bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Printout X-Ray Pole Figures from Digital Computers
Authors: Chao Hung-Chi 
Published: March 2019

AbstractThe texture of sheet metal Is best described, by means of pole figures, which are very expensive and time-consuming to prepare. About 8 to 12 hours of effort by a specially trained, and. highly skilled technician are needed to prepare each pole figure. Accordingly, pole figures are not used as extensively in research studies as they would, be if they could be obtained more easily.A method has been developed for automatically producing pole figures by printing results directly from a digital computer. This method does not require the use of additional plotting attachments and, is therefore less expensive and time consuming than other methods. With this method, any laboratory with access to a digital computer can produce pole figures automatically.X-ray diffraction intensities are recorded on punched tape or on punched cards and are fed into the digital computer. A computer program corrects X-ray data obtained, by either transmission or reflection X-ray techniques, maps the stereographic projection, and prints pole figures directly. The time required, to prepare an accurate pole figure is reduced from 8 to 12 hours to 20 minutes or less depending on the type of digital computer used.
A Computer-Controlled X-Ray Diffractometer for Texture Studies of Polycrystalline Materials
Authors: Desper C. Richard 
Published: March 2019

AbstractThe Picker Four-Angle Computer System (FACS-1), a computercontrolled x-ray diffractometer originally designed for single crystal studies, has been adapted for use with polycrystalline samples. The system is controlled by a PDP-8S, a small time-sharing computer with teletype input and output. Programs have been written to take advantage of the high degree of flexibility inherent in online computer control. Four basic operations are possible: (a) simple 2θ step-scanning with variable step width; (b) 2θ stepscanning with randomization of orientation; (c) determination of Legendre expansion coefficients for oriented specimens; and (d) determination of pole figures. In operation (a), data is gathered at a series of 2θ values at a prefixed count and/or time. In (b), the sample is rotated to average out orientation, giving the “randomized” intensity (2θ) at various 2θ values. The on-line computer reads the scaler and timer every two degrees of x rotation and forms the appropriate integrals for calculating (2θ) as the sample rotates. Operation (c) is an extension of (b): not only is (2θ) determined, but also various moments of the orientation distribution of the form , where Pn is the nth order Legendre polynomial. Operation (d) may be used to measure pole figures of sheet specimens in reflection or transmission, or of fibers or small particles. Optional modes of operation allow for (a) use of the Ross “balanced filter” technique; (b) integration across diffraction peaks by continuous scanning in 2θ, with background correction; and (c) application of absorption corrections.
Measurement of Thin Oxide Surface Film Thicknesses and Atomic Densities by the Analysis of Positive Ion Excited Soft X-Ray Spectral
Authors: Saylor W. P. , Marks C. L. 
Published: March 2019

AbstractCharacteristic soft x-ray emission lines created as a result of low energy (10-100keV) positive ion excitation of a target material has been applied to the study of thin films of oxygen that form naturally on metal surfaces. The specific metals investigated were aluminum and nickel aa well as a number of their corresponding alloys.Low energy positive ions are well suited as projectiles for the study of thin films in that they have low penetrating powers, yet produce high x-ray yields for K-, L-, and M-shell elemental x-ray lines. Perhaps the most important feature is the fact that no background bremsstrahlung continuum x-radiation is generated in the slowing processes of the ions. Exploiting the advantages of these facts, a special high sensitivity detection technique has been developed for the soft x-ray analysis of the constituents that make up a particular thin surface film.The physical basis for thickness and atomic density measurements of thin surface films by positive ion excitation are discussed. Calibration data are presented for thin films of known thickness and composition establishing the sensitivity of the method for the measurement of the elemental atomic densities of thin films down to a few monolayers or approximately 10 Å in thickness. Finally, the results of the analysis of oxide surface films of aluminum, nickel and some of their alloys are presented and discussed.The objective of this continuing program is to gain an understanding of the mechanisms and principles governing the formation of oxide surface films on metals with the basic goal of producing new alloying techniques for metal passification in a saline environment.
Solid Solutions of Cadium Sulfide-Cadium Selenide Films: Preparation and Determination by X-Ray Flourescence Method*
Authors: Chan Frank L. , Carpenter James T. 
Published: March 2019

