bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Technique for Quantitative SiO2 Determinations of Silicate Materials by X-Ray Diffraction Analysis of Glass
Authors: Nash Douglas B. 
Published: March 2019

AbstractResults of an experimental X-ray study on 96 synthetic glasses show that the 2θ positions of glass diffraction maxima have an inverse relation to SiO2 concentration in silicate glasses. This relationship is the basis of a new technique for semiquantitative determinations of SiOa in silicate materials by X-ray diffraction methods. Samples to be examined are fused and the resulting glass scanned from 12 to 40° 2θ using CiiKa radiation. The mean 2θ position of the diffraction maximum is a measure of the SiOs content of the glass. Calibration curves for both weight and molecular percent SiO2 vs. 2θ are presented in this report. The technique requires only small, unweighed amounts of sample for analysis ; it is simple, rapid, and utilizes standard diffraction equipment without modification. Its accuracy, at present, allows SiOa determinations to within ±1 to 4% of the actual concentration.
A Study of Copper-Chromium Oxide Catalysts and a Method to Determine Catalytic Activities
Authors: Stammler M. , Pyzyna M. 
Published: March 2019

AbstractAn extensive investigation of chemical composition, particle size, and surface area of copper-chromium oxide catalysts has been made. The two phases present in the activated material are copper oxide (CuO) and copper-chromium spinel (CuCr2O4). The crystallite size of the CuO phase (determined by X-ray diffraction line broadening) can be correlated with the catalytic activity measured on a CO-CO2 oxidation reaction. The catalytic activity of the oxide catalyst can be expressed as a function of the X-ray fluorescence intensity of the Cu Kα line even on changing the absolute copper concentration up to 3%. An attempt is made to explain this phenomenon by the heterogeneity effect caused by the difference in the linear absorption factors for the Cu Kα radiation in the system CuO-CuCr2O4.
The Design and Use of Special-Purpose Attachments for the Horizontal Diffractometer
Authors: Baun William L. , Renton John J. 
Published: March 2019

AbstractSeveral special-purpose attachments have been designed and built for the Siemens horizontal diffractometer. Design details and experimental results are shown for the following equipment: (1) Low-temperature mount for poly crystalline materials—examples are shown illustrating identification of organic liquids crystallized at low temperatures, and results are presented on coefficient of thermal expansion of alloys in the binary system copper—platinum from −185 to 25°C. (2) Low-temperature mount for single-crystal studies—this design allows recording of higher-level layer lines by use of a domed beryllium window. Illustrations are shown for organic single crystals and for organic liquids crystallized in the lowtemperature mount. (3) Focusing attachment—this attachment uses a curved specimen mounted on the focusing circle (Seeman-Bohlin mounting). Comparisons of dispersion are made and examples such as the (400) reflection from molybdenum are shown using both curved and flat specimens. (4) Full-circle goniometer—this device has been used primarily for determining distribution of intensity in amorphous and semicrystalline polymers, but is applicable to study of single crystals. Examples of both of these applications are discussed.
A Single-Crystal Orienter for the Philips Wide-Range Goniometer
Authors: Miller D. P. 
Published: March 2019

AbstractA single-crystal orienter for the Philips -wide-range goniometer is described. The orienter has a large (3.562 in.) carriage radius for convenient access. The carriage rides on twin V-ways ground accurate to ±0.0002 in. Carriage settings arid spindje settings can be made to 1′. The spindle mounts a standard goniometer head and translates to center the head arcs. An accessory collimator, beam trap, and scatter tube are described.
Limitations of the Linear Intensity-Concentration Approximation in Electron Probe Microanalysis
Authors: Brown James D. 
Published: March 2019

