bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical Estimation of the Fourth-Order XRF Intensity
Authors: Fernandez J. E. , Molinari V. G. 
Published: March 2019

AbstractA theoretical expression for the fourth-order XRF-intensity has been found using the transport theory. An exact solution of the Boltzmann equation for the photon flux in a semi-infinite homogeneous medium has been applied iteratively to find the intensity, XRF emission has been isolated from the scattering processes by considering only the photoelectric effect in the interaction kernel. The incident and emitted beams have been assumed as well-collimated.Fourth-order intensity computations for a multicomponent material are reported as an example. Results show that the fourth-order intensity remains below a tenth of the tertiary and therefore may be neglected in most cases.
The Use of Field-Portable X-ray Fluorescence Technology in the Hazardous Waste Industry
Authors: Raab G. A. , Kuharic C. A. , Cole III W. H. , Enwall R. E. , Duggan J. S. 
Published: March 2019

AbstractAs the Environmental Protection Agency adds ever more sites to the National Priorities List for Superfund clean-up, there is a tremendous need for a fast method of screening for contaminants. In the case of inorganics, we can apply field-portable X-ray fluorescence technology.With commercially available field-portable X-ray fluorescence equipment using in-situ measurements we can quickly screen a site (hundreds of measurements), input the data to a portable computer, process it, and print a colored concentration isopleth map of the contaminant of interest, all in realtime.The in-situ measurement approach pioneered by Lockheed is the key to rapid screening capability. Problems arising from particle size distribution, soil heterogeneity, and bulk density are minimized by employing site-specific standards in the construction of our calibration curves. Inherent in these site-specific standards are all the matrix problems which occur in the routine samples.The strength of field-portable X-ray fluorescence technology is the accuracy of analysis above the quantitation limits. The difficulty in measuring low concentrations near the detection limit is the weak point of field-portable units.NOTICE: Although this research was funded in part by the U.S. EPA through Contract 68-03-3249 to Lockheed Engineering & Sciences Company, it has not undergone Agency review and does not necessarily reflect Agency policy.
Micro X-Ray Fluorescence Analysis with Synchrotron Radiation
Authors: Hayakawa Shinjiro , Iida Atsuo , Aoki Sadao , Gohshi Yohichi 
Published: March 2019

AbstractA synchrotron radiation X-ray micro analyzer(SRXMA) was developed at Photon Factory in Japan. The present SRXMA combines a double crystal monochromator and mirror optics and either a white or a monochromatic microbeam can be used. Micro X-ray fluorescence analysis was carried out, and a minimum detection limit of 1 ppm for Mn was obtained for 100 sec measurement with the white beam. With monochromatic beam excitation, micro X-ray spectroscopies are now feasible.The obtained beam size was 1.6 μ;m - 34 μm* The beam was blurred in one direction by the scattered X-rays caused by the surface irregularities of the focusing mirror. Improvements in the mirror quality will ensure a beam spot of just a few microns with sufficient intensity.
High Resolution X-Ray Fluorescence Si Kβ Spectra: A Possible New Method for the Determination of Free Silica in Airborne Dusts
Authors: Purton J , Urch D S , West N G 
Published: March 2019

AbstractHigh resolution x-ray emission spectroscopy (HRXES) has been used to record the Si Kβ spectra of a variety of minerals. Distinct changes in peak profile can be related to mineral typo. Representatives spectra were chosen and incorporated, into a computer programme to allow the determination of free silica in binary and quaternary mixtures. The potential of HRXES for the analysis of airborne dust samples is discussed.
X-ray Diffraction Analysis of High Tc Superconducting Thin Films
Authors: Huang T. C. , Segmuller A. , Lee W. , Lee V. , Bullock D. , Karimi R. 
Published: March 2019

