bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation and Application of an Improved Slit Probe for the X-Ray Secondary Emission Spectrometer
Authors: Bertin Eugene P.
Published: March 2019

X-ray probe accessories for commercial flat-crystal X-ray secondary emission (fluorescence) spectrometers have consisted of pinhole apertures in the primary or secondary X-ray beam. The smaller the aperture the lower the intensity, and apertures having diameters less than approx. 0.1 mm are of real value only for relatively high concentrations of elements having intense spectral lines.

There are two practical methods for increasing the intensity obtained with small apertures. One method is use of curved crystals ; it is applicable to any type of sample. The other method m use of a slit instead of a pinhole. It is limited to samples such as long linear inclusions ; sections of coated surfaces, diffusion couples, and metal-to-metal and metal-to-ceramic interfaces; and other layered structures where composition varies in a direction normal to the layers, but not along any one layer. The slit also has several other disadvantages that do not apply to the pinhole. However, when used with samples of the proper type, the slit has two outstanding advantages : Increased sensitivity and statistical precision are realized by replacing a pinhole of a given diameter with a slit of the same width ; alternatively, improved resolution is realized without loss of intensity by replacing the pinhole with a slit of smaller width. Moreover, the slit can be installed on a commercial X-ray spectrometer quickly and conveniently, and often allows useful X-ray probe work to be done on samples for which pinhole apertures would be inadequate.

A slit probe of the type already described by the writer has been improved and evaluated on a General Electric X-ray spectrometer equipped with a curved crystal. The improved accessory has been applied to studies of several metal-tometal and metal-to-ceramic systems. Some of these studies are discussed in detail.
The Use of an X-Ray Fluorescence Semi-Microprobe Attachment in Metallurgy
Authors: Wittig W. J.
Published: March 2019

Standard X-ray fluorescence spectrogmphs are capable of measuring elements in areas as small as ⅛-in. diameter, while an electron mitroprobe specialises in areas less than 10 μ. Frequently, a sample of an intermediate size (0.1 mm to 2 mm) requires analysis, so an attachment was designed for Philips Electronics Company equipment. Reasons for its design, sensitivity of the system, and several metallurgical examples showing its versatility are discussed in the report.
Some Measurements of Carbon K Excitation in a New Ultrasoft X-Ray Spectrometer
Authors: Mattson Rodney A.
Published: March 2019

An ultrasoft X-ray spectrograph employing a demountable, water-cooled, cleanable X-ray target will be described. The effects of the spectra emanating from various target materials, operated under several conditions, on the efficiency of excitation of C K radiation will be discussed.
Microprobe Analysis of Binary Systems Containing Uranium*
Authors: Colby J. W.
Published: March 2019

Several binary systems of uranium with lighter elements (atomic numbers of 6 to 26) have been analyzed in an ARL microprobe analyzer using conventional X-ray techniques and also by sample-current measurements. The techniques of the analysis, the parameters employed, and the results obtained are discussed.
Determination of Rubidium in Cesium Metal by X-Ray Fluorescence Spectroscopy
Authors: Laib Roger D.
Published: March 2019

A rapid method for the determination of rubidium in cesium metal by X-ray fluorescence is described. Cesium metal is converted to the chloride, and pellets are pressed with molybdenum trioxide as an internal standard. The rubidium to molybdenum intensity ratio is used to eliminate the effect of small amounts of the other alkali metals. The analytical curve is linear from 0.05 to 15% rubidium, which covers the range of samples normally encountered. Rubidium can be determined with a coefficient of variation of 1.3% in this range. Good agreement was shown with results obtained by flame photometry.
A Camera for Borrmann Stereo X-Ray Topographs
Authors: Young F. W. , Baldwin T. O. , Merlini A. E. , Sherrill F. A.
Published: March 2019

A relatively inexpensive camera which was designed for taking Borrmann topographs with standard X-ray diffraction equipment is described. This camera has been used to take stereo pairs of Borrmann topographs by rotating the crystal around an axis normal to the diffraction planes. Topographs have been taken of nearly perfect copper crystals up to 0.2 cm thick using silver, molybdenum, copper, and chromium radiation, and comparisons have been made with topographs obtained with crystal monochromated radiation. Geometrical factors affecting the resolving power of the technique are briefly reviewed. In addition, the resolution inherent in the diffraction phenomenon is analyzed on the basis of the theory of anomalous transmission. Comparisons are made between calculated and observed image widths of a few dislocations.
Lattice Defect Research by Kossel Technique and Deformation Analysis
Authors: Umeno Masataka , Kawabe Hideaki , Shinoda Gunji
Published: March 2019

