bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microhotplate Chemical Vapor Deposition and in the Environmental SEM Chamber
Authors: Wight S A , Cavicchi R E , Nystrom M J , DiMeo F 
Published: July 2020

Abstract
Metal oxide films are are an emerging sensing technology for the identification of gas phase species. Metalorganic chemical vapor deposition (MOCVD) on microhotplate structures provides a method of fabricating gas sensing layers in self-patterned structures. Investigation of the morphological characteristics of film growth is normally not possible inside a MOCVD reactor, especially the nucleation phase and subsequent deposition of a continuous film. The environmental scanning electron microscope (ESEM) operates at a pressure range of 133-666 Pa (1-5 Torr) which is similar to the growth condition normally used for oxide film MOCVD on microhotplates. Our results show that microhotplate MOCVD can be monitored in situby secondary electron and backscattered electron imaging in the ESEM.
The microhotplate chemical sensor devices employed in this work are mounted in conventional 40 pin packages which provide separate electrical connections to each of the four micromachined heater and contact structures.
In Situ HREm of Reactions at Interfaces
Authors: Sinclair R , Itoh T , Lee H J , Kwon K W 
Published: July 2020

Abstract
Reactions at solid-solid interfaces are important both scientifically and technologically. Firstly, there is quite a wide variety of possibilities. Materials can react with one another, forming equilibrium, meta-stable or even amorphous phases. The interface can provide a means to promote phase reactions kinetically, in an analogous manner to catalysis. Even when the materials are mutually compatible chemically, the interface topography and atomic structure can evolve over the course of time. From the practical point-of-view, changes in the interface chemistry and structure can profoundly alter the physical properties. This is especially notable in thin film technology, whereby the interfaces constitute a signigicant proportion of the whole device. In this article, contributions to understanding this field are illustrated through application of in situ and high-resolution electron microscopy (HREM).
Basic studies of metal-semicoductor interfacial reactions have been successfully carried out for a number of years. of increasing importance in microelectronics is the stability of layers which prevent chemical interaction, namely the diffusion barriers.
HREM Analysis of TiB2 - Ti3B4 Precipitates Grown in-Situin TiAl
Authors: Inkson BJ , Rühle M 
Published: July 2020

Abstract
TiAl alloys are being developed for future use as lightweight, high strength structural materials for the aerospace and automotive industries. The growth of titanium borides in-situ in a TiAl melt can lead to a variety of structures, such as TiB (Bf and B27 structures) and TiB2, depending on the Ti/Al ratio in the melt, and on the presence of further alloying additions [1,2]. The morphologies of the boride particles can be significantly altered if they grow coupled with other boride or intermetallic phases [2-4]. Since the morphology and distribution of the borides with the intermetallic matrix can significantly affect their effectiveness as creep reinforcements, the structures and growth mechanisms of these composites need to be quantified at the atomic scale.
In a Ti-45.5at.%Al-1.6at.%Fe-l.lat.%V-0.7at.%B alloy know to contain TiB2 precipitates [2,3], the morphology of the boride particles have been investigated using HREM. The Stuttgart JEOL-ARM, operated at 1250kV using the side-entry pole-piece with 0.12nm point resolution, enables the distinction between individual boron and titanium columns in the titanium borides to be achieved for the first time.
Chemically Clean Planar Interface Synthesis: Substrate Surface and Interface Cross Section Microscopy
Authors: Xu J , Cox MJ , Kim MJ 
Published: July 2020

Abstract
An ultra high vacuum (UHV) planar interface unit has been constructed to study the effect of interface/boundary structure and chemistry on properties. We report here initial observations of substrate morphology and chemistry prior to bonding and resulting interface morphology obtained using austenitic stainless steel.
To synthesize chemically clean planar interfaces by diffusion bonding, the substrate must be macroscopically and microscopically flat and chemically clean. Macro-flatness, necessary for bonding to occur over large areas, was ensured by conventional mechanical polishing and lapping. Substrate surfaces were cleaned by a broad (3cm) 500 eV ion beam (Ar or Xe) at 15° incidence. The resulting changes in substrate near-atomic-scale roughness and chemistry were analyzed using Auger spectroscopy (AES) and Atomic Force Microscopy (AFM). Before ion beam cleaning, the sub-strates exhibited high oxygen and carbon contamination (Fig la). Both Xe and Ar ion cleaning reduced these values; the result for 5 minutes Ar cleaning is shown in Fig lb.
Subnanometer electron probes and their capabilities for internal interface characterization
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Lakner H 
Published: July 2020

