bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Microprobe Analyses and X-Ray Diffraction Study of SrSi2
Authors: Faulring G. M. , Malizie E. S. 
Published: March 2019

AbstractAlthough the phase SrSi2 has been previously recognized, it has been described only briefly in the literature.An alloy comprised of FeSi2, silicon, and the SrSi2 phase was examined on the electron microprobe. Optical and electron scanning images are correlated with X-ray scanning images for iron, silicon, calcium, and strontium. Quantitative microprobe analyses were made and corrected for absorption and the atomic number effect by several noncomputer methods. The corrections include as variables the X-ray intensities measured at several accelerating voltages. The effects of varying the electron beam size and accelerating potential are included. The results are compared to chemical analyses. The advantages of varying the accelerating voltage when correcting intensity data, increasing the beam size when surface preparation is a factor, and the importance of surface preparation at low accelerating voltages are discussed.An X-ray diffraction examination showed that the phase SrSi2 has a cubic unit cell with an a0 of 6.515 Å. There are four molecules per unit cell, and the most probable space group appears to be P213. The density was calculated as 3.45 (observed density >3.3).Metallographic observations with ordinary and polarized light and microhardness measurements are included.
A Glass Fusion Method for X-Ray Fluorescence Analysis
Authors: Larson J. O. , Winkler R. A. , Guffy J. C. 
Published: March 2019

AbstractA thermally tough, low-melting, low-viscosity glass composition is described that has been used as a fusion mixture in sample preparations for X-ray fluorescence analysis.The fusion mixture is cast into a glass disk which, after annealing, is used directly for the X-ray measurements. Problems arising from disk surface imperfections have, in the past, been minimized by either prolonged polishing of the glass surface, or grinding the disk and pressing the powder into a peltet. This practice has been eliminated through the incorporation of appropriate internal standard elements into the glass fusion mixture. This approach also minimizes interelement effects and errors due to instrumental drift.A variety of corrosion products have been successfully analyzed by this method. Results will be given.
Quantitative X-Ray Emission Analysis of Magnesium Through Fluorine with X-Ray and Electron Excitation
Authors: Bernstein F. , Mattson R. A. 
Published: March 2019

AbstractThe analysis of dry powder samples for magnesium, sodium, and fluorine by X-ray and electron excitation has been studied. As in the case of heavier elements, the form of chemical combination influences the elemental sensitivity; sensitivity changes due to self-absorption can be adequately predicted using published absorption coefficients. Where both absorption and enhancement effects are possible, selection of X-ray target or excitation potential can. eliminate the enhancement problem. Matrix effects were found to be extremely variable and unpredictable. Finally, X-ray and electron excitation results are compared for the three elements in a series of geological samples. Efficiency of excitation was far better for electron excitation, but limits of detectability were lower for X-ray excitation due to significantly lower backgrounds.
X-Ray Fluorescence Spectroscopy in the Analysis of Ores, Minerals, and Waters*
Authors: Rose Harry J. , Cuttitta Frank 
Published: March 2019

AbstractX-ray fluorescence spectroscopy has been used in solving a wide variety of geologic problems involving mineral, ore, and water analysis. The technique has been a powerful analytical tool in the survey of mineral deposits, as a control to monitor ore flotation processes, for the semimicroanalysis of mineral separates and of rare new mineral species, and for the determination of trace elements in lake and saline waters. Many preparation techniques have been developed for the analysis of complex mineral systems, some combining X-Ray fluorescence with other analytical techniques to provide a complete analysis. These, coupled with improvements in instrumentation, have given the X-ray analyst a means of extending analytical ranges to the microgram level and to include elements that were previously not detectable. Significant advances in sample preparation and methods development have been made in the analysis of milligram quantities of complex geologic materials. The fusion and the solution of specimens appear to be the preferred methods of sample preparation. For samples that vary markedly in composition, the slope-ratio technique offers a new approach to solving matrix problems.
Use of Primary Filters in X-Ray Spectrography: A New Method for Trace Analysis*
Authors: Caticha-Ellis S. , Ramos Ariel , Saravia Luis 
Published: March 2019

