bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Straight and Curved Braun Position-Sensitive Proportional Counters on a Huber-Guinier X-Ray Diffraction System
Authors: Newman R.A. , Moore Kirchhoff P. , Fawcett T.G. 
Published: March 2019

AbstractThe interfacing of both straight and curved Braun Position- Sensitive Proportional Counters (PSPC's) to a high resolution Huber-Guinier camera system has been accomplished, resulting in a 10 to 100-fold decrease in data collection times when compared to conventional Guinier (film or scintillation counter) detector techniques.Various factors causing line broadening were evaluated for both PSPC Guinier systems. The depth of the PSPC gas chamber was found to Have the greatest influence on line profiles. An R0% increase in peak half-widths was observed for PSPC-Guinier data compared to our highest resolution Guinier film data, but still yielded significantly better resolution than conventional powder diffractometer data obtained in our laboratory.
High Temperature Guinier X-Ray Diffractometry for Thermal Expansion Measurements in the Hexagonal form of Cordierite ((2MgO•2Al2O3•5SiO2)
Authors: Pressnall J. S. , Fitzpatrick J. J. , Predecki Paul 
Published: March 2019

AbstractA computer-controlled high temperature Guinier diffractometer system for accurate determination of lattice thermal expansion is described. A critical test of the system using α-Al2O3 (0.3μ polishing alumina) showed close agreement with the single crystal expansion data of Wachtman et al. Lattice thermal expansion of cordierite doped with the following dopants: Ge+4, P+5, Zn+2, Li+1 and Ca+2 was investigated. Of these the Li+1 at the 5% level (5% of Si+4 replaced by Li+1 + Al+3) produced the largest decrease in mean lattice expansion.
Diffraction Peaks in X-Ray Spectroscopy: Friend or Foe?
Authors: Tissot Ralph G. , Goehner Raymond P. 
Published: March 2019

AbstractDiffraction peaks can occur as unidentifiable peaks in the energy spectrum of an x-ray spectrometric analysis. Recently, there has been increased interest in oriented thin polycrystalline films and epitaxial films on single crystal substrates for electronic applications. Since these materials diffract x-rays more efficiently than randomly oriented polycrystalline materials, diffraction peaks are being observed more frequently in x-ray fluorescent spectra In addition, micro x-ray spectrometric analysis utilizes a small, intense, collimated x-ray beam that can yield well defined diffraction peaks. In some cases these diffraction peaks can occur at the same position as elemental peaks. These diffraction peaks, although a possible problem in qualitative and quantitative elemental analysis, can give very useful information about the crystallographic structure and orientation of the material being analyzed. The observed diffraction peaks are dependent on the geometry of the x-ray spectrometer, the degree of collimation and the distribution of wavelengths (energies) originating from the x-ray tube and striking the sample.
Elemental X-Ray Imaging of Fossils
Authors: Morton R. W. , Witherspoon K. C. 
Published: March 2019

AbstractThis paper describes the imaging of fossils using elemental x-ray area mapping (EXAM). The technique utilizes a commercially available instrument originally designed for the silicon chip industry. The EXAM data are processed digitally with imaging software to remove surface irregularities and enhance specimen details. Applications of this technique to specimens with irregular surfaces are described.
Quantitative XRF Determinations of Additive Elements in Greases for Manufacturing Specifications
Authors: Sieber John R. 
Published: March 2019

AbstractAdditive elements are now included in manufacturing specifications for greases. Texaco uses X-ray fluorescence at lubricants manufacturing locations; however, analyses of greases in the neat form are difficult due to problems with uniform and repeatable filling of sample cups and outgassing of greases during measurements. This preparation procedure allows quantitative determinations of additive elements in a variety of greases using a single analytical program. Having a single method for all greases is important at busy manufacturing locations.The preparation method involves dilution of samples in a binder powder. This approach eliminates outgassing and overcomes differences among greases such as type of soap, presence of MoS2 and graphite, and varying oil content. The powder absorbs oil and creates a uniform particle structure. Thorough mixing and careful cup packing yield repeatable measurements. The method allows the use of liquid oil standards for calibration, eliminating the need to obtain analyzed greases. Accurate calibrations have been created for both wavelength-dispersive and energy-dispersive spectrometers.
Grazing Incidence X-Ray Characterization of Materials
Authors: Bowen D.K. , Wormington M. 
Published: March 2019

