bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anaysis of Lacbed Patterns from A Microtwin in Cobalt
Authors: Su Kim Hwang , Ahn Byung Ryang 
Published: July 2020

Abstract
Recently LACBED (Large Angle Convergent Beam Electron Diffraction) studies for identifying the nature of stacking faults has been reported in [1,2]. Here we report the LACBED study for a microtwin whose images are usually similar to those of an intrinsic or an extrinsic stacking faults (for this discussion, see [3]).
Observations: Thin foils of cobalt with the thickness of about 180 nm (f.c.c phase, a=0.354 nm) were examined by a Philips CM200. Fig. 1 shows strong beam dark field images of microtwins or stacking faults. Fig. 2 shows the bright field LACBED pattern taken near the area marked as a circle in fig. 1. The specimen height, from the convergent point of beams, was about 0.0586 mm and the convergent angle was 0.615 degrees.
Calculations and analysis: Analysis of fig. 1 alone indicates the encircled fault an extrinsic stacking fault.
Uncertainties in Stereo Lattice Imaging
Authors: Qin W , Fraundorf P 
Published: July 2020

Abstract
Three-dimensional reconstruction in TEM is an established technique in both electron diffraction crystallography and electron tomography [1,2]. By stereo lattice imaging, we refer to a different task: determination of unit cell parameters in 3D using only direct-space lattice images at two or more (often widely varying) orientations [3,4], This note concerns the uncertainties associated with lattice parameter determinations by this technique. in particular, for decreasing crystal thickness the broadening of reciprocal lattice spots increases one’s chances to visualize lattice fringes. At the same time, however, it introduces uncertainties in reciprocal lattice vector length and direction.
In the following discussion, sources from which uncertainties arise are assumed to be uncorrected. Three sources of uncertainty for reciprocal lattice vectors which lie in the plane of the specimen stage (and hence can be imaged directly as fringes) are, in order of decreasing relative size as follows:
Fringe Visibility Maps
Authors: Fraundorf P , Qin W 
Published: July 2020

Abstract
The phrase “fringe visibility map” here refers to high-resolution images of uniform-thickness single crystal foils showing locally hemispheric deformation (i.e. bent into the shape of a watchglass), and to various mathematical analogs thereof. As the availability of “diffraction information” in direct-space form increases, for example with the availability of HREM and z-contrast lattice images, fringe visibility maps may serve as the direct space analog to Kikuchi maps, i.e. to diffraction pattern maps of Kikuchi line pairs as a function of specimen orientation, and their various cartoonifications.
Figures 1 to 3 are schematic Mathematica-generated fringe visibility maps for face-centered, body-centered, and diamond face-centered cubic lattices, respectively. Here we have turned the “locally hemispheric” concept around and drawn fringes visible when one is viewing a spherical particle of the appropriate thickness, along varying beam directions (rather than lattice orientations) parallel to the local radius vector on that sphere.
Exit Wave Reconstruction and Elemental Mapping of Twin Boundaries in the System Zno - Ga2O3
Authors: Barf J , Walther T , Steinecker A , Mader W 
Published: July 2020

Abstract
Polycrystalline ZnO was sintered with 5 mol.% Ga2O3 at 1350°C for lhour in air. Samples for transmission electron microscopy (TEM) were prepared by cold pressing, grinding, dimpling and Argon ion-milling.
ZnO crystallizes in the hexagonal wurtzite structure. Bright field and dark field images reveal lamellar defect structures which are not observed in undoped ZnO. Electron diffraction shows that the lamellar regions consist of heavily twinned ZnO. The twin boundaries (TB) of both twin variants are parallel to lattice planes of type { }. Lattice images along reveal narrow planar twin boundaries as well as a diffuse image contrast within the twin lamellae (Fig. la). to characterize the nature of the boundaries we recorded dark field images of the twinned regions using reflections of type ±{0002}. in combination with microdiffraction it can be shown that the diffuse boundaries are inversion domain boundaries (IDB) which alternate with the sharp TB. This microstructure is related to the polarity of ZnO.
Measuring Interface Potential of Bi2sr2cacu2O8 (001) Twist Boundaries by off-Axis Electron Holography
Authors: Schofield M A , Zhu Y 
Published: July 2020

