bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Oxygen on Diffusion and Compounding at Ni-GaAs(100) Interfaces
Authors: Solomon J. S. , Thomas D. R. , Smith S. R. 
Published: March 2011

ABSTRACTThe effects of the presence of surface oxides and oxygen incorporated in deposited Ni films on intermixing and compounding at Ni/GaAs(100) interfaces was investigated with Auger sputter profile analysis. The Ni/GaAs structures were heated in vacuum with a high intensity incoherent lamp. Chemical changes and compound distributions were extracted from profile data by factor analysis of the Auger peaks. Diffusion coefficients for Ni at different temperatures were obtained from profile concentration gradients. The results showed that Ni diffusion was faster and activation energy lower for clean versus oxide covered GaAs substrates. Without the presence of oxygen, Ni2 GaAs readily formed at 300°C while with oxygen, the formation of Ni-Ga and Ni-As compounds prevailed over the formation of a distinct Ni2 GaAs layer.
SIMS, SAM and RBS Study of High Dose Oxygen Implantation into Silicon
Authors: Lau W. M. , Ratnam P. , Salama C. A. T. 
Published: March 2011

ABSTRACTSecondary Ion Mass Spectrometry, Scanning Auger Microscopy, and Rutherford Backscattering Spectroscopy have been used to study a buried oxide structure on silicon formed by high dose implantation. All these surface analytical techniques give useful information about the oxygen distribution in the buried oxide structure. The difficulties in these techniques have also been assessed.
Cation Solute Segregation to Surfaces of MgO and α-Al2O3
Authors: McCune Robert C. 
Published: March 2011

ABSTRACTLow energy ion scattering spectroscopy (LEIS) and Auger electron spectroscopy (AES) were used to measure the extent of impurity cation solute segregation to MgO (100) and various surfaces of single and polycrystalline Al2O3, following equilibration anneals at temperatures above 1000°C in ulfra-high vacuum. Systems studied include Ca/MgO, Ni/MgO, Ca/A12O3 and Y/Al2O3. Calcium segregation to MgO (100) is reversible and exhibits monofayer adsorption behavior with an enthalpy of segregation of approximately -55 kJ/mole with maximum occupation of surface cation sites approaching 40%. Nickel segregation to MgO(100) is masked by a preferential segregation of calcium. Calcium segregation to A12O3 surfaces has been found to be transient with a maximum surface cation site occupation of less than 10% as determined by LEIS and estimated enthalpy of segregation in the range -go to -190 kJ/mole. Yttrium segregation to surfaces of a polycrystalline Al2O3 compact was limited by competing calcium segregation at temperatures be ow 1600°C. An estimated enthalpy of segregation for yttrium to A12O3 surfaces was in the range -23 to -43 kJ/mole, with maximum cation surface site occupation of about 15%. Practical limitations to free surface measurements of solute segregation in these materials are discussed.
Secondary Ion Mass Spectroscopy of Ceramics
Authors: Taylor Jenifer A.T. , Johnson Paul F. , Amarakoon Vasantha R.W. 
Published: March 2011

ABSTRACTApplication of SIMS to ceramics is a complicated but rewarding technique for characterization. The variable composition, hardness and insulating nature of these materials render spectra interpretation complex. Basic data reduction procedures from graphical data collection are presented along with spectra from SIMS applied to a glass frit, magnesium sialon, silicon and PTCR barium titanate.
Sims Analysis of Pure and Hydrated Cements
Authors: Naegele Erich , Schneider Ulrich 
Published: March 2011

ABSTRACTSIMS-measurements permit a direct determination of the hydration depth of cement particles from the depth profiles of various elements. Furthermore, surfactants containing an aromatic ring system can be analysed qualitatively and quantitatively using the SIMS-intensities of characteristic aromatic fragments. In addition, a new model for the evaluation of SIMS-spectra of oxidic materials is proposed.
Application of Sims Depth Profiling to Ceramic Materials
Authors: Taylor Jenifer A.T. , Johnson Paul F. , Amarakoon Vasantha R.W. 
Published: March 2011