AbstractSolid solutions of cadmium sulf ide and cadmium selenide prepared by several methods at temperature in excess of 1000°C in inert atmosphere are described. The compositions of these solid solutions varied widely, ranging from pure cadmium sulfide to pure cadmium selenide.Films of solid solutions have been successfully prepared by the vacuum deposition on various substrates using a procedure previously reported. Conditions for the depositions have been investigated to prevent noticeable alteration of the composition of the solid solution dur ing vacuum deposit ion. Films of various thicknesses have been prepared to date.Determination of film thicknesses have been carried out by the fluorescence method based on the elements existing in these solid solutions. Chemical analysis in which specimens were consumed have also been used primarily for the construction of calibration curves. X-ray fluorescence intensity versus film thickness are established for films of 0, 25, 50, 77, and 100 percent by weight of cadmium selenide up to 10.00 microns thick on aluminum substrates. Thickness determinations using selenium Kαand cadmium Kαspectra give accuracies of 0.200 ± 0.05 to 10.00 ± 0.40 microns depending on film thickness and composition. Correction factors are given for films on substrates other than aluminum.Procedures have been established for the determinat ion of both composition and film thickness based on fluorescence intensity data. There is a relationship between the fluorescence intensity and appearance when deposited films are not of the same thickness. Correlation of these phenomena will be demonstrated.
Some Applications of Energy Dispersive X-Ray Fluorescence Analysis in Minerals Exploration, Mining and Process Control
Authors: Clayton C.G. , Packer T.W. 
Published: March 2019

Energy dispersive X-ray fluorescence (EDXRF) analysis is finding increasing application in field assay of soils and stream sediments for geochemical prospecting; in borehole logging and core analysis for formation evaluation in mine control, and in on stream analysis for process control.The analytical capability of the method is determined by the choice of source, the energy of the exciting radiation and the energy resolution of the detector. The nature of the samples, their atomic number and concentration are also important. However, the most dominant constraints on limits of detection are often imposed by the environment at the region of measurement: by the borehole condition, the nature of the rock face or the form of the particulates and stability of the fluid in a process stream.
The Fitting of Powder Diffraction Profiles to Ananalytical Express Ion and the Influence of Line Broadening Factors
Authors: Brown Allan , Edmonds J. W. 
Published: March 2019

AbstractPowder diffraction profiles of well crystallized compounds can be fitted to distributions of the type Iθ=I°(1 + k2x2)-n where k is a scale factor related to the half width of the profile. The value of n varies with the diffraction angle, 2θ, and is generally different for the low-angle and high-angle sides of the same profile. Limiting values of n for a specific Guinier camera-micro-densitometer combination are 1.2 ≤ n ≤ 2.3. Similar values are obtained for diffracto meter profiles after Ktt2 stripping. Line broadening due to departure from perfect crystallinity in the specimen affects the value of n a swell as that of k.The above observations are interpreted interms of the convolution of a Gaussian with a Lorentzian distribution, the exponent n of the convolute being dependent upon the relative half widths of these two functions, expressed as the ratio bL/bG.
A Pinhole Camera for Photographing X-Rays from Laser-Produced Plasmas*
Authors: Hohlfelder J. J. , Palmer M. A. 
Published: March 2019

AbstractA pinhole camera has been used to record low-energy x rays produced from CD2 microsphere irradiation with Sandia Laboratories four-beam, pulsed laser system. Camera useful energy range, spatial resolution, and x-ray energy sensitivity are discussed. Camera x-ray energy sensitivity which was determined by laboratory calibration is compared with measurements obtained with a multi-channel x-ray spectrometer. X-ray photographs of laser-irradiated microspheres are presented. Spatial information about the x-ray source derived from these photographs is discussed.
Low Energy X-Ray Microradioghaphy of Laser Fusion Targets
Authors: Prevender T. S. , Lynch A. W. 
Published: March 2019