An electron probe microanalyzer (EPMA) was applied for the deformation analysis of aluminum single crystals. The lattice distortions caused by tensile stresses were observed by Kossel patterns, which are sensitive in their change of shape to lattice distortion. The effects of lattice distortion would appear as splitting, tearing, bending, broadening, disappearance, and shift of Kossel lines. This distortion behavior can be analyzed successfully. The jnhomogeneities and anisotropy appearing on every line were explained by the crystallographic cons (deration of slip mechanisms. The lattice distortions and corresponding changes in Kossel patterns depend on the direction of elongation ; the deformation modes of those crystals which show typical fee behavior in stress-strain curves can be reasonably explained by a fragmentation model. It was also found that there are some portions in Kossel patterns where some specific Kossel lines, i.e., {200} and {111}, are very sensitive to lattice deformation.
Rotational Polymorphism of Methyl-Substituted Ammonium Perchlorates
Authors: Stammler M. , Bruenner R. , Schmidt W. , Orcutt D.
Published: March 2019

The thermal transformations which take place in solid methyl-substituted ammonium perchlorates have been studied using high-temperature X-ray diffraction and differential thermal analysis techniques. In the temperature range from 20°C to their decomposition temperature (above 300°C), ammonium perchlorate and tetramethyl ammonium perchlorate undergo only one enantiomorphic phase transition, namely at 240 and 340°C (with decomposition), respectively. This I—II transition is ascribed to the beginning of the free rotation of the ClO4− ions. The rotation of the cations, however, begins below room temperature. If the symmetry of the cation is lowered by having both methyl groups and hydrogens arranged around the nitrogen (as in monomethyl, dimethyl, and trimethyl ammonium perchlorates), there is an additional enantiomorphic phase transition. This I—II transformation is ascribed to the rotation of the cations which have, in the partially substituted ions, two sets of non-equivalent symmetry axes (different moments of inertia). The temperatures of transformation are discussed in terms of the space requirements for rotation. Symmetries and cell dimensions of some modifications were determined.
A Combined Focusing X-Ray Diffractometer and Nondispersive X-Ray Spectrometer for Lunar and Planetary Analysis
Authors: Das Gupta K. , Schnopper Herbert W. , Metzger Albert E. , Shields Rex A.
Published: March 2019

An instrument is described which is intended to perform a dual purpose (elemental-structural) analysis consistent with the environmental conditions implied by lunar or planetary operation. The dififractometer section is based on a modified Seeman-Bohlin focusing principle in which a sharp-line focus target, a powdered sample, and a movable detector slit all lie on the focusing circle. The convolution of the projections on the focal circle, of a narrow receiving slit on the detector, the line focus target, combined with a high dispersion produce higher resolution and intensity than is common with Bragg focusing diflfractorneters with simitar instrumental parameters. The range of d-spacings covered is from 1 to 7 Å (chromium target). The chemical analysis section of the instrument utilizes the fluorescent X-rays produced in the specimen by the primary beam. A proportional counter and pulse-height anaiyzer accomplish detection and energy discrimination. Resolution is low, but the analysis can distinguish between elements in the range of atomic numbers 11 to 29. Data from a breadboard model is presented. The entire unit, although primarily intended to meet the requirements of space, performs equally well as a routine laboratory analyzer. The horizontal, stationary nature of the specimen holder suggests several specific applications.
Two-Crystal X-Ray Spectrometer Attachment
Authors: Azároff Leonid V.
Published: March 2019

A two-crystal spectrometer that makes full use of conventional diffractometet: or spectrometer motions has been constructed so that it can be easily attached to a commercial instrument. The requisite degree of parallelism of the two crystalrotation axes is maintained by keeping both parallel to a single ground surface. Special alignment aids have been constructed to facilitate the rapid alignment of the instrument, which can be operated manually in 1″ intervals or used for automatic scanning in steps of 0.01°. Some guide lines for comparing the relative performance of spectrometers in X-ray absorption spectroscopy are suggested.
Evaluation of Quantitative Electron Microprobe Analyses of Multiphase Microcrystalline Refractory Materials*
Authors: Speidel David H.
Published: March 2019

An appropriate test for homogeneity of composition of standards and of unknown samples is an analysis of variance of the intensity ratios of the components within the grains opposed to the variance between the grains under conditions of constant beam current capacitor change. Replication of analyses is necessary to distinguish inherent instrumental variation from actual chemical inhomogeneities present in the samples. This replication permits an estimate of the imprecision caused by in homogeneities and the statistical variation of X-ray quanta. The total uncertainty of an analysis is the sum of systematic error—primarily reference standard uncertainty—and the imprecision. For multiphase mixtures of microcrystalline refractory oxide material, an uncertainty of ±2% of the amount of oxide component present in a given phase should be considered a good analysis. This value is based on experimental work in the system MgO–FeO–Fe2O3–SiO2.
The Effect of Chemical Combination on Some Soft X-RayKandLEmission Spectra*
Authors: Fischer David W. , Baun William L.
Published: March 2019

X-ray spectrochemical analysis is a versatile technique that can be used to determine considerably more than just the elemental composition of a sample. X-ray lines and bands are, in many cases, influenced by the state of chemical combination of the element whose spectrum is being investigated. Significant effects due to changes in bonding are seen in theKandLspectra of the low atomic number elements which fall in the 20 to 90 Å region. Results using primary excitation, a stearate crystal, and a flow proportional counter are shown for theKspectra of boron, carbon, and nitrogen. Chlorine and sulfurLspectra from some simple metal compounds of these elements are also shown.
Chemical Effect on X-Ray Absorption-Edge Fine Structure
Authors: White E. W. , McKinstry H. A.
Published: March 2019