AbstractX-ray diffraction techniques have been used for the structure characterization of Y-Ba-Cu-O and Tl-Ca-Ba-Cu-O thin films. A powder diffraction analysis of Y-Ba-Cu-O films showed that the films deposited at 650°C on Si are polycrystalline and have an orthorhambic structure similar to that of the YBa2Cu3O7 bulk superconductors. In addition to the conventional powder diffraction technique, both the rocking curve and the grazing incidence diffraction methods were used to characterize a YBa2Cu3O7 film on (110) SrTiO3 substrate. Results showed that the film was epitaxially grown and aligned with its substrate in a true epitaxy. Phase identification and line broadening analyses of Tl-Ca-Ba-Cu-O films showed that the films are comprised of one or more superconducting phases and probably contain stacking faults.
Texture Analysis of Thin Films and Surface Layers by Low Incidence Angle X-ray Diffraction
Authors: Heizmann J. J. , Vadon A. , Schlatter D. , Bessières J. 
Published: March 2019

It is necessary to know the orientation of thin surface layers for the electronic industry as well as for different studies on interphases (epitaxy, topotaxy, phase transformation, reactivity of solids).It is difficult to obtain information with a conventional Schulz goniometer (Bragg-Brentano geometry) because of the insufficient amount of diffracting material.
Fast Thickness Measurement of Thin Crystalline Layers by Relative Intensities in XRPD Method
Authors: Kimmel G. , Shafirstein G. , Bamberger M. 
Published: March 2019

In this work a continuous wave CO2 laser was used for melting a layer of amorphous alumina obtained by anodizing 6061 aluminum plates. Melting the surface of the anodized plates led to the formation of a new uniform corundum layer at the expense of some of the amorphous coating, resulting in a double layer coating of crysta11ine on amorphous.The characterization of the corundum layer is essential for process optimization study. Among the non-destructive methods X-ray diffraction is useful, because it provides us with selected data on the crystalline layer.
Separation of the Macro- and Micro-Stresses in Plastically Deformed 1080 Steel
Authors: Winholtz R. A. , Cohen J.B. 
Published: March 2019

AbstractThe stress tensors were measured with x-ray diffraction in both the ferrite and cementite phases of a 1080 steel specimen deformed in uniaxial tension. The macro- and micro-stresses were separated for all the components of the stress tensors. All the components except the hydrostatic components of the micro-stresses could be determined without an accurate value of the unstressed lattice parameter. Tensile stresses were found in the cementite and compressive stresses in the ferrite along the deformation direction. The tensile stresses in the cementite were quite large.
Parallel Beam and Focusing X-ray Powder Diffractometry
Authors: Parrish W. , Hart M. 
Published: March 2019

AbstractComparison of results using synchrotron radiation and X-ray tubes requires a knowledge of the fundamentally different profile shapes inherent in the methods. The varying asymmetric shapes and peak shifts in focusing geometry limit the accuracy and applications of the method and their origins are reviewed. Most o f the focusing aberrations such as specimen displacement, flat specimen and θ-2θ mis-setting do not occur in the parallel beam geometry. The X-ray optics used in synchrotron parallel beam methods produces narrow, symmetrical profiles which can be accurately fit with a pseudo-Voigt function, They have the same shape in the entire pattern. Only the width increases as tanθ due to wavelength dispersion but with higher resolution systems dispersion can be eliminated. The constant instrument function contribution to the experimental profile shape is an important advantage in studies involving profile shapes, e.g., small particle sizes and microstrains, and accurate integrated intensities. The absence of systematic errors leads to more precise lattice parameter determinations.
Optimizing the Calculation of Standardless Quantitative Analysis
Authors: Jinsheng Lu , Ronghou Xie , Xiaoqun Tan , Nieuwenhuizen C. 
Published: March 2019

A method for quantitative phase analysis without standards (QPAWS) has been published in 1977 and has gained considerable interest, as the calibration for quantitative XRD may sometimes be difficult. Standards for quantitatative XRD are not generally available, and in many cases even the pure phases cannot be obtained.The QPAWS method is based on (i) analysis of all phases present in the samples, (ii) foreknowledge of mass absorption coefficients (MAC)(iii) measuring samples which contain all phases in varying concentrations. In this method the number of samples used is equal to the number of phases to be analysed.
X-ray Diffraction Studies of Solid Solutions of Pentaglycerine-Neopentylglycol
Authors: Chandra D. , Barrett C. S. , Benson D. K. 
Published: March 2019