AbstractA review of the methods of characterization of materials using X-rays incident at grazing angles is presented. The rationale of all such methods is the need to obtain information from near-surface regions. The methods include grazing incidence diffraction, reflectivity, diffuse scatter and fluorescence. The experimental techniques are outlined, and the information obtainable and the methods of interpretation are discussed.
Proposed Methods for Depth Profiling of Residual Stresses using Beam-Limiting Masks
Authors: Predecki Paul , Ballard B. , Zhu X. 
Published: March 2019

AbstractMethods are described which make use of x-ray absorbing masks to either limit beam penetration in the sample (Type I), or confine the diffracting volume within definite limits (Type II). The masks consist of a metal film of Au or U, containing many long, parallel apertures of effective width w and spacing c. The mask is either applied directly to the sample surface (Type I), or to a weakly absorbing film (Be or Kapton) on the sample surface (Type II). With the Type I mask, the diffracting volume can be limited to a surface layer whose maximum depth zm at ψ=0 varies linearly with w, irrespective of sample or wavelength. The masks can be used with ψ-tilts in an Ω-type goniometer, and strains and stresses can be determined by the Sin2ψ method. Depth profiles as a function of depth z (z-profiles) can be obtained with layer removal if gradients over the depth Zm can be neglected. With the Type n mask, the diffracting volume can be limited to a discrete subsurface layer whose average depth depends on (c+w) and the Bragg angle 2θ, and whose thickness depends on w and 2θ. z-Profiles can be obtained by varying the wavelength for a given reflection using a synchrotron source, without the need for layer removal. The methods have not yet been tested experimentally.
Practical Determination of the Acceptable 2θ Error for Non-Ambiguous Identification of Pure Phases wtth Diffrac-at
Authors: Nusinovici J. , Beitelmann D. 
Published: March 2019

AbstractSearch/match of XRD patterns of pure phases can prove useful for verifying the internal consistency of search algorithms. An additional benefit is to check whether there are other materials giving similar powder patterns. If displacements and/or distortions are applied to the input patterns, such trials become a convenient way to estimate the program's tolerance to 2θ errors.This study has been performed on a set of 70 diffraction patterns from pure phases prepared by the International Centre for Diffraction Data (ICDD) for another purpose. Three search runs were performed on the background corrected full patterns, each time with the default parameters, and on the complete database (59,990 potential candidates): the first run without applying an offset, secondly with +0.20° 2θ offset and thirdly with -0.20°.The results show that a +/- 0.20° error is still acceptable for non-ambiguous identification of pure phases.
Disposable Heater Strips for High Temperature Powder Diffractometer Furnaces
Authors: King H.W. , Payzant E.A. , Stanley M.B. 
Published: March 2019

AbstractCommercial resistance heating and thermocouple materials specified for use in air at temperatures up to 1200°C were examined as possible alternatives to Pt-Rh for use as heater strips in high temperature x-ray diffractometer furnaces. Tests in air at 1150°C, showed that Chromel oxidized excessively, Nichrome oxidized moderately, while Kanthal was very slightly oxidized. Nichrome and Kanthal strips were sufficiently ductile to fabricate into strip heaters. The thickness of the Kanthal strip had to be reduced to 0.020 mm to match its resistance to the power and temperature control software of the high temperature diffractometer. Heater strips made from Nichrome proved effective, in terms of resistance to grain growth and surface degradation by adhesive liquid phases, at temperatures up to 1000°C, while Kanthal was effective up to 1150°C. The relatively low costs of these materials also make them viable as disposable heaters for use with chemically reactive or strongly adherent materials.
Residual Stress Measurements in Continuous Fiber Titanium Matrix Composites
Authors: James M. R. , Bourke M. A. , Goldstone J. A. , Lawson A. C. 
Published: March 2019