Existing theories of X-ray absorption-edge fine structure do not adequately explain details of spectra observed for solids. However, the possibility that X-ray absorption spectra might eventually be used as tools for the characterizatiori of new insulator materials has prompted the study of an extensive selection of simple oxides of known chemistry and structure. The complete K absorption fine structure has been measured for some forty simple oxides of six elements of the fourth period. The L absorption-edge spectra have been measured for metallic lead and several lead oxides. The several isostructurat and polymorphic sets included among these oxides, as well as the Magnéli phases for three of the elements, have made it possible to study the effects of valence, coordination number, electron configuration, and crystal structure. The applicability of current theories of the fine structures are discussed in the light of these findings. An automated single-crystal spectrometer is described.
The Application of a Soft X-Ray Spectrometer to Study the Oxygen and Fluorine Emission Lines from Oxides and Fluorides
Authors: Mattson R. A. , Ehlert R. C.
Published: March 2019

Results are shown for O and F K emission lines from several oxide and fluoride compounds. The spectra are examined for both structure and wavelength. Excitation of the spectra is by both electrons and X-rays. The emission spectra from several oxygen- and fluorine-bearing gases and the influence of the composition of the diffracting crystal on the shape of the observed oxygen spectra are also discussed. Curved crystals of potassium acid phthalate and lead stearate, and a thin-window flow proportional counter, are used to obtain the results.
Applications of Neutron Activation Analysis to Environmental and Biomedical Studies
Authors: Lukens H. R. , John J.
Published: March 2019

The field of neutron activation analysis (NAA) has expanded significantly in the past decade, with the number of publications increasing from approximately 100 to more than 1000 per year. This phenomenon correlates with the greater availability of useful neutron sources, improvements in gamma-ray spectrometry equipment, and a rapid increase in successful NAA applications. A significant number of applications have been in the biomedical and environmental fields, especially in cases where elements must be measured at ultra-trace levels.
Flash X-Ray Diffraction Systems
Authors: Dantzig Jonathan A. , Green Robert E.
Published: March 2019

In order to develop an optimum system for flash x-ray diffraction, consideration must be given to both optimum x-ray generation and optimum x-ray detection in the correct wavelength regime suitable for diffraction. Historically, most workers have concentrated their efforts in either the generation area or detection area, but not both. As early as 1942, experimental recording of Laue diffraction patterns was reported using a pulsed x-ray generator and exposure times of milliseconds. Recently, successful x-ray diffraction experiments have been reported with exposure times less than 100 nanoseconds.

The purpose of the present paper is to trace the development of generation and detection systems for flash x-ray diffraction and to summarize the present state-of-the-art for such systems. A comparative evaluation is presented for flash x-ray diffraction systems using generators which rely on increased electron beam current and those which rely on higher potential difference. Comparison is also made between detection systems incorporating film recording, scintillators fiber-optically coupled to photomultiplier tubes, and image-intensifier systems both lens and fiber-optically coupled to fluorescent screens.

A detailed description of the most rapid flash x-ray diffraction system developed to date is given. This system uses a Field Emission Fexitron single channel 300 kilovolt pulsed x-ray generator incorporating an x-ray tube with a beryllium output window. A fluorescent screen converts the x-ray diffraction image into a visible one and this visible image is focused on the first stage photocathode of an image intensifier tube either by direct fiber-optic coupling or by using a coupling lens. The image intensifier tube used is a cascaded three-stage electrostatic focus type with fiber-optic input and output faceplates and inter-stage couplers. Using this system Laue transmission diffraction patterns of single crystals and powder patterns of polycrystalline aggregates have been obtained with exposure times of 30 nanoseconds.
An X-Ray Investigation of Fatigue Behavior of Cold Worked Aluminum
Authors: Gould R. W. , Pittella C. F.
Published: March 2019

Double bending fatigue tests were performed on cold worked 1100 aluminum, with a maximum bending stress varying from 100 to 50% of the yield stress. Variation of residual macrostress from the cold worked state during the fatigue tests was measured by the photographic x-ray diffraction method. A general decrease of this macrostress was observed. Line profile analysis was used to study the change in the mean effective domain size and microstrain. A rate dependence of the increase in the effective domain size with respect to the maximum bending stress was observed. Microhardness and tensile tests were also made on the specimens during the fatigue testing and the results are correlated with the x-ray Parameters.
Contrast of Dislocation Images in X-Ray Transmission Topography
Authors: Authier A.
Published: March 2019

A brief review of the different topographic methods is given in order to attempt a classification of the various types of contrast observed. Depending on whether the image is obtained by a reflection or transmission method, is simple or integrated, dynamic, direct, or intermediary, the contrast and image width vary greatly. A detailed analysis is given in the case of transmission section topographs.
Dynamical Theory for Simultaneous X-Ray Diffraction
Authors: Penning P.
Published: March 2019