Abstract
The potential variation, charge transfer and lattice distortion across grain boundaries in polycrystalline superconductors play a crucial role in the transport properties of the material. in particular, the grain interfaces often act as weak links to the superconducting current, which limits the critical current densities that may be obtained. in the case of the high Tc superconductor Bi2Sr2CaCu2O8 (Bi-2212), special interest is paid to (001) twist boundaries since, in part, they are dominant in c-axis aligned tapes and wires, but more interestingly because the superconducting critical current is found to be independent of twist angle for this system. Such grain boundary behavior is presently not understood, and is further puzzling since “impurity phases” of Bi-2223 or Bi-2201 (consisting of additional or missing Cu-Ca-0 planes, respectively) are commonly observed at the (001) twist boundaries. with the rich structure found at these types if interfaces, understanding the potential distribution may lead to new insight about the boundary properties.
Evaluation of Methods for Extracting Chemical Information from Eels Line-Spectra Across Interfaces
Authors: Imhoff D , Sikora T , Pailloux F , Tencé M , Colliex C 
Published: July 2020

Abstract
EELS fine structures on characteristic core edges are closely related to the bonding type and structural environment around the excited atoms. Consequently, they constitute useful hints for investigating the electronic properties at interfaces. One major difficulty then lies in the extraction of the information relevant to the involved atoms, from that due to neighbouring atoms on both sides of the selected interface seen end on by the impinging electrons. We have investigated possible ways to reach this goal, using the spectrum-line method, which consists in acquiring sequences of spectra at well defined increments (0.3 nm) while scanning a subnanometer electron probe (0.7 nm) across the interface. This approach constitutes one step forward with respect to the spatial-difference (SD) method which processes spectra acquired on two adjacent areas, one encompassing the interface, the other one on a reference area nearby. A normalized version (NSD) has been introduced to extend its field of application from grain boundaries to heterophase interfaces in order to enhance their specific ELNES contribution
TEM of nanodot arrays fabricated by direct laser interferometry
Authors: Liu Y , Zheng M , Yu M , Skomski R , Liou S H , Polushkin N I , Sellmyer D J 
Published: July 2020

Abstract
Patterned nanostructures and nanodots are attracting increasing interest in the information storage industry. The ultimate recording density of a magnetic medium will have single domain dots aligned in arrays and each dot in such an array acts as a recording bit. The ideal structure is that the dots are magnetic and the surrounding medium is non-magnetic so that each dot can switch magnetization direction freely without the interference from other dots. This paper presents the nanostructure of the nano-dot array investigated by transmission electron microscopy and magnetic force microscopy. The Co:C film was deposited by alternatively sputtering Co target and C target. The as-deposited specimen has an amorphous structure as revealed by electron diffraction in TEM. Such films transform to ferro-magnetic ones after heat treatment [1]. A laser beam of wavelength of 308 nm and a flux of 0.24 J/cm2 was split into two beams of an approximately equal intensity and then recombined, generating an interference pattern and a periodic modulation of the light intensity.
Better Transparency and Conduction Via Alchemi: Site-Occupancy of Cations in Transparent Conducting Oxides (TCOs) Cd1+xIn2-2xsnxO4
Authors: Brewer LN , Dravid Vinayak P 
Published: July 2020

Abstract
Transparent conductive oxide materials (TCO) are currently under development for use as electrodes in devices such as photovoltaics and flat panel displays. As electrode area increases in large-area applications (e.g. photovoltaics), the resistivity of the TCO must decrease in order to maintain efficiency. The ideal next generation TCO will be a low cost material with a substantially higher conductivity than ITO obtained by improving mobility. Two promising TCO's are CdIn2O2 and Cd2SnO4 which both exhibit high conductivities (4300 S/cm and 8300 S/cm, respectively) and high mobilities (44 and 60 cm2/Vs, respectively).
A bulk investigation of the system CdIn2O4 - Cd2SnO4 reveals a large spinel solid solution, Cd1+xIn2.2xSnxO4 (0&lt;x&lt;0.75) at 1175°C exhibiting a sharp decrease in measured optical gap (from 3.0 to 2.8 eV) at x=0.2 and an increase in conductivity (from 2200 S/cm to 3500 S/cm) for reduced specimens between x=0.4 and x=0.60) with increasing x. It is suspected that the cation distribution (e.g. normal, random, or inverse) on the spinel lattice may be important in understanding these shifts in electrical and optical properties.
Variation of the ELNES Under Channeling Conditions
Authors: Köstlmeier S , Nufer S , Gemming T , Rühle M 
Published: July 2020

