bluuebunny/crossref_metadata_2025_split huggingface dataset:
Total Nondestructive Analysis of Caas Syenite
Authors: Volborth A. , Fabbi B. P. , Vincent H. A. 
Published: March 2019

AbstractDetermination of 35 trace and 8 major elements in a granitic rock by nondestructive X-ray emission and fast-neutron activation methods has been accomplished. Trace elements arsenic, barium, cadmium, cerium, cobalt, chromium, cesium, copper, gallium, gadolinium, germanium, hafnium, mercury, indium, lanthanum, molybdenum, manganese, niobium, neodymium, nickel, rubidium, antimony, scandium, samarium, tin, strontium, tantalum, thorium, titanium, vanadium, yttrium, ytterbium, zinc, and zirconium and major elements aluminum, calcium, iron, potassium, and silicon have been estimated in the vacuum X-ray spectrograph. Phosphorus has been excited by a chromium-target tube. Major elements magnesium, sodium, and oxygen have been estimated by the Henke aluminumtarget X-ray spectrograph. Major elements oxygen and silicon have also been determined by fast-neutron activation. Detection limits for traces are in cur system in the range of 1 to 100 ppm with standard deviations of about 1 to 10 ppm. Precision in the determination of major constituents is better than 1% in relative standard deviation. The data are reported in parts per million for the trace elements and for the major elements as well. It is suggested that this type of repotting of geochemical data be preferred to the conventional reporting of major constituents as oxides.
X-Ray Fluorescence of Suspended Particles in a Liquid Hydrocarbon
Authors: Gunn E. L. 
Published: March 2019

AbstractIn the application of X-ray fluorescence to the inspection of petroleum or petrochemical products, the measured element may not be ideally dispersed in the organic substrate but may exist as suspended particles. A question naturally arising is how small the particles must be to approximate the fluorescent intensity level of the true solution. The fluorescent emissions of suspensions of particles in a viscous hydrocarbon were measured and the intensities compared with true solutions of zinc, iron, and silicon, respectively. Particle segregates were classified by raicrosieve and photomiorographic inspection. Iron or zinc particles of 8-μ size yield 65% of the intensity of the solution state. Increase of particle size to 70 μ reduces intensity by several fold. Silicon, dispersed as porous silicon dioxide particles of 28-μ size, yields 80% of the intensity of the solution form. Reliable measurement of a suspension can be made provided it is stable and a standard closely simulating it is available for reference or if proper intensity corrections are applied for a known particle size in suspension. Comparisonsof experiment with theory for the particle size-intensity effect agree only moderately well. This is attributed to uncertainties in the parameters relating the two. Theory indicates that zinc or iron in suspended form should be less than 1 μ in size to approximate the intensity of the elements in solution. Additional research aspects of particles in suspension are suggested.
Rare-Earth Analyses by X-Ray-Excited Optical Fluorescence
Authors: Burke W. E. , Wood D. L. 
Published: March 2019

AbstractX-ray excitation causes rare-earth impurities in yttrium oxide and gadolinium oxide to emit intense and highly characteristic optical line fluorescence, which enables their analyses at low concentrations. The limits of detection for praseodymium, ncodymium, samarium, europium, gadolinium, terbium, dysprosium. holmium, erbium, thulium, and ytterbium in these two oxides range from 1 to 100 parts per billion (ppb). In other rare-earth oxides which have been investigated. the fluorescent intensities arc greatly reduced. Successful analyses can be made only by dilution in high-purity Y2O3. This dilution raises the detection limits for rare earths in these other oxides to the part per million range. X-rays from the chromium target of a cual-target X-ray tube are about two times more efficient in exciting rareeaith optical fluorescence than are the tungsten-target X-rays, even though the total energy output of the chromium target is only about one-third that of the tungsten target. With either target material, the rare-earth intensities vary linearly with the X-ray tube current, but a plot of intensity versus the square of the accelerating potential is not linear; it drops off at higher voltages.
The Effect of Micro Segregation on the Observed Intensity in Thin-Film Microanalysis
Authors: Judd G. , Ansell G. S. 
Published: March 2019

