chemical properties. New techniques are needed to manipulate the self-assembling process and the nanostructures formed.

In this work, polystyrene (PS) spheres were used as the template to form large bulk ordered anatase nanostructure with cobalt doping. The ordered PS template was infiltrated with absolute alcohol solution of titanium butoxide. After the precursor was dried, it was treated at 160°C for 5 hours and then at 450°C for another 5 hours. To dope cobalt into the structure, the porous titania host was immersed in a heptane solution with cobalt carbonyl. After drying in vacuum at room temperature, it was treated at 160°C.
The Measurement Of Subtle Structural Changes In Yba2cu3O7-x By Processing High Resolution Tem Images
Authors: Barry JC , Alarco JA
Published: July 2020

Since the discovery of high temperature superconducting (HTS) ceramics there has been a great deal of discussion about theories of superconductivity. In a recent theory it has been proposed that the Tc's in these new materials are related in some way to a subtle phase separation in the structure. HTS ceramics have been studied quite intensively by high resolution transmission electron microscopy (HRTEM) and by electron diffraction (ED). In such studies the major focus invariably has been on the periodic structure of the object. However, early HRTEM work on Yba2cu3O7-x by Barry found that in addition to the crystalline order, the Yba2cu3O7-x HTS has a non-periodic structural modulation. In this work we have used an image processing method to look for subtle structural changes in Yba2cu3O7-x by measuring the bending of lattice fringes at twin planes. The image processing method is similar to the method used by Hetherington to study rigid body displacements at gold grain boundaries.
Soft Phonons and Anti-phase Domains in SrTiO3 : an Electron Diffuse Scattering Study
Authors: Wang Renhui , Zhu Yimei
Published: July 2020

It is well known that cubic SrTiO3 possesses a typical perovskite structure whose reciprocal unit cell is shown in Fig. 1 where X, M, and R designate particular points at Brillouin zone boundaries with the Γ point being the zone origin. The instability of the phonon mode designated by the R point leads to the cubic-to-tetragonal phase transition of SrTiO3 at Tc=103 K. By using the same unit-cell as the cubic SrTiO3, reflections (h k 1) / 2 with h, k, and 1 all odd are superlattice reflections characteristic of tetragonal SrTiO3. Previous investigations of diffuse scattering were carried out by neutron and xray diffraction at Temperatures below 240 K. In the present work, observation of the diffuse scattering was extended to a broad Temperature range of 20 ∼ 700 K.

Selected-area electron diffraction patterns (EDPs) reveal splitting and streaking of the superlattice reflections as shown in Fig. 2. We can see streaks along the [1 0 0]* direction, e.g., the streak connecting (5 3-5) / 2 and (7 3-5) / 2, the streak connecting (-3-5 7) / 2 and (-1-5 7) / 2. Splitting of the superreflections (7-1-1) / 2, (9-1-1) / 2, and (-7 1 1) / 2, along [0 1-1]* direction is evident. All the splitting and streaking behaviors shown in Fig. 2 and observed in other EDPs may be interpreted as being formed by the intersection of the Ewald sphere with reciprocal rods MRM shown in Fig. 1, which are along the <100>* direction passing through superlattice points.
Phase Identification Using EBSD in the SEM: What Can be Done Today and What we Hope to do Tomorrow
Authors: Michael J R
Published: July 2020

Phase identification using electron backscatter diffraction (EBSD) in the SEM has become a useful and important tool for the characterization of crystalline materials. Phase identification is accomplished using EBSD in the following manner. First, a high quality camera must be added to the SEM. Suitable cameras use slow scan CCD imagers coupled either by a lens or a fiber optic bundle to a phosphor screen that is situated near the sample. A EBSD pattern is collected and EDS or WDS is used to determine qualitatively the chemistry of the area. An automated routine is then used to extract the positions and widths of the lines in the pattern followed by a calculation of the unit cell volume. This information coupled with the chemistry of the sample is then used to search a database of crystal structures. Currently, the ICDD's Powder Diffraction file of over 100,000 compounds is used. Once a list of potential matches is found the patterns are indexed and then simulated to demonstrate that the phase has been identified. This paper will demonstrate use of EBSD for phase identification and then will speculate on future developments.