AbstractA method to improve the detectability of trace elements by X-ray fluorescent spectrography is described. The method consists of using appropriate filters in the primary, or exciting, beam. The effects of using filters in the primary beam on the peak-to-background ratio R of a fluorescent line have been analyzed on theoretical grounds. In fact,where I1(λ0) is the intensity of the analytic fluorescent line, I1(λ0) is the background intensity due to coherent and Compton scattering of the primary radiation by the specimen, and I2 is the background intensity due to scattering of the fluorescent radiation by the analyzing crystal. Analytical expressions were derived for I1(λ0), I2, and I1(λ0), from which it has been concluded:1.The ratio I1(λ0)/I1(λ0) decreases when the filter used has its absorption edges at wavelengths longer than λ0.2.The ratio I2/I1(λ0) can be separated into two parts which vary in opposite ways. The influence of these two parts on the value of R is discussed in the text.It is then shown that the method should work well at short wavelengths and less well at longer wavelengths. The method was tested in the difficult case where overlapping of the analytical line with a characteristic line of the tube occurred, i.e., in the determination of traces of selenium by using tungsten radiation. The analytic line Se Kα. has a wavelength of 1.106 Å, while W Lγ1occurs at 1.098 Å. There is a marked effect of the filter thickness on the detectability; an optimum thickness appears to exist for each case. In the analysis of selenium, the best filter thickness (which can be selected by mere inspection of the diagrams reproduced in the text) increased the detectability of selenium traces by an order of magnitude. Finally, from statistical considerations, the quantity tσ2 is proposed as an index of the effectiveness of the filter: the smaller tσ2 is, the better the filter is. Here σ is the standard deviation of the intensity of the analytic line and t is the total counting time spent on the measure of the analytic line arid background. In order to study the dependence of the index tσ2 on the filter thickness, measurements were made on samples of sugar containing known concentrations of strontium. Then tσ2 was plotted against the thickness of the filter for each concentration; these curves do show a minimum. Thus, an optimum filter thickness exists in each case.
Precision and Accuracy of Silicate Analyses by X-Ray Fluorescence
Authors: Baird A. K. , Welday E. E. 
Published: March 2019

AbstractThe relative merits of different methods of sample preparation, of different instrumental operating procedures, and of different calibration techniques for major and minor elemental analyses of silicates must be judged by adequate estimates of precision and accuracy. Sources of imprecision in the X-ray method include electronic deviations, counting statistics, and sample collection and preparation. The variations attributable to these sources set limiting values to any X-ray method. Because most X-ray methods are comparative and thus dependent upon standards, the accuracy is more difficult to establish. Sources of inaccuracy in calibration methods include biases introduced by instrumental design or operation, matrix and particle size effects reflected as scatter or calibration line curvature, and an inadequate knowledge of the chemistry of the standard or standards used. With an adequate estimate of the precision, a practical measure of the accuracy of the X-ray fluorescence method can be obtained by the predictions of the compositions of standard silicates—standards whose compositions are assumed to be established by repeated wet-chemical analyses. This practical approach to an assessment of errors suggests to us that the comparative X-ray methods are highly precise. Within the limits of precision and with appropriate standards, accurate predictions of the compositions of silicate rocks can be made without applying empirically or theoretically derived correction factors. In this paper tests of precision and accuracy will be described which have been used to assess variabilities in quantitative analysis from the sample collection, through the sample preparation, to the calibration with standards.
Applications of Computerized Statistical Techniques in Quantitative X-Ray Analysis
Authors: Mitchell Betty J. 
Published: March 2019

AbstractThe place of statistical techniques and the digital computer in analytical chemistry is clearly exemplified in the X-ray spectrograph laboratory. As the statistician is obsolete who uses only a desk calculator for his calculations in this era of rapidly changing technology and the need for increased productivity, so the X-ray man is severely handicapped who ignores the place of statistical techniques and associated digital computation in his work. For his calculations, the statistical X-ray analyst may choose from among the following: a small specialized computer designed as part of his X-ray equipment, a medium-size computer located in the laboratory building with the capacity to handle all the problems generated by the various analytical specialists, a time-sharing computer station which he shares with other analytical or testing sections of his main laboratory, or batch processing of his data by his company's computer center. Advanced types of desk calculators are now available which will permit rapid completion of some types of complex calculations, especially if they are set up in a systematic fashion. Careful study of an individual laboratory's problems will provide economic justification for the most appropriate type of computer calculation; the choice is dependent on many factors. This paper describes the advantages and disadvantages of the various computer systems for the X-ray spectrographer and the numerous statistical techniques which he may employ as an aid in hi? work. Statistics provide him with the tools to design his experiments, interpret his data, control the process which supplies his samples, improve sampling procedures, calibrate his X-ray equipment, perform theoretical studies, and calculate, correct, average, and evaluate his analyses. Digital computation provides him with an extraordinarily rapid means of making these calculations; in some cases, they are virtually impossible without computerization. Examples of analyses are described which are made practicable only by this combined statistical computerized approach. The accuracy and precision of computerized analyses are higher than for results obtained by the usual X-ray methods; analyst error is reduced to a minimum. The economics of present-day industrial life, especially applied to the analytical laboratory as a service organization, demand the most efficient possible operation of all analytical equipment. The X-ray laboratory presents an outstanding example of the need for statistical analysis and its associated digital-computer computation.
Production Control of Gold and Rhodium Plating Thickness on Very Small Samples by X-Ray Spectroscopy
Authors: Glade George H. 
Published: March 2019

