bluuebunny/crossref_metadata_2025_split huggingface dataset:
EDXS in the electron microscope: The hardware
Authors: Garratt-Reed Anthony J. 
Published: June 2020

The hardware employed for microanalysis by energy-dispersive x-ray analysis in the electron microscope consists, logically enough, of two principal parts, i.e. the electron microscope and the x-ray detector/analyzer combination. There are a number of excellent sources which discuss in depth how these work and interact to allow an analysis to be performed, and how to obtain the best possible results.The basic principle of operation of an energy-dispersive x-ray detector is as follows: a small piece of single-crystal intrinsic semiconductor (typically silicon doped with lithium for compensation, although high-purity germanium detectors are for some applications an attractive alternative) about 10-30 mm2 in area by 2-3 mm thick is subject to a moderate electric field, generated by applying a bias of about 500V between electrodes plated on the two opposite faces of the crystal. When an x-ray enters the crystal, it ionizes one of the atoms of semiconductor, generating a photoelectron of well-defined energy (i.e. the energy of the incoming x-ray less the ionization energy of the excited energy level). The photoelectron travels through the crystal, ionizing further atoms as it goes, each ionization requiring on average 3.86 eV (in the case of silicon detectors).
Semiautomatic liquid-nitrogen delivery system for safe refilling of overhead instrument dewars
Authors: Behrens Melanie A. , Laurion Tristan A. , Yanarella James A. , White John E. , Landol Marie D. 
Published: June 2020

On many instruments, a liquid nitrogen dewar is positioned above the easy reach of a person who has to refill it regularly. Under these circumstances, it is necessary to devise a safe way with which to add LN2 without the operator coming in contact with this potentially hazardous cryogenic liquid. We have such a LN2 dewar on an energy dispersive X-ray detector for a scanning electron microscope in our laboratory. Refilling the dewar is performed about every three days. Because refilling is not needed every day and because we wished to be present when filling, we chose not to fully automate the delivery system. Instead, we designed a semiautomatic delivery system which allows us to push a button to start delivery and yet shuts off automatically when the dewar is full.A low level sensor is already included as part of the EDX system. This sensor fits along the cap and the probe reaches down inside the dewar canister. When the level of LN2 drops below the probe tip an alarm sounds.
Developments in TEM for life-science research
Authors: Lücken U. , Busing Wim M. , Felsmann Michael , de Jong Frank , Otten Max T. 
Published: June 2020

The study of Life Science materials with the TEM faces a number of problems such as low contrast in unstained specimens and specimen sensitivity to electron-beam damage and poor vacuum. Providing solutions to these problems has been the basis for several new developments on the Philips CM-series TEMs.Objective lenses traditionally have been optimised for parameters that are important in materials science: high resolution and very small spot sizes. With these parameters comes a short focal length which reduces the contrast from the specimen - no problem in the high-contrast materials science specimens, but highly problematic in the case of low-contrast biological specimens. A new objective lens - the BioTWIN - has been developed specifically for high-contrast imaging and analysis of biological specimens. Its long focal length (6.2 mm; 2 to 3 times larger than that of a typical materials science objective lens) ensures high contrast by enabling the removal of the majority of elastically and inelastically scattered electrons by the objective aperture. Figure 1 shows a comparison of images of a stained section imaged at low magnification, recorded with a TWIN and a BioTWIN lens.
The (111)/(100) interface in cubic materials
Authors: Ramamurthy Sundar , Carter C. Barry 
Published: June 2020

Descriptions of crystalline interfaces have concentrated on grain boundaries using the framework of the coincident-site-lattice (CSL) model. Within this framework, an interface-plane scheme can be formulated to describe all types of crystalline interfaces, homophase or heterophase. Low Σ values, the inverse density of CSL sites, are associated with boundaries with low energies. However, stable interfaces that cannot be described by such models are often found experimentally in thin-film, semi-bulk and bulk forms. The stability of such interfaces thus depends on factors other than the geometry of the interface.Crystallography of the (111)/(100) interface in the cubic system has been studied extensively in a wide range of materials using different electron-microscopy techniques. Recently, this interface has spurred interest in the growth of tri-crystal microstructures to study junctions in polycrystalline thin films where three identical grain boundaries meet along a line. In this paper we review the (111)/(100) interface showing different examples from our recent work.
Characterization of diamond single-crystal substrates and homoepitaxial films
Authors: Posthill J. B. , Graham R. J. , Malta D. P. , George T. , Rudder R. A. , Hudson G. C. , Humprheys T. P. , Thomas R. E. , Markunas R. J. 
Published: June 2020