AbstractIn the electron-probe microanalysis of thin alloy samples, particularly for areas which contain a high degree of solute segregation as are often obtained in extraction replicas or in electro chemically thinned foils, a correlation between the measured intensity and the sample microstructure has heen difficult to perform. The purpose of this study was to isolate the effect of micro segregation, i.e., segregation with respect to the beam size (∼2 μ) itself, on the characteristic intensity generated by a microvolurne. To accomplish this, a model system consisting of silver-powder particles (∼1 μ diameter) supported on an evaporated carbon film was investigated by using a thin-film microprobe accessory of an electron microscope (Hitachi HXA-1). The silver particles served as analogs to a highly concentrated segregation area, and the carbon film was analogous to the corresponding matrix. The simplicity of this system readily allowed for an analysis of the geometric positioning factor dependence of the generated intensity.It was observed that the intensity measured for a given particle could vary by as much as 1000% depending only on the relative position of that particle within the electron beam. This variation was derived to be due to both the distribution of electrons within the beam and the amount of mass occupied by the particle at each distance from the beam center. A computer program was developed to perform the necessary calculation to predict the relative intensity as a function of position within the beam. These calculated intensities were found to compare favorably with the experimental measurements.
Computerized Multi Phase X-Ray Powder-Diffraction Identification System
Authors: Johnson G. G. , Vand V. 
Published: March 2019

AbstractA computer search system utilising the Powder Diffraction File compiled by the Joint Committee on Powder Diffraction Standards, originally developed for an IBM 7074 in FORTRAN II and reported at the Pittsburgh (1966) conference, has beer. revised and extended to run on IBM 360/50. The system is now written in FORTRAN IV. This search system, which uses all the lines of the reference patterns, has successfully identified up to six standard reference patterns from a multiphase unknown X-ray diffraction pattern in less than 2 min running time. No chemical information is necessary for the system to run. In the revised program, the chemical composition of the patterns is now available from the magnetic tapes in immediate conjunction with the printout of the “most likely” components of the mixture. However, this chemical information is not used by the program itself in the search procedure since, if the unknown pattern is absent from the file, it is helpful to know those compounds which are isostructural with the unknown pattern. With the immediate use of chemical information, these patterns would be eliminated. An estimation of the relative concentration of each of the components, based on absolute intensities, is also calculated by the program. This identification system has been run on experimental data both of the Guinier type and of a less reliable type, with the present Powder Diffraction File on the search tape. Although the number of false matches was increased with the poorer quality of input data, the programs yielded excellent results for both single- and multiple-phase patterns even with poor data and the absence of any chemical information. A series of results from the Materials Research Laboratory of The Pennsylvania State University, illustrating the system in operation with increasingly difficult mixtures, will be given. With such a system in operation at such a small cost, the diffractionist can concentrate on the results and meaning of the identification rather than on the method of identification itself.
Standard Data for the Identification of Phases By X-Ray Diffraction
Authors: McMurdie Howard F. 
Published: March 2019

