bluuebunny/crossref_metadata_2025 huggingface dataset:
Calibration of the Diffractometer at Low Values of Two Theta
Authors: Jenkins R. , Hom T. , Villamizar C. , Schreiner W. N.
Published: March 2019

A set of experimentally obtained “d” values is subject to a variety of random and systematic errors, some of which are inherent to a given diffractometer configuration and some of which may result from incorrect alignment of the diffractometer or technique in establishing peak positions and subsequent calculation of “d” values. In a previous paper (1) we have discussed the problems involved in the identification and control of errors in the computer controlled diffractometer and in that paper we indicated that it is useful to differentiate between different types of two-theta values. Firstly the Theoretical 20 values are those values which are dependant only on the size and distribution of atoms in the unit cell of the phase. The Practical 20 values on the other hand result when aberrations inherent in a given diffractometer geometry are convoluted with the Theoretical 20 values. In terms of their typical magnitudes the most important of these aberrations in decreasing order are: Specimen Displacement, Axial Divergence, Flat Specimen and Transparency Errors. Other inherent errors include refraction and the effects of focal line and receiving slit widths etc., but these latter effects are generally considered small. At the second level, Experimental 20 values also depend on misalignment errors. The third level errors accrue in the conversion of the experimental 20 value to “d” spacing. These errors may arise simply from round-off errors or from more fundamental reasons arising from the polychromatic nature of the source and uncertainties in the wavelength of the diffracted radiation.
Sample Preparation and Methodology for X-Ray Quantitative Analysis of Thin Aerosol Layers Deposited on Glass Fiber and Membrane Filters
Authors: Davis Briant L. , Ronald Johnson L.
Published: March 2019

The purpose of this paper is to summarize the theoretical basis and experimental techniques for application of the referenee intensity method to quantitative, multi-component analysis by x-ray diffraction (XRD). Detailed descriptions of the technique and formal error analysis are discussed by Davis (1978, 1980, 1981a, 1981b, 1981c).
Differential X-Ray Diffraction by Wavelength Variation: A Preliminary Investigation
Authors: Nichols M. C. , Smith D. K. , Johnson Quintin
Published: March 2019

In powder diffraction experiments involving mixtures of compounds, identification of each individual phase is complicated by the presence of other phases. The interpretation of such complex patterns is often very difficult, and much effort has gone into computational search-match algorithms which attempt to identify individual phases (Nichols, 1966; Johnson, 1977; Frevel, 1976). The success achieved by these programs and by manual search-match methods accounts for the fact that X-ray diffractionists have, in the past, not actively searched for other techniques that could be used to simplify such complex problems. In a recent work (Nichols & Johnson, 1980), a comparison was made of the search-match methodologies employed by several similar technologies (mass spectroscopy, fingerprint identification, X-ray diffraction etc.). A significant observation was made that only in the X-ray method was there so much emphasis on analysis of phases in their “as received” condition. In the other cases, emphasis was placed on the separation of phases before obtaining the spectra. A classical example is the GC-MS instrument which employs a gas chromatograph to separate phases before the mass spectrographic analysis is carried out on what are, by that time, essentially pure phases.
A Comprehensive Approach to in Situ Stress Measurement
Authors: Holt R. A.
Published: March 2019

Recent developments in position sensitive detectors (PSD's), solid state power and computer technologies make it possible to design accurate instruments for in-situ stress measurement. Such instruments require compromises in the interests of portability, size and speed stiich may limit accuracy and/or versatility. Furthermore, extraction of a stress tensor from X-ray data is not always straightforward and considerable research is required before an instrument for X-ray stress measurement can be treated as a “black box” to be given to an uneducated operator.

The development of a new instrument for in-situ stress measurement is described in this paper. It was conceived as a field instrument with two position-sensitive proportional counters (PSPC's) for use in the single exposure mode (SET), and incorporates precise angular qontrol of the incident X-ray beam and data analysis to eliminate irregular Bragg peaks owing to coarse grain structure, An experimental instrument was built tc test the concept (1).
The Use of Person VII Distribution Functions in X-Ray Diffraction Residual Stress Measurement
Authors: Prevey Paul S.
Published: March 2019

The fitting of a parabola by least squares regression to the upper portion of diffraction peaks is commonly used for determining lattice spacing in residual stress measurement. When Kα techniques are employed, the presence of the Kα doublet is shown to lead to significant potential error and non- linearities in lattice spacing as a function of Sin2ψ caused by variation in the degree of blending of the doublet. An algorithm is described for fitting Pearson VII distribution functions to determine the position of the Kα component, eliminating errors caused by defocusing of diffraction peaks of intermediate breadth. The method is applied to determine the subsurface residual stress distribution in ground TI-6 AI- 4 V, comparing directly the use of parabolic and Pearson VII peak profiles, and is shown to provide precision better than ± 1%% in elastic constant determination.
Rapid Composition-Depth With X-Ray Diffraction: Theory and Practice
Authors: Wiedemann Karl E. , Unnam Jalaiah
Published: March 2019