ABSTRACTDepth profiling is becoming a common method of determining composition gradients for those research facilities that have access to SIMS. The problems with this procedure are briefly discussed but well referenced for those interested in using the technique. Spectra for application of depth profiling to a tantalum pentoxide layer on tantalum, silicon implanted in silica, preferential sputtering of niobium and surface treated lithium alumina silicate glass are presented.
Properties of Single-Crystal Silicon Films on Amorphous SiO2on Single-Crystal Cubic Zirconia Substrates
Authors: Golecki I. , Maddox R. L. , Glass H. L. , Lin A. L. , Manasevit H. M. 
Published: March 2011

ABSTRACTA new approach to achieving a large-area silicon-on-insulator technology without pre-patterning is described. (100) Si films are first grown epitaxially on (100) yttria-stabilized cubic zirconia (YSZ) substrates by the pyrolysis of SiH4. The Si side of the <Si>/<YSZ>interface is then oxidized in pyrogenic steam (at 925 °C) or dry oxygen (at 1100°C) to form the structure <Si>/amorphous SiO2/<YSZ>. The oxidation occurs by the rapid diffusion of oxidants through the 0.42 mm thick YSZ substrate; e.g., a 0.3 μm SiO2layer is obtained in 6 h in steam. The samples are analyzed by Rutherford backscattering and channeling spectrometry, X-ray diffraction, infra-red reflectance, Auger electron spectroscopy and sheet resistance measurements. In addition to forming the preferred Si/SiO2interface, the back-side oxidation eliminates the most defective part of the Si film.
Materials Characterization with Intense Positron Beams
Authors: Rosenberg I. J. , Howell R. H. , Fluss M. J. , Meyer P. 
Published: March 2011

ABSTRACTWe have developed an apparatus that provides a high flux, low energy, monoenergetic positron beam to investigate various processes which occur when a positron beam impinges on a metal surface, including annihilation at the surface, trapping in vacancies, and the emission of both fast and thermally desorbed positronium. We report here the first angular correlation of annihilation gamma-rays measurements and positronium time of flight experiments at a material surface. We applied a simple free electron model which explains the general trend of the data but differences due to the surface specific properties and the deviation from a free electron metal are evident.
Effects of Ambient Gas on the Out-Diffusion of Nickel and Copper through Thin Gold Films
Authors: Lewis R. K. , Ray S. K. , Seshan K. 
Published: March 2011

ABSTRACTThe low temperature (300–400°C) out-diffusion of an underlying metal through a thin film overlayer of another metal has been studied in ambients of N2 and forming gas. Surface oxidation of this out-diffused metal can interfere with the attachment of terminating components used in semiconductor devices. AES depth profile analysis has shown that the out-diffusion of Ni through Au is suppressed in a forming gas ambient. It has also been shown that the extent of this out diffusion can be modified considerably by the presence of Cu.
Applications of Surface Analysis by Laser Ionization (Sali) to Insulators and II–VI Compounds
Authors: Becker C. H. , Stahle C. M. , Thomson D. J. 
Published: March 2011

ABSTRACTExamples of the mass spectrometry of sputtered or evaporating neutral species obtained by SALI are presented for NBS Glass 610 (primarily a silicate), and an anodic oxide of HgCdTe. For the NBS glass, a SIMS spectra was recorded for comparison with SALI using the same apparatus. The raw SALI spectra of the glass is in semiquantitative accord with the known composition, in contrast to SIMS. Relative secondary ion yields can be determined for unknown complex materials by comparing SALI and SIMS spectra. Depth profiling measurements on the anodic oxides of Hg1−xCdxTe show a significant though depleted concentration of Hg in the oxide in contrast to numerous other analyses; this result is corroborated by RBS studies. Hg and also Te evaporation is monitored in real-time by SALI with large dynamic range capabilities.
High Temperature Raman Studies of Phase Transitions in Thin Film Dielectrics
Authors: Exarhos Gregory J. 
Published: March 2011

