bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early stages of oxygen precipitation in si: morphology and structure
Authors: Bergholz W. , Hutchison J. L. 
Published: June 2020

Intrinsic gettering in Si - VLSI technology depends on a controlled initial stage of oxygen precipitation and is characterized by a complicated interaction of growth-induced microdefects, self interstitial (SiI) generation and strain caused by SiO2 precipitate growth and secondary defects, table 1. We address the controversial issues of the identity of ribbon-like defects (RLDs) and of the nature of oxygen precipitate nuclei.RLDs were initially identified by HRTEM as coesite, a high pressure phase of SiO2. Recently, both Bourret and Reiche et al have interpreted the RLDs as hexagonal Si, or agglomerates of Si. We wish to make the point that the evidence against coesite is, as yet, not conclusive, and present circumstantial evidence in favour of coesite: (1) The loss of interstitial oxygen correlates with the density of RLDs (Fig. 1) at 450 - 485°C.
TEM and cathodoluminescence of precipitates in II-VI semiconductors
Authors: Batstone Joanna L. 
Published: June 2020

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-xTe are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.
Microstructural characterization of inconel alloy 690
Authors: Burke M. G. , Hyatt B. Z. 
Published: June 2020

Inconel 690 is a nickel-base superalloy which, because of its superior corrosion resistance, is being considered as a substitute for Inconel 600. The composition of Alloy 690 is nominally 30wt.%Cr-10wt.%Fe-0.3wt.%Ti-bal Ni. This alloy is generally used in the thermally treated condition: solution anneal in the range 1030-1120*C for ∼0.07-lh followed by a thermal treatment (∼550-875*C for ∼10h) [1,2]. The purpose of this study is to characterize the microstructure during the post-annealing thermal treatment by scanning/transmission electron microscopy (STEM/TEM). Of particular importance is the identification of precipitates and the documentation of Cr depletion at grain boundaries and precipitates. Specimens were examined in the 1) annealed, and 2) annealed and thermally treated conditions.TEM examination of the annealed alloy revealed that the conventional annealing treatment did not result in the complete dissolution of the M23C6 precipitates. Numerous coarse matrix carbides were visible in the alloy. In addition, notable intergranular precipitation of M23C6. occurred during cooling from the annealing temperature (Fig. 1.).
Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications
Authors: Franck R. E. , Hawk J. A. , Shiflet G. J. 
Published: June 2020

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.
Effect of inert gas on the structure/property relations in rapidly solidified 304 stainless steel
Authors: Chan Bae Jung , Kelly Thomas F. , Flinn John E. 
Published: June 2020

Recent research reported that significant amounts of helium (about 8 appm) are entrained in extruded Type 304 stainless steel powder that has been rapidly solidified by centrifugal atomization with helium cooling gas. The entrained helium was reported to be directly related to a desirable improvement in properties of materials such as a notable resistance to grain growth, improved room temperature tensile properties with little reduction in ductility and improved creep properties.The purpose of this work was to study the effect of inert gases on the microstructure of powder-metallurgy (P/M) Type 304 stainless steel with different preconditioning heat treatments. The heat treatments performed on the specimens include 1 hour anneals at 900,1000,1100, and 1200C followed by water quenching. In addition, the 1100 and 1200C annealed specimens were subjected to aging treatments at 600C for 1000 hours. The TEM specimens were thinned by electropolishing at 13C using a solution of 5% perchloric acid in acetic acid.
Fibrous and columnar grain structures in chromium films
Authors: Jiang-zhong Duan , Hetherington Crispin , Fisher R.M. 
Published: June 2020

Vapour-deposited and sputtered thin films are widely used in optical and microelectronic components. The optical, electrical and mechanical properties of such films depend primarily on microstructural features such as grain size, shape and crystallographic orientation, defect and impurity content, and substrate surface topology. The microstructure is determined by deposition conditions and especially substrate temperature andinclination relative to the source, metal deposition rate, and residual gaspressure in the chamber. These parameters affect the transition fromirregular, defect-laden, fibrous grains and rough film surfaces to smooth, highly reflecting surfaces and well-formed columns with little void space between them.Factors affecting the adherance of thin films to substrates are under study as part of a broad program on interfacial adhesion. Important parameters are internal stresses that drive spontaneous delamination and the fracture energy of the interface that resists crack growth. Internal stress levels in Cr films can be exceptionally high, so this metal is being studied extensively to determine the origin of tensile stresses in relation to microstructure.
Microstructural characterization of AIN sintered with Y2O3
Authors: Chiang S-K. 
Published: June 2020