AbstractAn array of molecules that is anisotropic in the extreme has been discovered in certain thermal-energy storage materials and is reported here: neopentylglycol (NPG) and NPG-rich solid solutions with pentaglycerine (PG) have a crystal structure, stable at room temperature, that consists of bimolecular chains of molecules that are all unidirectionally aligned throughout a crystal. There are hydrogen bonds between every molecule in one chain and its neighbors in that chain, but none between molecules of one chain and any molecules of the neighboring parallel chains. Thus there are strong intermolecular bonds along each chain and only weaker bonds between the chains. The structure has been determined by using modern single crystal techniques with 529 independent reflections from a crystal of NPG (C5H12O2). The structure is monoclinic with space group P21/c - C2h5. This anisotropic structure transforms to a cubic structure at higher temperatures.
Applications of Dual-Energy X-ray Computed Tomography to Structural Ceramics*
Authors: Ellingson W. A. , Vannier M. W. 
Published: March 2019

AbstractAdvanced structural ceramics (Si3N4, SiC, A12O3, ZrO2) are rapidly being developed with sufficient fracture toughness to be considered for engineering applications such as internal combustion engine components, rotating turbine engine components, and heat recovery systems. X-ray computed tomography (CT) is a promising nondestructive evaluation method for these ceramics, but beam hardening presents a serious problem in the interpretation of CT images generated with polychromatic X-ray sources by creating artifacts . Dual-energy X-ray techniques have the potential to eliminate these problems. In addition, in theory, dual energy allows generation of quasimonochromatic equivalent images, which should allow verification of theoretically determined optimum energies. In using dual-energy methods, the high-and low-energy images are nonlinearly transformed to generate two energy-independent images characterizing the integrated Compton/photoelectric attenuation components. Characteristic linear combinations of these two "basis" images can serve to identify unknown materials and generate synthesized monoenergetic images.The dual-energy method has been used to study structural ceramics as well as liquids that are close to ceramic materials in atomic number and mass density. The work was done on a Siemens DR-H CT machine with 85- and 125-kVp energy levels. Test samples included Si3N4 cylinders ranging from 10 to 50 mm in diameter, liquid Freon TF, and densified SiC.
Low Level Iodine Detection by TXRF in a Reactor Safety Simulation Experiment
Authors: Hegedüs F. , Winkler P. , Wobrauschek P. , Streli Christina 
Published: March 2019

In the event of an accident in a light water moderated nuclear plant, the fission products escape from the water moderator in form of gas bubbles. One of the most important fission products is Iodine. Presently there are only rough estimations of the escape of Iodine. The aim of the experiment planned at the Swiss Federal Institute for Reactor Research (EIR) is to simulate the conditions of an accident and to measure the amount of Iodine which escapes from the moderator water into the space inside the reactor containment.It is supposed that at 5 m depth in a water pool, the canning of the fuel element explodes releasing 1-3 liter large gas bubbles containing the volatile fission products. The Iodine vapor concentration, saturated in the gas bubble, will be about 3 mg/l. It is expected that the water strongly absorbs the Iodine vapor and the I concentration in the gas bubble arriving at the water surface will be strongly reduced to a few ug/l.
Background Intensities and Their Utilization in Quantitative Analysis by Monochromatically Excited Energy-Dispersive X-Ray Fluorescence
Authors: Rachetti Alessandra , Wegscheider Wolfhard 
Published: March 2019