Abstract
Internal interfaces in materials like e.g. semiconductor heterostructures get more and more interest not only under aspects of basic research but as well under aspects of new electronic and optoelectronic devices. The interface properties often govern the device performance. Thus, the evaluation of individual heterointerfaces with respect to chemical composition and crystal structure requires characterisation techniques which offer the necessary high spatial resolution. The fine focused electron probe (&lt; 0.3 nm at 100 keV) in a field-emission STEM (Scanning Transmission Electron Microscope) allows the application of special imaging and analytical techniques to cross-sectional specimens of semiconductor heterostructures. Qualitative information on the chemical composition is provided by atomic number (Z) contrast imaging with atomic resolution. The same fine probe can be used to analyse subnanometer areas by both spectroscopic and diffraction techniques. Quantitative compositional information is provided by electron energy-loss spectroscopy (EELS) which allows the detection of concentrations of specific elements.
Chemistry and Bonding at {222}Mgo/Cu Heterophase Interfaces
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Müller D A , Shashkov D A , Benedek R , Yang L H , Seidman D N , Silcox J 
Published: July 2020

Abstract
Adhesion at ceramic/metal (C/M) interfaces often controls the macroscopic behavior of materials containing metallic and ceramic phases, and experimental studies of bonding at C/M interfaces have recently been reported. Electron energy loss spectroscopy (EELS) offers unique opportunities to examine bonding at interfaces on an atomic scale. The EELS near edge fine structure is sensitive to local atomic arrangements and thus can be used as a coordination fingerprint. Much more can be done, however, by analyzing the connection between the EELS fine structure, the underlying local electronic structure and the cohesive energy of an interface to gain a deeper understanding of the nature of the adhesion at the interface.
In this work, we apply high spatial-resolution EELS instrument to study {222} MgO/Cu interfaces produced by internal oxidation. We determine interfacial chemistry of this interface with subnanometer resolution (Fig. 1) and use EELS to directly measure the electronic states pertaining to the interface
Combined Spectroscopy and STM Studies of (-Cu-O-) Strings on the Ag(110) Surface
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Matsumoto Yuji , Sakamoto Kazuyuki , Suto Shozo , An KS , TakayaFujita  , Kakizaki Akito , Tanaka Ken-ichi 
Published: July 2020

Abstract
It has been found that when Cu atoms are deposited on a p(2×l)-O Ag(ll0) surface, a (2×2)p2mg LEED pattern appears. The STM image has proved that zig-zag (-Cu-O-) strings grow along the [110] direction on Ag(ll0) (Fig. I)1, where a chemical reaction of (-Ag-O-) + Cu =&gt; (-Cu-O-) + Ag take place. The (-Cu-O-) strings grown on a Ag(l10) surface shows a unique reversible reaction given by an equation of (Cu)6+O2⇄ (-Cu-O-) at 570K. In this paper, we studied the bond property, the growth mechanism and electric structure of the (-Cu-O-) strings on Ag(ll0) by using XPS, HREELS and ARUPS as well as STM.
As increasing the deposition of Cu atoms on a p(2×l)-O Ag(l10) surface, the O(ls) peak in the XPS shifted from 528.2 eV to 529.9 eV(Fig. 2a). An energy loss peak at 41meV being assignable to (Ag-O) bond disappeared and a new loss peak concomitantly appeared at 35 meV in the HREELS (Fig. 2b).
Quantitative Characterization of Grain Boundary Films In Si3n4 by Eels and Z-Contrast Imaging
Authors: Gu H 
Published: July 2020