A particularly nice application of EBSD is the use of the technique for the identification of phases that form in welds. Figure 1a is an EBSD pattern obtained from a acicular phase in a superalloy weld. The phase was determined to be primarily Ti and Ni. Analysis of the patterns showed that the phase is Ni3Ti. Figure 1b shows the simulation for Ni3Ti overlaid on the experimental pattern demonstrating that the phase has been identified.
Texture Determination of Ceramic Materials by EBSD
Authors: Cosandey F , Markondeya Raj P , Cannon W R
Published: July 2020

Texture determination of ceramic materials is important in ceramic processing since it will ultimately govern the resulting material properties. For instance, recent results have indicated that preferred particle orientation leads to anisotropic shrinkage of tape cast ceramics. In this work, we report results on the effect of pressing as well as shearing during tape casting followed by sintering on particle orientation and texture development in ceramic materials. Oxides with different particle shape anisotropy and crystal structures have been investigated including tetragonal rutile titania (TiO2) and hexagonal alumina (A12O3).

Ceramic samples were processed by either pressing or by tape casting of a high ceramic particle loading aqueous suspensions. The samples were then pyrolized at 425°C followed by sintering for one hour at 1200 and 1500°C for TiO2 and A12O3 respectively. High spatial resolution Electron Backscatter Diffraction (EBSD) (OPAL-Oxford) in a field emission SEM (LEO-982) has been used for texture analysis and for crystallographic orientation determination of particles. Between, 3000 to 5000 measurements per sample were recorded automatically to develop an orientation map.
Texture Analysis of Earth Materials. Comparison of EBSD With Other Diffraction Techniques
Authors: Wenk H-R
Published: July 2020

An important feature of polycrystalline materials is the orientation distribution of crystallites also known as crystallographic preferred orientation or texture [1]. Conventionally it is measured by x-ray diffraction, averaging over sample surfaces. With demands for more quantitative material characterization, both in engineering and earth sciences, new methods have been developed. Two dimensions are of interest: Averages over larger sample volumes give a better representation to estimate bulk physical properties. Here neutron diffraction is advantageous. Because of minimal absorption large sample volumes (1-50 cm3), rather than surfaces can be analyzed [2]. If textures are locally heterogeneous, it may be of importance to analyze small regions. With a synchrotron microfocus beam volumes as small as 5 μm3 can be characterized [3]. These methods have been quantified and are extensively applied in metallurgy and geology. They provide good statistics for appropriate sample grain size but they analyze bulk textures and contain no information on local orientation correlations. Furthermore, for geological samples with low crystal symmetry, the diffraction patterns are often very complex with many overlapping peaks, making identification difficult. In such cases orientation imaging, using electron backscattered diffraction patterns (EBSD) in the SEM is useful [4]. Though grain statistics are generally much inferior, new information can be gained.
Extraction of Grain Boundary Energies from Triple Junction Geometry
Authors: Rollett A D , Yang C-C , Mullins W W , Adams B L , Wu C T , Bauer C L , Kinderlehrer D , Ta'asan S , Manolache F , Liu C , Livshits I , Mason D , Talukder A , Ozdemir S , Casasent D , Morawiec A , Saylor D , Rohrer G S , El-Dasher B , Yang W
Published: July 2020