AbstractThe identification of crystalline phases by x-ray diffraction, either by powder or single crystal techniques requires a dependable body of reference data. It is not only necessary to have data on each phase which are accurate and complete, it also is desirable to have data on as wide a range of compounds as possible, and to have the data organized in such a manner as to be readily usable. The outstanding compilations which approach these goals are the Powder Diffraction File and Crystal Data.The Powder Diffraction File, published by the Joint Committee on Powder Diffraction Standards has data covering about 22,500 phases, both organic and inorganic. These data are of various degrees of accuracy as is indicated by symbols. The File is continuously being improved by the addition of evaluated data from the general literature and by data produced by supporting projects, the principal one being the Joint Committee Associateship at the National Bureau of Standards.To be noted in the File with a star, and to be truly considered standard data a powder pattern must be complete in the sense of including all reflections above the minimum “d” spacing covered, both weak lines and those with large “d” spacings. Since the best test of a pattern is its own internal consistency, the reflections must all have hkl's assigned and must show a good agreement between the spacings observed and those calculated from a refined cell, and they must be consistent with the known space group. This agreement can be best obtained by the use of an internal standard and a computer program. The intensities should be measured by a method which minimizes the effect of crystal orientation.The PDF is provided with search procedure manuals arranged on a scheme of the strongest lines to help in locating data matching that from an unknovm. A computer program for rapid searching is available. A recent development is the inclusion of a “reference intensity” to aid in estimating the quantitative analysis of mixtures.Crystal Data is a compilation now in the third edition made at the National Bureau of Standards and published by the Joint Committee on Powder Diffraction Standards. It contains data on the unit cell parameters of over 24,000 phases. These data are arranged by crystal system and axial ratios to simplify identification of phases from unit cell data obtained from Single crystal cameras.Both of these large compilations are also important reference sources for crystallographic information giving structural information and literature references.
Role of Diffractometer Geometry in the Standardization of Polycrystalline Data
Authors: Parrish William 
Published: March 2019

AbstractThis paper reviews the factors in diffractometer geometry most likely to cause large errors in intensity measurements due to imperfect specimen preparation, particularly preferred orientation. It is recommended the same specimen be transferred to two or more diffractometer geometries in which the specimen has different orientations to obtain sets of complementary data. Three geometries are illustrated: θ-2θ scanning with reflection and transmission specimens, and Seeman-Bohlin with reflection specimen.
Can Regression Equations be Optimized By Finagling X-Ray Intensities?
Authors: Fatemi M. , Birks L. S. 
Published: March 2019

AbstractThe application of the null-determinant technique to eliminate the inconsistency of x-ray empirical equations is investigated. Experiments with a series of stainless steel standards show that, in general, calculated compositions obtained by the null-determinant technique agree more closely with chemical analysis than do those obtained by simple averaging. Since it is usually errors in measured intensities which lead to inconsistent estimates of concentrations, the advantages of the null-determinant technique in adjusting the intensities become evident.
An X-Ray Amorphous Scattering Investigation of the Corrosion of a Potassium Silicate Glass K2O-3Si02
Authors: Gould R. W. , Hill M. S. 
Published: March 2019

AbstractStructural modifications occurring in corroded potassium silicate glasses were studied using x-ray amorphous scattering techniques. Pair function distribution curves are compared and the differential method is used to follow the structural changes. The structure appears to approach that of vitreous silica after long leaching times.
Qualitative Analysis of the Kossel Back Reflection Pattern from Selected Semiconductors
Authors: Fitzpatrick Robert L. 
Published: March 2019

AbstractThe value of the divergent beam method as a powerful tool for investigating crystal perfection over rather wide limits has been known since the analytical work of K, Lonsdale. This method has been treated experimentally and theoretically by numerous authors and was popularized by Sigmund Weissmann. Although not nearly as useful as the reflection and transmission topographic techniques of Berg-Barrett and Lang for crystal characterization, it is potentially very useful for three dimensional quantitative strain analysis. The “technique phase” as Harvey Yakowitz remarked, is essentially over; however, refinements and optical improvements are certain to evolve if quantitative measurements are to become useful. Very short exposures and the non-destructive nature of the reflection divergent beara - Kossei method is a useful survey tool that has gained limited acceptance.Presently, the reflection mode is useful in the qualitative survey of numerous semiconductor materials and processes, some of which have been considered from time to time by various authors. A range of crystal perfection, as well as some surface modifications, are surveyed. Kossel reflection pattern artifacts and irregularities are discussed.
A Spherically Bent Crystal X-Ray Specteometer with Variable Curvature
Authors: Parker Donald L. 
Published: March 2019

