bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lattice Constant and Crystallite Size of Condensed Gold Vapor
Authors: Karioris Frank G. , Woyci Jerome J. , Buckrey Richard R. 
Published: March 2019

AbstractGold wires were vaporized by the exploding-wire phenomenon using a 20 μF capacitor bank charged to voltages up to 14 kV. The resulting condensate, an aerosol or metallic smoke, was collected on membrane filters and subjected to X-ray analysis to determine lattice constant, crystallite size, and behavior with isothermal annealing. Wire explosions were conducted in au ambient atmosphere of ait or nitrogen at barometric pressure. It is estimated that the quench rate for this material is of the order of 108 deg/sec from the melting point although no substrate is involved and it is expected that any effects of epitaxial origin on the structure would be minimized.Before annealing, diffractograms showed broad peaks apparently shifted to the high-angle side. Line breadth may be attributed primarily to particle size broadening, since ft correlates well with size determined by electron microscopy, (β cos θ) is linear with θ, and [(β cos θ)/λ] is approximately constant for three radiations used. Crystallite size is of the order of 400 Å and is observed to decrease roughly with increasing voltage used for vaporization. The observed lattice decrement, approximately 0.2%, generally increases with voltage used for vaporization, and apparently correlates rather well with the inverse of sise as has been reported in some work on thin gold films. However, studies of colloidal gold particles do not show significant lattice shifts, although the particle size is less than 100 Å so that the decrements observed may be due to factors other than size alone. For this black, particulate material, some lattice decrement apparently persists even after protracted isothermal annealing below the melting point. Crystallite size increases with annealing but remains below about 1000 Å. Results suggest that the lattice decrements observed in condensed gold vapor are due to surface tension effects and the presence of vacancy aggregates.
The Application of the Electron Microprobe in the Analysis of Nuclear Fuel Meltdown Experiments*
Authors: Stachura S. J. , Cooper L. 
Published: March 2019

AbstractTransient (nuclear) heating experiments were conducted with uranium carbide fuel rods to study the failure characteristics of typical rod designs. Extremely unusual changes in microstructure were observed and the electron microprobe was employed to establish the disposition of materials resulting from the meltdown experiments. The probe results indicated substantial fuel-clad interactions and permitted the resolution of several uncertainties regarding the course of fuel rod failure and material redistribution. The electron microprobe represents a unique capability in the post-test analysis of such meltdown tests.
Characteristics of Flow Proportional Counters for X-Rays
Authors: Spielberg N. 
Published: March 2019

AbstractGas flow proportional counters for the detection of soft X-rays were introduced about ten years ago. These detectors offered the advantages of high sensitivity, good energy discrimination qualities and the ability to handle high counting rates. Since that time they have been used for ultra-soft and harder X-rays as well, both as detectors in standard spectrographic instruments and as energy discriminating instruments themselves in various so-called nondispersive applications. Depending upon the particular instrumental application, however, their use has led to considerable complication of the associated electronic circuitry in order to realize their advantages. For the most effective use of these counters (and of sealed proportional counters as well) it is necessary to have a clear understanding of the effect of various design parameters and operating conditions on their performance. The dependence of the shape of the pulse height distribution on the operating voltage, pressure and counting rate is described as a function of the energy of the radiation detected and the nature of the gas. Stability requirements on. counter tube high voltage supplies and operating pressure are discussed. Shifts of pulse height distributions toward smaller pulse sizes with increasing counting rate are described and the dependence of these shifts on the various parameters and on wavelength are discussed. Techniques for eliminating the shifts and the implications of these techniques for the associated electronics are described.
X-Ray Fluorescence Analysis of a Manganese Ore
Authors: Egan W. D. , Achey F. A. 
Published: March 2019

AbstractTo replace time-consuming chemical analysis, a procedure was developed for applying X-ray fluorescence to the analysis of a manganese ore. This X-ray fluorescence method is rapid; the total time for both sample preparation and analysis is ½ hr. The method is also simple enough for routine laboratory use. The components determined, the concentration ranges, and the agreement between chemical and X-ray analysis in terms of standard deviation are:The agreements between chemical and X-ray analysis noted for manganese and iron are obtained by correcting for CaO concentration when determining the manganese and for manganese and SiO2 concentrations when determining the iron. The corrections employ empirical equations developed by a multiple regression technique.Sample preparation is reduced to a minimum because it consists of only two steps, pulverization of the manganese ore followed by briquet ring. Four minutes of grinding with Boraxo as the grinding aid gives sufficient uniformity to minimize the effect of particle size variation. The ground mix of manganese ore and Boraxo is pressed into 1.25-in. briquettes for analysis.
Standard Reference Materials and Meaningful X-Ray Measurements
Authors: Thomas Yolken H. 
Published: March 2019

