bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Evaluation of Peak Height Approximation for X-Ray Diffracted Integrated Intensity Method
Authors: Gazzara Charles P. 
Published: March 2019

The mathematical description of an X-ray peak, diffracted from a powder or polycrystalline material, using physically meaningful parameters has been of interest for many years. With the popularity of computers, this need to characterize a diffraction peak has intensified.A key problem which persists is how to describe the instrumental diffracted profile and therefore the observed diffracted characteristic peak with subsequent combinations of Kα doublets and mixed overlapping peaks. Many attempts have been made at finding a “true“ function to fit the observed diffracted peak; however, a practical solution has yet to be found.
On Stream Analysis of Lead and Zinc Ore Fractions Using Energy Dispersive and Wavelength Dispersive Techniques
Authors: Kawatra S. K. , Dalton J. L. 
Published: March 2019

AbstractOn-line X-ray fluorescence analysis is used in the mineral processing industry to monitor the composition of the solids contained in various slurry streams. This study compares wavelength dispersive and energy dispersive techniques by using a slurry recirculation system employing both an X-ray tube excitation-wavelength dispersive system, and an isotope-excitation energy dispersive system. The results showed the less costly energy dispersive system yields accurate information that can be used to control milling operations.
A General Method of Blank Subtraction for Quantitative X-Ray Fluorescence Intensity Measurements
Authors: Quinn Alan P. 
Published: March 2019

AbstractResidual analyte intensity exists in a spectrometer when, for example, the x-ray source is contaminated with the analyte. A blank specimen, identical to the sample but devoid of the analyte, may be used to determine this residual analyte intensity, and, thereby, allow quantification of that intensity due to analyte in the sample. It is generally considered that a single pure material could serve as a blank for many analytes in many matrices. In practice, at least for low average atomic number matrices such as glasses, the reflectivity of similar samples may differ substantially, rendering inaccurate this simple blank subtraction. In such cases a blank is needed for each sample, where the reflectivity of the blank is matched to that of the sample. In order to eliminate the need for generation of blanks to match each of the samples, a general method to quantify the net residual analyte intensity as a function of specimen reflectivity by measurement of two pure material blanks is proposed herein.
Erroneous Peaks in Energy Dispersive X-Ray Spectra
Authors: Russ J. C. 
Published: March 2019

The necessary first step in using an x-ray fluorescence spectrometer for quantitative analysis is to obtain the intensities for the various elements. With a wavelength dispersive system this usually requires simply setting the crystal to the proper angle (and possibly adjusting the pulse height selector) and making a dead-time correction. With the energy dispersive x-ray fluorescence analyzer it is necessary to take into account the presence of erroneous peaks in the spectrum, to obtain true intensity values.False peaks due to diffraction of white tube radiation from the sample can usually be shifted to portions of the energy spectrum where they do not interfere with emission lines of interest by selection of the proper tube-sample-detector geometry. Modern amplifier design provides a built – in dead time correction and greatly reduces the effects of pulse-pile-up, although the latter phenomenon will still produce small peaks at exact multiples of major peaks.
Predicting some Effects of Lattice Vibrations on Proton Scattering Patterns
Authors: Barrett C. S. 
Published: March 2019

AbstractA method of predicting the approximate relative intensities of lines in proton blocking patterns recently proposed, which is based on summing the squares of structure factors for the various orders of reflection of a plane, is found to predict certain effects of lattice vibrations on the lines in some recently reported patterns. The mean square amplitude of vibration enters the calculations through a Debye-Waller temperature factor like that used in X-ray diffraction. When patterns are compared for groups of crystals that are nearly identical except for this temperature factor, the qualitative predictions by this method agree with the observations. If it is also arbitrarily assumed that the integrated intensity dip at a spot where lines intersect is approximated by summing the calculated Integrated intensity dips for all of the lines crossing at the spot, one has a simple and convenient method of predicting relative spot intensities. Such calculations have been successful in establishing the order of decreasing intensity for most of the spots along a given line, with several different kinds of crystals. This method also serves to predict qualitatively how prominent the spots appear relative to the lines, in general, in patterns of crystals that differ appreciably only in the amplitude of the thermal vibrations.
Errors in Residual Stress Measurements due to Random Counting Statistics
Authors: Kelly C. J. , Short M. A. 
Published: March 2019