ABSTRACTRapid and unambiguous characterization of crystalline phases in submicron sputter deposited TiO2 films on silica substrates can be inferred from measured Raman spictra. Pure anatase and rutile, mixed phase, and amorphous films to thicknesses of several hundred Angstroms and greater yield Raman spectra exhibiting little interference from the substrate when the appropriate component of the scattered light is analyzed. In situ Raman spectra were acquired as a function of temperature to 900°C using conventional radiant heating techniques and to temperatures near 2000°C using 10.6μ radiation from a CW CO2 laser as a localized heating source. Pulsed Raman excitation/gated deiection techniques were used to minimize blackbody radiation interference at these high temperatures. Anatase and amorphous TiO2 films transform irreversibly to the rutile phase at temperatures below 900°C while rutile appears to be stable at much higher temperatures. Measurements performed on uncoated silica substrates at temperatures where the glass becomes fluid suggest that the strongly crosslinked glass has partially transformed into a chain-like structure.
Atomic Interactions in Silicon-Metal Complexes on W(110)
Authors: Wrigley John D. , Ehrlich Gert 
Published: March 2011

ABSTRACTWith the field-ion microscope one not only can locate individual atoms at a surface, but under some circumstances also can discriminate between chemically different species. These capabilities are illustrated in an examination of the strength of binding in silicon-metal surface clusters and in a detailed analysis of their mobility.
The Thickness Effect on the Microstructure of Sputtered Films Studied by a New X-Ray Diffraction Method
Authors: Hecq M. 
Published: March 2011

ABSTRACTThe microstructure of sputtered platinum thin films has been investigated by X-ray diffraction analysis. The (111) reflection was analysed by the variance and the Fourier methods. The effective particle size was calculated from the variance slope coefficient and the microstrain from the Fourier cosine coefficients assuming that the effective sizes calculated from both methods are identical. Various thickness thin films have been studied. The effective particle size (Dev) increases with ev increasing film thickness until a thickness of ≈ 1500 Å, then Dev becomes constant and independent on the thickness. The microstrain varies in an inverse way to Dev ; it decreases with increasing thickness. Above a thickness of 1500 Å, the microstrain is constant.
Convergent-Beam Diffraction in the Characterization of Crystalline Phases
Authors: Eades J. A. , Kaufman M. J. , Fraser H. L. 
Published: March 2011

ABSTRACTConvergent-beam diffraction in the transmission electron microscope is a powerful technique for the characterization of crystalline materials. Examples are presented to show the way in which convergent-beam zone-axis patterns can be used to determine: the unit cell; the symmetry; the strain of a crystal. The patterns are also recognizable and so can be used, like fingerprints, to identify phases.
Cold Alchemi: Impurity Atom Site Location and the Temperature Dependance of Dechannelling
Authors: Spence J. C. H. , Graham R. J. , Shindo D. 
Published: March 2011

ABSTRACTRecent applications of the “Atom Location by Channelling Enhanced Microanalysis” (ALCHEMI) are summarised. This is a quantitative method for determining the sites of impurity atoms in crystals using an electron microscope and X-ray analysis system. Since the fractional site occupancies are given in terms of measured X-ray counts alone, it involves no adjustable parameters. New experiments have been performed on the temperature dependence of characteristic X-ray production under channelling conditions for InP and GaAs. We conclude that low temperatures will give more accurate results for “ALCHEMI” in some materials due to the reduction in diffuse inelastic phonon scattering, and that the study of this temperature dependence may provide new information from small areas or particles on the correlations amongst atom motions due to thermal vibration.
Role of the Critical Voltage Effect in Materials Characterization
Authors: Fisher Robert M. 
Published: March 2011

ABSTRACTThe HVEM “critical voltage” effect can provide quantitative information about intrinsic crystal parameters that cannot be obtained easily on a microscopic scale by other techniques. For pure elements, more accurate atomic scattering amplitudes and Debye temperatures have been determined. In binary alloys, the occurrence of segregation, short or long range order or clustering can be evaluated and charge distribution or transfer and atomic bonding changes detected in favorable cases.
Diffusion Measurements by Analytical Electron Microscopy
Authors: Romig A. D. 
Published: March 2011

ABSTRACTThe analytical electron microscope (AEM) has been used to measure the concentration gradients which form in single and multiphase diffusion couples. The procedures used to collect x-ray microanalytical data and reduce that data to elemental compositions are typical of those used to quantify x-ray data generated in thin films. The primary difficulty in analyzing diffusion couples with the AEM is sample preparation. The principle advantage of the AEM as a tool to measure diffusion induced concentration gradients is its high spatial resolution, approximately 20 to 100 times better than that of the electron microprobe which has been traditionally used to measure these concentration profiles. As a consequence, the AEM data can yield diffusivities as much as 5 orders of magnitude smaller than those obtained from electron microprobe data. This paper will review the fundamental principles of the determination of diffusion coefficients from the concentration gradients measured in single and multiphase diffusion couples and the basic considerations of thin foil x-ray microanalysis. With this understanding of the basic concepts, recent studies of diffusion in Ta-W and U-Nb will be discussed.
AEM Microanalysis of Phase Equilibria in Ni3Al Intermetallic Alloys Containing Iron
Authors: Bramfitt Bruce L. , Michael Joseph R. 
Published: March 2011