Aluminum nitride's high thermal but low electrical conductivity make it a potential ceramic packaging material. Processing history, however, can have significant effects on these properties and studies aimed at correlating them to the processing and microstructure are sparse.Pure AIN cannot be readily sintered without additives. Addition of Y2O3 significantly improves its densification behavior and the results presented here concern microstructural analysis of AIN sintered with Y2O3.High-purity AIN powder (containing 1.24% oxygen impurity) with 3 or 9 weight% Y2O3 added was sintered in N2 at 1850°C for 1 hour followed by a further 3 hours at 1900°C. Samples made using this treatment were >95% dense. Specimens for microstructural investigation were prepared using standard techniques and examined using a JEOL 200 CX AEM.The general microstructure of all specimens consists of AIN grains with pockets of intergranular phase(s) located at triple points and some grain boundaries (FIG. 1).
TEM studies of line defects in interfaces
Authors: Pond R.C. 
Published: June 2020

Line defects are ubiquitious features in interfaces, and have important structural and mechanistic role. Recently, a crystallographic theory of such defects has been presented which appears to offer a comprehensive framework for their classification. The object of the present paper is firstly to outline the characterisation and classification of defects according to this treatment. Secondly, we illustrate examples of defects in the distinctive classes observed using tern, and discuss the various imaging techniques which have been employed.In the absence of a rigorous treatment of line defects in single crystals and interfaces, which would require the development of a discrete field theory, approximate methods of defect characterisation are used. The most popular method involves mapping a contour, initially constructed around a defect of interest, into a reference space. For defeats in single crystals this Burgers circuit method, introduced by Frank, is very helpful, but suffers from certain procedural inconveniences in the case of interfacial defects.
Grain boundary structure in Ni3Al
Authors: Mackenzie R.A.D. , Vaudin M.D. , Sass S.L. 
Published: June 2020

Ni3Al is a potentially useful high temperature alloy. In its single crystal form it exhibits good ductility, however in polycrystalline form the pure alloy is highly prone to intergranular failure. It has been seen that in slightly nickel-rich alloys the addition of small amounts of boron has the effect of dramatically increasing the material ductility and of changing the failure mode from intergranular to transgranular. In alloys which have been ductilitized by boron addition, atom probe investigation has shown the boron to be segregated to grain boundaries. This segregation may induce a change in the boundary structure as has been seen by Sickafus and Sass in gold doped iron bicrystals.Small angle boundaries in polycrystals and fabricated bicrystals have been examined using transmission electron microscopy. The bicrystals were produced by hot pressing misoriented single crystals of either pure or doped Ni3Al. Boundaries have been observed in a variety of fabricated bicrystals.
Are major instrumental developments in TEM still to be Expected?
Authors: van der Mast K.D. , Koster A.J. 
Published: June 2020

In general instrumental developments are caused either by new application demands or by the availability of new technologies. If we investigate the trends in application demands, some predictions can be made safely: More and more the TEM will be used as an analytical instrument. The number of desired signals (detectors) will increase and the quality of the signals must be improved in terms of noise and electron efficiency. Examples are parallel collection EELS and Auger detectors (Kruit and Venables, 1988).The first experiments on coincidence techniques are also promising (Kruit et al, 1984) and exciting new ideas are investigated today. Besides this, another area of applications will probably become more important: surface science in situ experiments. Especially for this type of experiments it is difficult to transfer the specimen to another system without spoiling the experiment. So these applications will lead to an ultra high vacuum specimen environment - constructed in a way that many accessories necessary for surface experiments can be added: Ion guns, preparation chamber, knudsen cells etc.
A compact, digital, optically isolated control and support system for a field-emission source on the 200 kV STEM
Authors: Mooney P. E. 
Published: June 2020

In the third order corrected STEM, optimization of the probe subject to the limits of fifth order spherical aberration and chromatic aberration leads to a choice of 200 KY for the accelerating potential. In order to obtain sufficient stability at this voltage it Is necessary to house the accelerator, high voltage pover supply and electron beam source in a dry N2 pressure vessel and to cover the source housing vith a polished corona discharge shield. All support electronics for the the beam source must be mounted vlthin this shield. The field emission tip beam source requires a stable extraction voltage, a tip chamber high vacuum system, and a flashing circuit. A compact, optically isolated, digitally controlled system has been built which provides these primary functions along with support functions such as tip alignment, current and voltage monitoring and pover storage.The major concerns in design of the control system were pover conservation, transient protection, acoustic isolation and compactness.
Reactivity and structure of nickel-cobalt bimetallic catalysts
Authors: Woo Ho K. , Srinivasan R. , Rice L. , Reucroft P.J. , De Angelis R.J. 
Published: June 2020