AbstractA review of the procedures and efforts at the National Bureau of Standards (NBS) to provide for meaningful measurements through the use of Standard Reference Materials (SRM's) is presented.The examples of NBS Standardization efforts for x-ray analysis range from basic metrology to applied environmental measurements. These examples include a determination of x-ray wavelength by a method which in part utilizes simultaneous x-ray and optical interferometry measurements of the atomic planes of near perfect silicon. In addition, Standard Reference Materials (SRM's) are being developed and applied to trace element analysis using x-ray fluorescence techniques. These efforts include development of SRM's for trace element analysis of air particulates. In another area, work is proceeding on the development of a silicon powder Standard Reference Material intended for x-ray diffractometer calibration. An effort to develop a suitable x-ray diffraction technique to determine the amount of quartz in mine dust is also underway. NBS efforts to provide SRM's for the calibration of electron microprobes and the validating of correction factor calculations are also described.
Standard Reference Materials - Their Production and Use
Authors: Gillieson A. H. 
Published: March 2019

AbstractThe purpose and the value of standard reference materials (S.R.M.) are defined, and their increasing world importance is emphasized. The desirable features of an S.R.M. are outlined and the procedures necessary to meet, as far as possible, the necessary requirements in S.R.M. production are discussed. The method and organization of certification for homogeneity and composition are detailed, as well as the statistical proceduces to evaluate the certification analysis. The present Status and future plans for the production of S.R.M.'s by the Canadian Standard Reference Materials Project, Mines, Branch, Department of Energy, Mines and Resources, are outlined.
Quantification of Sub-Microgram Elemental Concentrations Using Micro-Dot Samples
Authors: Mathiesen James M. 
Published: March 2019

AbstractThe following study describes the experimental results obtained by energy dispersive x-ray analysis on a series of representative samples, concentrated by precipitation, to spots 1.5 mm in diameter on Millipore (R) membranes.Using modified detector collimation, the contributions of air scatter and membrane (Substrate) scatter to the background under a peak, can be minimized to achieve limits of detection approaching a nanogram of the element present in the precipitate.The equipment used here is composed of an 80 mm2 Si(Li) detector connected to a computer based data handling unit. Excitation was achieved with a Rhodium target x-ray tube having a maximum output of 50 kV at 5.0 ma. Even with the high detection efficiency of the Si(Li) detector and the capability of minimizing the source to sample and sample to detector pauh lengths, it was found with these samples that at least 3.0 ma of tube current is needed in the excitation source.A mechanism has been developed for this work that allows reproducible sample positioning for standards and unknowns. This mechanism is used to produce element profiles on larger precipitated standards to measure radial uniformity.
A Rapid Direct X-Ray Fluorescence Method for Simultaneously Determining Brass Composition and Plating Weight for Brass-Plated-Steel Tire Cord Wires
Authors: Gianelos James 
Published: March 2019

AbstractA rapid direct x-ray fluorescence (XRF) method has been developed for simultaneously determining brass composition and plating weight for brass -plated-steel tire cord wires. On a manual XRF instrument, a complete analysis can be done in ten minutes including calculations. A complete analysis can be done in only two or three minutes on a multi-channel Quantometer-type instrument. The method can easily be adapted to “on line” use.Analysis is done directly on the “as received wires. Sample preparation is simple and non-critical with no surface pre-treatment of any kind required. Sample weighing and dissolution of the brass plating are entirely eliminated. Wire samples may be either stranded or unstranded. Rather large variations in sample size can be tolerated because of the ratio-type calculation system used. Analytical precision is high.Calibration curves were established by wet chemical, atomic absorption, and solution-XRF methods. No serious calibration problems were encountered because the plating is an alloy, or because count data were taken from round, non-flat samples. Low impurity levels of iron in the brass plating are shown to have an insignificant effect on the plating weight calibration curve.
X-Ray Emission from Laser-Produced Plasmas
Authors: Dozier C. M. , Burkhalter P. G. , Klein B. M. , Nagel D. J. , Whitlock R. R. 
Published: March 2019

AbstractIntense x-rays are emitted by plasmas formed when sub-nanosecond laser pulses are focused onto materials, Plasmas produced by pulses containing up to 100 J can re-emit over ten percent of the energy as x-rays above about 1.0 keV. These plasmas may be useful flash x-ray sources.
Some Biomedical Applications of Charged-Particle-Induced X-Ray Fluorescence Analysis
Authors: Campbell J. L. , Herman A. W. , McNelles L. A. , Orr B. H. , Willoughby R. A. 
Published: March 2019