AbstractThe design and performance of a spherically bent crystal x-ray spectrometer with variable curvature are given. A thin crystal with the diffracting planes parallel to the face is mounted on a vacuum chuck consisting of an O-ring in a brass mounting. A controlled partial vacuum is applied behind the crystal to cause spherical deformation of the lattice. Thus, rays from a point source on the focusing circle are diffracted to a line image also on the focusing circle. The differential pressure is automatically varied such that the source-to-crystal and crystal-to-image distances are equal and constant for all Bragg angles and hence the simple θ-2θ motion of a one flat crystal spectrometer is used.The data are accumulated by a scanning proportional counter tube placed behind a vertical slit (perpendicular to the scattering plane) located at the image line. The fixed chord length is 22 cm and the instrument is designed to scan from zero up to 120° 2θ. Crystals are easily interchanged and the automatic vacuum regulator has sufficient flexibility to allow tailoring the spherical bending to crystals of materials of various thicknesses. The resolution is easily adjusted by either the size of the x-ray source or the width of the detector slit. The performance of the spectrometer has been evaluated by characteristic x-rays produced by various samples placed in a demountable x-ray tube. The main advantages of this three-dimensional focusing instrument are the very high signal-to-noise ratio and the very low levels of x-ray flux required.
Measurement of the X-Ray Sensitivity of Silicon Diodes in the Energy Region 1.8 to 5.0 Kev
Authors: Hohlfelder Jacque J. 
Published: March 2019

AbstractPlanar, Silicon diodes have been calibrated in the energy region 1.8 to 5.0 keV using low-energy, continuous-mode x rays. The spectral energy distribution of each of six x-ray spectra used in the calibration was measured using a non-dispersive Si(Li) x-ray spectrometer. X-ray spectral fluxes were measured using a xenon-filled, parallel-plate ionization chamber. A chopper-wheel and phase-sensitive detector combination was used to enhance the signal- to-noise of the silicon diode signals in order to measure the x-ray induced diode currents, ∼10-10) A., in the presence of diode dark currents of order, 10-5 A. Measured data were consistent with diode silicon dead layers of from 0.3 to 0.4 μm. Average agreement to within five percent was found between measured diode sensitivities and calculated diode sensitivities. The measured diode x-ray sensitivities are compared with independently-measured diode x-ray sensitivities of similar diodes.
Development of the High Performance 'Solfa' On-Line Analyser to Measure Total Sulphur in Petroleum Distillates and Residual Fuels Using Non-Dispersive X-Ray Fluorescence
Authors: Gamage C.F. , Topham W.H. 
Published: March 2019

In any petroleum product, a high sulphur content is considered undesirable. Sulphur in diesel fuels is claimed to aggravate problems of wear and deposit. With residual oils used in some metallurgical operations, the sulphur combustion products can have an adverse effect on the metal. In combustion equipment, the oxides of sulphur together with water vapour can lead to undesirable acid condensatlon on cool metal surfaces.The more general problem is air pollution. Local and national legislation present the oil industry with a continuing demand for fuels of lower and lower sulphur content. Best use must therefore be made of crude oils of inherently low sulphur content. Desulphurising processes are comnonly used for distillates and are available for residual products. Such processes however tend to add significantly to produetion costs.
Changes in the Bragg-Williams Parameter with Deformation in Ordered Au4V
Authors: LeFevre B. G. , Starke E. A. 
Published: March 2019

AbstractThe intermetallic compound Au4V is known to be ferromagnetic at temperatures below 43°K. Its ferromagnetism, which has been attributed to long range order, can he destroyed by cold deformation. The present study was undertaken to determine how the Bragg and Williams long-range-order parameter of the fully-ordered alloy varied as a function of deformation by cold rolling. Because of complexities in the diffraction spectrum it was not possible to determine 5 by a simple ratio of integrated intensities as is frequently done in other ordered systems, A treatment was developed to handle these difficulties using a modification of a method developed by Giamei and Freise for determining volume fractions of mixed phases. These results are correlated with magnetic measurements made by Chin and coworkers at Bell Laboratories.
Deformation Textures of Ordered and Disordered Cu3Au*
Authors: Starke E. A. , Ogle J. C. , Sparks C. J. 
Published: March 2019