High precision composition-depth profiles can be determined quickly using a recent development. This method requires that noncompositional broadening arising from the instrument, crystal defects, and the radiation source be removed from the diffraction pattern before calculating the composition-depth profile. Effective deconvolution techniques, profiling theory, methodology of profiling, and the effect of residual noncompositional broadening on the profile are discussed. Examples include statistical analyses of error in the profile due to random counting errors and variance in the lattice parameter calibration.
Quantitative Analysis of thin Samples by X-Ray Diffraction
Authors: Brandt C. G. , van der Vliet G.H.
Published: March 2019

For phase analysis of small amounts of material in an x-ray powder diffractometer the sample is often spread on a sample mounting plate or support plate. Different types of plates on which thin samples can be mounted are:

- silver membrane filters

- metal or other polycrystalline plates

- polymer membrane filters, for example PVC, polycarbonate, cellulose nitrate

- glass slides

- single crystals; cut so that no diffraction lines occur.

Filters are often used to collect environmental dust; these samples can be analysed “as received,” Glass slides are inexpensive, flat, and readily available. Polycrystalline filters and plates have the disadvantage of possible line overlap with lines of the sample material (refer to figure 1), Glass plates or polymer filters have the high and curved background due to amorphous scatter as shown in figure 2.
The Use of Calculated Patterns as an Aid in Preparation of Powder Diffraction Standards: Minyulite, Kal2(PO4)2(OH,F).4H20, As an Example
Authors: Blanchard Frank N.
Published: March 2019

As part of a continuing project dealing with evaluation, testing, and preparation of new high quality X-ray powder diffraction standards for phosphate and arsenate minerals, new X-ray and supporting data for minyulite, KAl2(PO4)2(0H,F).4H20, have been obtained and Interpreted with the aid of a calculated powder pattern.
Adjustment of Solid-Solid Phase Transition Temperature of Polyalcohols by the Use of Dopants*
Authors: Chandra D. , Barrett C. S. , Benson D. K.
Published: March 2019

The transition temperatures of solid-solid phase changes in selected polyalcohols, “plastic crystals,” can be adjusted by using interstitial and substitutional dopants. An investigation is under way of the structural changes in these during heating and cooling, and of the thermodynamic properties such as the transition, temperatures and enthalpy changes, as a function of the percent of dopant. The purpose of the investigation is to find and evaluate materials having potential value In thermal storage applications. Dopants for pentaerythritol discussed in this report are trimethylolpropane (TMP), ammonia, boron trifluoride, pentaglycerine (PG) and neopentylglycol (NPG).
Analysis of the Thermo-Structural Behavior of Polyethylene Using Simultaneous DSC/XRD
Authors: Crowder C. E. , Wood S. , Landes B. G. , Newman R. A. , Blazy J. A. , Bubeck R. A.
Published: March 2019

Over the past 25 years, numerous studies of polymers utilizing both X-ray diffraction (XRD) and differential scanning calorimetry (DSC) have been reported in the literature. These studies have suffered because the two techniques must be performed on separate samples and under conditions that are often dissimilar. By combining the two techniques into one instrument, typical problems encountered with variations in sample preparation and thermal and atmospheric environment are eliminated. This is quite important in the study of polymers since one must match not only temperatures between the two techniques, but also heating rates as well. Matched thermal conditions are necessary because polymer properties such as crystallinity and crystallite size depend on both the temperature and thermal history of the sample under study.
Analyses of Multi- Phase Pharmaceuticals Using SImultaneous Differential Scanning Calorimetry and X-Ray Diffraction
Authors: Fawcett T. G. , Martin E. J. , Crowder C. E. , Kincaid P. J. , Strandjord A. J. , Blazy J. A. , Armentrout D. N. , Newman R. A.
Published: March 2019

The analysis of multi-phase pharmaceuticals, particularly when similar structures are involved (i.e. polymorphs, salts or hydrates), can often be a difficult task. Historically, x-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) have been utilized to study pharmaceutical samples. Relative to other materials, diffraction data for pharmaceuticals are often complex due to the large number of diffraction maxima caused by the size of the molecule and/or the molecular symmetry. Multi-phase mixtures tend to have a large number of overlapping peaks which can hinder the difftactionist's ability to identify phases and interpret the data. When similar structures are analyzed calorimetrically, their thermal events may severely overlap (as will be shown), preventing accurate interpretation of the data. In addition there are several types of thermal events which may not be related to structural transitions. A common one in pharmaceuticals is the loss of solvent or absorbed (versus molecular) water.
Simultaneous Determination of the Lattice Constant and Elastics Strain in Cubic Single Crystal
Authors: Ortner Balder
Published: March 2019

In epitaxial single crystal growing it happens very often that the composition of the grown film, say AxB1-x C, is not known exactly. Usually it would be possible to find out that compositions imply by determining the lattice constants of the film. The problem of such a measurement lies in the fact of internal and unknown stresses in the film. On the other side the knowledge of the state of stress σ and strain ε can also be of great importance. To calculate the stresses from X- ray measurements we need the lattice constants in the unstrained condition.