AbstractX-ray fluorescence induced by charged particles has been employed in trace element analysis of both animal and human blood, tissue and bone samples. Preparation techniques included microtome slicing and wet digestion in nitric acid, internal chemical standards being used in the latter case.Most of the specimens arose from a study of interactions between the toxic elements lead and zinc in growing foals; this was motivated by reports of sickness and death in foals raised near lead-zinc smelters. The cause of toxicity in animals from environmental pollution is often attributed to Single factors, whereas in reality interactions among many factors, including a variety of toxic and nutrient trace elements, should be considered.A variety of spectra are presented and elemental concentrations derived. Agreement between the X-ray data and atomic absorption spectrophotometry is encouraging. The results demonstrate the potential of particle-excited X-ray fluorescenee as a broad-range analytical technique for the study of trace element interactions.
Auger Electron Emission Micrography and Microanalysis of Solid Surfaces
Authors: Hayakawa K. , Okano H. , Kawase S. , Yamamoto S. 
Published: March 2019

AbstractAn electron probe Auger emission microanalyzer has been constructed. The instrument is composed of an electromagnetic focussing primary probe column and a cylindrical mirror electron energy analyzer. By using this instrument, Auger electron spectroscopy studies have been carried out in the modes of both emission microanalysis and emission micrograph. The feasibility o£ this method is investigated through its application to the study of iron surface.
Close-Packed Ordered Alloys
Authors: Beck Paul A. 
Published: March 2019

AbstractSystematic procedures are used for generating the geometrically possible close-packed ordered layers for any desired binary “ideal composition” and the various geometrically possible stacking sequences with a given number of layers of known structure. The known ordered close-packed cyrstal structure types in AB3 and AB4 alloys are characterized by the structure of the layer and by the stacking sequence. Their occurrence is reviewed in relation to pertinent variables, such as electron concentration and atomic size.
A Study of Guinier-Preston Zone Growth Kinetics Through the Use of X-Ray Small-Angle Scattering*
Authors: Harkness Samuel D. , Gould Robert W. 
Published: March 2019

AbstractThe relation of the X-ray small-angle scattering parameters to the results of transmission electron microscopy for spherical Guinier-Preston zones was investigated. Experimentally, the Guinier radius is found to equal (<R7>/<R5>1/2) and the Porod radius to equal <R3>/<R2>. These results were theoretically predicted by Baur and Gerold, A log normal distribution was found to be in close agreement with the experimental data. The use of this distribution allowed the size-distribution curve of spherical Guinier-Preston zones to be constructed from the X-ray parameters and from a knowledge of the metastable miscibility gap. This approach is used to follow the evolution of size distribution in both Al-Ag and Al-Zn alloys. The application of this approach to nncleation and growth as well as redistribution processes is discussed. Growth paths are established from the size distribution evolution curves through an Nv> construction. A brief discussion of the technique is included.
Antiphase Domains in Long-Period Superlattices
Authors: Chaudhari P. , Gangulee A. 
Published: March 2019

AbstractThe antiphase boundary in a superlattice has been defined as the boundary between two neighboring zones which are out ofsphase with each other. This difference in phase is usually represented by a translation vector. In long-period superlattices, however, antiphase boundaries of the above mentioned type occur with regular spacings, thereby introducing another element of order which shows up as satellite peaks in the diffraction pattern. A second kind of antiphase boundaries may be defined in a one-dimensional long-period superlattice as the boundary between two neighboring zones which have different directions of repetition of the antiphase boundaries of the first kind. A theory of X-ray diffraction to obtain the size of the domains of the second kind in a one-dimensional long-period superlattice has been developed. An application of this theory to the ordered alloy Ag3Mg, known to have a one-dimensional long-period superlattice, is described and the results of the X-ray measurements are compared with those obtained by transmission electron microscopy.
A High-Precision Kossel Camera for Research and Routine Analytical Use
Authors: Reichard T. E. 
Published: March 2019

AbstractA transmission Kossel camera unit has been built for the Cambridge Mark II electron probe. It replaces the standard specimen stage assembly, and is useful also for regular electron probe microanalysis and projection microradiography.Its design extends the attainable precision of lattice parameter measurements to near-ultimate practical limits, while providing special features for research studies, and speed, flexibility, and convenience of operation for routine analytical use on a wide variety of specimens, particularly semiconductor materials.The most significant feature is a novel X-ray projection box structure which casts index-mark images on each pattern. From these images, the exact source distance and pattern-center positions are determined for each exposure. Precise crystal-piane spacings can be measured, therefore, from conic intersections anywhere on the exposed area of the plate. Since the conics need not be in any particular favorable location, it is not necessary to achieve an exact orientation of the sample. Precise lattice dimensions in several different crystallographic directions are obtainable from a single pattern exposure if their various sensitive conics appear anywhere on the pattern. The need for a reference measurement of “fixed” conics is eliminated, being replaced by a much more precise measurement of very sharp, high contrast, widely spaced index-mark images.Camera length is 12.5 cm and exposed pattern area is 9.4 cm square. Glass photo plates are used to eliminate errors due to film shrinkage and warp. A removable cassette holds ten 4″×5″ glass plates, interchangeableiunder vacuum. The X-ray shutter has ten positions for making exposure-time sequences. The specimen stage is thermostatted to ±0.01° C, controllable from room temperature up to 200° C, and;temperature is measured to +0.005° C. Stage movement range is 25mmx50mn, with coordinates shown on external digital dials. Interchangeable inserts provide for a wide range of specimen sizes and shapes. Electrical contacts to the specimen are available.An externally adjustable plate holds 24 different target foils or target-filter combinations for pseudo-Kossel patterns. An open position provides for true Kossel work and for scatteredelectron image viewing.
X-Ray Diffraction Study of the Effects of Uniaxial Plastic Deformation on Residual Stress Measurements
Authors: Esquivel A. L. 
Published: March 2019