AbstractMetal matrix composites develop residual strains after consolidation due to the thermal expansion mismatch between the reinforcement fiber and the matrix. X-ray and neutron diffraction measured values for the longitudinal residual stress in the matrix of three titanium MMCs are reported. For thick composites (> 6 plies) the surface stress measured by x-ray diffraction matches that determined by neutron diffraction and therefore represents the stress in the bulk region consisting of the fibers and matrix. For thin sheet composites, the surface values are lower than in the interior and increase as the outer rows of fibers are approached. While a rationale for this behavior has yet to be developed, accounting for composite thickness is important when using x-ray measured values to validate analytic and finite element calculations of the residual stress state.
Residual Stresses in Aluminum-Mullite (α-Alumina) Composites*
Authors: Balzar Davor , Ledbetter Hassel 
Published: March 2019

AbstractWe studied particle-reinforced 6061-aluminum-alloy composites with particle volume fractions ranging from 0 to 0.25. The mullite particles are approximately spherical and contain embedded α-alumina phase. We obtained lattice parameters of all three phases in the composites and starting materials by using Rietveld refinement of x-ray diffraction patterns. In all three phases stresses are tensile and approximately of the same magnitude, contradicting a requirement for mechanical equilibrium. Stresses increase with both increasing particle size and volume fraction. Measurements of extracted-from-composites particles showed no evidence of a possible chemical reaction at the matrix-particle interface. The matrix is [111] and [100] textured, but measurements of elastic constants reveal only small anisotropy. Thus, explanation of the mechanical-equilibrium violation remains uncertain.
Neutron Diffraction Study of the Pseudo-Macro Residual Stresses in ZrO2(CeO2)/Al2O3 Ceramic Composites
Authors: Wang Xun-Li , Hubbard C. R. , Alexander K. B. , Becher P. F. , Fernandez-Baca J. A. , Spooner S. 
Published: March 2019

AbstractNeutron powder diffraction techniques have been used to characterize the pseudo-macro (PM) residual stresses in ZrO2(CeO2)/Al2O3 ceramic composites as a function of ZrO2(CeO2) volume fraction and fabrication procedures. The diffraction data were analyzed using the Rietveld structure refinement technique. From the refinement, we found that the CeO2 stabilized tetragonal ZrO2 particles were in tension and the Al2O3 matrix was in compression. Different sintering time had little impact on the PM stresses. On the other hand, the magnitude of the PM stresses in both ZrO2 and Al2O3 decreased linearly with the increase of their volume fractions.
X-Ray Fractography Evaluation of the Plastic Zones of Dynamic Fracture
Authors: Matsui Kazuyuki , Nakada Osamu , Hirose Yukio , Tanaka Keisuke 
Published: March 2019

AbstractTo evaluate the plastic zones of dynamic fracture, instrumented Charpy impact tests of high carbon bearing steels are conducted. The amount of plastic zone size left on the fracture surface is evaluated from the X-ray diffraction profiles. An analysis is presented of the relationship between the X-ray diffraction profiles and fracture mechanics parameters. The results are discussed in correlations between dynamic stress intensity factor and absorbed energy values. A good correlation exists between the plastic zone size and the dynamic stress intensity factor.The fraction of retained austenite is determined from X-ray diffraction profiles at surfaces of fractures and also beneath the surfaces of fractures.It shows the work hardening is introduced by the strain energy in the plastic zones. The values of the proportionality constant, α, determined for various kinds of dynamic fracture are related to half-value breadth by the functionwhere B0and BFare average of half-value breadth which are given by core of material and plastic zone of dynamic fracture.
The Ladell Diffractometer: Geometry and Applications
Authors: Greenberg Berton 
Published: March 2019