We have continued to investigate different diamond single crystal substrates to assess their suitability for the growth of homoepitaxial diamond. Surface topography and defect microstructure of the resulting films are two important qualifiers for the choice of a suitable substrate. Previously developed methods to prepare plan-view TEM samples from bulk diamond substrates and homoepitaxial films have been employed. This contribution describes some of our most recent observations of the surfaces andmicrostructure of natural and synthetic diamond single crystals and homoepitaxial diamond thin films using SEM and TEM - including spatially resolved cathodoluminescence (CL) results.Figs. 1 and 2 show TEM micrographs taken from a (100) natural type Ila diamond crystal and a (100) synthetic type lb diamond that have been ion milled to electron transparency. The mottled background contrast observed in both images which has been observed previously and is believed to result from the extended ion milling used to produce these thin foils.
Reflection electron microscopy of ferroelectric domains
Authors: Tsai Feng , Cowley J. M. 
Published: June 2020

The intersections of ferroelectric domain boundaries with crystal surfaces have been studied by optical microscopy. The method is widely used but usually of low resolution. Transmission electron microscopy (TEM) can provide high-resolution images but may not be appropriate for studying crystal surfaces. Scanning electron microscopy (SEM) has also been used to study the intersections of ferroelectric domain boundaries with the surfaces of ferroelectric crystals. However, the resolution is still low and is destructive if an etched crystal surface is used. Other alternatives have also been attempted to study ferroelectric domain boundaries on surfaces, such as scanning tunneling microscopy (STM), atomic force microscopy (AFM). But, no reports have been known so far.On the other hand, reflection electron microscopy (REM), as a branch of dark-field imaging technique dedicated for surface studies in TEM, has been developed to study crystal surfaces, surface reconstruction and surface defects with a resolution of about 10Å. It has been considered as a powerful technique to study surface defects and may be used to study the ferroelectric domain boundaries emerging on surfaces.
TEM studies of sol-gel derived ferroelectric oxide thin films
Authors: Mecartney M. L. 
Published: June 2020

Sol-gel processing has proven to be a commercially viable process for the production of certain ferroelectric films, most notable Pb(Sr, Ti)O3 (PZT) and related compounds. The extension of this process to other ferroelectric oxide systems is still in the developmental stages because much is not yet understood about how the specific sol-gel chemistry influences microstructural development. In the PZT system, optimization of the sol-gel chemistry and the resultant microstructure were key developments in obtaining optimal ferroelectric properties. In this talk, the role of analytical TEM in studying microstructural development in sol-gel derived ferroelectric oxide thin films will be discussed. Examples will be drawn from LiNbO3, KNbO3, (Sr, Ba)NbO3 (SBN), and BaTiO3.Mixed alkoxide precursors were used as sols and all films were spin coated onto substrates. Substrate choices ranged from (100) MgO for SBN, BaTiO3 , and KNbO3 and (0001) Al2O3 for LiNbO3 as well as (100) and (111) Si and Pt coated Si. Films were pyrolized after each coating at temperatures from 300-400°C.
Advances in strain measurement using electron-backscatter diffraction in the Scanning Electron Microscope
Authors: Dingley D. J. 
Published: June 2020

The technique of electron back scatter diffraction, EBSD, is well established for measurement of crystal orientation in bulk polycrystalline samples. Analytical procedures for determining crystal phase from them have also been established. In addition several papers have been published describing the application of the method for strain measurement. In these latter studies the EBSPs were recorded on photographic film and all measurements made after digitising the patterns and transferring the data to a SEMPER image processing package. Strain measurement was based on determination of the diffuseness of the diffraction pattern. In the present studies analysis was carried out on digitised television images of the diffraction patterns imaged live on a phosphor screen.EBSPs were obtained in a JEOL 6400 SEM fitted with a tungsten filament. The patterns were imaged on a P20/P40 phosphor directly coupled through a coherent fibre optic bundle to a SIT low light level television camera with 700 line resolution.
Automated EBSP studies of deformation microstructures
Authors: Jensen D. J. 
Published: June 2020