Hornstra and Bartels have shown that the lattice constant can be det ermined by X-ray measurements if the strain is isotropic in the film plane. In the following we show that the lattice constant and the full strain tensor can be calculated fromat least four X- ray measurements also in the general case.
A Combined Fundamental Alphas/Curve Fitting Algorithm for Routine XRF Sample Analysis
Authors: Kalnicky Dennis J.
Published: March 2019

Analysis of sample composition and/or thickness in a routine, process-control or monitoring environment generally requires rapid turn-around time with minimal sample handling. X-ray Fluorescence (XRF) is well-suited for these kinds of analyses and has been applied to various bulk and thin sample applications (1-7). This technique is rapid, precise, non-destructive, and requires minimal sample handling.

X-ray Fluorescence is generally considered a secondary analysis technique, that is, instrumentation must be calibrated using known standards before unknown samples may be analyzed (quantitative analysis). Continuing work on standardless approaches, particularly for Energy-Dispersive XRF (EOXRF) systems, relax this requirement for some samples but the large share of XRF analyses still require calibration with standards. A number of mathematical and non-matheraatical techniques have been devised to calibrate XRF measurements for many different sample types (1,2,8,9).
Comparison of Strategies For Dealing With Unanalyzed Light Elements in Fundamental Parameters X-Ray Fluorescence Analysis
Authors: DeGroot Peter B.
Published: March 2019

The total elemental composition of a sample must be measured or specified for successful application of fundamental parameters type matrix corrections in x-ray fluorescence analyses. Unanalyzed light elements can be dealt with in three ways. They can be related to the concentration of another element by stoichiometry, calculated by difference, or their effects minimized by addition of a diluent of known composition, ‘The relative success of these approaches depends on the composition of the sample. Limiting cases tested are high or low concentrations of analytes having long or short wavelength emission lines, in the presence of additional heavy or light elements. Molybdenum oxide is used as the analyte, with the oxygen serving as a typical unanalyzed light element to be treated by stoichiometry, difference, or dilution. The accuracy and precision of the analysis for molybdenum, using either the Kα or Lα line, is the criterion for judging the success of the strategy. Experimental results and theoretical calculations using the XRF11* matrix correction program are employed. Generally, the difference strategy is inferior to stoichiometry or dilution. However, difference methods can give acceptable results except in the case of a high concentration of short wavelength analyte in a light element matrix. Where stoichiometry is not known, an assumed stoichiometry that is correct within one oxidation number gives results comparable to the difference method.
X-Ray Fluorescence Spectroscopy as a Technique for Studying Surface Concentration Profiles of Heterogeneous Catalysts
Authors: Kenny Eva M. , Palmer Burton J.
Published: March 2019

X-ray fluorescence spectroscopy is usually not considered a surface technique in the same sense as ESCA or Auger spectroscopies. However, it can be a useful tool in studying the “surface” and bulk concentrations of elements in heterogeneous catalysts. The “surface” is defined by the effective penetration depth of the analyte line of the element of interest in a specific matrix. In the example which is presented, silver on alumina, the “surface” using the Ag KB1,3 is defined by a shell 3000 microns deep while for the Ag LAI it is 15 microns. Two methods of sample preparation are discussed and data obtained using three different calculation methods is presented. Data from the x-ray fluorescence method is compared to the silver depth profile in the alumina pellets obtained by electron microprobe analysis. The XRFS method allows rapid screening of many catalyst samples for the fraction of the cost of the microprobe technique.
Sample Homogeneity and Representation in X-Ray Fluorescence Analysis of Foods*
Authors: Nielson K. K. , Rogers V. C. , Mahoney A. W.
Published: March 2019

Method validation is vital for regulatory and nutrient analysis of foods, and imposes criteria for representative sampling and analysis along with more common requirements for precision and accuracy. When solid food samples are directly analyzed by x-ray fluorescence (XRF), they must be homogeneous on a mass scale at least similar to that penetrated by the interrogating and fluorescent x-ray beams. This mass varies with x-ray energy, and hence with the elements being determined, and few data are available documenting the scale on which homogeneity can be assured. This paper examines the effective sample masses that are represented in measuring 21 different elements in pelletized dry food samples, and also the homogeneity of mimerous foods and biological standard reference materials.
On-Stream WDXRF-Analysis of Low Concentrations
Authors: Sipilä Heikki , Koskinen Jouko
Published: March 2019

Outokumpu Company has gone a long way in the last 20 years in the development and application of WDXRF-techniques in on-stream analysis of slurries in ore concentrators. The applications in which the samples were in solution form came only about 4 years ago when these analyzers were used for the first time in hydrometallurgical plants, During the past 15 years many improvements have been made in most parts of the equipment to Biake the performance and reliability better. The most important work to improve the analytical capability of the analyzer has been done on the spectrometers and detectors. This has resulted in better sensitivities and has given the possibility to go down to ppm levels in many determinations. The technical details of the improvements have been presented in several papers (1-4).
Particle Size Effects in Geological Analyses by X-Ray Fluorescence
Authors: Nielson K.K. , Rogers V.C.
Published: March 2019