AbstractThe Ladell x-ray diffractometer (LD) is designed to study “practical” polycrystalline materials. These are materials which exhibit some combination of texture, strain, and large grain size, or are inhomogeneous or anisotropic in other ways. LD features which make this possible are: the ability to study crystal planes inclined to the sample surface; a versatile reflection geometry; high 2θ resolution via a focusing geometry; a large irradiated sample area (up to 1.5 cm2) for improved intensity and sampling statistics; the ability to examine different sample areas to test for homogeneity; and the use of one sample with no instrument reconfiguration. Scans and/or applications are described that measure texture, strain, twinning, improve quantitative phase analysis, and eliminate substrate scattering.The LD makes use of five independent computer controlled motions. These enable one to study a large fraction of that part of reciprocal space which is accessible by reflection. Instrument geometry and scans are described in terms of α, θ and reciprocal space diagrams. The effect of specimen displacement on peak position is described as are the effects of a number of geometrical factors on integrated intensity.
The D5000 HR System: Increased Resolution for the Multipurpose Siemens X-Ray Diffractometer
Authors: Brügemann L. 
Published: March 2019

AbstractLately available X-ray optics and 4-axis sample cradles increased the versatility of the Siemens D5000 diffractometer to high resolution applications. The possibilities of the D5000 HR hardware setup are illustrated by presenting diffraction measurements on systems relevant to semiconductor and thin film technology. Well known theoretical approaches are used for the software supported interpretation of the data.
Synchrotron and Laboratory Studies Utilizing a New Powder Diffraction Technique
Authors: Knapp G. S. , Beno M. A. , Jennings G. , Engbretson M. , Ramanathan M. 
Published: March 2019

AbstractWe have developed a new type of powder diffractometer. The diffractometer has the potential of both high count rates and very high resolution when used at a synchrotron source. The laboratory based instrument can achieve an order of magnitude improvement in count rate over existing methods with proper optics. The method uses a focusing diffracted beam monochromator in combination with a multichannel detector. The incident x-rays fall on a flat plate or capillary sample and are intercepted by a bent focusing monochromator which has the focus of the bend at the sample surface. The powder diffraction lines emerging from the bent crystal monochromator are detected by a linear or 2-dimensional detector. This allows us to eliminate the background from fluorescence or other scattering and to take data over a range of 3° to 4° instead of one angle at a time thereby providing a large improvement over conventional diffractometers.
High Resolution X-ray Diffraction for the Characterization of Semiconducting Materials
Authors: Tanner B. K. 
Published: March 2019

AbstractUse of a reference crystal to condition the beam in the double-axis diffractometer permits the Bragg peak width to be reduced to the correlation of the two crystal reflecting ranges. Some recent applications of double axis diffractometry to the study of heteroepitaxial layers are discussed. The advantages of multiple reflections for beam conditioning and the four reflection DuMond monochromator are examined. Glancing incidence and exit diffractometry permits the study of very thin layers, down to a few tens of nanometres in thickness and both synchrotron radiation and skew reflections can be used to tune the glancing angle close to the critical angle. Recent applications of triple-axis diffraction, where an analyzer crystal is used after the specimen, to the study of very thin single epitaxial layers and multiquantum well structures are reviewed.
Deformation, Recovery and Stress Corrosion Cracking of Nickel-Base Alloy 600 by X-ray Rocking-Curve Measurements
Authors: Lo Chi Fung , Feng Gajiang , Mayo William E. , Weissmann Sigmund 
Published: March 2019

AbstractThe aim of this investigation was the establishment of a quantitative link between micro and macrodeformation and kinetic recovery of nickel-base Alloy 600 as well as the early detection of microcracks in this alloy when exposed to stress corrosion. To reach these objectives, X-ray rocking-curve measurements were carried out using the method known by its acronym CARCA (computer-aided rocking-curve analysis). Supported by transmission electron microscopy, a calibration curve was established relating dislocation density, X-ray rocking-curve halfwidth and strain. Applying CARCA, deformation levels and work-hardening characteristics of the alloys were measured by quantitative characterization of the induced defect structure. By correlating the analysis of the defect structure to the kinetic recovery of the alloys, including determination of the activation energies, it was possible to infer from the thermal stability of the alloys the dislocation obstacles responsible for hardening at different strain levels. It was shown that the recovery of the alloys was conditioned by their low stackingfault energy and that it depended on the strain level. Rapid recovery associated with grain boundary diffusion occurred at very small plastic strains up to about 0.7% with measured activation energies of recovery of about 25.6 Kcal/mol. At higher strains bulk diffusion was necessary to overcome the obstacles by dislocation climb with Q — 67 kcal/mol, The CARCA method proved itself to be a valuable research tool for assessing quantitatively the defect density and the mechanically and thermally induced changes. Relaxation effects, recorded by CARCA in the apex region of stressed C-rings exposed to a caustic medium, may open a path for early nondestructive detection of microcracks in stress-corrosion cracking.
X-ray Characterisation of Residual Surface Strains after Polishing of Silicon Wafers
Authors: Hart Linda , Bowen D. Keith , Fisher Graham R. 
Published: March 2019