AbstractManufacture of reed switches, critical components in present-day dataprocessing support devices, requires a means of accurate, rapid analysis of elements used in plating tlie levers of the switch. Because of gready reduced feedback time, X-ray spectroscopy has replaced metallographic sectioning and optical measurement as a plating-thickness control method. While 6 hr were required to obtain thickness data for a given sample size by sectioning, X-ray spectroscopy requires only 2 hr, which permits better control of the plating operating. X-ray spectroscopy is now used routinely to control both gold and rhodium plating thicknesses in the 20- to 100μin. (1 × 10−6) thickness range. The large number of samples prevents long count duration, while the small sample size (0.110 by 0.033 in.) reduces the precision of the analysis. However, the precision of the X-ray and optical methods is approximately the same, 8% variance. X-ray accuracy is comparable to that of sectioning since the standards are obtained by sectioning. Simplicity of operation is required since relatively untrained operators are used. An aperture system is used to reduce background. The rhodium thickness measurement is obtained from gross rhodium intensity. Attenuation of gross nickel intensity from the base material was found to be a better measure of gold thickness intensity. Calibration for hoth gold and rhodium is performed by using the same wide detector conditions. The choice of analysis is made by changing only the 2θ angle, thus avoiding the time required for recalibration when changing analysis.
The Influence of Sample Self-Absorption on Wavelength Shifts and Shape Changes in the Soft X-Ray Region: The Rare-Earth M Series
Authors: Fischer David W. , Baun William L. 
Published: March 2019

AbstractThe Mα and Mβ emission spectra and the Mjv and My absorption spectra have been studied for the entire series of rare-earth elements. It is conclusively shown that the complicated multiplet structure observed in the emission spectra is not real emission structure but is, instead, produced by sample self-absorption. This is demonstrated by observing the emission spectra over wide variations in take-off angle and bombarding electron energies and finally by comparing the detailed structure of both the emission and absorption spectra. The MIV and MV absorption structure completely overlaps the Mα and Mβ emission lines, which are each found to have but one intensity maximum when obtained under conditions of minimum. self-absorption. Some of these spectra have never been shown previously, while others have been studied in detail by several investigators. Points of agreement and disagreement with previous work are mentioned, and the wavelengths of the emission lines and absorption edges are listed for all of the rare-earth elements. It is concluded that the 4f → 3d electron transitions are reversible in these elements.
Quantitative Microprobe Analysis of Thin Insulating Films
Authors: Colby J. W. 
Published: March 2019

AbstractThe analysis of thin insulating films occurring in various stages of the manufacture of integrated circuits has in the past been difficult, if not impossible. Their dimensions usually preclude analysis by conventional chemical techniques, hence very little is known concerning their relative stoichiometrics. However, by microprobe analysis, films as thin as 540 Å (∼18μg/cm2) have been successfully analyzed. In general, two different approaches are taken, depending on the film thickness. Usually, films thicker than 2500 Å (∼50μg/cm2) are analyzed by conventional microprobe techniques. A computer program, called MAGIC, has been written, which converts the raw X-ray intensities to chemical composition. All data are corrected for dead time, background, absorption, atomic number effects, and fluorescence by characteristic radiation, if required. A minimum of input is required, only the chemical symbols. X-ray lines employed, and the accelerating voltage being necessary in addition to the raw X-ray intensities. All constants such as atomic weights, critical excitation potentials, X-ray wavelengths, and absorption coefficients are stored or calculated internally, which reduces the errors and time associated with looking up and key-punching these values. New fluorescent yields are used for K and L radiation. No fluorescence correction is made for M radiation. The use of this correction program generally gives results, accurate to about 2 to 4%, relative to the amount present. For films thinner than 2500 Å, a new model is proposed which allows the X-ray spectra from the film and substrate to be unfolded to give the composition of the film only. To accomplish this, the atomic number correction of Duncumb and deCasa employed in MAGIC has been used in conjunction with a mean electron energy concept. Results obtained to date through the use of this model have been surprisingly good, being of the order of 5% relative to the amount present. Potential errors and uncertainties are discussed, and results given which illustrate the accuracy of the two methods.
Study of Extended X-Ray Absorption Fine Structure with the Use of Thick Targets
Authors: Hach J. T. , White E. W. 
Published: March 2019