AbstractA low energy x-ray radiography apparatus has been developed primarily for the nondestructive inspection of LiD laser fusion targets. Exposure times of 15 minutes at 6 keV have been found satisfactory for the detection of voids in nominal 100 micron diameter spheres.
Math Model Design for X-Ray Analysis of Iron Base Alloys
Authors: Dryer H. T. , Appelman T. A. 
Published: March 2019

AbstractAn analytical system has been defined and developed which provides the x-ray analysis of iron base alloys (metal samples) corrected for an absorption, secondary fluorescence and interference effects. The analytical system provides for the transfer of analytical data and curves from basic or reference instrument to each new installation. One of the specifications for this system is the stringent accuracy requirements of the production analytical laboratory. Two major advantages of this system are:(1)The reduction of operator error because no decision is required for alloy identification,(2)A minimum of time required for new instrument calibration by the use of the analytical transfer procedure.
Measurement of Anisotropic Compressibilities by a Single Crystal Diffractometer Method*
Authors: Mauer F. A. , Hubbard C. R. , Piermarini G. J. , Block S. 
Published: March 2019

AbstractThe beryllium diamond-anvil pressure cell described by Weir, Piermarini and Block has been mounted on a Bond diffractometer equipped with an orienter of the fixed-x type. Molybdenum radiation is used to penetrate the diamonds and beryllium of which the cell is constructed, and special techniques are required to retain adequate precision in measuring cell parameters using diffraction angles in the low 2θ range. The method described provides high sensitivity in determining peak positions and eliminates the effect of centering errors on measured values of 2θ. Under favorable conditions, diffraction angles are measured with an accuracy of ±0.001° in 2θ. The method has been tested by measuring the lattice parameter of vacuum float zone refined silicon. Measurements of the compressibilities of silicon and of α-Pb(N3)2 (orthorhombic) have been carried out using the method of Barnett, Block, and Piermarini to determine pressure by measuring the shift in the R-line fluorescence spectrum of ruby.
The Pseudo-Kossel Technique in Back Reflection as a Tool for Measuring Strains
Authors: Berg H. M. , Hall E. L. 
Published: March 2019

AbstractThe back reflection x-ray divergent beam technique is examined as a tool for studying elastic strains. In particular, a method of calculating interplanar spacings using a least squares fit of experimental "conic" coordinates to Newman's general equation for back reflection (J. Appl. Cryst. 3 (1970) 191) is described. Using this technique, interplanar spacings can be obtained from partial conies. To determine the precision of this method an unstrained silicon single crystal is studied, and the errors associated with determining its interplanar spacings are discussed. The technique is then applied to elastically strained silicon and the results compared to theoretical predictions. It is shown that strains down to 2 × 10−5 are readily measured on high angle planes in silicon.
Self Absorption Corrections for X-Ray Fluorescence Analysis of Aerosols
Authors: Dzubay T. G. , Nelson R. O. 
Published: March 2019

AbstractA procedure is described for making self absorption corrections for x-ray fluorescence analysis of ambient air aerosols which are collected in two size ranges with a dichotomous sampler. Calculations for fine particles are based on the assumption of a uniform layer of accumulated deposit which has an exponentially decreasing depth profile within a membrane filter. Coarse particles are treated as spheres with a log normal mass distribution which is subject to modification by the sampling device. An average attenuation and the associated uncertainty is deduced for coarse particles by considering a wide variety of possible chemical compositions.
On-Stream Analysis of Float Process Slurries by XRF
Authors: Ereiser J. , Frank G. , Guy J.W. , Litchinsky D. 
Published: March 2019

AbstractAn on-stream XRF analysis system for monitoring the concentrations of the elements in float process slurries is described. The system consists of multiple XRF stations monitored by a central computer. The stations utilize high resolution Si(Li) detectors and radioisotope x-ray sources for stability and for good separation of adjacent elements such as Cu and Zn. Results obtained from an on-stream slurry analysis of Copper and Lead Tails and Copper and Lead Concentrates are presented and these are compared to assay lab results.
Applicability of Pixe and XRF to Fast Drill Core Analysis in Air
Authors: Carlsson Lars-Eric , Akselsson K. Roland 
Published: March 2019