Abstract
High temperature mechanical properties of structural ceramics Si3N4 are controlled by ∼1 nm thick silicate amorphous films covering all grain boundaries. The composition of the film dictates the equilibrium film thickness resulted from a force balance at grain boundary. Many efforts arc brought to alter film chemistry and thickness, and this system offers ideal model materials to understand grain boundary and property relationship. Using a dedicated STEM (VG HB601) with high spatial resolution EELS analysis and high resolution Z-contrast imaging, various novel quantification data of the grain boundary in Si3N4 can be obtained. The methods described here can also be applied to other types of grain boundaries.
EELS profiling was performed to acquire a full spectrum from each position at a lateral increment of 1Å across a boundary in a pure Si3N4 sample with only SiO2 impurities from surface oxidation. It gives directly elemental distributions near the boundary such as Si, N and O profiles shown in Fig. 1.
Plutonium Alteration Phases from Vapor Hydration of Lanthanide Borosilicate Glass for Weapons Material Disposition: a TEM Study
Authors: Fortner J A , Mertz C J , Chamberlain D C , Bates J K 
Published: July 2020

Abstract
A lanthanide borosilicate glass, also known as LaBS glass, is being considered for the disposition of surplus weapons plutonium and plutonium residues. The LaBS glass, based upon Löffler-type glasses, is chemically durable and can dissolve substantial amounts of plutonium as well as the neutron absorbers gadolinium and hafnium [1]. Samples of a prototype LaBS glass composition containing 10 wt. % plutonium were subjected to water vapor at 200 °C for periods of 14 to 56 days. The Argonne Vapor Hydration Test Procedure was followed [2]. This test, while not designed to replicate specific conditions that may be found in a potential geologic repository (e.g., Yucca Mountain), has been shown to accelerate alteration phase formation that is usually observed in low-temperature tests over extended time periods [2]. The surfaces of the glass samples, along with alteration phases, were examined with a transmission electron microscope (TEM) to determine the characteristic alteration products.
Digital Moiré Analysis of Interface Dislocation Structure Between S-Phase (Al2CuMg) and Al-Based Matrix
Authors: Radmilovic V , Ratkovic S , Dahmen U 
Published: July 2020

Abstract
Using the moiré technique or the related geometrical phase technique [1,2], lattice displacement fields can be derived from high resolution micrographs by comparison with an undistorted reference lattice. A moiré image gives a magnified view of the distortions in a high resolution image, whether they are due to a distortion of the crystal lattice or result from imaging artifacts. The magnification of a moiré image is determined by the choice of the reference lattice. The closer the reference lattice is to the average lattice period in a high resolution image, the larger the magnification. To first order, both rotations and extensions of the lattice are magnified by the same factor g/Δg, where Δg is the difference between the image lattice and the reference lattice [1]. When the moiré technique is applied to interfaces, care must be taken interpret only patterns from corresponding sets of lattice planes. Thus, the technique gives a good representation of the distortions around a precipitate, but the interpretation of the moiré pattern inside a precipitate or across an interface must be made with caution.
Microstructure of Grain Boundary Junctions in Bicrystal High-Tc Superconductor SQUIDs and its Relation with the Device Noise
Authors: Huang Y , Lee L , Teepe M , Merkle K L , Char K 
Published: July 2020

Abstract
Superconductor Quantum Interference Devices (SQUIDs), because of their extreme sensitivity to magnetic fields and radiation, have found important applications in biomagnetism, non-destructive evaluation and geophysics. One problem in the application of high-Tc SQUIDs is their noise performance. Recently, considerable progress has been made in reducing the noise. To understand the underlying mechanism, it is important to identify the microstructural origin of the junction noise.
In this work actual SQUIDs of good and poor noise performance are studied and compared by TEM. The devices were made by epitaxially growing YBa2Cu3O7-x (YBCO) films using laser ablation on 24° SrTiO3 bi-crystal substrates. The TEM samples were prepared by polishing and ion milling. The TEM observation was performed on a JEOL EM-4000EXII and a Hitachi H-9000 microscope.
Observation shows that the YBCO films and the grain boundary junctions (GB J) in the low-noise devices are in good quality. The microstructure of the films and the boundaries in the films are shown in fig. 1 and 2.
Electron Microscopy Study of Stoichiometric and Non-Stoichiometric Titania
Authors: I.G. Solórzano , T. Kotani , H.L. Tuller , J.B. Van der Sande 
Published: July 2020