In monochromatically excited energy-dispersive X-ray fluorescence spectrometry, the spectral background has mainly been investigated for a better understanding of its origin and nature, or with the aim to reduce its magnitude for an improvement of detection limits.The observation that the background intensity can largely be ascribed to a residual polychromatic fraction of the exciting radiation has led to the derivation of an empirical relationship between the scattering characteristics of a sample and the observed background intensity. This dependence constitutes the basis of a matrix correction procedure useful for samples with a considerable fraction of light elements.Two algorithmic variations are presented: one that relies on the definition of a single matrix element, and a second one that can be used in conjunction with the measurement of the incoherently scattered exciting radiation. These options are useful if direct quantification of either or both scatter peaks is not feasible.Results are presented for a variety of Standard Reference Materials.
Comparison of Dilution Strategies for Dealing with Unanalyzed Elements in X-Ray Fluorescence Analysis
Authors: DeGroot Peter B. 
Published: March 2019

AbstractOne method of dealing with unanalyzed light elements in x-ray fluorescence analyses is to add a relatively large quantity of a diluent to the sample. The interelement effects on the measured radiation are then essentially all due to the diluent, and the effects of the unanalyzed elements are ignored. The general practice has been to use a diluent compound composed of light elements. The rationale for this is that light elements absorb the analyte radiation less strongly than heavy ones, leaving higher net intensity available after dilution. However, since absorption effects are greater with heavy elements, a smaller dilution factor can be used to reach the analyte concentration at which the effects of unanalyzed elements on the analyte radiation are negligible compared to diluent effects. In many cases, the smaller dilution factor almost exactly compensates for the increased absorption. There is essentially no intensity penalty for using a heavy element diluent. In fact, there are some advantages to doing so. The lower dilution factor with heavy elements can avoid problems with multiple dilutions or accurate weighing and homogeneous blending of very small quantities necessary to achieve high dilution factors. Significantly less continuum radiation is scattered from heavy element matrices, and signal-to-background ratio can be higher in some parts of the spectrum. With high energy analyte lines, heavy element dilution results in infinitely thick samples, simplifying sample preparation. Theoretical intensity calculations using the XRFll matrix correction program are used to predict the appropriate dilution factor for a range of analyte x-ray emission wavelengths with a variety of diluents. The results are verified experimentally.
Comparison of Dual-Channel Wavelength and Secondary-Target Energy-Dispersive X-Ray Spectrometers
Authors: Croke John F. , Nicolosi Joseph A. 
Published: March 2019

Over the past 30 years, X-ray fluorescence spectrometry has become one of the more valuable methods for the qualitative and quantitative analysis of materials. Today, there are many methods of instrumental analysis available, and among the factors that will be taken into account in the method of selection are: -Accuracy-Range of application-Speed-Sensitivity-ReliabilityNo one technique can provide all of the features that a given analyst requires. XRF does offer good overall performance over the widest range of elements. Speed, accuracy, and versatility are among the features that have made XRF the method of choice for over 15,000 laboratories worldwide.
The Efficiency of the Recessed Source; Geometry for EDXRF Analysis of Metal Impurities in Oils
Authors: dos Santos J.M.F. , Conde C. A. N. , Ferreira L. F. Requicha , De Campos A. J. 
Published: March 2019

AbstractThe efficiency of the recessed source geometry for the analysis of the content of wear metals in engine lubricant oils by Energy Dispersive X-Ray Fluorescence (EDXRF) methods is calculated by a Monte Carlo simulation considering X-ray detectors of the Gas Proportional Scintillation Counter type and excitation by Cd-109, Cm-244 and Fe-55 radioactive sources. Calculated spectra for the case of a typical aircraft oil with Cu, Fe, Cr, Ti, Sn and Ag impurities in the p.p.m. range were obtained and results are presented that allow the prediction of the counting rate per mCi and p.p.m. of the impurity content. The performance of the system is discussed concerning its potential applications to in-line monitoring of the wear metals.
X-Ray Fluorescence Determination of Trace Elements in Complicated Matrices
Authors: Yawen Liu , Qinmin Fan , Daolun Li 
Published: March 2019

AbstractA method for the direct determination of trace elements in light element matrices is described. The intensity of Compton scatter of the incident X-rays from the specimen was used to evaluate the apparent absorption factor for the direct correction for matrix effects. This permits the use of single element standards for samples of varied and complicated matrix composition. Relative errors of approximately 5% were obtained for results in the concentration range of 10-200 ppm.
Rapid Non-Destructive X-Ray Characterization of Solid Fuels/Propellants
Authors: Ananthanarayanan T. S. , Mayo W. E. , Rosemeier R. G. , Miller R. S. 
Published: March 2019