ABSTRACTIn order to fully exploit the potential of Ni3Al alloys containing iron, it is necessary to characterize the phase relationships at the Ni-rich region of the Ni-Al-Fe ternary phase diagram. Due to the fine scale structures observed, a technique with high spatial resolution is required. X-ray microanalysis in the analytical electron microscope (AEM) provides a sufficiently high spatial resolution to determine the composition of the various phases occurring in this system. In this study, the isothermal section at 1000°C was evaluated in a series of alloys having nickel contents greater than 65 wt%. In Ni3Al, Fe can substitute for either Ni or Al in the ordered face-centered cubic lattice having an Ll2 structure. However, in substituting Fe for Ni one finds that the solubility limit is quickly exceeded at about 5 wt% Fe with the resultant formation of a ordered body-centered cubic (B2) phase at high temperature, which transforms martensitically upon quenching. Also, in substituting Fe for Al, the solubility limit is exceeded at about 5 wt% Fe with the formation of a disordered, face-centered cubic Ni-rich terminal solid solution. Thus, a very narrow range of alloy compositions exist where Fe can substitute for Ni and Al and preserve a single-phase L12 structure. It was found that the maximum solubility of Fe in Ni3Al at 1000°C was 17.3 wtpercnt; at 70.3 wt% Ni and 12.4 wt% Al.
High Resolution Moire Imaging of Small Precipitates
Authors: Kesternich W. 
Published: March 2011

ABSTRACTSmall precipitates of high lattice mismatch with respect to the matrix may be investigated by high resolution and high contrast moiré fringe images in TEM. One group of such precipitates are the MX-type precipitates with M = Ti, V, Zr, Nb, Hf, Ta, and X = C,N that form in austenitic steels. The usefulness of moiré images for the investigation of these MX-type precipitates is demonstrated and compared to other electron imaging and diffraction methods. The moiré technique has been used to study (a) nucleation and growth of precipitates, (b) the evolution of dual precipitate structures at grain boundaries, (c) morphology and faceting of small precipitates (∼10 nm diameter), (d) lattice parameter differences due to variation in precipitate chemical composition, (e) interaction of precipitates with dislocations, (f) gas atom trapping at precipitates, and (g) irradiation induced precipitate nucleation at point defect clusters.
TEM Studies of Precipitate Growth at the Atomic Level
Authors: Howe J. M. , Gronsky R. 
Published: March 2011

ABSTRACTRecent advances in transmission electron microscopy instrumentation and technique now make it possible to study the shape-evolution of precipitates in metallic alloys at the atomic level. This investigation demostrates how a combination of transmission electron microscopy techniques; namely, high-resolution electron microscopy, image simulation, energy-dispersive x-ray spectroscopy and convergent-beam electron diffraction are used to characterize the atomic structures, chemistry and growth mechanisms of γ' precipitate plates in an Al-4.2 a/o Ag alloy aged for 30 min. at 350°C. The complimentary information obtained from each of these techniques allows modelling of the growth process at the atomic level, thus providing insight into the basic precipitation behavior of alloys.
A Quasicrystalline Decagonal Phase in Al-Fe-Ce
Authors: Angers L. H. , Marks L. D. , Weertman J. R. , Fine M. E. 
Published: March 2011

ABSTRACTA number of dispersed phases in Al-Fe-Ce alloys, varying structurally and chemically, have been observed by TEM. Of particular interest were rod-like particles which showed five-fold symmetry and irrational spacings. These dispersoids contain linear features, a periodic, columnar structure parallel to the five-fold axis, aperiodic spacings perpendicular to the five-fold axis and were coherent in one direction with the Al matrix. The evidence indicates a two-dimensional Penrose tiling with a columnar structure, possibly a stacking of eclipsed pentagonal units.
Quantitative Microanalysis of Fine Precipitates in Microalloyed Steels
Authors: Michael Joseph R. 
Published: March 2011