Measurement of the geometry of triple junctions between grain boundaries in polycrystalline materials is used to generate large sets of dihedral angles from which maps of the grain boundary energy are extracted. A preliminary analysis has been performed for samples of magnesia and aluminum based on a three-parameter description of grain boundaries. An extended form of orientation imaging microscopy (OIM) was used to measure both triple junction geometry via image analysis in the SEM and local grain orientation via electron back scatter diffraction. Serial sectioning with registry of both in-plane images and successive sections characterizes triple junction tangents from which true dihedral angles are calculated. If there is local equilibrium at each triple junction, we may apply Herring's relation. By limiting grain boundary character to a (three parameter) specification of misorientation for the preliminary analysis, we can neglect the torque terms and apply the sine law to the three boundaries. This provides two independent relations per triple junction between grain boundary energies and dihedral angles. By discretizing the misorientation and employing multiscale statistical analysis on large data sets, (relative) grain boundary energy as a function of boundary character can be extracted from triple junction geometry. The results are discussed with respect to current understanding of grain boundary structure based on their crystallography. The results suggest that a three parameter characterization of grain boundaries (lattice disorientation) is not an adequate description of boundary character. A full analysis including torque terms and a five parameter boundary description is under development.
Grain Subdivision During Deformation Studied by Automatic EBSP
Authors: Juul Jensen D
Published: July 2020

During plastic deformation of typical metals the original grains subdivide. Subdivision by cell formation is a well-known phenomena in metals with medium to high stacking fault energy, but the subdivision may also take place on larger length scales by: i) Formation of single-walled dense dislocation walls (DDWs) and/or double-walled microbands (MBs). The DDWs/MBs are seen as elongated, nearly straight, vertically parallel dislocation boundaries which delineate several cells, thus bounding cell blocks. Typical examples are shown in Fig. 1. ii) Subdivision on a grain scale, for example due to grain-grain interactions or due to the formation of transition bands separating matrix bands. This subdivision is typical for both single crystals and polycrystals. For a general description and recent overview, see [1, 2].

The grain subdivision depends on the orientation of the grains. The morphology may appear different in grains of different orientations and the DDW/MBs can be parallel or inclined to a slip plane.
Investigation of γ/γ' Alloy by Simultaneous EDS and EBSP Analysis
Authors: Sutliff J A , Sitzman S D
Published: July 2020

This work describes an investigation of the microstructure of a γ/γ' Ni-base superalloy using the automated Electron BackScattering Pattern (EBSP) technique with simultaneous energy dispersive x-ray spectrometry (EDS). The goal of the investigation was to determine if EDS measurements necessary to discriminate γ' from γ' could be obtained when acquired simultaneously with a normal, high speed automated EBSP scan. The acquisition conditions that impact the EDS collection are: surface tilted ∼70 degrees from the beam axis, 70mm spectrometer to specimen distance limited by interference from the EBSP detector and approximately 300 ms available acquisition time.

Thermo-mechanical processing of superalloys can produce coarse γ' that appears both within grains and at grain boundaries. In some conditions, the coarse γ' may be as large as many γ grains. As the crystal structure of γ and γ' are very similar, it is not possible to discriminate between the two phases using typical EBSP analysis. However, one needs to discriminate these phases in order to measure properties of the γ matrix such as texture and grain size.
Mapping the Mesoscale Interface Structure in Polycrystalline Materials
Authors: Wu C T , Adams B L , Bauer C L , Casasent D , Morawiec A , Ozdemir S , Talukder A
Published: July 2020

Using the new method known as Orientation Imaging Microscopy (OIM), characterization of mesoscale aspect of the internal structure of polycrystalline materials in the two-dimensional section plane has become routine. However, in some applications which primarily focus either on the characterization of interface types or on their connectivity, OIM is rather inefficient since only the scan points that lie adjacent to the interfaces are used to determine interface character. When the OIM grid spacing is dictated by the precision with which the interfacial in-plane inclination must be determined in the section plane, the efficiency with which conventional OIM can harvest interfacial data is rather poor.