AbstractUniaxial Plastic Deformation (UPD) has been known to produce anomalies in residual stress measurements based on x-ray diffraction techniques. This study was undertaken to determine the magnitude of the effects, if any, on residual stress calculations from various materials subjected to UPD. An x-ray diffraction study using the two-exposure method ( ψ = 0° and ψ = U5°) was made on several iron, aluminum, and titanium alloys (AISI 4340, 4330M, 4130; 2024-13, 7075-T611; Ti-6Al-4V) before and after these alloys were deformed plastically by bending on a U-bend test fixture. The x-ray peak shifts, Δ2θ0-ψ, were recorded and the x-ray stress factors, Ki, calculated by three different methods. The results indicate that UPD of the calibration specimens will increase or decrease Ki depending on the alloy. These results are discussed together with observations on the additivity of residual and applied stresses, and the per cent differences in the stress measurements based on stress factors calculated by three different methods.
Role of Residual Stresses as Determined by X-Ray Diffractometry on Magnetic Properties of 4-79 Molybdenum Permalloys
Authors: Bhattacharyya A. , Darling H. E. 
Published: March 2019

AbstractResidual stresses in several batches of heat-treated 4-79 molybdenum Permalloy finished laminations were measured by X-ray diffraction technique. This involved determination of macrostresses from line shift of (331) reflection by the two-exposure diffractometric technique as well as the determination of microstresses from half breadth of the same line profile. It was observed that the residual stresses In all batches of laminations were small and the variations in residual stresses from one batch of laminations to another were not appreciable, considering the scatter in laminations within each individual batch. Simultaneous magnetic measurements showed considerable variation in magnetic properties from batch to batch; e.g., a five-fold variation in normalized hysteresis loop and a two-fold variation in the magnetic “softness” parameter. On subjecting individual batches of laminations to various thermal and thermomagnetic treatments below 650 C, considerable change in magnetic properties was achieved without significantly changing residual stresses. The variation in magnetic properties in finished laminations was ascribed to the difference in effective crystal anisotropy and uniaxial anisotropy caused by variations in thermal and thermomagnetic annealing treatments. The study showed that the variation was not due to any major variation in stress induced magnetostrietive anisotropy.
X-Ray Studies of Plastically Deformed Silver Alloys - Effects Due to Oxygen, Hydrogen, and Tin Solutes*
Authors: Newton C. J. , Ruff A. W. 
Published: March 2019

AbstractSolid specimens of silver were charged at different temperatures in atmospheres of oxygen and of hydrogen. X-ray diffraction line profiles were obtained using powders filed from the treated specimens. Fourier analysis of the diffraction lines was conducted following the method of Warren. The effective particle sizes and root-mean-square strains were obtained from the line shape analysis. Stacking fault and twin fault probabilities were determined from peak-position and center-of gravity displacements, respectively. For the purpose of comparison, two vacuum-melted silver samples and two different silver-tin alloys were studied. The stacking fault and twin fault probabilities were observed to be nearly unaffected by charging in either oxygen or hydrogen. These results are consistent with recent direct determinations of the effect of oxygen on the stacking fault energy of silver. In contrast, the rms strains and particle sizes changed significantly after charging in oxygen. A decrease in the root-mean-square strain and a corresponding increase in the particle size was found. These effects were opposite to those obtained by adding substitutional solute to silver. These findings are interpreted to indicate the effect of oxygen clustered with impurities on the dislocations and stacking faults in silver.
Precise Cell Parameters of Semiconductor Crystals and their Applications
Authors: Pierron E. D. , McNeely J. B. 
Published: March 2019

AbstractA precise method for detenaining unit cell dimensions of semiconductor single crystals has been developed. An accuracy of ± 0.00002 Å and a precision of ± 0.00001 Å is achieved.The method is used to determine variations in the cell parameter of GaAs as a function of surface defects, homogeneity across and along an ingot, evaluation of epitaxial layers, effects of heat treatments and structure defects induced by oxide diffusion masks on a substrate. The application of the technique to GaAsP alloys permit accurate and rapid study of sample composition and homogeneity.