Complete dynamical solutions for three coupled plane-wave components in crystal structures with inversion symmetry have been found. After reviewing briefly the dynamical solutions for wave fields with two coupled plane-wave components, the results for the three-beam case are discussed in qualitative terms. Attention is paid to singular points and lines on the ω-surface, and to the attenuation of the mode-intensity because of absorption. The most surprising result is that in the case one of the reflections is forbidden (Umweganregung) the absorption is reduced in comparison with the adjoining two-beam cases. Experimental data are in reasonable agreement with the theory. Quantitative data are presented for a few three-beam cases of simultaneous diffraction of Cu Kα. radiation in germanium.
Some Recent Applications of X-Ray Topography
Authors: Lang A. R.
Published: March 2019

Dislocations, Inclusions, and Precipitates. Impurity precipitated after growth and foreign particles accidentally included during growth both produce intense local strain fields which give rise to diffraction contrast effects resembling those seen in electron microscope images of precipitates. The relationship between the dislocation configuration and these localized strain centers can show whether the latter arise from inclusions or precipitates. Precipitates will generally be found strung along the grown-in dislocations, decorating them. On the other hand, inclusions often generate dislocations by lattice closure errors; such dislocations then fan out from the inclusion in the general direction of advance of the growth interface.

Twin Boundaries and Fault Surfaces. The cases when the twins have parallel lattices, such as in Brazilian and Dauphiné twinning in quartz, are interesting. When the crystals on either side of the twin boundary are both Bragg reflecting, the twin boundary may exhibit ‘stacking fault’ type fringes. From an analysis of the variation of visibility of these fringes in different reflections, the fault vector at the twin boundary and its variation with boundary orientation may be found. In quartz, other types of fault surfaces producing fringe contrast may lie parallel to growth horizons or they may mark growth sector boundaries. In synthetic quartz, they can also mark cell boundaries under conditions of cellular growth.

Internal Magnetic Domain Structures. In plates of Fe + 3% Si roughly parallel to (110), a variety of previously undetected domain structures has been discovered and analyzed. Diffraction contrast is produced by 90° domain walls but not by 180° walls. The 90° walls produce strong diffraction contrast even though the magnetostriction of silicon-iron is only about 10−5. In plates parallel to (112), the main lamination pattern below the complex pattern of surface closures can be revealed and, in favorable cases, interpreted.

X-ray Moiré Patterns. The most direct method of observing X-ray moiré patterns—by topography of one crystal closely superimposed upon another—involves considerable theoretical complexities and produces a variety of curious diffraction patterns. However, it shows promise of providing a means for the comparison of lattice spacings to about one part in 107and for mapping strain fields very sensitively.
Experimental Procedures in X-Ray Diffraction Topography
Authors: Austerman Stanley B. , Newkirk J. B.
Published: March 2019

The quality and interpretation of diffraction topographic images are strongly dependent on. the detailed laboratory techniques that are used in making them. In this paper practical instructions are given for the preparation of Berg-Barrett and Lang topographs. It is hoped that these suggestions will enable the novice in the field of X-ray topography to produce high quality images and to interpret them with a minimum of learning time. The topics treated include adjustment of the critical conditions for attaining highest resolution, choice of radiation and the specific hkl planes to be used, conditions limiting the size of the image, cause and avoidance of image distortion, choice of photographic emulsions, plate processing for best contrast and resolution, photomicrographs of the original image, and plate preservation.
The Effect of Small Additions of Magnesium on the Preprecipitation Behavior of Al-Zn Alloys
Authors: Gould Robert W.
Published: March 2019

Magnesium has been shown to have a marked effect upon preprecipitation processes occurring in aluminum-13 wt.% zinc alloys containing 0.025, 0.098, 0.17, 0.19, 0.23, and 0.27 wt.% magnesium. X-ray small-angle scattering and resistance measurements have been used to monitor the rate of growth of Guinier-Preston zones in quenched foils and wires. The following results have been obtained: (a) small additions of magnesium noticeably decrease the rate of growth of G-P zones but the final zone size reached in the magnesium containing alloys is generally larger than in Al-Zn alloys quenched and aged under identical conditions; (b) the general pattern of preprecipitation found in Al-Zn alloys is not seriously changed by these small additions of magnesium; (c) the dependence of the rate of preprecipitation on quenching temperature is shown to be a function of magnesium content and aging temperature; (d) the dependence of the rate of preprecipitation on aging temperature is influenced by the range of aging temperature, magnesium content, and the quenching temperature.
Analysis of High Angle Diffuse Scattering from Small Platelets
Authors: Thomas A. D. , Liedl Gerald L.
Published: March 2019