AbstractThe measurement of residual stress, using X-ray diffraction techniques, is based on the change in diffraction angle determined for the Intensity maximum of some suitable reflection from the sample when this is placed consecutively with its surface at two different angles to the diffracting planes. These diffraction angles may be obtained in a variety of ways, but are most often calculated from measurements of three X-ray diffraction intensities at angles selected in the immediate vicinity of the peak maximum at each sample angle and fitting each set of data to a parabolic curve. A simple mathematical expression may be derived relating the diffraction angles, and hence the residual stress, to the measured X-ray intensities; there will, however, be statistical errors in the calculated diffraction angles due to random counting errors in the measurement of the X-ray diffraction intensities. From the expression relating the residual stress to the X-ray intensities an equation has been derived giving the standard deviation in the residual stress due to random counting errors. In addition, a simple approximation has been obtained from this equation showing that the standard deviation is decreased by increasing the number of counts accumulated for each X-ray intensity measurement and by increasing the size of the angular increments between the data points. It will also be shown that, using the approximation, it is possible to estimate in advance the number of accumulated counts at each point necessary to attain a desired standard deviation in a residual stress measurement.
Variable Step-Counting Times for Rietveld Analysis, or, Getting the Most Out of Your Experiment Time
Authors: Madsen I.C. , Hill R.J. 
Published: March 2019

AbstractThe magnitudes of the peak intensities in a powder diffraction pattern are not uniformly distributed as a function of diffraction angle. The Lorentz-polarization factor, X-ray form-factor and the thermal vibration parameters all conspire to progressively decrease the intensities of the peaks as sinθ/λ increases. In spite of this, diffraction data for Rietveld analysis is universally collected using the same counting time for each step in the pattern. As a result, peaks at high angles are collected with lower counting precision than those at low angles, despite the fact that the high-angle region has a higher density of peaks and therefore contains more information than the low-angle part of the pattern. Indeed, the intensity, position and profile of reflections at medium and high sinθ/λ are often more easily modelled since they are subject to less interference from systematic effects such as extinction, specimen transparency and α1/α2 overlap errors. In the present work a novel variable step-counting-time regime has been devised that increases the counting times with diffraction angle in a manner inversely proportional to the intensity fall-off calculated from the Lorentz-polarization, form-factor and thermal parameters. The effect of this new data collection regime on the results of Rietveld refinement of a number of materials of varying structural complexity is discussed.
Electron Density Distribution Obtained from X-Ray Powder Data by the Maximum Entropy Method
Authors: Sakata Makoto , Takata Masaki , Kubota Yoshiki , Uno Tatsuya , Kuhazawa Shintaro , Howard Christopher J. 
Published: March 2019

AbstractThe electron density distribution maps for CaF2 and TiO2 (rutile) were obtained from profile fitting of powder diffraction data by a Maximum Entropy Method (MEM) analysis. The resultant electron density maps show clearly the nature of the chemical bonding. In order to interpret the results, the nuclear density distribution was also obtained for rutile from powder neutron diffraction data. In the electron density map for rutile obtained by HEM analysis from the X-ray data, both apical and equatorial bonding can be seen. On the other hand, the nuclear density of rutile Is very simple and shows the thermal vibration of nuclei.
A Multi-Line Standardless Method for X-Ray Powder Diffraction Phase Analysis
Authors: Li D.Y. , O'Connor B.H. 
Published: March 2019

AbstractQuantitative phase analysis (QPA) methods which employ only one diffraction line for each phase arc generally unreliable due to the influence of systematic errors such as preferred orientation and extinction. Gazzara and Messier (1977) proposed a multi-line QPA method using normalised line intensities for line j of phase i,where Iij = measured Bragg intensity, m = multiplicity, Lp = Lorentz-polarisation factor, |F| = structure amplitude and Vi = cell volume. The method proposed here is a refinement of the Gazzara-Messier procedure. Phase compositions are calculated directly from the mean normalised Intensity for resolved lines which span the 2θ range of the instrument. The method makes use of the variance in to estimate standard deviations for the phase compositions. Test results are given for binaries of corundum-quartz and corundum-ceria.
Characterization of Epitaxial High Tc Superconductors using a Parallel Beam X-Ray Diffractometer
Authors: Houtman E. , Ryan T.W. , David B. , Doormann V. 
Published: March 2019