AbstractIn interpreting X-ray intensity data from electron probe microanalyzers, the simplest approximation that can be made is that the X-ray intensity is a linear function of concentration. This linear relationship has been found to hold only in very limited cases. Where this simple relationship does not hold, it is generally assumed that increased concentration of an element is reflected in increased intensity of its characteristic X-ray lines. This assumption, which is always valid for binary samples, has been extremely useful, particularly for the interpretation of X-ray scanning pictures. However, in analyses based solely on observed X-ray intensities, large deviations from the linear relationship can make semiquantitative results misleading.For multielement systems, the deviations from linearity result in ranges of concentration for each element within which increased concentration of the element does not result in an increase of its characteristic X-ray intensity. The magnitude of these deviations, and. hence the ranges of concentration, is related to the X-ray absorption and secondary fluorescence in the sample, which are in turn dependent on instrumental parameters such as X-ray take-off angle. Such inversions in the normal intensity-concentration relationship can result in gross misinterpretation of X-ray scanning pictures on even a qualitative basis. The various factors that lead to deviations from linearity are evaluated, and methods are given for correctly interpreting X-ray intensity data on a qualitative and semiquantitative basis.
The Applicability of Theoretically Calculated Intensity Corrections to Practical Metallurgical Problems in the Electron Probe
Authors: Moll Sheldon H. 
Published: March 2019

AbstractRecent studies have indicated only limited agreement between theoretically calculated X-ray absorption, fluorescence, and electron penetration correction factors and calibration curves obtained from alloy standards in binary systems. For some practical metallurgical problems, including diffusion gradient studies, intermediate phase identifications, etc., where analytical precision is required, alloy standards must be employed.Most metallurgical investigations, however, are concerned with alloys containing a variety of elements. The use of theoretical calculations in these analyses is severely limited. At present, the precision of analyzed chemistries in such systems is somewhat poorer than the precision of the measured X-ray intensity values. Methods for applying combinations of theoretically calculated corrections, extrapolations from nominal alloy chemistries, etc. have been employed which yield reasonable analytical precisions but at best are first-order approximations. Approximate calculations for use in determining the chemistries of fine precipitates or inclusions where matrix excitation is unavoidable are also discussed.
Standards in Electron Probe Analysis of Minerals*
Authors: Adler Isidore 
Published: March 2019

AbstractThe application of electron probe analysis to complex mineral systems has pointed out the great need for suitable standards. It is often difficult to obtain highly accurate analytical results on these complex systems using pure end members because of the large number of correction factors involved, particularly since some of these factors are not well known.The requirements for electron probe standards are rather stringent. They must be well analyzed chemically, and be homogeneous on the micron level so that the small volume sampled by the probe is representative of bulk analysis. Unfortunately minerals suitable for standards are difficult to obtain. Minerals may appear to be single phases, but a careful microscopic examination will disclose that there are in fact two or more phases closely intergrown, so that the probe is not actually sampling a single phase. There are instances where the knowledge of homogeneity of the standards can only be obtained by an analytical tool like the electron probe. It is for reasons such as these that caution must be used in the selection of mineral standards. Because of the increasing use of the probe for mineral studies it has become desirable to establish a clearing house for well established standards and a comprehensive exchange program.
X-Ray Spectrographic Analysis of the 3-d Transition Metal Corrosion Products Using Potassium Bromide Disks*
Authors: Schluter L. A. 
Published: March 2019

AbstractA technique has been developed for quantitative analysis of the major constituents in small samples (less than 0.1 g) of corrosion products found On various missile parts. The technique was developed primarily to aid in interpretation of X-ray diffraction patterns of multicomponent corrosion products. The corrosion sample is mixed with KBr and the mixture is pressed into a disk in the same fashion commonly used in infrared work. The Br Kβ1 line serves as an internal standard. Intensities of the element's Kα line and the internal standard are established by scanning through the appropriate Bragg angle and recording peak heights on a strip-chart recorder. A xenon-filled proportional detector and a pulse-height analyzer were used.The percent of an element is determined by references to calibration curves which relate intensity ratios to weight ratios for the 3-d transition metals. The oxides of the metals were used in the preparation of the calibration curves. The weight ratio vs. intensity ratio relationship is linear over the weight ratio range 0.01 to 0.11. Data were collected using an air path and a helium path; the higher intensity ratios obtained with, the helium path, and the dependence of intensity on atomic number are illustrated. A comparison is made between the intensity ratios in a KBr matrix and in a NaBr matrix. The technique developed requires about 15 min sample preparation time.
X-Ray Fluorescence Analysis of Niobate-Tantalate Ore Concentrates
Authors: Rose Harry J. , Brown Robena 
Published: March 2019