AbstractDetailed x-ray double-axis rocking-curve analysis has been made of a series of silicon wafers, polished using various colloidal silicas with a number of different conditions. Significant differences, attributable to the polishing conditions, were observed in the tails of the rocking curves, using a four-reflection, non-dispersive beam conditioner. These have been compared with theoretical simulations in order to deduce the strain profile near the surface.
X-ray Line Broadening Analysis of Tl-Superconducting Films
Authors: Eatough M. O. , Ginley D. S. , Morosin B. 
Published: March 2019

AbstractSuperconducting thin films (0.3-0.7μm) in the TI-Ca-Ba-Cu-0 system have been prepared on various single crystal substrates by sequential electron beam evaporation followed by appropriate sintering and annealing. Oxygen-annealed films show Tc as high as 110K and critical current densities to 600,000 A/cm2. X-ray diffraction analyses of these films show predominantly the Tl2Ca2Ba2Cu2O10 phase (c-parameter near 36Å), but some also contain up to 50 at% of the Tl2CaBa2Cu2O8 phase (c-parameter near 30Å). The complete absence of hkl reflections other than 00I demonstrates the highly oriented nature of the films as well as the absence of other Tl phases. The diffraction peaks are noticeably broader for the 36Å phase than for the 30Å phase. For a 0.7μm film such broadening is consistent with coherent sizes along the c-axis of 1200 - 1400Å and 500Å, respectively, for the 30Å and 36Å phases, and of strain values near 1.4-1.8 x 10-3 for both phases.
Residual Stress Distribution of Ceramic-Metal Joint
Authors: Kurita Masanori , Sato Makoto , Ihara Ikuo , Saito Akira 
Published: March 2019

AbstractCeramics are sometimes bonded to ductile metals in order to make up for their brittle behavior for industrial use. The residual stress will be induced in ceramics bonded to metals at high temeprature, and it has a strong influence on the strength of ceramic-metal joints. A silicon nitride plate was bonded to a carbon steel plate by brazing to a copper sheet sandwiched between the two materials. The residual stress distribution of the joint specimen was determined by x-ray diffraction using the Gaussian curve method. The measured residual stress distribution almost agreed with that calculated by the three-dimensional thermoelastoplastic stress analysis using FEM, but differed remarkably from that calculated by the two-dimensional stress analysis. This is because a stress concentration occurs at the ceramic-metal interface and the stress distributes three - dimensionally. The stress σx in the axial direction on the surface of the specimen takes maximum values at the center and the edge of the interface.
The Determination of Quartz in Perlite by X-ray Diffraction
Authors: Hamilton R. D. , Peletis N. G. 
Published: March 2019

AbstractIARC's designation of crystalline silica as a “probable carcinogen” triggered the requirement to label products containing greater than 0.1 % crystalline silica. For perlite and other materials which may contain crystalline silica in levels close to 0.1% an accurate determination is critical from both legal and marketing considerations.Existing analytical techniques for the determination of crystalline silica at levels of less than 1.0% were found to be inadequate to meet the new requirements. An improved technique based on x-ray diffraction has been developed specifically to analyze perlite for crystalline silica, which occurs largely in the form of quartz, at the 0.1%. level. The technique employs long counting times and improved sample preparation and mounting to increase both precision and accuracy, and to lower the detection limit to less than 0.1%.The technique was tested on a large number of samples from a variety of sources and proven to give excellent results for all types of expanded perlites and perlite ores. The procedures developed are applicable to a wide variety of materials in addition to perlite.