AbstractThe properties of particle-induced X-ray emission, PIXE, and secondary target mode X-ray fluorescence, XRF, applied to the analysis of unprepared drill cores in open air have been evaluated. Typical detection limits for elements heavier than Mg have been determined for a PIXE-system with an external 2.55 MeV proton beam and for an XRF-system with Ti, Mo and Tb secondary targets. These two systems were found to have similar detection limits for most elements in a typical geological sample. The heterogeneous composition of drill cores prevents the performance of accurate matrix corrections, though calculations using fundamental parameters show that in the PIXE analysis of elements heavier than Ca, these corrections are much less sensitive to variations in the matrix composition than in the XRF analysis.
Diffracted Beam Monochromators for Powder Diffractometry
Authors: Proctor E. M. , Furnas T. C. , Loranger W. F. 
Published: March 2019

AbstractThe efficiency and effectiveness of diffracted beam x-ray monochromators used in powder diffractometry have been described in so many ways that much confusion exists regarding their true performance. Although significant improvements in signal to noise ratios are readily achievable, and they offer a solution to the sample fluorescence problem, it is not without sacrifice to total intensity or achievable resolution or both. This paper discusses and describes a series of comparisons between filtered direct beam, LiF and graphite monochromators.These comparisons include the considerations necessary for the appropriate selection of diffracted beam slit system, the effect of vertical divergence as a function of two theta for singly bent crystals, the effects of a non-uniformity of contribution over the length of the crystal, and the geometry necessary for the singly bent and doubly bent crystals. The total intensity and the resolution of LiF and graphite are discussed, in particular, it is noted that the performance of monochromators with randomly oriented samples is quite different than their performance with samples showing preferred orientation or grain effects.A new diffracted beam monochromator based on the Rowland focusing geometry is described.
X-Ray Investigation of a 2H-3C Phase-Transformation in Silicon Carbide Single Crystals
Authors: Krishna P. , Marshall R. C. 
Published: March 2019

AbstractThis paper reports the results of a detailed X-ray diffraction study of a new phase-transformation observed in SiC crystals grown by a vapour-liquid-solid mechanism involving the hydrogen-reduction of methyltrichlorosilane. The 10.ℓ reciprocal lattice rows of these crystals, as recorded on X-ray diffraction photographs, reveal sharp reflections corresponding to the hexagonal close-packed 2H (ABAB….) structure and sometimes also corresponding to the cubic close-packed 3C (ABCABC…) structure. These reflections are invariably connected by a diffuse but continuous streak whose intensity is a measure of the random faulting on the basal planes. The crystals were needle shaped and the structure sometimes varied along their length.Several crystals were annealed in an inert atmosphere at progressively higher temperatures and their 10.ℓ reciprocal lattice row re-examined to determine the annealing behaviour as well as possible structural transformations. For a number of dark green needles having a faulted 2H structure the 2H reflections disappeared around 1400° C and the 10.ℓ reciprocal lattice row revealed only a continuous streak with increased intensity around positions for 3C reflections. On further heating the structure went over to a strongly faulted 3C. Around 1600°C the appearance of a 6H structure became discernible while highly diffuse 30 reflections still persisted. The reversible part of the transformations, if any, could not be observed. Some of the structures were, however, found to be much more stable and did not transform even up to 1650° C.The above results, in particular the discovery of a 2H-3C phase-transformation around 1400°C, throw fresh light on the thermodynamic stability of the different SiC types. The mechanism of the 2H-3C transformation, the possible influence of faults and impurities and the thermal stability of various SiC structures are discussed on the basis of the experimental results stated above.
Developments in Analytical Diffraction Using Isotopic X-Ray Sources
Authors: Toothacker W. S. , Preuss L. E. 
Published: March 2019