Particle-size effects can cause significant errors in x-ray fluorescence (XRF) analysis of particulate materials. The effects are usually removed when samples are fused or dissolved to standardize the matrix for quantitative analysis. Recent improvements in numerical matrix corrections reduce the need to standardize the sample matrix via fusion or dissolution, particularly when the CEMAS method is used to estimate unmeasured light-element components of undefined materials for matrix calculations. A new method to correct for particle-size effects has therefore been examined to potentially avoid the need for destructive preparation of homogeneous samples.
A Paper Tape Controlled X-Ray Diffractometer for the Measurement of Retained Austenite
Authors: Kelly Carol J. , Short M. A.
Published: March 2019

The instrumentation and software for performing X-ray intensity measurements with a paper tape controlled diffractometer are described. The hardware includes two addressable axis positioners which control Slo-Syn stepping motors on the 2θ and ω) axes of the diffractometer, an addressable scaler-timer, a multiaxis programmer and a Teletype, in addition to the normal counting electronics. This system may be manually controlled with front panel switches or with instructions entered on the Teletype. In the automatic off-line mode instructions for motor speed, motor direction, starting angle, final angle, angular increment and scaler preset (time or counts) punched on paper tape are read and executed in sequence. A Teletype output of 2θ and ω angles, time and counts is obtained at each step. This off-line system was used for the measurement of austenite in H12 hot work die steel austenitized at various conditions and which contained a maximum of 13% austenite. A helium chamber was used to extend the limit of detection to 0.4% austenite. The X-ray analysis involved measuring the areas of the (200) austenite diffraction line and the (200) martensite line. For each of these lines, the system was programmed to integrate the counts over angular intervals corresponding to a low-angle background, the peak and a high-angle background using the ability of the axis positioner to stop the scaler-timer at the end of each angular interval. The additional capability of slewing rapidly between the various diffraction lines reduced the time required for automatic data collection. The present off-line system can be used to simplify other types of X-ray diffraction analysis such as residual stress and microstrain/particle size determinations, since the manual data handling can be eliminated with the computer compatible punched paper tape output. Future development of this instrumentation includes direct computer control of the diffractometer and computerized data reduction, with the advantage of a paper tape back-up system.
An Automated Electron Microprobe System
Authors: Kunz F. , Eichen E. , Matthews H. , Francis J.
Published: March 2019

An automated- electron microprobe system using an on-line 8,000 word minicomputer has been designed. The general principles and need for such a system is discussed. The microprobe-computer interface hardware consists of computer addressable axis positioners, scalers, timer and a digital to analog converter. The axis positioners are used to position the spectrometers and specimen stage, whereas the digital to analog converter is used to position the electron beam in a 1000 × 1000 point matrix. The digital to analog converter is also used to drive a X-Y recorder for computer plotting of calibration curves, pulse amplitude distributions, X-ray line profiles and wavelength scans. System software is written in the interactive CLASS language which was designed specifically for laboratory instrument control. The language permits large computer programs to be chained through a minicomputer while passing variables from one function to the next. The operating software consists of automatic peak location, sequencing of data collection, statistical analysis of data, and correction of data for fluorescence, absorption and atomic number effects. An automated quantitative analysis of several copper-gold alloys and a computerized test for specimen homogeneity is described to demonstrate system operation. Future automation considerations are also discussed.
An Automatic X-Ray Analytical Instrument for the Chemical Laboratory
Authors: Gray A.L.
Published: March 2019

Although isotope excited non-dispersive X-ray analysis has shown considerable promise for use in portable instruments and in on-line control applications, its use as a general analytical tool in the chemical laboratory has not developed as well as expected. Much of this is thought to be due to lack of flexibility in the instruments available and to difficulties with their use by unskilled operators. Wide element coverage is essential and many analytical problems arise at the light element end of the periodic table. While developing on-line techniques for light elements it was found that a measuring head using a very compact source-sample-detector geometry was well suited to a number of routine analytical laboratory problems, and enabled high precision to be obtained with minimum sample preparation for rapid single element analysis. Sensitivities in a light matrix from 100. p.p.m. for silicon to 10 p.p.m. for heavy elements were attainable. An instrument specifically for chemical laboratory use was therefore designed to accept solid, liquid and powder samples for single element analysis of silicon and all heavier elements. The instrument can give direct numerical readout of concentration and achieves high stability and precision. In its basic form it is equipped with a range of isotope excitation sources but will also accept a small X-ray tube which has been specially developed for it to provide higher sensitivity and precision. The measuring head may be removed for remote use, and multiple sample changing facilities with printout of results can be added, permitting unattended automatic routine analysis.
Small X-Ray Tubes for Energy Dispersive Analysis Using Semiconductor Spectrometers
Authors: Jaklevic J. M. , Giauque R. D. , Malone D. F. , Searles W. L.
Published: March 2019

Fast X-ray fluorescence analysis with radioisotope excitation requires intense sources to produce reasonable counting rates. The inconvenience of handling such sources and the small number of suitable radioisotopes places severe limitations on their use.