In this paper a new approach and system of microscopy is described, called the Mesoscale Interface Mapping System (MIMS). MIMS overcomes the challenges associated with OIM by directing the beam to the vicinity of interfaces which have been identified by a microstructural contrast image.
Electron Backscatter Diffraction. Characterization of Polyphase Materials
Authors: Medevielle A , Hugon I , Dugne O
Published: July 2020

Electron diffraction was observed in 1928 by Kikuchi. In electron diffraction, diagrams characteristic of the crystal lattice and the phase orientation are formed. Consequently, Venable, then Dingley recently developed electronic diffraction coupled with scanning electron microscopy. Their approach enables micrometric scale examination of a specimen obtained by simple metallographical preparation (polished surface). Since the 1980’s, this technique has benefited from strong technological and computerized development which have led to the sale of the first systems under the name of Electron Backscatter Diffraction (EBSD). Niobium is used in the cast industry of uranium to refine it (getter function). The strong affinity of niobium for carbon leads indeed to the formation of small precipitates of niobium carbides. Whereas carbon cannot be detected by EDS because of its high absorption by the niobium (absorption coefficient μ=29000), hardness measurement indicates the presence of carbides (HV30 = 2000), but without further information on the nature of those carbides.
Low Voltage Microanalysis and Imaging: Opportunities and Limitations of High-Resolution Analysis in Fe-SEM Instruments
Authors: Liu Jingyue
Published: July 2020

The use of a high-brightness field-emission gun and a high-resolution lens system in modern SEM instruments allows us to perform high-resolution chemical analysis and atomic-number contrast imaging of bulk materials at low voltages. Low voltage microanalysis is especially useful for analyzing surface coatings or deposits, catalyst particles, small inclusions or precipitates, and biological samples. In this report, we present useful applications as well as limitations of low voltage microanalysis in studying surface-related problems.

In the study of film formation on metal coupons for inhibiting metal corrosion in drinking water supplies, highly porous films were found to form on fresh metal coupons after treatment with various corrosion inhibitors. Figure 1a shows a low voltage (1.5 kV) SE image of a copper test coupon that was exposed to flowing water for a period of two months. The SE image clearly shows the porosity of the surface film and the presence of different phases.
On the Microanalysis of Small Precipitates at Low Voltage with a FE-SEM
Authors: Gauvin Raynald , Hovington Pierre
Published: July 2020

The observation of microstructural features smaller than 300 nm is generally performed using Transmission Electron Microscopy (TEM) because conventional Scanning Electron Microscopes (SEM) do not have the resolution to image such small phases. Since the early 1990’s, a new generation of microscopes is now available on the market. These are the Field Emission Gun Scanning Electron Microscope with a virtual secondary electron detector. The field emission gun gives a higher brightness than those obtained using conventional electron filaments allowing enough electrons to be collected to operate the microscope with incident electron energy, E0, below 5 keV, with probe diameter smaller than 2.5 nm. Furthermore, what gives FE-SEM outstanding resolution is the combination of new magnetic lenses with a virtual secondary electron (SE) detector. The new lenses are designed to reduce the spherical and chromatic aberration coefficients, giving a smaller probe size. Contrary to the conventional systems, the SE detector is located above the objective lens and it becomes a virtual or through-the-lens (TTL) detector. Therefore, the SE image is mostly made up of all SEs of type I, almost eliminating those of type II and III which are generated by the backscattered electrons inside the specimen as well as in the chamber. It has been shown recently that Nb(CN) precipitates in Fe, as small than 10 nm, can be imaged with a FE-SEM Hitachi S-4500 with the TTL detector.
High Spatial Resolution Low Energy Electron Beam X-ray Microanalysis
Authors: Barkshire IR , Karduck P , Rehbach W , Richter S
Published: July 2020

Conventionally, x-ray microanalysis on scanning electron microscopes (SEM) with energy dispersive spectrometers (EDS) has been performed with relatively high primary energies (>10 kv). for most samples this results in reasonably good separation of the generated x-ray line series from different elements enabling unambiguous identification and therefore accurate qualitative analysis. Under these circumstances it is widely accepted that quantitative analysis of polished bulk samples is possible on a routine basis with relative errors around 1-5% and detection limits of the order of 0.1%.