Ni and Co catalyst systems have been extensively dealt with in the catalyst research literature but investigations on Ni/Co alloy systems have been relatively sparse. An early study attempted to correlate catalysed hydrogenation activity with metal/alloy lattice parameter. Matsuyama et al. investigated catalytic hydrogenation of ethylene by nickel alloys as a function of surface and bulk composition. The activity increased as the proportion of Ni increased but decreased from 90 to 100%Ni. A study has been initiated to relate catalytic activity to the structure of Ni/Co bimetallic catalyst particles.Silica supported catalysts were prepared by the incipient wetness (impregnation) technique. Nickel, and cobalt nitrate in the desired proportions were dissolved in the impregnating solution. The wet catalyst samples were dried overnight at 120C after impregnation,. Catalysts were reduced by heating at 400C in flowing hydrogen for 18 hrs. Reactivity was determined by passing a 3/1 mixture of hydrogen and carbon monoxide over the catalyst and analyzing the effluent stream at hourly intervals by gas chromatography for hydrocarbon products.
Effects of compression during formation on the microstructure of composite hydroxylapatite/plaster implants for bone reconstruction
Authors: Hanker J. , Cowden K. , Noecker R. , Yates P. , Georgiade N. , Giammara B. 
Published: June 2020

Composites of plaster of Paris (PP) and hydroxylapatite (HA) particles are being applied for the surgical reconstruction of craniofacial bone defects and for cosmetic surgery. Two types of HA particles are being employed, the dense sintered ceramic (DHA) and the porous, coralline hydroxylapatite (PHA) particles. Excess water is expressed out of the moistened HA/PP mixture prior to implantation and setting by pressing it in a non-tapered syringe against a glass plate. This results in implants with faster setting times and greater mechanical strengths. It was therefore of interest to compare samples of the compressed versus noncompressed mixtures to see whether or not any changes in their microstructure after setting could be related to these different properties.USG Medical Grade Calcium Sulfate Hemihydrate (which has the lowest mortar consistency of any known plaster) was mixed with an equal weight of Interpore 200 particles (a commercial form of PHA). After moistening with a minimum amount of water, disc-shaped noncompressed samples were made by filling small holes (0.339 in. diameter x 0.053 in. deep) in polypropylene molds with a microspatula.
Microstructure in soft magnetic E3 (S1, Al) (Sendust) alloys
Authors: Kim June D. 
Published: June 2020

Iron-base alloys containing 8-11 wt.% Si, 4-8 wt.% Al, known as “Sendust” alloys, show excellent soft magnetic properties. These magnetic properties are strongly dependent on heat treatment conditions, especially on the quenching temperature following annealing. But little has been known about the microstructure and the Fe-Si-Al ternary phase diagram has not been established. In the present investigation, transmission electron microscopy (TEM) has been used to study the microstructure in a Sendust alloy as a function of temperature.An Fe-9.34 wt.% Si-5.34 wt.% Al (approximately Fe3Si0.6Al0.4) alloy was prepared by vacuum induction melting, and homogenized at 1,200°C for 5 hrs. Specimens were heat-treated in a vertical tube furnace in air, and the temperature was controlled to an accuracy of ±2°C. Thin foils for TEM observation were prepared by jet polishing using a mixture of perchloric acid 15% and acetic acid 85% at 10V and ∼13°C. Electron microscopy was performed using a Philips EM 301 microscope.
Vanadia-induced transformations in yttria-stabilized zirconia
Authors: Susnitzky D.W. 
Published: June 2020

Thermal-barrier coatings for jet-engine components are typically composed of Y2O3-stabilized ZrO2 (YSZ) since this material provides improved ceramic-to-metal bonding, thermal-stress resistance and stability. One problem associated with YSZ thermal barriers is the increased rate of coating failures encountered when trace amounts of impurities, such as 50ppm vanadium, are present in the jet fuel. V2O5 reacts with YSZ to form YVO4 and a monoclinic ZrO2 phase. Although coating failures are attributed to the 3-5% volume change associated with the tetragonal- to-monoclinic transformation, the exact mechanism of V2O5 attack has been unclear. The present study addresses the deleterious effects of V2O5 on YSZ at 810°-950°C by directly exposing perforated TEM specimens of single-crystal YSZ to the vapor produced by a small quantity of V2O5 powder. The experimental details of this thin-film reaction technique have been described elsewhere.Fig.l shows a bright-field (BF) image recorded from a (100)-oriented YSZ (9mol% Y2O3) specimen which was exposed to V2O5 vapor for 30 min at 810°C.
TEM sample preparation of superconducting oxides
Authors: Sarikaya Mehmet , Thiel B. L. , Bradley J. P. 
Published: June 2020