We have explored the possibility of using low-power X-ray tubes as exciting sources for energy-dispersive fluorescence analysis. The principal advantage to X-ray tubes is the ability to produce X-ray fluxes to three orders of magnitude higher than those obtained with convenient radioisotope sources while dissipating only a few watts in the tube. Furthermore, the variety of possible anode materials and range of currents in the tube make possible optimum choice of exciting energy and intensity for particular applications.

We have designed and tested such tubes in a variety of anode configurations suitable for fluorescence excitation. Using either X-ray filtering techniques or multiple fluorescence geometries It is possible to significantly reduce the Bremsstrahlung background relative to characteristic radiation.

As compared with normal radioisotope-target assemblies, excitation of a sample by the X-ray tube results in comparable sensitivity in only a tenth to one hundredth of the time.
Old Errors and New Corrections in X-Ray Line Profile Analysis
Authors: Kidron A. , Angelis R.J. De
Published: March 2019

In recent years there has been an increasing awareness of the errors involved in X-Ray line profile analysis which is used to calculate coherently diffracting particle size, local strains and stacking fault probabilities in materials. Here a modified version of a Least Squares Analysis (L.S.A.) of the Fourier coefficients is presented. This method gives a possibility of making new corrections in a more natural and accurate way to the errors in the line profile analysis.

The first error involves the fact that experimentally one accumulates data as a function of θ - the Bragg angle, whereas the Fourier analysis is made in terms of equidistant steps in sin θ, In the L.S.A. the data does not have to be given in equidistant steps of sin θ in order to be analyzed, so that this type of error does not exist at all.

In the L.S.A. there is also no need for the explicit separation of the Kαl component from the total doublet line profile. This type of analysis is taken here one step further and it is shown that one can calculate the Fourier coefficients of each one of two merging lines. Each of these lines may be doublets in themselves and the two series of Fourier coefficients are calculated around the centers of gravity of their Kαl components respectively.

The existence of an extra background which usually affects the Fourier coefficients when calculated by the Fourier transform method does not affect the L.S.A. except for a normalization factor. Here it is shown that this gives the possibility of calculating the strains without errors associated with the extra background.
The Effects of Self-Irradiation on the Laitice of 238(80%)Puo2
Authors: Roof R. B.
Published: March 2019

As a function of self-irradiation, the crystalline lattice of 238(80%) PuO2 is gradually altered. The technique of x-ray line broadening was used to search for changes in the crystallite size and strain in the lattice following an initial annealing treatment. She integral breadth, Fourier coefficient, and variance methods were used to analyze the broadening of the x-ray powder pattern lines. The mechanism of alteration appears to be one of retained strain as no evidence was forthcoming from these techniques to indicate that the material undergoes significant crystallite size change. The strain in the lattice increased from zero at time zero to approximately 0.2% during a 2-year period.
The Disorder-Order Transformation in Ni4Mo
Authors: Ling Fu-Wen , Starke E. A.
Published: March 2019

The progressive ordering of a single crystal of Ni4Mo by isothermal ageing at 650°C (transformation temperature = 868°C) has been studied by x-ray line broadening techniques using the Warren- Averbach method employing computer techniques. The long-range-order parameter, antiphase domain size, and internal strains were measured as a function of ordering time and compared with those previously obtained at 700°C. The activation energies for domain growth and ordering were found to be 91 kcal/mole and 44.5 kcal/mole respectively. The rms strain developed during ordering was found to be dependent on the degree of tetragonality of the structure.
Elemental X-Ray Cross Sections at Selected Wavelengths
Authors: Bracewell Bobby L. , Veigele William J.
Published: March 2019

Revised tables of x-ray mass attenuation and absorption cross sections have been prepared for the elements with atomic numbers one to 94 at selected wavelengths of interest to spectroscopists, microprobe users, diffraction workers, etc. The tables are derived from an x-ray cross section compilation to be published during the summer of 1971. The new compilation is a revision of a previous work and provides photoelectric, coherent scattering, incoherent scattering, absorption component of incoherent scattering and total attenuation cross sections for 94 elements for the photon energy range 0.1 keV to 1 MeV (0.0124 Å to 124 Å). The cross sections for energies greater than 1 keV (12.4 Å) were determined from experimental attenuation data and theoretical scattering cross sections calculated using form factors and incoherent scattering functions based on a relativistic self consistent field method. For hydrogen, the photoelectric absorption cross sections were calculated exactly. Least squares procedures were used to interpolate and extrapolate for elements and photon energies where no experimental data were found. Cross sections for the energy range 0.1 keV to 1 keV (12.4 Å to 124 Å) were calculated using nonrelativistic, single electron, self-consistent field theory with Herman-Skillman bound state wavefunctions, A brief description is given of the assumptions and methods used in preparing the revised compilation, and estimated uncertainties in the cross section are reported. Examples illustrating agreement between tabulated values and experimental data are given and a comparison is made with values taken from earlier x-ray cross section compilations.
Use Of A Solid-State Detector for the Analysis of X-Rays Excited in Silicate Rocks by Alpha-Particle Bombardment
Authors: Franzgrote Ernest J.
Published: March 2019

The analysis of alpha-excited X-rays has been studied as a possible addition to the alpha-scattering technique used on the Surveyor spacecraft for the first in situ chemical analyses of the lunar surface.