However, in order to address the analysis requirements of new advanced materials with sub-micron features, there is growing interest in performing x-ray microanalysis at low beam energies(<5kv). this is now a more realistic goal due to the routine availability of field emission sem's which can operate with much improved beam sizes at low beam energies with sufficient beam current to perform practical microanalysis, in conjunction with the improved low energy performance of current, commercially available EDS systems.
Low Voltage ED-X-ray Microanalysis of Bulk Organic Materials
Authors: Echlin Patrick
Published: July 2020

An earlier investigation had shown that it is possible to perform quantitative energy dispersive x-ray microanalysis at primary beam voltages as low as 5kV on bulk biological material maintained in either the fully frozen hydrated or the dried state. This present study extends the earlier work and provides data which shows that the same type of analysis can be achieved at voltages as low as 3kV on organic samples composed primarily of hydrogen, carbon and oxygen which contain varying amounts of bromine, sulphur and chlorine. Such materials are equally beam sensitive as fully frozen hydrated biological samples and range in density from 1.1 to 2.2kg.m3. The samples fall into three main classes. 1. Chlorinated and/or sulphonated organic polymers. 2. A brominated organic sample. 3. Three experimental brominated plastics kindly supplied by Ms. B.S.Chuah, Melville Laboratory for Polymer Synthesis, Cambridge University. The remaining samples were purchased from Aldrich Chemicals at the highest purity available. The atomic weight percent and density was calculated for each of the eight specimens using the Electron Flight Simulation™ software programme.
LVEDS For Advanced Materials and Semiconductor Technologies
Authors: Boyes E D
Published: July 2020

The need to analyze bulk samples containing features with submicron dimensions has driven revaluation of the processes controlling the interaction of electron beams with inorganic, polymer and semiconductor materials, and to development of LVEDS analysis at lower beam energies of E0 <5kV (1,2).

It has previously been shown (1,2) that the physics is much as expected with the vertical penetration range (R) along the beam direction in many cases predicted quite accurately for beam energy E0 by the simple Bethe (e.g. in 3) power law with R = F(E0)5/3. These same factors are effective to varying degrees in all three dimensions. The strong dependence of the range on energy has practical importance for the identification of sub-micron particles, including to help to determine the root cause of a defect Fig. 1 is an example of the sequential analysis of the exact same sub-micron particle, with the very real potential for a processing disaster, on the surface of a silicon wafer. When this feature is analyzed with a 3kV electron beam we learn it is alumina (A12O3). The analysis comes only from the target particle and the data have a simple relationship to the chemistry and the sensitivity for the light element (O) is excellent, providing simple and direct qualitative identification of the oxide compound.
NETSEM Collaborator - an Application in Telemicroscopy
Authors: Breton BC , Chand G , Howard PJ , Caldwell NHM , Holburn DM
Published: July 2020

Telemicroscopy, sometimes called remote microscopy, is an expanding set of microscopy techniques, made possible by the advent of ubiquitous and pervasive Internet technologies such as the World Wide Web. Recently, telemicroscopy has moved from laboratory prototypes to commercially available software. This paper discusses a real-world application of telemicroscopy in terms of a microscopy consultancy service offered by ERA Technology Ltd. in Leatherhead, UK.

Many organisations require microscopical services on an occasional basis. These needs are not however, sufficiently frequent as to justify the purchase and upkeep of an SEM or the recruitment and retention of a trained instrument operator Such organisations employ consultancy firms to perform the required analyses. In many such consultancies, a sample is sent to the microscopist with appropriate instructions. Once the investigation is complete, the consultant returns sample, micrographs and other results. The SEM service run by ERA has always offered its customers the opportunity for personal participation in any investigation, by attendance at SEM sessions at the Leatherhead laboratory.
A Miniature Low Voltage SEM with High Resolution
Authors: Krans JM , van Rooy TL
Published: July 2020

Miniaturization of electron optical systems has gained much interest over the last decade [1,2]. In a scanning electron microscope, downscaling of the column dimensions is expected to allow for high resolution imaging at low electron beam voltage. Main advantages of low voltage imaging are lower penetration depth, increased secondary electron yield, less specimen charging and better topographic contrast [3].