Abstract
The orientation dependence of the fine structure of the Al L1 and L2,3 electron energy loss (EELS) edges in (α-Al2O3 has been investigated by measurements with a dedicated scanning transmission electron microscope (VG HB501 STEM, 100 keV acceleration voltage). α-Al2O3 is an anisotropic solid with a complicated alternating stacking sequence of fee Al and hcp O planes along the [0001] direction [1]. This distingiushes the [0001] direction crystallographically, as the highest-order three-fold rotation axes (C3) of the trigonal crystal structure are parallel to [0001], whereas all other symmetry elements are of lower order. Group theory predicts, that more stringent symmetry selection rules apply when electronic transitions are excited by irradiation parallel to the low-index [0001] zone axis than by irradiation along any other arbitrary direction.
Yet, even for a low-energy EELS edge (θE = 0.4 mrad) both scattering parallel and perpendicular to the incident beam direction are likely.
Teoretical Tools for Practical ALCHEMI
Authors: Allen L J , Oxley M P 
Published: July 2020

Abstract
Precisely known atomic scattering factors are essential for accurate atom location by channelling enhanced microanalysis (ALCHEMI) based on inner-shell ionization.1 For ALCHEMI using energy dispersive x-ray analysis (EDX), first principles calculations of ionization cross sections, realistically modeling the “delocalization” of the ionization interaction, give excellent agreement with experiment.2 Such calculations are complex and computationally intensive. Hence, simple analytic forms are often assumed to describe the ionization potential. However such analytic forms require prior knowledge of the “delocalization” of the effective ionization interaction. Such an approach assumes that the precise shape of the ionization potential is not important but that at least the half width at half maximum (HWHM) should be accurately estimated, for example using estimates of the HWHM from root-mean-square impact parameters for ionization. However this is generally not a good approximation3 and we have provided more realistic estimates (Fig. 1).
ALCHEMI as holography
Authors: Spence JCH , Koch C 
Published: July 2020

Abstract
Two-dimensional Atom Location by Chanelling Enhanced Microanalysis ( Alchemi ) maps of characteristic Xray emission as function of the diffraction conditions of a 200kV electron beam hav been obtained from thin crystals by several workers. Reciprocity shows that these are equivalent to the diffraction patterns produced at infinity by 200kV point sources of electrons on atom sites, sue! as D in figure 1, for CsCl. Here ray SCD at left has been time-reversed at right. Using multislici superlattice simulations which launch a spherical wave from an atom site, we find that the resultinj Kikuchi pattern breaks up into separated blobs along the K-lines at small thickness, with one blol generated at infinity along each atomic string direction. Each blob (e.g. ID) is a Gabor in-lim hologram (e.g of atom C, formed by source S at right). Each source atom on equivalent sites (E, D produces identical holograms, whose intensities add.
Harecxs Measurements of Elemental Disordering
Authors: Zaluzec Nestor J , Smith Katherine L 
Published: July 2020

Abstract
It has been long known that orientation effects in crystalline materials can influence characteristic x-ray emission and microanalysis1-7. High Angular Resolution Electron Channeling X-ray Spectroscopy (HARECXS)6-7. a variation of ALCHEMI4-5, has been used at ANL for the last few years to investigate the effects of channeling on quantitative XEDS analysis of materials. More recently we have also been using HARECXS to carefully measure elemental disordering in a number of systems and have found that it can be used very successfully to elucidate the various stages of disorder.
Perovskite (nominally CaTiO3) is a host phase for actinides in various wasteforms for the immobilization of high level radioactive nuclear waste. Over geologic time, alpha decay damage of the actinides in perovskite will cause displacive effects that influence the dimensional and chemical stability of the wasteform. in the past, the progression of damage has been studied by monitoring changes in selected area electron diffraction (SAED) patterns with increasing dose (e.g. 11).
Study of Garnets by ALCHEMI
Authors: Lábár János L , Tόth Lajos , Dόdony István , Morgiel Jerzy 
Published: July 2020