Targets of pure elements, simple compounds, and silicate rocks have been exposed to alpha particles and other radiation from a curium-214 source and the resulting X-ray spectra measured by means of a cooled lithium-drifted silicon detector and pulse-height analysis.

Alpha-particle bombardment is a simple and efficient means of X-ray excitation for light elements. Useful spectra of silicate rocks may be obtained in a few minutes with a source activity of 50 millicuries, a detector area of 0.1 cm2 and a sample distance of 3 cm. An advantage over electron excitation is the higher characteristic response relative to the bremsstrahlung continuum. Peak-to- background ratios of greater than 100 to 1 have been obtained for elemental targets. Relative efficiencies of X-ray excitation by alpha particles and by X-rays from the curium source have been determined.

Resolution of the detector system used is approximately 150 eV for the lighter elements. This is sufficient to resolve the Kα X-rays of the geochemically important elements, Na, Mg, Al, and Si in silicate rocks. Although these and lighter elements are analyzed as well or better by the alpha-scattering and alpha-proton technique, the X-ray mode enables results to be obtained more quickly.

The study shows that the addition of an X-ray mode to the alpha-scattering analysis technique would result in a significant improvement in analytical capability for the heavier elements. In particular, important indicators of geochemical differentiation such as K and Ca (which are only marginally separated in an alpha-scattering and alpha-proton analysis) may be determined quantitatively by measuring the alpha-excited X-rays. An X-ray detector is under consideration as an addition to an alpha-scattering instrument now under development for possible use on a Mars-lander mission.
Evaluation of X-Ray Image Intensifiers as Detectors for X-Ray Astronomy
Authors: Andrus W. S. , VanSpeybroeck L. P. , Kellogg E. M. , Gursky H.
Published: March 2019

Proposed experiments in X-ray astronomy require a detector capable of forming a high resolution image of a weak source. An X-ray image intensifier incorporating a microchannel plate (MCP) has been studied as a candidate for this application. Experiments have shown that the device is sensitive to single X-ray photons and has adequate quantum efficiency. Consideration has been given to the possibility of improving the quantum efficiency by deposition on the input surface of the MCP of a material with high photoelectric yield in the wavelength region of interest. Photographs of the output light from the image intensifier show than an X-ray photon detected at the MCP results in a spot on the film of about 60μ M diameter. Since the position of the centroid of the spot could be determined to better accuracy, the device h as sufficient resolution for the contemplated experiment. Detector noise is found to be so low that it would no limitation on the experiment's sensitivity. The image can be retrieved and transmitted to the ground by focussing a television camera on the face of the fiber optic output of the X-ray image intensifier; the data show that a Secondary Electron Conduction vidicon is sensitive enough to se e the output resulting from a single X-ray photon. An alternative technique would sense charge pulses from the MCP on a fine wire grid, avoiding the need for a phosphor and providing superior time resolution and simpler data compression. Since the detector is to be used in a satellite-borne experiment, its space qualification must be established. Two launches on sounding rockets have failed to impair the usefulness of one unit that has been studied over a period of more than a year. A long term test of continuous performance in high vacuum has so far shown encouraging results. A count life test has shown that an MCP can last through detection of orders of magnitude more counts than could be expected in the course of a mission. X-ray image intensifiers appear entirely suitable for high resolution X-ray astronomy.
The Determination of the Axis of Lattice Rotation With Respect to a Change is Texture
Authors: Feng C.
Published: March 2019

It is known that a change in texture may take place in various metals and alloys following cold working, fabrication and recrystallization processes. Such change may be determined by an analysis of the pole figures obtained from the x-ray diffraction data. In numerous occasions, it is analogous to a lattice rotation.

In the present paper, a method is derived to identify the axis of rotation with respect to the starting and final texture of a given specimen. Once this axis is identified, the amount and the direction of the lattice rotation can be accurately determined. The techniques in obtaining a solution by mathematical calculation, and by stereographic presentation will be described. Discussion will be made also of the various parameters which may affect the validity and accuracy of the determination.
X-Ray Investigations of Spinel Substrates
Authors: Maurits J. E. A. , Hawley A. M.
Published: March 2019

Recent advances in MOS integrated circuit technology have opened new, high-volume applications utilizing epitaxial silicon-on- insulating substrates. To provide good quality heteroepitaxial silicon films for the semiconductor industry, a development program has been established to improve both the crystalline quality and the fabrication techniques for the most promising current substrate, magnesium aluminum spinel.