AbstractAn X-ray fluorescence method is described for the analysis of niobotamalate concentrates, bringing speed and accuracy to determinations that are difficult chemically. Many of the problems inherent in the X-ray fluorescence analysis of powdered samples are eliminated by fusion of the sample in a mixture of Li2B4O7 and La2O3. Absolute amounts can be determined without reliance on chemically analyzed standard concentrates. Standards in a wide range of concentrations are readily prepared from pure chemicals. La2O3 plays a dual role, aiding in the fusion of highly refractory oxides and minimizing absorption differences between samples. In addition to niobium and tantalum, elements commonly present in niobate-tantalate ore concentrates, such as titanium, iron, tin, and manganese, are readily determined.The fusion mixture consists of 80 mg of sample, 120 mg of La2O3 and 800 mg of Li2B4O7. The fusion is made in graphite crucibles at 1100°C for 15 min. The cooled bead is ground in a mixer-grinder and pressed into a pellet. X-ray fluorescence measurements yield linear calibration curves for each of the elements over a wide range of concentration.
Improved Trace Analysis with the Use of Synchronized Electronic Discrimination in an X-Ray Scanning Procedure
Authors: Salmon Merlyn L. 
Published: March 2019

AbstractThe use of electronic discrimination at a fixed goniometer position for an X-ray spectrographic determination is a conventional means of improving the signal-tonoise ratio and minimizing interferences due to multiple-order diffractions of radiation with shorter wavelengths. The same advantage can be gained with a moving goniometer in a scanning procedure if adjustment of the baseline of the electronic discriminator is properly coordinated with the movement of the goniometer. Å study of optimum baseline levels for various wavelengths in the range of 0.3 to 3.0 Å indicated a hyperbolical correlation of optimum baseline voltage vs. 2θ angle. This experimental correlation is the basis for synchronization of electronic discrimination with movement of the goniometer during the scanning procedure. A suitable mechanism for coordinated baseline adjustment was developed by Technical Equipment Corporation, Denver, Colorado, and improved results are obtained for trace analysis with a scanning technique routinely used for qualitative, semiquantitative determinations for elements with atomic numbers 22 and higher.
The Study of Electrical Contact Surfaces with an Electron Probe Microanalyzer
Authors: Schreiber H. 
Published: March 2019

AbstractThe field of electron probe microanalysis has rapidly spread from metallurgy, geology, and biology to many allied fields. It is the purpose of this discussion to cover an application that has not received much attention—namely, the study of relay contact surfaces with this technique.In this case, many of the problems encountered are somewhat different, but the ultimate results are quite gratifying. Sample preparation is greatly simplified inasmuch as the surface condition is of prime interest and absolutely no preparation is a prerequisite. Unfortunately, this does lead to some problems of sample mounting and makes the interpretation of results more difficult. Examples are given of the types of information that can be obtained on the substrate materials as well as the finished plated contacts.
The Effect of Valence and Coordination on K Series Diagram and Nondiagram Lines of Magnesium, Aluminum, and Silicon*
Authors: Baun William L. , Fischer David W. 
Published: March 2019

AbstractWavelengths and intensities are reported for the K series of magnesium, aluminum, and silicon, using primary excitation. Included in the tabulation for magnesium and aluminum are the diagram lines α1α2 and β and the nondiagram lines α', α3, α4, α5, and α6. Data are given for the Si K spectral lines α1α2, β, α3, and α4, Spectra are shown and line positions and intensities are detailed using both metal and oxide as the X-ray source. Significant differences are seen between metal and oxide spectra especially in wavelength and shape of Kβ, and large changes are noted in the intensities of some satellite lines. Spectra from a number of aluminum intermetallic compounds are discussed, including line positions, satellite line ratios, and line shape. It is shown that the spectra fall into three predictable groups; good conductors; poorer conductors; and semiconductors and insulators. Structurally similar compounds give similar spectra. For instance, line positions, shapes, and intensities are nearly identical for NbAl3 and TaAl3. It is not possible to correlate spectra with aluminum coordination number, and previous work using Kα, where secondary excitation was used, could not be reproduced using primary excitation. Possible reasons for this disagreement are discussed.
A Lunar X-Ray Diffraction Experiment
Authors: Speed Robert C. , Nash Douglas B. , Nickle Neil L. 
Published: March 2019