AbstractNumerous studies have been conducted into the microstructural origin of the instability and unpredictability of various energetic materials. Some of these materials are RDX/HMX, Ammonium Perchlorate, Aluminum, etc. Many techniques both destructive and non-destructive have so far been utilized in an attempt to quatify the energetic properties of their composites. These composites may contain one or more energetic constituents in an elastomeric binder. Non-destructive X-ray characterization techniques have been successfully employed to measure several microstructural parameters. Previous studies have shown considerable differences among various production grade RDX. These studies reveal marked differences in the amounts of residual elastic strain and the distribution of dislocations (residual plastic strain) in the constituent RDX phase.The focus of this study is to develop a technique for quantitative constituent phase analysis of solid-propellant (fuel) composites using conventional diffractometry. The use of a Curved Position Sensitive Detector (CPSD) greatly enhances the technique and allows real time applications in production environments. Through the use of computer based Systems and "user friendly" software the required Operator, skill and training have been considerably reduced. The CPSD System has been successfully used to quantify constituent phases (peak heights) and the amounts of residual elastic strain (peak shifts) in these molecular crystal powder mixtures.It is envisioned that rapid, automated, non-destructive X-ray characterization techniques will greatly facilitate production based propellant quality control. A thorough understanding of the relationship between the energetics and microstructural parameters can also he obtained.
Computing X-Ray Powder Diffraction Intensities and Bragg Angles Using a Microcomputer
Authors: Sujjayakorn P. , Stadelmaier H. H. , Russ J. C. 
Published: March 2019

Programs exist to compute X-ray diffraction patterns (angles and intensities) for specified atomic arrangements using mainframe computers. We report here a microcomputer version (in Basic, to n m on a standard Apple ][ computer with two disk drives and optionally a printer). Additionally, the program offers considerable flexibility in entering atomic positions and using symmetry relations to simplify the input for complex unit cells, and provides a visual display of the unit cell in any orientation.There are a variety of search-match algorithms that compare measured powder diffraction patterns to previously determined standards, such as the JCPDS powder diffraction file. These have been implemented on computers ranging from mainframes to microcomputers, with tradeoffs in the practical size of the standards file and the speed of the search.
Experimental Methods for Determination of Precision and Estimation of Accuracy in XRD Residual Stress Measurement
Authors: Ruud C.O. , Snoha D.J. , Ivkovich D.P. 
Published: March 2019

AbstractIt is important to establish precision and accuracy of an X-ray diffraction (XRD) residual stress measurement procedure in order to compare capabilities of instrumentation and techniques, as well as to provide confidence limits for experimental data. There is no broadly acceptable method for establishment of precision and accuracy. This paper describes a proposed approach and one which is used at The Pennsylvania State University.One impediment to the measurement of precision and accuracy is that no standard specimen with a known residual stress level is available. Proposed standard specimens have been abandoned for various reasons, including the concern for stability of the original stress condition and the existence of stress gradients, i.e., stress inhomogeneity, in the specimens. However, there is one type of specimen which has been accepted by ASTM as an alignment and zero residual stress confirmation standard. That type of specimen is a powdered sample of metal or ceramic which provides XRD peaks in the vicinity of the Bragg angle in which residual stress measurements are to be performed.Some researchers tend to report detector counting statistics as the uncertainty of stress measurement but such statistical scatter accounts for only one part of uncertainty in precision and accuracy. The total uncertainty is best determined directly through repeated residual stress measurements performed by removal and readdressing the test specimen or through a repetition of measurements under predictably changing conditions. This paper describes results from the use of powder specimens to establish the repeatability of measurements with a portable instrument after removal and readdressing of the specimens. Also, results showing the uncertainty of the measured stress change in specimens subjected to known loads are discussed.