Abstract
Garnets were one of the first materials in which an occupation of separate lattice sites by different atomic species was determined with an ALCHEMI technique proposed by Spence and Tafto in l982. The reason of so much interest in this material was twofold, i.e. first its known high sensitivity of X-ray generation depending on orientation especially in the axial orientation and second its complicated crystal structure allowing different atomic arrangements in the unit cell depending on its chemical composition. The dodecahedral (X), octahedral (Y) and tetrahedral (Z) sites between the relatively large oxygen atoms can be filled with a variety of small cations in accordance with the formula X3Y2Z3O12. Partial substitution of one cation with another is common in this structure. The results presented in the previous literature indicated that ALCHEMI can only separate the Y-sites from the sum of the other two (X+Z), while the latter has to remain unresolved.
Is Negative Staining Capable of High Resolution?
Authors: Massover William H 
Published: July 2020

Abstract
Everyone presently answers “no” to this question, since this methodology for specimen preparation and preservation commonly is believed to be inherently limited to 20-25Å (2.0-2.5nm) resolution. Achievement of resolution levels smaller than this figure have been published only rarely. This report presents experimental evidence from electron diffraction showing that negative staining can preserve periodic protein structure to the level of at least 4Å.
A suspension of bovine liver catalase crystals (orthorhombic: a= 69Å, b= 174Å, c= 206 Å [1]) is deposited on a hydrophilic carbon support and negatively stained using an on-grid protocol [2,3]. For low-dose electron diffraction with a JEOL 100CX transmission electron microscope (l00kV), the set-up for routine selected area diffraction is modified to keep the second condenser lens maximally overfocused; by a defocusing of the diffraction pattern, the grid can be surveyed and suitable thin single crystals centered in the diffraction aperture with only negligible irradiation.
Considerations for Multi-Phase and Low-Symmetry Com Analyses
Authors: Camus Patrick P , Rohde David B , Schwarzer Robert A 
Published: July 2020

Abstract
EBSD analyses are routine for understanding and quantifying the orientations of materials. Analyses of single-phase cubic materials are by far the most prevalent reported in the literature. However, the understanding of the orientations of multi-phase materials are just as important from a technological standpoint. The analysis of non-cubic and non-hep materials is also of interest to investigators. However, analyses of these materials provide some unique challenges for accurate and precise orientation and phase determination compared to cubic materials. The ORKID analysis system was designed from the beginning to address these materials and analysis concerns.
Single-phase materials, especially with cubic symmetry, do not require any special treatment for indexing of diffraction patterns. Because only one crystal system is under investigation, the algorithm for matching the measured bands and the expected bands can have some relaxation in error limits. Furthermore, d-spacing measurements of the bands are not strictly required because the bands angles are sufficiently unique.
Nucleation of Aln on 6h-Sic (0001) by Sublimation Technique
Authors: Liu B , Walker LR , Shi Y , Edgar JH 
Published: July 2020

Abstract
A study of the initial stage of AIN growth on SiC substrate by the sublimation re-condensation technique was undertaken to understand the origin of crystal defects in bulk AIN crystals. When SiC was used as a seed crystal the AIN crystals did not completely coalesce, and individual grains were observed. Such crystal growth features were determined by the initial nucleation of the crystals. in this study, the nucleation of AIN on 6H-SiC(0001) was investigated by Scanning Electronic Microscopy (SEM), S-4700 Hitachi, and Electron Backscattered Diffraction (EBSD), Thermo Noran Phase ID.
At high temperatures (&gt;1800°C) in the presence of AIN, the surface of the SiC substrate first decomposed along remnant polishing scratches[l], ultimately leaving hexagonal hillocks; simultaneously, the AIN nucleated on these SiC hillocks. Surprisingly, the AIN nuclei appeared out of alignment with the underlying SiC hillocks. By measuring several points from the SEM image (figure 1), this misorientation is in the range of 15° to 30°.
Effect of oxygen deficiency on Charge Ordering in La0.5Ca0.5MnO3-δ
Authors: Tao J , Jiang N , Spence JCH 
Published: July 2020