Measurements of the crystallographic orientation within selected local areas of the microstructure is important to achieve further understanding of the development of deformation microstructures and texture; for example for studies of grain subdivision and texture formation. Different techniques may be applied. The most clear and precise results relating directly specific microstructural features to given orientations (or misorientations) are obtained by TEM methods. However, better statistical data may be obtained by the electron back scattering pattern (EBSP) technique in the SEM. The present paper concentrates on the EBSP technique and result obtained thereby.Characterization of the distribution of orientations in the deformation microstructures by EBSP generally requires measurements of hundreds or more orientations. Automatic techniques are therefore very adequate. By using a modified Hough transform routine, lines in an EBSP are easily and rapidly identified. Figure 1 shows an example of computer identified lines in an EBSP of aluminum. Based on this data the crystallographic orientation is calculated by standard routines.
Influence of boundary microstructure on the abrasive wear of a high-alumina ceramic
Authors: Doğan C. P. , Hawk J. A. 
Published: June 2020

The glassy melt present at the grain boundaries of many commercially-produced, polycrystalline ceramic materials will often crystallize during cool down from the sintering temperature, or during subsequent exposure to elevated temperatures. The extent of devitrification of the boundary glass, and the types of phases that form, depend upon the composition of the original glass melt and the thermal history of the material. In a 96% Al2O3 ceramic, for example, a boundary glass that is high in CaO will crystallize to anorthite (CaAl2Si2O8), gehlenite (Ca2Al2SiO7), garnet ((Mg,Ca)3Al2Si3O12) and spinel (MgAl2O4) upon exposure to temperatures between 1050° and 1350° C. Devitrification is essentially complete within one hour of exposure to these elevated temperatures. The microstructure of such a material, before and after a 100-hour heat treatment at 1150° C, is illustrated in Figs. 1 and 2, respectively.Although the microstructure of such materials can change dramatically with heat treatment, there is little evidence that this difference results in a change in the room temperature mechanical properties of the bulk material.
Structural relationships in the synthesis of cubic boron nitride thin films by ion-assisted deposition
Authors: Medlin D. L. , Friedmann T. A. , Mirkarimi P. B. , Mills M. J. , McCarty K. F. 
Published: June 2020

The allotropes of boron nitride include two sp2-bonded phases with hexagonal and rhombohedral structures (hBN and rBN) and two sp3-bonded phases with cubic (zincblende) and hexagonal (wurtzitic) structures (cBN and wBN) (Fig. 1). Although cBN is synthesized in bulk form by conversion of hBN at high temperatures and pressures, low-pressure synthesis of cBN as a thin film is more difficult and succeeds only when the growing film is simultaneously irradiated with a high flux of ions. Only sp2-bonded material, which generally has a disordered, turbostratic microstructure (tBN), will form in the absence of ion-irradiation. The mechanistic role of the irradiation is not well understood, but recent work suggests that ion-induced compressive film stress may induce the transformation to cBN.Typically, BN films are deposited at temperatures less than 1000°C, a regime for which the structure of the sp2-bonded precursor material dictates the phase and microstructure of the material that forms from conventional (bulk) high pressure treatment.
EM studies of oxidized Y and Zr-doped β-NiAl
Authors: Schumann E. , Yang J. C. , Nadarzinski K. , Ruhle M. 
Published: June 2020