A detailed analysis of the high angle diffuse scattering from small platelets is given. A large number of statistically centrosymmetric platelets is considered, and it is shown that, in this cage, the positive square root of the diffuse intensity from the platelets is proportional to the amplitude of the scattered radiation over particular regions in reciprocal space. The measured amplitude distribution is truncated from the true amplitude distribution by the limits of measurement and the influence of Bragg scattering. A truncation function is introduced to describe this truncated amplitude distribution in terms of the true amplitude distribution. This truncation introduces modulations on the measured electron density distribution. The measured electron density distribution is described in terms of the convolution of the true electron density distribution and the transform of the truncation function. The transform of the truncation function is knowi analytically, so the true electron density distribution can be found by a relaxation method. The true electron density distribution is given in terms of composition and strain parameters which are independently adjusted during the relaxation procedure to fit the measured values. Examples of the influence of the truncation function arc given and the technique is applied to G–P 1 zones in an aluminum - 1.67 at % copper alloy.
X-Ray Diffraction Study of Ordering in Two Sigma Phases
Authors: Spor R. W. , Claus H. , Beck Paul A.
Published: March 2019

X-ray powder pattern line intensities were measured for the (Cr, Re)σ and (Re, Fe)σ phases by a step-scanning diffractometer, using CrKα radiation, scintillation counter, and a pulse height analyzer. The measured intensity ratios for all available pairs of adjacent lines were compared by means of a computer with the corresponding calculated intensity ratios based on approximately 1800 different ordering schemes for each alloy. The results showed ordering in both alloys, and indicated that the ordering was based on atomic size. These results are different from those obtained previously by Kasper and Waterstrat (no ordering), and by Ageyev et al. [In (Cr, Re)σ the Cr atoms are preferentially in large coordination number positions.]
X-Ray Measurement of Residual Stresses in Titanium Alloy Sheet
Authors: Braski David N. , Royster Dick M.
Published: March 2019

An X-ray diffraction technique was used to measure residual stresses in Ti-6Al-4V and Ti-8Al-1Mo-1V sheet created by glass-bead peening, sand and aluminum oxide blasting, and a vibratory tumbling treatment. For peening and blasting, the use of larger particle sizes produced greater compressive stresses. In the case of the vibratory treatment, an increase in vibratory frequency or treatment time increased the compressive stress. Glass-bead peening caused a 10% reduction in yield strength while the other treatments had little effect on the tensile properties. Significant stress relaxation occurred in all the treated Ti-6Al-4V coupons exposed at 600° and 800°F.
The Application of X-Ray Diffraction Techniques to the Study of Wear
Authors: Quinn T. F. J.
Published: March 2019

The relevance of X-ray diffraction techniques to the investigation of the chemical, physical, and crystallographic changes occurring during sliding wear is discussed in relation to existing theories of wear. By-way of illustration, the application of the powder X-ray cylindrical film technique to the unlubricated wear of a low-alloy, medium carbon steel is treated in some detail. The variation of the relative proportions of iron and its oxides in the wear debris with changes in sliding speed is described. It is shown that the results lend partial support to the oxidational hypothesis of the unlubricated wear of steel.
Precision Lattice Parameter Determination at Liquid Helium Temperatures by Double-Scanning Diffractometry
Authors: King Hubert W. , Preece Carolyn M.
Published: March 2019

The back-reflect ion double-scanning diffractometer method, by which lattice parameters can be measured with a reproducibility of one part in 150,000 has been applied at liquid helium temperatures. A cryostat attachment is described which enables diffraction profiles to be scanned on both sides of the primary X-ray beam up to 163°, 2θ. Alignment errors may, thus, be eliminated by measuring the included angle 4θ between respective Bragg reflections. The method is illustrated by measuring the lattice parameters of the I.U.Cr. standard specimens of silicon and tungsten at various cryogenic temperatures.
The Effects of Electronic Structure and Interatomic Bonding on the Soft X-Ray Al K Emission Spectrum from Aluminum Binary Systems
Authors: Fischer David W. , Baun William L.
Published: March 2019

The aluminum K X-ray emission lines and bands from a series of aluminum binary alloys and other binary compounds were investigated using 6 kV electron excitation and a flat crystal vacuum spectrometer. The overall shape of the emission band and its energy position as a function of alloy composition was determined. It appears from the data that the aluminum K band undergoes changes in shape and energy position which are dependent on the electronic configuration of the element with which the aluminum is chemically bonded. These band changes can be interpreted as indicating a change in the bonding character between the metal atoms. In the Al-Ni system, for instance, the Al K band becomes more symmetrical and shifts to lower energy as the nickel content is increased, indicating that perhaps the bonding on the aluminum atoms is becoming less metallic and more covalent in nature as the nickel to aluminum ratio is increased.