Abstract
It is currently well recognized that oxides are able to accommodate deviations from stoichiometry (1) and great advances in this understanding have been achieved by using transmission electron microscopy (TEM), particularly through lattice imaging and electron diffraction techniques (2). The physical properties of non-stoichiometric oxides are strongly influenced by their exact composition and for this reason they represent a class of materials with increasing and novel properties that are put to use in, for example, oxygen sensors and high-Tc superconductors. On the other hand, in electroceramic materials, such as TiO2, grain boundary structure and chemistry are important to be characterized in detail since these variables are responsible for the electric activity.
Rutile (TiO2) can accommodate relatively large deviations from stoichiometry (TiOx with 2.0≥x≤ 1.75) by the crystallographic shear (CS) mechanism (1). The formation of CS planes is effectively a two-step process which involves the ordering of oxygen vacancies on a crystallographic plane and on their elimination by a shear of the lattice.
Structure, Composition and Stability of Heterophase Boundaries
Authors: Rühle M , Wagner T , Bernath S , Plitzko J , Scheu C , Liedtke A 
Published: July 2020

Abstract
Heterophase boundaries play an important role in advanced materials since those materials often comprise different components. The properties of the materials depend strongly on the properties of the interface between the components. Thus, it is important to investigate the stability of the microstructure with respect to annealing at elevated temperatures. In this paper results will be presented on the structure and composition of the interfaces between Cu and (α -Al2O3. The interfaces were processed either by growing a thin Cu overlayer on α- Al2O3 in a molecular beam epitaxy (MBE) system or by diffusion bonding bulk crystals of the two constituents in an UHV chamber. To improve the adhesion of Cu to α -Al2O3 ultrathin Ti interlayers were deposited between Cu and α - Al2O3.
Interfaces were characterized by different transmission electron microscopy (TEM) techniques. Quantitative high-resolution electron microscopy (QHRTEM) allows the determination of the structure (coordinates of atoms) while analytical electron microscopy (AEM) allows the determination of the composition with high spatial resolution.
HRTEM Analysis of Defect Structures in AIN Thin Films
Authors: R. Heffelfinger Jason , F. McCarty Kevin , L. Medlin Douglas 
Published: July 2020

Abstract
HRTEM analysis and conventional TEM techniques were used to determine the nature and density of defects in AIN thin films grown by Molecular Beam Epitaxy (MBE). Extended defects, which act as phonon scattering sites, are detrimental to the thermal properties for which AIN is sought. [1] Previous research on defect structures in AIN has focused primarily on bulk materials. [2-5] This investigation extends previous studies by concentrating on defects native to AIN thin films.
The thin films for this study were grown by MBE onto annealed Al2O3 (corundum structure) substrates with a nominal (0001) surface orientation. The steps and structure of such (0001) Al2O3 surfaces have been previously characterized. [6] Films with thicknesses of 50 to 120 nm were grown at substrate temperatures between 700°C and 900°C. An RF driven source for atomic nitrogen and an aluminum effusion cell were used to generate deposition fluxes. TEM samples were prepared in plan-view and cross-section using conventional dimpling and ion milling techniques.
Complementary Use of APFIM and TEM for a Study of Precipitation in a Rapidly Solidified Stainless Steel
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Kelly T F , Wisutmethangoon S , Camus P P , Larson D J , Miller M K 
Published: July 2020

Abstract
Stainless steels are important technologically for a wide range of applications. Though they are attractive for their environmental stability, austenitic versions of these steels are not generally known for their very high strength. We have rapid-solidification-processed many stainless steels by gas atomization and achieved strength improvements of over 50% relative to conventionally-processed stainless steels with concomitant improvement in corrosion and oxidation behavior. These strength improvements are most pronounced when elevated concentrations of oxygen and vanadium are present in the metal and we need to know how these elements affect precipitation in the alloy.
The specimen material (FCC Fe-16%Ni-9%Cr-0.5%Mn-0.2%V-0.0137%N-0.008%O by weight) was prepared by gas atomization and hot extrusion followed by precipitation aging as described elsewhere. We observed the structure in TEM and found 20 nm precipitates on dislocations, Fig. 1a. We did not observe smaller precipitates in the grain interiors using diffraction contrast bright field imaging, however, with weak-beam dark field imaging, Moiré fringe contrast is observed throughout the material, Fig. 1b.
Type 316l Stainless Steels Exhibiting Five-Fold Symmetry Mo-Rich Phase
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Oh Yong-Jun , Ryu Woo-Seog , Hong Jun-Hwa , Kuk Il-Hiun 
Published: July 2020