We have developed a miniature scanning electron microscope (SEM) with high resolution at low beam energies. The outer dimensions of the miniaturized SEM column are 25 mm diameter and 95 mm length, including conventional field emitter electron source module. The column prototype is shown in Fig. 1. The size reduction has been achieved by the exclusive implementation of electrostatic column components. Electron optical simulations indicate that the retarding objective lens of the miniature SEM allows for a probe resolution of 3 nm at 1 keV beam energy. The secondary electrons are collected at an internal scintillator detector.
Thermophile Endospores have Responsive Exosporium for Attachment
Authors: Panessa-Warren B , Tortora George T , Warren J , Sabatini R
Published: July 2020

Recently studies examining the colonization of Clostridial pathogens on agar and human tissue culture cells, demonstrated that (C. sporogenes ATCC 3584, C. difficile ATCC 43594 [patient isolate], C. difficile ATCC 9689 [non-clinical], C. clostridioforme [patient isolate]) bacterial spores (endospores) of the genus Clostridia have an outer membrane that becomes responsive at activation and exhibits extensions of the exosporial membrane that facilitate and maintain spore attachment to a nutritive substrate during germination and initial outgrowth of the newly developed bacterial cell. Therefore this attachment phenomenon plays an important role in insuring bacterial colonization of a surface and the initial stages of the infective process. To see if other non-clinical members of this genus also have this ability to attach to a substrate or food-source during spore germination, and how this attachment process in environmental thermophiles compares to the clinical paradigm (in relation to time sequence, exosporial membrane structure, type of attachment structures, composition of the membrane etc.), sediment samples were collected in sterile transport containers at 4 geothermal sites at Yellowstone National Park in Wyoming.
Removal of Contamination Deposits from Defects on Thin Film Magnetic Disks by Oxidative Cleaning Inside the SEM
Authors: Myers Sharon , Vane Ronald
Published: July 2020

Scanning Electron Microscopy (SEM) of thin film magnetic disk defects is challenging due to lubricant on the disk surface. The lubricant aids disk durability but interacts with the electron beam to form a contaminantation layer over the area of interest. A new cleaning technology allows the removal of the surface contamination while the specimen is in the SEM.

Plasma dry ashing of SEM samples to remove surface hydrocarbons is a well-known technique for specimen preparation. A number of commercial external plasma cleaning units are on the market for sample preparation outside the microscope. Zaluzec developed a technique for plasma cleaning the specimen and stage together prior to insertion into the analytical region of the electron microscope. But similar plasma cleaning within the SEM chamber must be avoided due to ion bombardment damage to the SEM and the deleterious effect of argon plasmas on ion pumps. XEI Scientific has developed a new device that creates neutral oxygen radicals from air. This technique oxidizes surface hydrocarbons into volatile gases that are easily carried away to the roughing and diffusion pumps.
In-Situ HREM Observation of Reduction of PdO to Pd Metal
Authors: Crozier Peter A , Datye Abhaya K
Published: July 2020

A detailed understanding of phase transformation mechanisms in small particles is critical for the design of small metal particle catalysts and nanophase materials. For palladium supported on silica, it is known that under certain conditions, reduction of PdO can lead to the formation of small Pd metal particles containing central faceted voids[l]. In-situ microscopy studies show that the voids form when PdO is reduced at temperatures between 200 and 400°C but collapse when the temperature reaches about 550°C [2]. Here we present in-situ high resolution microscopy showing the details of the void formation process.

Model Pd/SiO2, catalysts were prepared by dispersing Pd metal over silica microspheres using techniques described elsewheretl]. The Pd/SiO2, catalyst were fully oxidize°C for 2 hours. The catalyst was crushed and dispersed over Mo grids and plasma cleaned to remove any residual carbonaceous material. A Philips CM 200 with a slow scan CCD camera and video recording system was used to recording HREM images during in situ reduction at 200°C.