Abstract
Elastically-filtered transmission electron diffraction patterns of La0.5Ca0.5MnO3-δ have been obtained between 105K to 288K using the Leo 912 Omega. On heating La0.5Ca0.5MnO3 undergoes a transition from antiferromagnetic insulator to ferromagnetic metal (TN ∼ 150K) and then to paramagnetic insulator (Tc ∼ 230K). The q modulation wave vector along the b-axis direction arises from charge ordering of Mn3+ and Mn4+, and orbital ordering of dz 22 orbitals associated with Jahn-Teller distortions in the Mn3+O6 octahedra at low temperature. Both the intensity and the position of superlattice peaks change as a function of temperature during heating. The large incommensurability we see between 105K to 260K differs from that seen previously and proposed model. Figure 1 a) shows the lattice constants a, b, c related to the simple perovskite lattice parameters ap (ap ∼ 3.9Å) by a≈b≈ap and c≈2ap, and indicates the octahedral coordination.
Low Angle Grain Boundary Dewetting in Sapphire
Authors: Hockey BJ , Kang M-K , Wiederhorn SM , Blendell JE 
Published: July 2020

Abstract
The structure and composition of low angle grain boundaries produced in sapphire by a liquid phase sintering process were investigated by conventional and high resolution transmission electron microscopy (CTEM and HRTEM, respectively). Considering the current emphasis on producing ceramics with textured microstructures for various applications, the question of grain boundary wetting vs. dewetting has become a relevant issue to determining the microstructure development and the properties of these liquid phase sintered materials. Accordingly, the present study was designed to cover a wide range of tilt misorientations, twist misorientations, and boundary orientations.
The boundaries were formed by the directed growth of two sapphire plates, both having nominal &lt;0001&gt;, , or surface orientations through an alumina tape-cast containing an anorthite composition glass phase. After an initial hot-pressing stage, followed by an anneal at 1600° C for 200 hours, the samples typically contained a single boundary delineated by isolated pockets of entrapped glass, Fig. 1.
High Resolution TEM and EDX Investigation of Metal Coated Nanoparticles
Authors: Jiao Jun , Tang Fangqiong 
Published: July 2020

Abstract
Nanoparticles are increasingly being heralded as the next-generation building blocks for modern materials design. Coating of semiconductor, metal, or metal oxide nanoparticles with a thin layer of a compatible material makes possible the control of interparticle and particle-matrix interactions, thereby further improving functional properties of devices and expanding the range of potential applications. The core-shell geometry has previously allowed for the enhancement of luminescence of semiconductor nanoparticles, charging of metal cores, chemical and colloidal stability, and optimization of magnetic properties of nanoparticles.
The work reported here uses new approaches to synthesize metal-coated nanoparticles characterized with high-resolution electron microscopy (HRTEM), micro-diffraction, and electron energy dispersive X-ray (EDX). Colloidal uniform composite nanoparticles of SiO2/TiO2 were synthesized using the sol-gel process. Fig. l-(a) shows a TEM micrograph of a group of particles coated with an outer layer.
Microindentation behavior of the shell of the conch Strombus gigas
Authors: Su X , Zhang D , Heuer AH 
Published: July 2020

Abstract
Microindentation using a hard indentor is a very useful tool to probe the local mechanical properties (plastic flow, fracture, toughness, creep, etc.) of hard solids. We have used a depth sensitive indentation (DSI) version of this technique to study the shell of the conch Strombus gigas.In particular, we prepared polished sections in which the third order lamellae, the basic building block of the structure, could be indented along the three orthogonal directions; the indentation behavior along these three directions is quite different. Besides the normal information such as the hardness H from some typical dimension (typically the diameter of a pyramid-shaped indentation produced by a so-called Vickers diamond indenter) after indenting with a given load, the DSI technique also provides much additional information available from the loading and unloading curves. As can be seen from Fig. 1, the loading and unloading curves for the three orientations are quite different, as is the depth of the residual impression.