ABSTRACTMatrix and grain boundary precipitation in austenite has been studied in two Nb/V microalloyed steels with different V levels, which were given a number of different heat treatments after hot deformation. The steel with a higher V level was found to have a greater number of fine carbonitride precipitates in the matrix. In both steels, the precipitates became more Nb-rich as the aging temperature was increased from 854°C to 1066°C. For a given steel and heat treatment, the matrix precipitates were generally more Nb-rich than the grain boundary precipitates.
Electron Microscopy Observations of Precipitation During Tempering of Vasco X-2M Steel and its Relation to Impact Toughness
Authors: Krzanowski James E. 
Published: March 2011

ABSTRACTVasco X-2M is a low carbon tool steel which is being considered for critical gear applications. Since toughness is an important property for these applications, the Charpy V-notch impact energy was tested as a function of tempering temperature and found to drop considerably at 480C temper and above. A TEM investigation was carried out in order to better understand the results of this test. The precipitation sequence of carbides was examined along with their morphology, structure and orientation relation to the matrix. The precipitation of the intralath M3C carbides occurred on quenching from austenite. These carbides were then present in all tempered samples. M2C carbides were observed at 480C and 590C temper, and evidence for precipitation of these carbides was based on hardness data at 480C temper and TEM observations at 590C temper. After aging 200h at 590C, the ceitientite was observed to be in the process of transforming in an in-situ manner to an M7C3 carbide. The minimum in the Charpy impact energy was found to occur when both coarse M3C and a very fine dispersion of M2C were present in the microstructure.
Crystalline-to-Amorphous Transitions in Ti-Ni Alloys
Authors: Pelton R. , Moine P. , Noack M. A. , Sinclair R. 
Published: March 2011

ABSTRACTTi-Ni alloys have been made amorphous over a broad composition range by sputter deposition, ion implantation and electron irradiation. Structural analysis of these alloys was made by electron diffraction techniques. Microdensitometer traces of diffraction patterns produced scattering profiles from which radial distribution functions (RDF's) were derived. The results from this analysis were comparable to those from x-ray diffraction studies on similar alloys. It was found that the positions of the intensity maxima vary systematically with alloy composition. However, values of coordination number were less precise due to experimental uncertainties. Furthermore, no dramatic differences were observed in the RDF's of the samples amorphized by the three techniques.
In-Situ High Resolution Transmission Electron Microscopy of Dynamic Events During the Amorphous to Crystalline Phase Transformation in Silicon
Authors: Parker M. A. , Sigmon T. W. , Sinclair R. 
Published: March 2011

ABSTRACTA technique has been developed which employs high resolution transmission electron microscopy (HRTEM) for the observation of the atomic mechanisms associated with solid state phase transformation as they occur at elevated temperatures. It consists of the annealing in-situ of cross-section transmission electron microscopy (TEM) specimens that have been favorably oriented for lattice fringe imaging and the video-recording of dynamic events as they occur in real-time. By means of this technique, we report the first video-recorded lattice images of crystallographic defect motion in silicon, viz. the motion of dislocations and stacking faults, as well as the first such images of the atomic mechanisms responsible for the amorphous to crystalline (a-c) phase transformation, viz. heterogeneous nucleation of crystal nuclei, coalescence of crystal nuclei by co-operative atomic processes, ledge motion at the growth interface, and normal growth in silicon. This technique holds great potential for the elucidation of the atomic mechanisms involved in reaction kinetics in the solid state.
Application of Hrem in Studying Amorphisation of Intermetallic Compounds
Authors: Luzzi D. E. , Mori H. , Fujita H. , Meshii M. 
Published: March 2011

ABSTRACTElectron irradiation induces many intermetallic compounds to become amorphous. As this irradiation is capable of producing only isolatedpoint defects for each collision event, an understanding of this amorphisation proqess has a special significance with respect to the understanding of amorphous materials. This paper will report the results of HREM observations of an intermetallic compound in the Cu-Ti alloy system. High resolution micrographs will be presented to demonstrate that the energy associated with the irradiation induced chemical disordering is the major driving force in the amorphisation process. Also, the utility of the HREM in the study of amorphisation and the amorphous structure will be discussed.