AbstractThe development of deformation textures of both initially disordered and ordered Cu3Au has been studied and discussed in terms of the stacking fault energies and twinning probabilities. No differences in the deforir.ation textures of the ordered and disordered materials were detected at deformations up to 40% reduction. However, at reductions of approximately 42% a marked difference was observed. This difference is attributed both to the degree of order and to the stacking fault energy of the ordered sample being conducive to deformation twinning at this stage of the rolling schedule. For samples which were reordered below the racrystallization temperature at intermediate stages of deformation (every 10% in total reduction) no differences between the ordered and initially disordered samples were observed up to 90% total reduction in thickness.
Solution Absorptiometry with Beta Excited Sources by Means of Balanced Filters
Authors: Toothacker William S. , Preuss Luther E. 
Published: March 2019

AbstractThe use of beta excited x-ray sources in solution absorptiometry has been reported upon by this laboratory. These sources produce characteristic K x-ray lines superimposed upon a bremsstrahlung continuum. The work previously reported made use of the entire beta excited spectrum. The resulting plots of In (Io/I) versus concentration of solute were not straight lines, (I0is the intensity of the x-rays after passing through the solvent, and I is the intensity after passing through both the solvent and solute), but curved downward, as is characteristic of polychromatic sources due to preferential absorption of the low energy photons. These sources have a bremsstrahlung end-point equal to the beta energy E-max. This continuum energy usually is relatively high, resulting in a high mean x-ray energy for the polychromatic beam. This is not a desirable condition. Ideal sources for absorptiometry would be monochromatic in nature with an overall energy range covering the values for the elements. The use of a monochromatic source has two advantages for solution absorptiometry. First, the sensitivity is much greater since the K peak is of lower energy than the bremsstrahlung continuum. Secondly, the plot of In (Io/I) versus solute concentration is a straight line since a fixed value of the mass absorption coefficient can be assigned to this fixed energy, thus simplifying calibration. To use only the monochromatic K energy from these beta excited sources, we have applied the method of balanced filters. These monochromatic K x-rays, with the remainder of the continuum filtered out, have been employed in solution absorptiometry. The resulting plots of In (Io/I) versus solute concentration are straight lines with very good sensitivity. Using this technique, a very wide range of monochromatic energies are available for use in solution absorptiometry.
Simple Two Crystal Spectrometer and its Application to X-Ray Spectrochemical Analysis
Authors: Gohshi Y. 
Published: March 2019

AbstractA simple two-crystal spectrometer was constructed, making use of a commercial one-crystal spectrometer. A detector attached to a 2θ-arm has been replaced by a second crystal. After adjustment, the second crystal is fixed to the 2θ-arm. The detector is placed at an appropriate position apart from the 2θ-arm. The spectrometer is operated as if it were a one-crystal spectrometer. The dispersion of the spectrometer in this mode of operation is the sum of those of the first and second crystals. Ge(220) crystals gave the best resolution which was about 3-3 eV fwhm for Cu Kα1. The strongest Intensity was observed using etched LIF crystals. The intensity was about 1/4 of that of a one-crystal spectrometer and the resolution was about 9.5 eV fwhm for Cu Kα1. The spectrometer was applied to the determination of hafnium in zirconium and sircaloy. The Zr Kα 2nd order line, which coincides with the Hf Lα1 line, was completely eliminated by successive reflections by Ge(111) crystals owing to the extinction rule and the high resolving power. The detection limit was about 7 ppm of hafnium. Another example is the separation of the As Kα2 line from the Pb Lα1 line. Arsenic in low alloy steel was determined without the correction for the well known Interference of lead. The very common interference of Cr Kβ on Mn Kα was also eliminated completely by this spectrometer. Though the spectrometer is not very suitable for a wide wavelength range spectroscopic measurement, owing to its narrow window region (about ±1°), the chemical effects on Kg spectra of sulfur in various compounds were investigated. Fine structures were found In the sulfur Kβ spectra of several thiocyanates and elemental sulfur. To observe long wavelength region spectra, the X-ray path of the spectrometer was modified to a hybrid path (vacuum and helium).