AbstractAn X-ray diffraction system is under development for remote analysis of lunar rocks from an unmanned, soft-landed spacecraft. The objective of this experiment is the identification of rock-forming phases and estimation of their abundances, compositions, and other data which are indicative of the nature of genetic processes on the moon. A 2:1 scanning parafocusing geometry was successfully miniaturized for this purpose by W. Pavrish, and a complete diffraction system, based on the design is in preparation. The diffract ometer including high-voltage power supply weighs 18 lb, occupies 0.9 ft3, and requires 56 W of continuous power. A sample acquisition and preparation system will be an integral part of the diffractometer. Diffraction analyses of a rhyolite, basalt, and chondritic meteorite are given as examples of the capabilities and limitations of rock analysis by this method.
The Crystalline Perfection of Melt-Grown GaAs Substrates and Ga(As, P)
Epitaxial Deposits
Authors: Howard J. K. , Cox R. H. 
Published: March 2019

AbstractThe preparation of semiconductor materials by epitaxial deposition has rapidly gained prominence in recent years. GaAs(1-x)Px alloys of variable composition, deposited on GaAs substrates, have been prepared in an open-tube reactor using H2, AsCl3, and PCl3 with GaAs source material, The deposits ranged in composition from GaAs to GaAs0.5P0.5 and were 10-30 microns thick.X-ray diffraction topography was employed to evaluate the structural perfection of the monocrystalline GaAs substrates and the perfection of the deposited Ga(As, P) films. A scanning-reflection technique was developed to study the concentration, type, and spatial distribution of imperfections over large areas (∼8 cm2) to depths of 25 microns. Some areas of investigation included (1) the poly cry stallinity of some deposits, (2) the effect of substrate perfection on the film quality, (3) the depth of mechanically induced damage, and (4) the structural perfection of magnesium-diffused GaAs and Ga(As, P).
The Application of Cylindrical Geometry for the Determination of Crystal Orientation
Authors: Forest Robert D. , Barton Richard J. , Schieltz N. C. 
Published: March 2019

AbstractA procedure for conveniently determining the orientation of noncubic crystals is presented. The methods usually employed for cubic crystals, flat-film backreflection Laue patterns interpreted with the aid of a table of interplanar angles, is not readily adaptable to noncubics. In general, tables of interplanar angles for noncubics do not exist and if the effort is expended to generate them, such a vast array of angles result that they are virtually impossible to use. It is thus necessary to use the symmetry of the pattern to identify the low-index planes. However, on flat-film geometry, due to the small angular range of the data, insufficient low-index points are present to permit orientation.In order to alleviate this problem we have developed the necessary techniques for the interpretation of back-reflection Laue patterns employing cylindrical-film geometry. The necessary overlays and their use are presented along with some of the results obtained.
Substructure Measurements by Statistical Fluctuations in X-Ray Diffraction Intensity
Authors: Sturcken E. F. , Gettys W. E. , Bohn E. M. 
Published: March 2019