The role of X-ray diffraction techniques in the investigation of crystal quality, substrate surface quality, and epitaxial film quality are discussed, and results interpreted as the program is traced from crystal growth to epitaxial film analysis.
Effect of Ion Exchange Resin Particle Size on X-Ray Fluorescent Analysis
Authors: Allen A. L. , Rose V. C.
Published: March 2019

The effect of resin particles on copper x-ray fluorescence was studied. For any given resin size the relationship between copper concentration and x-ray intensity was linear. As the particle size decreased, the x-ray intensity increased for any given copper concentration. The general shape of the curves are similar to the ones predicted by Bernstein for a minor constituent in a power sample. This study indicates that the variation in intensity with particle size can be eliminated by using resins with a mean particle diameter of 56 microns or less.
Flame Technique for High Temperature Single Crystal Weissenberg Photography (1000-3000°C)
Authors: Viswamitra M. A. , Jayalakshmi K.
Published: March 2019

Oxy-acetylene flame heating has been employed with an ordinary Nonius Weissenberg camera for high-temperature single-crystal studies over the the range 1000-3000°C. The regulator blow pipe is mounted horizontally on the camera track and one end of the experimental crystal (1 cm long) is heated by the vertical flame issuing out of a 0.5 mm bore nozzle* A long slot cut at the top of the film-cassette allows the flame to escape out without touching the X-ray film. The film-cassette consists of two split-halves hinged on one side so that it can be opened and slipped over the screen tubes. This arrangement avoids the necessity for removing the flame each time a new film is mounted on the camera. The goniometer arcs can be positioned during high-temperature exposures, and there is no need to water-cool the cassette up to the highest temperature. The device has been used to take photographs of MgO single crystals at 2100°C. It permits a ready application to diffractometers based on Weissenberg geometry.
Simultaneous X-Ray Emission Analysis of P, Si, Ca, Fe, Al, and Mg in Phosphate Rock Using a Small Computer to Correct for Matrix Variations
Authors: McKinney Charles N. , Rosenberg Arthur S.
Published: March 2019

Phosphate rock from different sources varies widely in composition. This results in a large interelement effect. A mathematical model was developed to correct for matrix variations in each sample. This model utilizes the X-ray intensity from each of the six elements considered and the mass absorption coefficients of the elements to calculate concentrations. Accurate analyses for P, Si, Ca, Fe, Al, and Mg are obtained using this model. The X-ray instrument is interfaced with a small computer that performs the calculations on each sample and prints the results.

Sample preparation, standardization and the computer programs used for sample calculation and standardization will be discussed.
X-Ray Spectrometric Properties of Potassium Acid Phthalate Crystals
Authors: Liefeld R. J. , Hanzgly S. , Kirby T. B. , Mott D.
Published: March 2019

The results of two crystal measurements of potassium acid phthalate crystal first order parallel position rocking curves, percent reflections, and reflection coefficients are presented. They cover the 4-24 Ǻ wavelength range and are typical of results with cleaved crystals illuminated over areas of one-half to two square inches. The energy resolution available with these crystals is shown to be nearly constant at about two-thirds of an electron volt over most of the energy range studied and the coefficient of reflection is also nearly constant at about 1 x 10-4 radians. A pronounced line-like reflectivity structure at 23.3 Ǻ is exhibited which is probably associated with oxygen atom K-shell absorption.
Grating Studies at X-Ray Wavelengths
Authors: Speer R. J.
Published: March 2019

A programme of grazing incidence grating studies is described, undertaken in collaboraion with A.W.R.S. Aldermaston, U.K.A.E.A. Culham and N.P.L. Teddington. The wavelength range of interest is from lǺ - 300Ǻ with special emhasis placed on focusing systems for use below 5Ǻ.
X-Ray Topographic Study of Vibrating Dislocations in Ice Under an Ac Electric Field
Authors: Itagaki K.
Published: March 2019

The behavior of charged dislocations in alkali-halide crystals has been drawing attention in connection with the charge transfer which occurs during plastic deformation.1-9 Recently, Itagaki proposed a charged dislocation mechanism to account for the dielectric properties of ice.10 His theory is in part supported by the dielectric measurements o f strained ice made by Ackley and Itagaki.11 Brantley and Bauer12 derived similar equations for the dielectric constant based on charged dislocation motion. They also proposed a new mechanism for apparent piezoelectricity based on moving charged dislocations in an electric field .
A Versatile Bragg-Brentano/Seeman-Bohlin Powder Diffractometer
Authors: King H.W. , Gillham C.J. , Huggins F.G.
Published: March 2019

An interchangeable Bragg-Brentano:Seeman-Bohlin diffractometer, with variable specimen setting, has been constructed. A study of the influence of the geometry on the resolution, angular displacement and intensity of diffraction profiles clearly demonstrates that the standard Bragg-Brentano method is to be preferred when recording Bragg reflections below 40°,2θ. At higher Bragg angles, which permit the specimen to be set further away from the X-ray source, it is demonstrated that the diffracted intensity of the Seeman-Bohlin method can be increased above that of the Bragg- Brentano because the use of an increased divergent angle does not reduce the resolution. A study of the effect of specimen setting on the systematic errors associated with the Seeman- Bohlin geometry indicates that a setting of 60° (half-angle from the X-ray source) gives optimum resolution with minimum displacement error.
Measurement of Long Range Order in the γ’ Phase of Nickel-Base Superalloys
Authors: Mihalisin J.R.
Published: March 2019

The long range order parameter (S) has been measured at room- temperature on the γ’ phase extracted from IN-731 and alloys 713C and 713LC by x-ray diffraction techniques. Measurements were obtained from specimens of IN-731 and alloy 713LC in the as-cast condition and after long time rupture testing. The alloy 713 c specimens were in the as-cast and high temperature heat treated conditions.