The highly beneficial effect of yttrium and zirconia dopants on the oxidation behaviour of β-NiAl has been known for over the past 50 years. Various theories have been proposed to explain the reactive element effect. The dopants may: improve the interfacial properties; favorably effect diffusion in the oxide scale; or getter the sulfur, which is a common impurity in nickel alloys, and prevents sulfur from diffusing to the interface where it may decrease the interfacial energy.To help determine which theory(s) explain the reactive element effect, we have examined oxidized Zr and Y doped β-NiAl by cross-section electron microscopy techniques on a VG-HB501 STEM and JEOLARM1250 in order to characterize the microstructure and the locations of the dopants.Polycrystalline 0.1% Y doped β-NiAl were oxidized at 1200°C for 24 hr and polycrystalline 0.1% Zr doped β-NiAl were oxidized at 1200°C for 200 hr. The CTEM images of the Zr (Fig. 1) and the Y (Fig. 2) doped NiAl show that α-Al2O3 scale forms after oxidation.
Influence of natural organic matter on the morphology of corroding copper surface
Authors: Korshin G. V. , Ferguson J. F. , Rock M. E. 
Published: June 2020

Natural organic matter (NOM) is a ubiquitous and important component of natural waters. Polymeric species related to humus found in soils constitute the major part of NOM. NOM is of major importance for the speciation of metals in waters but its effects on metal corrosion are little known. The influence of NOM on the morphology of corroding copper surfaces is discussed in this communication. The studies were performed for copper coupons exposed for 7 weeks to waters supporting an intense localized corrosion attack called pitting. Two types of waters were used: highly mineralized water at pH close to 7.3 (water A) and soft water at pH close to 9.3 (water B). The morphology of the surface was examined using conventional photography and SEM (JEOL 5200). The range of accelerating voltages was from 10 to 25 kV.Profound effects of NOM on the state of the corroding copper surface were found.
Morphology of Σ3{<110>/70.53°} grain boundaries in a C15 intermetallic compound
Authors: Chu Fuming , Pope D. P. , Zhou D. S. , Mitchell T. E. 
Published: June 2020

A C15 Laves phase, HfV2+Nb, shows promising mechanical properties and here we describe the structure of its grain boundaries. The C15 Laves phase has a fcc lattice with a=7.4Å. An alloy of composition Hf14V64Nb22 (including a C15 matrix and a second phase of V-rich bcc solution) was made by arc-melting. The alloy was homogenized at 1200°C for 120h. Preliminary study concentrated on Σ3{<110>/70.53°} grain boundaries in the C15 phase using Philips 400T and CM 30 microscopes.The most-commonly observed morphology of Σ3{<110>/70.53°} grain boundaries in the C15 phase is a faceted boundary. A bright field image (BFI) of the faceted boundary and the corresponding diffraction patterns with the grain boundary edge-on are shown in Fig. 1(a). From the diffraction patterns using a <110> zone axis for both grains, it is obvious that this is a Σ3{<110>/70.53°} grain boundary. Crystallographic analysis shows that the Σ3{<110>/70.53°} grain boundaries selectively facet with the following relationships between the two grains: {111}1//{111}2, {112}1//{112}2, {111}1//{115}2, and {001}1//{221}2.
Shape training of Ge precipitates in an Al-1.8at% Ge alloy
Authors: Hinderberger S. , Xiao S. Q. , Westmacott K. H. , Dahmen U. 
Published: June 2020

Ge precipitates in Al are known to form in a rich variety of shapes and orientation relationships. In this work it is shown that initial non-equilibrium shapes such as plates, laths, needles and tetrahedra can be induced to change to the equilibrium shape of an octahedron by proper temperature cycling. Analysis of this effect in bulk samples was complemented by direct observations of its mechanisms during in-situ temperature cycling.A bulk sample of an Al-1.8at%Ge alloy was solid solution annealed at 420°C for 2h, quenched in ice water, pre-aged at room temperature for 72h and then annealed for 5h at 250°C. Subsequently, part of the sample was repeatedly cycled between 250°C and 360°C. TEM specimens were prepared from both the cycled and non-cycled bulk sample by conventional electropolishing and examined in a JEOL 200CX electron microscope. The in-situ temperature cycling was carried out in a Kratos 1.5 MeV HVEM equipped with a double tilt heating stage.
Interaction between dislocations and the Ω. phase during deformation of Al-Cu-Mg-Ag alloys
Authors: Li Qiong 
Published: June 2020