The aluminum Kα4/Kα3 satellite line intensity ratio also varies in an orderly manner in aluminum binary compounds. In general, these satellite line changes go hand-in-hand with the K band changes. If the K band shifts to lower energy, the Kα4/Kα3 intensity ratio will always increase in value.
Nondispersive X-Ray Fluorescent Spectrometer
Authors: Jones W. Barclay , Carpenter Robert A.
Published: March 2019

Recent advances in semiconductor particle detector resolutions along with new electronic circuitry associated with these detectors make possible their application in nondispersive elemental analysis. The use of radioactive sources for exciting the characteristic X-rays provides highly stable systems which can be used to accumulate data for prolonged periods. Due to the inherent stability of the detector and the excitation source, the only limitation in sensitivity is the ability to accumulate statistics above the background of scattered counts. Since this method of analysis is nondispersive, it has the capacity to determine many elements simultaneously. Solutions composed of mixtures of three or four elements were studied. The elements selected were bromine, rubidium, and strontium. These elements exhibit wide variations in mass absorption coefficients for the various characteristic X-rays emitted. The concentrations of the elements in solution varied from 10 ppm to 5% by weight. The relative intensities of the characteristic X-ray lines were compared with the concentration of the solutions to establish sensitivity curves and to study linearity of response as well. The interelemental interference was studied and the effect was evaluated for the particular elements under study. Means were developed for predicting and correcting for matrix effects.
An X-Ray Small-Angle Scattering Instrument
Authors: Koffman Donald M.
Published: March 2019

An X-ray small-angle scattering instrument is described which is used for recording X-ray diffraction patterns or small-angle X-ray scattering curves in an angular region very close to the direct beam. The measurement of X-ray intensity is accomplished with standard geiger or scintillation counter techniques. The instrument is designed for use with a spot-focus or vertical-line X-ray source, In essence, it is a multiple-reflection double-crystal diffractometer, based on a concept developed by Bonse and Hart, employing two grooved perfect germanium crystals arranged in the parallel position. Multiple diffraction from these crystals produces a monochromated X-ray beam which can be several millimeters wide while still exhibiting extremely high angular resolution. As a result, effective sample volumes can be employed with maximum volume-to-thickness ratios. The principal features of the instrument are discussed with emphasis on the advantages of this device over those employing complex slit systems and film-re cording techniques, Data are presented to illustrate the operation, intensity, and resolution of the unit.
Fully Automated High-Precision X-Ray Diffraction
Authors: Baker T. W. , George J. D. , Bellamy B. A. , Causer R.
Published: March 2019

X-ray diffraction angles are measured precisely, conveniently, and automatically by a specially designed instrument, the automatic precision X-ray goniometer connected on line to an Elliott 903B data processor. A monitor program controls two such instruments and two diffractometers simultaneously and allows a comprehensive set of experiments to be performed. The sensitivity is such that, when translated into terms of changes in the crystal-lattice parameter, a precision of 1 part in 10,000,000 is being attained, and indications are that absolute measurements are almost as good. The procedures, instrument, and automatic control are described, and the results of performance tests and some applications are given.
Irradiation Effects in some Crystalline Ceramics*
Authors: Cummings W. V.
Published: March 2019

Irradiation effects that have been observed in the structures of a number of ceramic materials are reviewed. Results of X-ray diffraction studies indicate that, to a great extent, the magnitudes of the crystallographic changes depend upon the type of crystal structure. However, the nature of the atomic bonding and the type of radiation can be the predominant factor in radiation stability in some materials. Damage mechanisms that have been investigated include: (1) fast-neutron and high-energy garnma-ray effects, (2) transmutation effects in high-neutron crosssection materials, and (3) lire effects of the (n, α) reaction in various bolide-containing structures. Some crystallographic changes observed include lattice parameter changes and structure damage of various magnitudes, the appearance of a transmutat. on product structure, and changes from the crystalline to the amorphous state.
Factors Limiting the use of Standard Minerals in the X-Ray Diffraction Analysis of Clays
Authors: Douglas Lowell A.
Published: March 2019

In the quantitative x-ray diffraction analysis of clays, “standard“ clays are compared with “unknowns” assuming both Standards and unknowns have similar diffraction characteristics. This assumption is valid in certain cases involving kaolinites, chlorites, vermiculites, and where standards have been obtained from the unknown clays. In other cases; especially those involving smectites, illites, and some chlorites and vermiculites; lack of hornogeneity within mineral species and inability to measure this inhomogeneity in mixed mineral suites limits the accuracy obtainable by diffraction methods.
Low Energy X-Ray and Electron Absorption Within Solids (100-1500 ev Region)
Authors: Henke Burton L. , Ebisu Eric S.
Published: March 2019

Quantitative analysis by x-ray fluorescence and photoelectron and Auger electron analysis can be effectively extended through a precise knowledge of the total aad subshell photoionization cross sections. Light element and intermediate element analysis, as based upon K and L series fluorescence respectively, involve x-ray interactions in the low energy region, Optimized analysis for essentially all the elements by x-ray induced photoelectron and Auger electron spectroscopy involves both x-ray and electron interactions in the low energy region. Unfortunately, theory and measurement for interaction cross sections in this 100-1500 eV region are difficult, particularly for the heavier elements. Nevertheless, recent advances in experimental and computerized-theoretical techniques for the determination of low energy interaction coefficients do permit establishing appreciatly more complete tabulations of cross sections than are currently available in this energy region.