AbstractLobov et al., in Leningrad, and workers at this laboratory have been working on the idea of using x rays from radioactive sources for x ray diffraction analysis. The Russians have been using iron-55 produced by the (n, Y) reaction in their work with a small focusing camera which operates in the back reflection region. We have been using iron-55 produced by the (p,n) reaction in conjunction with a small Debye-Scherrer camera. The preliminary work of this laboratory was reported at this conference two years ago. At that time a 13 mCi iron-55 source was used in a two inch diameter Debye-Scherrer camera to obtain x-ray diffraction patterns of LiF. The exposure times were of the order of 120 hours and the reflection from the 200 plane was about 3 degrees wide. Since that time a new and more intense source has been constructed at Oak Ridge National Laboratories. With the new source it was possible to produce LiF diffraction patterns of the same density and resolution as before in a period of less than ten hours.The above mentioned diffraction patterns were made with the LiF powder placed in a 1.0 mm diameter glass capillary. After reduction of the glass capillary diameter to 0.5 mm and appropriate reduction of the collimator width, we were able to improve the resolution considerably with no accompanying reduction in line density. The LiF patterns obtained in this way required an exposure time of about 20 hours and the width of the reflection from the 200 plane has been reduced to about 1.5 degrees.Hence we are able to report a reduction in exposure time from 116 hours to 20 hours and an increase in resolution by a factor of two over the data reported here two years ago. Thus the concept of using x rays from an isotope for powder diffraction has changed from a laboratory curiosity into a technique with practical possibilities. Both sources mentioned above were produced by the (p, n) reaction. The 135 mCi source had a specific activity of about 400 Ci/gm. Since iron-55 sources have been made with specific activities of about 1000 Ci/gm, a considerable decrease in exposure time could be accomplished by using such a source. The application to this work of a position sensitive proportional counter as developed by Semmler will also be discussed.
Application of Calculated Intensities for Reflection X-ray Topographs
Authors: Blish R. C. 
Published: March 2019

AbstractThis paper is an effort to quantify such variables as penetration depth, intensity, and defect contrast in reflection X-ray topographs. The analysis includes an appropriate combination of geometrical, polarization, absorption, and scattering factors. Quantitative measurements have been made for a variety of diffracting planes and-wavelengths on Si and Ge. The calculations also fit qualitatively (fluorescent screen intensity} with observations on Zn, ZnO, CdS, GaAs, GaP. Topographs from some or all of these materials will be shown to illustrate how these calculations can predict useful diffraction conditions.
Heavy Ion-Induced Characteristic X-Ray Generation as an Analytical Probe
Authors: Cairns J. A. , Holloway D. F. , Nelson R. S. 
Published: March 2019

AbstractIncreasing attention is currently focused on the generation of characteristic x-ray by proton irradiation. This has the advantage of yielding “clean” x-ray- i. e. free from background brerasstrahlung radiation, from even the lightest elements. The disadvantage is that the yields are naturally much lower than those produced by electrons of the same energy. A recent study has extended characteristic x-ray production to a variety of heavy ions and has shown that the cross- sections for the production of clean x-rays are often higher , by as much as several orders of magnitude, than those produced by protons of the same energy. In addition, there has emerged a further advantage, viz. the ability of specially chosen heavy ions to excite characteristic x-ray from a particular element in a selective manner. Since heavy ions penetrate only a few hundred Angstroms in to most solids, the phenomenon can be used as the basis of a technique for the examination of surface deposits, or to measure depth distributions of impurities. For example, Kr ions can be used t o determine the range distribution of antimony which had been implanted in to silicon at 100 keV. The antimony concentration was determined as a function of ∼ 150 Å steps, and was found to exhibit a maximum concentration of ∼ 1 part in 103of silicon at 450 Å below the surface, falling to zero concentration at ∼2000 Å a depth. In the past, in order to obtain the required degree of sensitivity, such range determinations have relied on radio active tracer techniques.An entirely new type of proportional counter has been developed during the course of these studies. This instrument, because of its special construction, can be positioned very close to targets in non-dispersive studies, so as to collect the highest possible fraction of emitted x-ray. It incorporates a replaceable anode unit, together with a built- in miniature head amplifier, and exhibits extremely good performance, particularly for ultra-soft x-ray. In addition, rotation of a dial on the end of the counter body allows alteration of the active gas volume during operation, and so permits tuning into x-rays of a particular energy.