It was found that long range order in the γ’ phase of IN-731 and alloy 713LC was changed very little after long time rupture testing, and after high temperature heat treatment in the case of alloy 713C.
A New Absolute-Scale Small-Angle X-Ray Scattering Instrument
Authors: Pessen H. , F. Kumosinski T. , N. Timasheff S. , R. Calhoun R. , A. Connelly J.
Published: March 2019

A small-angle X-ray scattering apparatus is described which is based on a Guinier focusing arrangement, utilizing a fine-focus tube, a Johann-type curved-crystal monochromator, two goniometermounted beam-defining slits and proportional detection. It differs from previously described instruments in important respects. Using a horizontal goniometer, it affords ease of access and mechanical stability to mounted parts, such as slits and beam stop. The major instrument assemblies--the horizontal tube housing producing the vertical line-shaped beam, and the goniometer table--are mounted on a granite surface plate for stability. For ease, precision and reproducibility in alignment, fine adjustments, with micrometer heads or dial indicators where advisable, are provided for all pertinent rotational and translational motions of the various subassemblies. In particular, provision is made for fine adjustment of the goniometer as a whole with respect to the X-ray source, to facilitate threading the monochromator-focused beam through the slit system and the center of rotation of the detector arm.
The Single Crystal Vs. The Powder Method for Identification of Crystalline Materials
Authors: Mighell Alan D.
Published: March 2019

Single crystal X-ray diffraction methods for the study of crystalline materials, although reliable, have been, mainly confined to the academic laboratory because of the rather lengthy and complex procedure necessary to determine the unit cell and the space group. The situation has now changed. Several recent developments give single-crystal methods considerable potential for routine Industrial use. They Include growth of the data base, advances in lattice theory, and automation of the single-crystal X-ray diffractometer. To identify an unknown, one can start with a single crystal, mount it on the diffractometer, determine a refined primitive cell, reduce the cell, and check against a file of known reduced cells. The entire procedure can be automated. As a result, the single-crystal X-ray diffraction method can now complement the powder method for the routine analysis of crystalline materials.
Chemical Identification and Pease Analysis of Transplutonium Elements and Compounds via X-Ray Powder Diffraction
Authors: Peterson J. R.
Published: March 2019

X-Ray powder diffraction (XRPD) techniques are compatible with studies of the transplutonium elements and their compounds. Only limited amounts of these materials are available for study, and microchemical techniques exist for the preparation of samples suitable for X-ray analysis. The microscale syntheses, systems for annealing/ quenching to bring about phase transformations, and a modified powder diffraction camera are described. Examples of recent and current work are presented to illustrate some specific applications of XRPD to basic, transplutonium element research.
Energy Dispersive X-ray Diffractometry
Authors: Mantier Michael , Parrish William
Published: March 2019

This paper describes the principles, methods, instrumentation and results of EDXKD and a computer method of profile fitting to obtain corrected intensities and peak energies from isolated and overlapping reflections. The profile, P, of a diffraction peak is a convolution of the incident X-ray spectrum, X, the geometrical aberrations, T, the contribution from the specimen, S, and the detector resolution function, D.
Some Topographic Observations of the Effects of Dynamical Diffraction in Imperfect Metal Crystals
Authors: Boettinger William J. , Burdette Harold E. , Farabaugh Edward N. , Kuriyama Masao
Published: March 2019

X-ray diffraction topographs obtained in the anomalous transmission geometry contain images which are quite different from those obtained from thin crystals (μL<=l). In this paper various topographic images which are unique to thick crystals (μL>10) will be presented and discussed in terms of dynamical diffraction in imperfect crystals. First, it is observed in topographs that images of crystal imperfections caused by disruption of the anomalous transmission effect are slightly broader or more diffuse in the H-diffracted (Bragg-diffracted) beam than in the O-diffracted (transmitted beam). These observations have been made in both copper and nickel crystals. Such broadening can be explained by the presence of unique extinction terms in the expression for the intensity of the dynamically diffracted beam in an imperfect crystal.
Direct Display of X-ray Topographic Images
Authors: Robert E Green
Published: March 2019

The purpose of the present paper is to give a comprehensive state of the art review of all electro-optical systems used to date for direct viewing of X-ray topographic images. Consideration is given to both direct conversion X-ray sensitive vidicon systems and to indirect conversion systems which use fluorescent screens to convert the X-ray image into a visible one. Included in this review is a discussion of the relative advantages and disadvantages of the various electro-optical systems, including cost, versatility, portability, simplicity of operation, sensitivity, and resolution capability.