AbstractA novel method has been investigated for the study of extended X-ray absorption-edge fine structures. The method takes advantage of the absorption of continuum X-rays that emerge at low takeoff angles from an electron-bombarded target. The extended fine structure is observed as undulations in the continuum X-ray intensity in the region of the self-absorption edge. Spectra from conventional X-ray diffraction tubes have been recorded for various values of kilovolts and takeoff angles. Spectra obtained by this method are compared with published data. Nearly all the features of the extended fine structures can be clearly resolved by this technique. In the case of iron ar.d copper targets, it is found, experimentally that the best contrast is obtained when using a 50-kV accelerating voltage. A takeoff angle of 3° yielded best results for copper, while an angle of 10° was best suited for iron. The Philibert absorption correction successfully used in electron microprobe analysis has been extended to account for the observed self-absorption effect where κΔλ = f(x)λ1/f(x)λ2. The primary advantage of the thick-target technique is in the ability to obtain absorption spectra without having to prepare thin films. The technique is essentially nondestructive in that the sample need not be pulverized or thinned.
Determination of Lattice Parameters by the Kossel and Divergent X-Ray Beam Techniques
Authors: Lutts A. 
Published: March 2019

AbstractThe principal aim of this article is to develop in a clear and orderly manner a general relationship and show how it can be used to determine with a high degree of precision lattice parameters of tetragonal and hexagonal as well as cubic crystals. The introduction and extensive use of electron-probe microanalyzers provides a ready-made means of obtaining both Kossel and divergent X-ray beam patterns which could previously be produced only with specially constructed X-ray tubes. The present ease of their production as well as the continuing need for precise lattice parameters for the study of many problems associated with crystallized solids has stimulated a renewed interest in these two techniques. As has been recently shown by several experimental results limited to cubic crystals, these techniques are capable of giving lattice parameters with the same degree of precision as those obtained by the more classical means. The development of the general relationship is preceded by a brief historical review, a discussion of the relative merits of the methods, a short description of the nature of the diffraction patterns, and the geometrical conditions necessary for realizing precision parameter measurements. In conclusion, the advantages and disadvantages of the Kossel and divergentbeam methods compared with those of the classical powder techniques are enumerated and discussed.
Measurement of Elastic Strains in Crystal Surfaces by X-Ray Diffraction Topography
Authors: Lawn Brian R. 
Published: March 2019

AbstractThe use of X-ray topographic techniques for studying elastic strains in crystals deformed at their surfaces is becoming widespread, especially in the field of silicon semiconductor devices. Although the broad features of the phenomenological processes involved in producing the strain patterns on the X-ray micrographs are understood, little attention has been devoted to evaluating the detailed nature or range of the strain fields in the crystal. In this paper, an clastic model is proposed for cases in which a region of crystal surface is uniformly deformed over a thin layer. With this model, the associated strain field in the surrounding crystal, which is readily computed from elasticity theory, may be characterized by a single parameter. The model is in accord with observed strain patterns on topographs of abraded diamond surfaces and silicon surfaces onto which a strip of metal film has been evaporated. From the spatial range of the diffraction contrast, an estimate of the parameter characterizing the strain field may be made.
Residual Stress and Shape Distortion in High-Strength Tool Steels
Authors: Gulbransen L. B. , Dhingra A. K. 
Published: March 2019

AbstractOne of the major problems that has plagued the tool and die maker for many years and more recently has come to the attention of the manufacturer of missiles and high-performance aircraft is the problem of shape distortion which occurs during heat treatment in the high-strength tool and die steels. Not only is shape distortion a problem in the heat treatment and use of these materials, but the origin of shape distortion has been a controversial issue among metallurgists for many years. The quantitative measurement of shape distortion on heat-treated steels is simply carried out hy machining standard shape samples, in this case, an L-shaped sample, and making a measurement of the variation after heat treatment from the 90° of the original 90° angle of the L. It is usually assumed that relief of residual stresses in heat-treated parts will occur by the shape changes which have been described above; however, it has been demonstrated that elastic residual stresses may still be present in heat-treated parts that have been tempered and theoretically should be stress free. By a very straightforward and simple application of the backreflection X-ray diffraction method for residual-stress determination, a very striking relationship has been demonstrated between the shape (angular) distortion of both A2 tool steel (air hardening) and O1 tool steel (oil hardening) and the residualstress pattern of these steels. Conversely, one could presumably utilize residualstress data at changes in cross section to estimate semiquantitatively the amount of shape distortion which occurs in rather complex parts.
Crystallite Orientation Analysis for Rolled Cubic Materials
Authors: Morris Peter R. , Heckler Alan J. 
Published: March 2019

AbstractRoe's method for deriving the crystallite orientation distribution in a series of generalized spherical harmonics is applied to the analysis of texture in rolled cubic materials. The augmented Jacobi polynomials, which are the basis of the generalized spherical harmonics, have been derived for cubic crystallographic symmetry and orthotopic physical symmetry through the sixteenth order. Truncation of the series expansions at the sixteenth order should permit treatment of textures having a maximum of 17 times random and a minimum angular width at half maximum of 34°. A numerical technique has been developed which permits approximate evaluation of the integral equations from a finite array of data points. The method is illustrated for commercial steels and is used to elucidate the primary recrystalization texture of a decarburized Fe-3%Si alloy.