The preparation and observation of high Tc superconducting TEM samples deserves a great deal of care since, as when characterizing any new material, mistreatment can bring about extrinsic features leading to erroneous conclusions. In dealing with materials such as these, where the structural origins of the electromagnetic properties are tantamount, this is especially true. The three most common practices of sample preparation are suspending crushed powder, ultramicrotomy, and ion-beam milling. The illustrations will be made with YBa2Cu3O7-x samples.The powder suspension technique requires grinding the material with a suitable mortar and pestle (e g., agate) to a size which will allow electron transparency. Dispersing the particles in a suitable solvent such as water or acetone prevents aggregation. If the sample has large amounts of extraneous phases, the choice of medium is crucial as reactions will occur. Ni or Ti grids (50 to 75 mesh) with carbon films are used to fish out the suspended particles.
Characterization of Y-Ba-Cu-O films grown on silicon substrates by sequential evaporation
Authors: Hall E. L. , Mogro-Campero A. , Turner L. G. , Lewis N. 
Published: June 2020

There is great interest in the growth of thin superconducting films of YBa2Cu3Ox on silicon, since this is a necessary first step in the use of this superconductor in a variety of possible electronic applications including interconnects and hybrid semiconductor/superconductor devices. However, initial experiments in this area showed that drastic interdiffusion of Si into the superconductor occurred during annealing if the Y-Ba-Cu-O was deposited direcdy on Si or SiO2, and this interdiffusion destroyed the superconducting properties. This paper describes the results of the use of a zirconia buffer layer as a diffusion barrier in the growth of thin YBa2Cu3Ox films on Si. A more complete description of the growth and characterization of these films will be published elsewhere.Thin film deposition was carried out by sequential electron beam evaporation in vacuum onto clean or oxidized single crystal Si wafers. The first layer evaporated was 0.4 μm of zirconia.
Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x
Authors: Thiel Bradley L. , R. P. Chan Han , L. C. Hutter Kurosky , Aksay I. A. , Sarikaya Mehmet 
Published: June 2020

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.
TEM characterization of Ge films grown On GaAs (111) and Ge (111) by RPECVD
Authors: Posthill J.B. , Vitkavage D.J. , Rudder R.A. , Hattangady S.V. , Parikh N.R. , Fountain G.G. , Markunas R.J. 
Published: June 2020

The fabrication of a Ge/GaAs heterostructure presents several attractive possibilities for device applications. The formation of a 2-D electron gas due to the difference in bandgaps between the two materials, and the increased hole mobility in Ge may allow a practical HMT-CMOS technology to be developed. Before this structure can be realized; however, it is essential to have a clean, low temperature growth process for the formation of electronic-quality Ge epitaxy. Remote plasma-enhanced chemical vapor deposition (RPECVD) in an ultrahigh vacuum compatible growth chamber is currently being investigated for this purpose. This paper addresses the ex-situ characterization of Ge/GaAs(111) heteroepitaxial structures grown by RPECVD at different temperatures and subsequent comparison with Ge/Ge(111) homoepitaxial material.Nominal GaAs(111) wafers that had been Ga-face polished and Ge(111) wafers were chosen for this study. Individual wafers were cleaned, loaded into the growth chamber and baked at 200°C for ∼ 10 hours.
TEM studies of dislocations in deformed Ga1-xInxAs single crystals
Authors: Rai R. S. , Guruswamy S. , Faber K. T. , Hirth J. P. 
Published: June 2020

The perfection of GaAs single crystals can be controlled by doping the GaAs with In, at a level of about 5x1019-1x1020/cm3, in single crystals grown by the LEC process. It has been observed that In doping at this level reduces the grown in dislocation density from 104-l05 to ≤ 102/cm2 and results in a large increase in high temperature strength . However, the role of In in dislocation density reduction is not clearly understood. Therefore, a systematic study has been performed with the help of high temperature deformation of In-doped and undoped GaAs single crystals followed by dislocation structural characterization by transmission electron microscopy of the deformed specimens. Here, some results of dislocation studies performed by TEM are descri bed.Samples were examined in a JEOL JEM 200CX transmission electron microscope equipped with a double tilt goniometer stage. The standard g.b criterion was employed for characterization of dislocations. Dark-field weak beam pictures were taken for characterization of partial dislocations and dipoles.