Al-Cu-Mg alloys containing a small amount of Ag have been known to show remarkable hardening by aging between 150°C and 250°C. Because of their excellent thermal stability, the alloys are leading candidates for high temperature aeronautic applications such as High Speed Civil Transportation (HSCT). Through recent investigations, it has been shown that this hardening is mainly due to the precipitation of the plate-like Ω phase on the {111} Al matrix planes. The Ω phase is semicoherent with the Al matrix and has a tetragonal structure , The nature of strengthening of the semicoherent precipitates is still unclear. This study shows that the shear of dislocations is the primary strengthening mechanism in the alloy strengthened by Ω phase.The present study was performed with an Al-3.2Cu-0.45Mg-O.5Ag (wt%) alloy which was prepared using an induction furnace. The alloy was cast into a mold, hot rolled, homogenized, solutionized, cold water quenched and peak aged at 200°C.
A TEM microscopical investigation of the magnetic domain structure of a metastable austenitic stainless steel
Authors: Fourlaris G. , Gladman T. 
Published: June 2020

Stainless steels have widespread applications due to their good corrosion resistance, but for certain types of large naval constructions, other requirements are imposed such as high strength and toughness , and modified magnetic characteristics.The magnetic characteristics of a 302 type metastable austenitic stainless steel has been assessed after various cold rolling treatments designed to increase strength by strain inducement of martensite. A grade 817M40 low alloy medium carbon steel was used as a reference material.The metastable austenitic stainless steel after solution treatment possesses a fully austenitic microstructure. However its tensile strength , in the solution treated condition , is low.Cold rolling results in the strain induced transformation to α’- martensite in austenitic matrix and enhances the tensile strength. However , α’-martensite is ferromagnetic , and its introduction to an otherwise fully paramagnetic matrix alters the magnetic response of the material. An example of the mixed martensitic-retained austenitic microstructure obtained after the cold rolling experiment is provided in the SEM micrograph of Figure 1.
A bonded metal fulleride structure in the PdnC60 system
Authors: Liu M. , Cowley J. M. , Ramakrishna B. L. , Peace T. S. , Wertsching A. K. , Pena M. R. 
Published: June 2020

The large-scale synthesis of C60 has stimulated considerable interest in the chemistry and structures of metal fullerides. Studies on compounds formed by C60 with metal-organic complexes have shown that some metal atoms can form bonds with the C60 molecules. Nagashima et al. have proposed that one-, two-, or three-dimensional polymers may be formed when Pd atoms link neighboring C60 molecules by being coordinated with the π electrons at the double-bond regions between hexagonal carbon rings. In the present study, PdnC60 (n= 1,3,4) were prepared from C60 and a Pd0 precursor by a liquid chemical combination method. The compositions of these compounds were determined with EELS. Their structures were examined with a Topcon 002B and a JEM-2000FX HRTEM.The electron micrographs and diffraction patterns of the Pd1C60 preparation showed regions of small Pd crystals embedded in near-amorphous carbon and also regions of heavily faulted FCC C60 structures. Fig. 1 is a HRTEM image showing a region of FCC structure viewed in the [110] direction with several groups of stacking faults.
TEM measurement of surface area of automotive catalysts
Authors: Yao M. H. , Liu D. R. , Baird R. J. , Usmen R. K. , McCabe R. W. 
Published: June 2020

The specific surface area of supported noble metal particles in an automotive catalyst is defined as the exposed surface area per unit mass of these particles. It is of great importance to know this parameter, since this is one of the major factors that determine the effectiveness of the catalyst. Commonly used methods for characterizing catalysts, such as X-ray diffraction and TEM, do not directly provide a measure of surface area, but, instead, provide a measure of the “average size” of supported particles. Moreover, the “average sizes” obtained from different experimental techniques are often not comparable. Furthermore, many previous electron microscopy catalyst studies measured only simple average particle size, and no detailed procedure for measuring area-weighted average size or surface area appear to have been reported.In the current study, a procedure for measuring surface area of supported particles by transmission electron microscopy(TEM) was developed, and applied to measure surface areas of various production three-way automotive catalysts.