AbstractMany analytical problems cannot be solved using a single XRD measurement. One example is the epitaxial growth of thin films of High Tc superconductors. To fully characterise such a sample it is necessary to study both the orientation (texture) and the phase composition of the layer.
X-Ray Texture Measurement Using a Position Sensitive Detector
Authors: Wcislak L. , Bunge H.J. , Haase M. , Nauer-Gerhardt C. 
Published: March 2019

AbstractFor pole figure measurement the flat sample has to be tilted which leads to peak broadening and peak overlap in peak-reach diffraction spectra. Using a linear position sensitive detector /PSD/, complete diffraction spectra can be obtained in each sample orientation. Peak separation can then be done by Gaussian fitting. When measuring with a PSD, each diffraction peak corresponds to a particular diffraction vector. This has to be taken into consideration by a coordinate transformation. The PSD-method is the only practical method of texture measurement for materials with complex diffraction spectra.
Introduction of a Nist Instrument Sensitivity Standard Reference Material for X-Ray Powder Diffraction
Authors: Cline James P. , Schiller Susannah B. , Jenkins Ron 
Published: March 2019

AbstractImprovements in sample preparation methods have resulted in increased accuracy in x-ray powder diffraction intensity measurements. This improvement has focused scrutiny on the instrument as a potential source of error. NIST Standard Reference Material, SRM, 1976 consists of a sintered α alumina, corundum, plate certified with respect to 12 relative intensity values from 25 to 145 degrees 2θ. Its function is to allow for standardization of powder diffraction intensity as a function of 2θ angle (instrument sensitivity). An increase in the accuracy of interlaboratory comparisons of diffraction intensity and related determinations will result. Utilization of the SRM requires the user to collect intensity data from the test instrument in a manner which conforms to that used in the certification. Graphical interpretation of the ratio of these data to those on the certificate will allow for appropriate judgment as to the condition of the test instrument. Discontinuities in the data indicate a malfunctioning or misaligned instrument. Systematic bias, introduced by design characteristics of the test instrument, manifests itself in terms of a pattern in the data other than a horizontal straight line with value of one. This bias may be removed with the calculation and application of a correction curve.
Application of Imaging Plate for X-Ray Diffractometry
Authors: Shibata Atsushi , Sasaki Katsunari , Kinefuchi Takao 
Published: March 2019

AbstractThe Fuji Imaging Plate (IP) is a 2-dimensional detector in which a latent X-ray image is stored as a distribution of color centers on a photostimulable phosphor (BaFBr:Eu2+) screen. It has a large effective area, wide dynamic range and high sensitivity. Thus it has been widely used not only in medical but also in scientific and industrial fields. Particularly in X-ray structure analysis, mainly of proteins, it has been used extensively and achieved good results.On the other hand, few applications have been reported in the field except for structure analysis, in spite of the superior performance of the IP which will give significant advantages in various measurements which have been done using an X-ray film such as electric device and fiber specimen.Therefore we report here the basic performance of R-AXIS II(Rigaku Automated X-Ray Imaging System II), an IP reader made by Rigaku, and some applications of X-ray diffraction measurements using IP.
Analysis of YBa2Cu3O7-δ Peritectic Reactions and Orientation by High Temperature XRD and Optical Microscopy
Authors: Snyder R. L. , Rodriguez M. A. , Chen B. J. , Matheis D. P. , Göbel H. E. , Zorn G. , Seebacher B. 
Published: March 2019