In this paper, the types of interaction cross section data that are needed for quantitative x-ray and electron analysis are defined. Such data that are available from experiment and from theory are reviewed and compared. Some newer techniques for the measurement of cross sections are discussed. And finally, new “state of the art” tables are presented for the mass absorption coefficients of all of the elements and of some special laboratory materials. These are tabulated specifically for twenty-six of the most commonly applied characteristic wavelengths in the 8-110 A region and are based upon the best currently available theoretical and experimental data.
Sampling and Standards in a Recycled World
Authors: Marr H. E. , Campbell W. J. , Neylan D. L.
Published: March 2019

A number of procedures for fluorescent X-ray analysis have been introduced to accommodate the samples that are produced from research on the recovery of values from secondary metal sources. For some applications, standards are conveniently available such as those that can be purchased from the National Bureau of Standards. For other applications, secondary standards must be prepared and analyzed by independent methods. The sample preparation procedures vary considerably. For monitoring process efficiency, sample preparation is often kept at a minimum such as simply pouring loose powders into disposable cups. For the most accurate analyses, sample preparatton requires casting the alloys and finishing the surfaces. Matrix correction procedures are employed where concentrations of major constituents vary over wide ranges.
X-Ray Cross-Sections in Design and Analysis of Non-Dispersive Systems
Authors: Clark Benton C.
Published: March 2019

In designing a radioisotope, energy-dispersive (proportional counter) x-ray fluorescence spectrometer for elemental analysis of geologic specimens, a theoretical framework has been developed to model instrument response. This model is based upon the fundamental physics of x-ray excitation, absorption, and scattering, and employs the most modern available values of the applicable physical constants. The model includes matrix absorption and enhancement effects. By explicitly including scattering in the model and the measurements, element concentrations can be calculated from the shape alone of the x-ray spectrum and the presence of elements having non-observable fluorescences can be detected.
The Effects of X-Ray Optics on Residual Stress Measurements in Steel
Authors: Jatczak Chester F. , Boehm Harald H.
Published: March 2019

The effects of various combinations of divergence, receiving and Soller slits on x-ray measurements were investigated for Siemens-Halske and General Electric diffractometers. Influences of the following factors which also affect accuracy and precision of x-ray R.S. results were determined in addition: (a) parafocus versus stationary detector focusing geometry, (b) method of peak location, (c) LPA intensity correction, (d) diffractometer electronic stability and (e) elastic constants.

The optimum choiees of beam optics and factors (a-e) were defined with regard to aecuraey, precision and minimurn time for stress deterniination, on sharp and broad line speeimens of soft (annealed) and hardened steel and of annealed Cr-powder.
Automatic Data Acquisition and Reduction for Elemental Analysis of Aerosol Samples
Authors: Harrison J. F. , Eldred R. A.
Published: March 2019

A PDF 15/40 computer wich ADC and CAMAC interfaces is used to control data collection apparatus, acquire data, and reduce data to determine the elemental composition of aerosol samples. The background is subtracted from each energy spectrum, peak centers are located automatically using a Gaussian correlation technique, peak multiplets are resolved with Gaussian fits, peak energies are compared with entries in a table of x-ray lines for possible identification, multiple identification of peaks and line interferences are resolved, and the elemental amounts are determined from the areas of the Gaussian fits.
A Secondary-Source, Energy-Dispersive X-Ray Spectrometer and its Application to Quantitative Analytical Chemistry
Authors: Larsen R. P. , Karttunen J. O.
Published: March 2019

An energy-dispersive X-ray spectrometer that (1) uses as the primary excitation source the power supply and tungsten X-ray tube from a conventional crystal spectrometer (General Electric XRD-6) and (2) uses as the secondary excitation source elemental metal foils that are readily interchangeable has been built and operated. The use of an X-ray tube with a high-voltage capability, 75 kilovolts max, enables the determination of elements with atomic numbers as high as 66 (terbium) to be based on the K series of X-rays; the highpower capability, 3.7 kilowatts max, enables a particularly intense beam of X-rays to be generated by the secondary source and hence, provides a particularly high detection capability for trace elements in a sample. An instrument that uses interchangeable secondary sources to irradiate the samples has several advantages over those instruments in which excitation is accomplished by direct irradiation with an X-ray tube: (1) the background radiation in the energy range where the X-rays of interest are measured is several orders of magnitude lower and is very uniform and (2) the energy of the excitation radiation can be closely matched to the absorption edges of the elements of interest in the sample.