Abstract
The existence of phases exhibiting five-fold symmetry patterns has recently been reported for conventional heat treated alloys as well as rapidly solidified alloys. The present paper reports initial results on the analysis of a Mo-rich phase in 316L stainless steel which exhibits this symmetry. The formation and growth of this Mo-rich phase were investigated as a function of aging time. In addition, the effect of nitrogen content on the formation of this five-fold phase was also investigated.
The materials investigated were type 316L stainless steels with nitrogen contents of 0.024% and 0.150%. The materials were solution-annealed at 1100 °C for 30 minites followed by an aging treatment at 700 °C for 10–50 hours in a vacuum sealed quartz tube. TEM samples were prepared by conventional twin-jet polishing and carbon replications extracted by use of a bromine-etch.
Irrespective of nitrogen content, the grain boundary phases after 50 hours of aging were totally observed as five different types of precipitates; M23C6 and M6C carbides, intermetallic η and χ phases, and the five-fold symmetry phase.
Microscopical Examination of a Super Austenitic Stainless Steel
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Fourlaris G , Gladman T , Maylin M 
Published: July 2020

Abstract
Stainless steels have significant applications due to their good corrosion resistance. However, for applications in a marine environment, i.e. for certain types of large naval structures, in addition to the good corrosion resistance, other requirements are imposed on the candidate material such as high strength and toughness coupled with suitable magnetic characteristics.
It has been demonstrated in earlier publications that significant improvements in the coercivity, maximum induction and remanence values can be achieved, by using a 2205 type Duplex austenitic -ferritic stainless steel (DSS) instead of the low alloy medium carbon steels currently being used. These improvements are achieved in the as received 2205 material, and after small amounts of cold rolling have been applied, to increase the strength. However, the 2205 type DSS exhibits “ marginal” corrosion protection in a marine environment as well as exhibiting some measurable ferromagnetic response. Therefore, a study has been undertaken to examine the mechanical properties and microstructures obtained in a super austenitic stainless steel of the 254 SMO type.
TEM Microscopical Examination of the Stepped Bainite Reaction in Silicon Steels.
Authors: Fourlaris G , Papadimitriou G 
Published: July 2020

Abstract
The bainitic reaction in steels has been extensively studied, however it is still controversial whether it proceeds by a diffusional or a shear mechanism. In a previous investigation of the bainite reaction in a Fe-3.9Si-0.9C steel the transformation was considered to be the result of two competing elementary mechanisms, i.e., the shear transformation of the α-iron lattice and the diffusion of interstitial carbon away from the transformation interface.
In this paper, the microstructural and crystallographic characteristics of the bainite products obtained through the step quenching experiments are examined, using TEM and Electron diffraction. The results are compared to those obtained by the corresponding bainitic transformation in a single step. The results obtained here support the proposed model in and the shear character of the bainitic transformation.
The same steel as in, an alloy with 3.9 w.t.% silicon and 0.9 w.t.% carbon, was used. After austenitizing at 1130°C for 30 minutes a number of samples were transformed at 420°C for 30 minutes and subsequently quenched in a second bath where they were kept for times increasing from one to thirty days at temperatures of either 360,340 or 290°C.
Atom Probe Field Ion Microscopy of Model Ni-Al-Be Superalloys
Authors: Thomson R C , Russell K F , Miller M K 
Published: July 2020

Abstract
Nickel-based superalloys used in jet engines consist of a face-centred cubic Ni matrix, γ, containing a high density of Ll2-ordered Ni3Al precipitates, γ´. At high temperatures the strength of the alloy depends primarily on the strength of the γ´ phase, which begins to decrease above approximately 750°C, limiting the maximum operating temperature of the superalloy. The possibility of strengthening the γ´ phase by solid-state precipitation within the γ´ phase has been investigated in model Ni-Al superalloys containing Be. Beryllium, a light element, is also expected to be a potent solid solution strengthener in the γ´ matrix.
Four alloys were manufactured with compositions Ni-18.8 at. % Al-1.6% Be, Ni-19.0 at. % Al-2.6% Be, Ni-17.9 at. % Al-5.4% Be and Ni-15.9 at. % Al-11.9% Be. These Al levels result in a volume fraction of γ´ phase similar to that present in a commercial superalloy, and the Be addition places the superalloys in the γ-γ´-NiBe region of the ternary phase diagram, Fig. 1.