AbstractReal time observations of the YBa2Cu3O7-δ (123) melting process by high temperature XRD and optical microscopy reveal a reaction sequence which does not correspond well with the literature. CO2 gas, present in the air, reacts with 123 to produce the Y2CU2O5 phase. This reaction begins well below 800°C and persists up to 970°C when BaCuO2 begins to form. The previously unreported BaCuO2 reaction occurs in either air or oxygen and this phase grows at the expense of the 123 until both rapidly disappear at 1050°C with the appearance of Y2B2CuO5 (211), Formation of Y2O3 from the 211 melt occurs more slowly, beginning at 1150°C. Dynamic 00ℓ orientation has been observed at 950°C upon cooling from the melt. The orientationa) growth is believed to be a surface tension dependent, liquid assisted sintering reaction.
Nonlinear Equations for High Accuracy X-Ray Crystal Orientation
Authors: Dragoi Danut 
Published: March 2019

AbstractNonlinear equations are given for determining the crystallographic orientation of surfaces of single crystals. The equations are solved by an iterative method in several variables. The angle ϕ between the surface plane and the lattice plane in question is decomposed into two components α and β. These two components are obtained from the solution of a non-linear system of equations using two measurements and the Bragg angle. The diffractometric system considered is the well known θ/2θ with a sufficiently large area of x-ray detection and the capability of holding single crystal samples. The results obtained are discussed from experimental and theoretical points of view.
A Statistical Comparison of Data Obtained from Pressed Disk and Fused Bead Preparation Techniques for Geological Samples
Authors: Dow Randall H. 
Published: March 2019

AbstractThe analysis of geological samples by x-ray fluorescence analysis is complicated by matrix effects and sample variability. Diluting the sample in a suitable matrix such as lithium tetraborate and then fusing it helps to reduce problems associated with sample inhomogeneities and reduces matrix effects considerably.Unfortunately, many of the trace elements in the sample can be diluted below their detection limits by this technique. Pressing the ground powder into a hard disk avoids this problem and is less time consuming. Matrix effects can be very serious however, but can be calculated and compensated for by fundamental parameters programs.
Trace and Minor Element Analysis of Obsidian from the San Francisco Volcanic Field Using X-Ray Fluorescence
Authors: Sanders Suzanne C. , Zahrt John D. , Bell Graydon 
Published: March 2019

AbstractObsidian from eight localities in the San Francisco volcanic field of Northern Arizona was analyzed for 21 minor and trace elements (Ti, Mn, Fe, Co, Zn, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, W, Au, Hg, Th) usincf x-ray fluorescence analysis. All samples exhibited irregular analyzing surfaces. This was a more in-depth study of a previous study (1) in which a very small number of standards were used.The data, in the form of intensity ratios relative to iron, were statistically analyzed and the trace and minor element patterns established. The obsidian clustered into four well-defined groups each consisting of two localities: Government Mountain/Obsidian Tank, Slate Mountain/Kendrick Peak, Robinson Crater/O'Leary Peak, and RS Hill/Spring Valley. The four distinct groups were treated individually to refine the separation between the similar sites. Classification function coefficients were calculated for each locality, then used to identify the source of thirteen obsidian artifacts recovered from a Northern Arizona archaeological site.
Direct Analysis of Plutonium Metal for Gallium, Iron and Nickel by Energy Dispersive X-Ray Spectrometry
Authors: Bramlet H. L. , Doyle J. H. 
Published: March 2019

AbstractAn x-ray secondary target method for routine determination of gallium, iron, and nickel in plutonium metal is described that has significant advantages over wet chemical analysis. Coupons requiring minimal preparation for analysis are produced as a breakaway tab on the plutonium ingot. All three elements are determined on the same coupon. Gallium is determined using an arsenic secondary target followed by iron and nickel using a zinc target. The analysis times are 5 minutes for gallium and 15 minutes for the combined iron and nickel. The method of analysis was evaluated in the range of from 0.5 to 1.5% gallium. Iron was investigated over the range of 67 to 3000 ppm and nickel from 64 to 110 ppm.
Application of Automated X-Ray Diffraction to Alteration Mineral Zoning Studies
Authors: Salek H. , Vincent H. A. , Thorpe L. 
Published: March 2019