In the application of the instrument, particular emphasis has been placed on the development of tectmiques that will enable an energy-dispersive X-ray spectrometer to be used as the detection instrument for quantitative elemental analysis. Methods for the determination of the individual rare earths, plutonium and uranium at the microgram level with an accuracy of ± 1% are outlined and for the determination of plutonium and uranium at the milligram level with an accuracy of ± 0.1% are proposed.
Crystal Chemistry of Stable and Metastable (Rapidly Quenched) B-Metal Alloy Phases
Authors: Giessen Bill C.
Published: March 2019

The crystal structures of elements and alloy phases in the B-metal region (B2(Zn) to B5(As) groups) have been classified into phase fields determined by their position in the periodic table. The limited number of equilibrium phases with element-like, disordered crystal structures and of extended terminal solid solutions has been more than doubled by the addition of metastable phases produced by ultra-rapid quenching from the melt (splat cooling). Strong structural correlations exist. Some high pressure phases have been included; in some cases, a qualitative discussion from the viewpoint of pseudopotential theory is given.
A Dynamical Theory Approach to the Berg-Barrett Technique
Authors: Roessler B. , Armstrong R.W.
Published: March 2019

Crystals with a dislocation density low enough so that individual dislocations can be resolved by X-ray diffraction contrast techniques should be regarded as highly perfect crystals. A complete description of the diffraction process, therefore, requires the approach of the dynamical theory of X-ray diffraction. In the Berg-Barrett arrangement each point on the crystal surface integrates the incident X-ray intensity over the angular range received from the X-ray source. For most experimental arrangements this range is about 1/2 degree and corresponds, therefore, to integrating over the entire range of reflection of the crystal, which is of the order of a minute or so of arc. The Berg-Barrett image is a recording of a localized integrated intensity, integrated over the complete range of incident angles. We consider as essential, however, primarily the range of total reflection, since it makes the major contribution to the integrated intensity.

The dynamical theory shows that the details of the diffraction process depend very strikingly on the boundary ocnditions at the crystal surface through two angles of incidence - one between the incident beam and the crystal surface, the other between the incident beam and the diffracting plane of atoms. Calculations of the parameters of the dynamical theory which describe the diffraction process in the Berg-Barrett arrangement show that the description depends very strongly on the details of the specific boundary conditions employed. In particular, two parameters seem especially important in dislocation image formation: 1) ΔθR, the angular range of the exit beam diffracted from the crystal, which we call the range of total rejection to distinguish It from ΔθA, the angular range over which the entrance beam is totally accepted, and 2) σe, the extinction coefficient, the parameter which describes the X-ray penetration depth. Both parameters are extremely sensitive to the specific boundary conditions employed.

This dynamical theory approach suggests that, by suitable choice of the experimental conditions, the boundary conditions can be advantageously adjusted so that satisfactory Berg-Barrett images can be obtained.
X-Ray Analysis of Fatigue Softening in Cold Worked Copper
Authors: Baggerly Roy G. , Pelloux Regis M. N.
Published: March 2019

The recovery and recrystallization of cold rolled copper during reverse bending fatigue at room temperature has been studied with x-ray diffraction, optical microscopy and transmission electron microscopy techniques. Recovery of x-ray line breadth was recorded as a function of number of cycles at all strain amplitudes investigated. Recrystallization was observed to take place only at small strain amplitudes (life of 106 to 107 cycles). The rate of nucleation of the recrystallized grains increases with increasing strain amplitude and is a linear function of the number of cycles. The formation and growth of the grains was confined to regions near the surface of the specimen. Since comparable thermal recovery occurs at approximately 435°F it is concluded that the dynamic generation and migration of numerous point defects during fatigue is responsible for the room temperature recrystallization.
A Total reflection X-Ray Spectrograph for Fluorescent Analysis of Light Elements
Authors: Davies R. D. , Herglotz H. K.
Published: March 2019

A novel x-ray spectrograph for the analysis of light elements has been developed based on previous computations and confirming experiments by one of as (H. K. Herglotz). The major components of the instrument are an efficient fluorescent source, a totally reflecting mirror, and an open window photomultiplier. Identification of wavelengths in the range 15 < λ < 80 Å is achieved by the wavelength dependence of the critical angle of reflection of an x-ray beam incident on a suitably chosen low absorption reflector. As the incident angle is increased through the critical angle for a particular wavelength, the reflected beam intensity is sharply reduced; hence, a periodic vibration of the incident beam through a small angular range about the critical angle furnishes a strong a.c. reflected signal characteristic of one narrow wavelength band only.

Initial results promise a simple, easy-to-operate instrument for the routine analysis of elements boron to fluorine.
A Correction Method for Elemental Interactions and Physical Effects in the X-Ray Fluorescent Analysis of Silicate Powders
Authors: Poole A. B. , Holloway S. M.
Published: March 2019

Brieketted rock powder discs provide a convenient type of specimen for use in x-ray fluorescent analysis for both major and trace elements. The method is limited because variation of matrix makes calibration difficult over more than a limited range of specimen compositions.

Standard grinding and preparation procedures together with a ratio technique of measurement eliminate variation except that arising from chemical, mineralogical and particle size differences. Several series of standard rock samples have been prepared and the variation of measured intensity per unit concentration have been investigated for the analytical Lines of silicon, aluminium, iron, selenium and cadmium. Computer methods of multivatiate regression analysis have been used to calculate empirical correction factors based on this data and the mineralogical and chemical composition of the specimens. These correction factors have been used to correct the measured intensities of other specimens measured in separate experiments.