AbstractThe substructures of a bet a-quenched and a recrystallized form of high-purity uranium were measured by a method based on statistical fluctuations in X-ray diffraction intensity. For these measurements, Warren's statistical equation for determining grain size was modified to make the equation applicable to materials with high absorption coefficients or moderate-to-large grain size ( > 20 microns) or both, since many metals fall into this category, and to allow for defocusing of the X-ray beam which occurs as a natural consequence of the experiment.The beta-quenched uranium was found to have numerous subgrains with a range of misorientation angles that was smaller and larger than the limits of the X-ray measurements (Ω = 10−4 to 10−2 steradians). The presence of the large subgrains was corroborated by optical microscopy. The presence of very small subgrains was corroborated by transmission electron microscopy which showed 0.1- to 1-micron subgrains relatively free of dislocations bounded by dense dislocation networks, and by micro Laue diffraction patterns (30-micron beam diameter) which showed partial rings similar to a powder pattern.The recrystallized uranium had no misorientation within the grains greater than 5.5 × 10−3 steradians. In contrast to the beta-quenched case, no subgrains were found either by transmission electron microscopy (TEM) or micro Laue diffraction patterns. The TEM micrographs showed a uniform distribution of dislocation networks. Since no other substructural elements were observed, the dislocations are believed to be the cause of the misorientation within the grains for solid angles of less than 5 × 10−3 steradiflns.These preliminary experiments show that the statistical method may be used in conjunction with transmission electron microscopy and micro Laue diffraction for the study of substructure. The statistical method gives quantitative data on “bulk” specimens that can be given a meaningful interpretation with the aid of the other techniques.
Generation of a Two-Dimensional Silicon Carbide Lattice*
Authors: Prickett R. L. , Hough R. L. 
Published: March 2019

AbstractSilicon carbide vvas generated by pyrolysis of gas mixtures consisting of silicon tetrachloride, hydrogen, and organic vapors, such as acetone, on fine tungsten wires resistance-heated at 1500°C. Prominent two-dimensional structure was demonstrated for the 220 reflection. All other lines were of the normal threedimensional lattice type.Elevation of less than 100° in the pyrolysis temperature eliminated the twodimensional reflection, and simultaneously changed the visible crystallite size.Specialized techniques were used td generate the silicon carbide deposits and also to examine the structure of these deposits by X-ray diffraction to obtain lines from only the silicon carbide while ignoring the tungsten wire core. Diffraction techniques include offset collimation and vertical integration.
A Method for Trace Analysis with an Electron Microprobe
Authors: Fergason L. A. 
Published: March 2019

AbstractA “chopped beam” system of analysis has been devised for a scanning electron microprobe equipped with a 400-channel analyzer. The system has been programed with circuitry which places a signal onto the X or Y scanning coils of the probe, so that the beam jumps back and forth between two analytical areas. The same signal is used to activate alternate halves or quadrants on the 400-channel analyzer in a synchronous manner. The analyzer accumulates X-ray intensity data in the appropriate halves and quadrants as the electron beam oscillates between sample and standard or, in the case of trace analysis, between the unknown and the pure major constituent for background correction. The probe may be left unattended while it is gathering information in this manner. The dwell time of the probe on a given analytical area is 6 sec “live” time.Errors due to instrumental drift and sample contamination are nullified or minimized by this technique. Consequently, theoretical precision is closely approached for extended counting times. 100 ppm levels of aluminum, silicon, nickel, and iron in uranium have been determined to precisions as good as ± 10 ppm at the 95% confidence level.
Electron Probe Microanalysis of Zinc-Bearing Hexagonal Ferrites
Authors: Shappirio J. R. 
Published: March 2019

AbstractThe electron probe is shown to be an effective tool for the analysis of the series of ferrimagnetic oxides referred to as the hexagonal ferrites. This series of compounds) containing barium, Fe3+, and a divalent metal cation, is formed by an ordered stacking of basic structural units in varying ratios. The ideal, complex stoichiornewy of these polytype-like mixed-layer structures can be computed from X-ray unit cell data; the various structures and their predicted stoichiometry are reviewed. Results of electron probe analysis of zinc-bearing single-crystal hexagonal ferrites are compared with theoretical values, the various correction procedures applied to the probe data are presented, and the limitations of the method in the analysis of hexagonal ferrites are discussed. The information obtained from this study has laid the groundwork for the determination of chemistry in substituted members of the hexagonal ferrite group, and will contribute significantly to the interpretation of the magnetic properties exhibited by these compounds.