AbstractThe purpose of this study was to develop a quick and valid X-ray method to determine the alteration models for acidic and intermediate type of altered rocks. Four alteration minerals--alunite, kaolinite, montmorillonite, and sericite--and total quartz in certain altered porphyritic rocks were determined and evaluated by using the APD (Automatic Powder Diffractometer) system with external standard methods.The findings indicate that the APD system can successfully be used in the quantitative analysis of these five mineral phases. The best results are obtained from samples with low iron minerals and of a grain size not coarser than 325 mesh.
Evaluation of Macro- and Micro-Residual Stresses on Textdeed Materials by X-ray, Neutron Diffraction and Defection Measurements
Authors: Hauk Viktor M. 
Published: March 2019

AbstractTo evaluate the state of macro- and micro-residual stresses in cold rolled materials of 0.2 to 3 mm thickness the following test methods were used: Measurements of lattice spacing in different directions (φ,Ѱ)with X-rays and neutron-rays on many diffraction peaks. The X-ray method was employed on the surface of the sheet and of the thinned piece after removing several layers from both sides. The neutron-ray method allows measurements in the interior of a specimen and the average of the strain distribution of the total cross section. The etching deflection method determines the macro-residual stresses. The calculation of the macro- anci micro-residual stresses using X-ray elastic constants (XEC) for polycrystalline material and the compliances of single crystals for groups of grains are described. Homogeneous and heterogeneous materials like steels, (α + β)-brass, nickel and copper with 3 % silver were investigated. The state of residual stresses on the surface and with the depth over the cross section was evaluated or is in the final process of investigation.
X -Ray Elastic Constants and Their Meaning for Al and Fe
Authors: Zhong Rui Mei , Noyan I. C. , Cohen J. B. 
Published: March 2019

AbstractIn the measurement of residual stresses via diffraction (using x-rays or neutrons) it is strains that are actually determined, by employing the interplanar spacing (dhkl) of the ﹛hkl﹜ planes as an internal strain gauge. The change in this spacing is measured from the shift of diffraction peaks (and Bragg's law) at several orientations of the sample to the incident beam, and the resultant strains are converted to stresses with the “diffraction elastic constants”, S1 (hkl) and S2 (hkl)/2. While these take on the values (- v/E) and (1 + v )/E respectively for an isotropic solid, in anisotropic materials their values depend on marry factors: preferred orientation, shape and orientation of second phases, interaction between grains. In fact there are reports of variation these constants with plastic deformation and theory predicts variations with morphology. While it is possible to calculate approximate values for these constants from theory and the single crystal elastic constants , Si and S2/2 are really not elastic constants in the strictest sense because or these other factors, and it is best to measure them. One of us (I. C. Noyan) has recently examined this problem in some detail , and we summarize his results here.
X-Ray Stress Determination in a Single Lap- Joint Containing a Debonded Region*
Authors: Lankford A. , Barrett C. S. , Predecki Paul 
Published: March 2019

XRD has been found to be a useful technique for investigating both surface and interior stresses in. adhesive bonded joints. For the interior stresses, to gain access to the joint interface, adherends were chosen such that one adherend was relatively transparent to the X-radiation used and the other was not. Incident X-rays then penetrated the first adherend and the adhesive, and were diffracted from just below the surface of the second adherend.In prior work it was shown that the measured stresses due to an applied load agreed quite well with stresses calculated for the same joint using the TEXGAP-2D finite element program, except at one extremity of the bond. One explanation proposed for the discrepancy was that a small debond was present at this extremity. In the present study, therefore, an investigation was made of a joint contfli'nitig an intentional debond at this extremity.
X-Ray Measurement of Residual Stress Near Fatigue Fracture Surfaces of High Strength Steel
Authors: Hirose Yukio , Tanaka Keisuke 
Published: March 2019

The residual stress left on the fracture surface is one of the important parameters in X-ray fractography and has been used to analyse fracture mechanisms in fracture toughness, stress corrosion cracking and fatigue tests especially of high strength steels.In this study, the distribution of residual stress near fatigue fracture surfaces made in air and in 3.5% NaCl solution was measured by the X-ray diffraction method. The effect of aqueous environment on the plastic deformation near fatigue fracture surfaces was discussed on the basis of the residual stress distribution.