bluuebunny/crossref_metadata_2025 huggingface dataset:
The Evaluation and Improvement of X-Ray Emission Analysis of Raw-Mix and Finished Cements
Authors: Andermann George , Allen J. D.
Published: March 2019

With modern X-ray instruments, precision is generally satisfactory for the analysis of MgO, Al2O3, SiO2, CaO, and Fe2O3 in finished and raw-mix cements and other similar materials. Accuracy, that is, agreement between cheraicaland X-ray values, quite frequently is much worse than precision. Some typical examples illustrating this point are reviewed.

In the soft region, generally, it has not been possible to assign the cause of iuaccuracy to interelement effects. The hypothesis is formulated that in the soft region this problem could be due to mineralogical differences and inhomogeneity on a micro scale. Theoretical calculations support the plausibility of this argument.

To improve accuracy, present techniques have been based on type standardization, acid digestion fusion using a high flux-to-sample ratio, etc. In general, these methods have certain basic limitations. In order to retain useful intensities and lineto- background ratios for the soft region, 8 new fusion technique has been developed. The experimental data based on this method of reducing micro-inhomogeneity and eliminating minaralogical differences indicate improvements in accuracy. In the case of finished cements the improvements in accuracy have been quite modest. With rawmix cements, startling improvements have been obtained for the analysis of SiO2 and CaO.
New Instruments for X-Ray Analysis
Authors: Furnas Thomas C. , White Eugene W.
Published: March 2019

New Instruments for X-ray or neutron diffraction or for analyses by X-ray spectrographic methods are described. They incorporate a variety of new features which open a broad new scope of experimental techniques to the investigator. The diffractometer can be used with the diffraction plane either horizontal or vertical. The X-ray tube is conveniently supported by the diffractometer, allowing one to adjust the take-off angle from 0 to 10° without disturbing the precise alignment of the instrument. The 2θ angle bisecting mechanism functions throughout a 360° range and allows independent rotation (ω) of the specimen about the common axis. It is designed specifically for fully automatic remotely programed operation in addition to the usual manual modes.

The constant-potential generator is rated up to 50 ma at 50 kvcp and up to 40 ma at 60 kvcp, A monitor-type switch selects combinations of kilovolts and milliamperes in a manner such that exact reproducibility of settings is assured.

The dual-function strip-chart recorder incorporates both linear and three-cycle logarithmic slide wires so that each uses the output from the same linear rate meter.

The Integrated Radiation Analyzer consists of a pulse-height analyzer, electronic timer, high-speed sealer, precision linear ratemeter, power supply, printer, and diffractometer control. Integration of these components has made possible unique programing for X-ray analysis.
Novel Features Incorporated in a New Automatic X-Ray Fluorescence Spectrometer
Authors: Whitcomb Peter B.
Published: March 2019

A flat-crystal spectrometer is described that is fully evacuated to permit analysis of light elements. A uniselector in conjunction with a programing unit allows the crystal to be moved to any series of angles with stopping intervals as close as 0.01°. Detectors are a scintillation counter and a flow proportional counter driven at twice the angular velocity of the crystal to maintain them in correct position, A further detector is used to monitor the primary X-ray beam. Programing is achieved by means of a patchboard, and each board allows up to 20 elements to be measured at one time and in a sequence as desired, Pinal results appear in tabular forrn on an electric typewriter. Provisions are also provided for continuous scanning, the X-ray spectrum being plotted on a strip chart recorder. The sample is brought into position with a slide arranged so that the spectrometer may be kept continually evacuated and only a small pocket of air need be pumped. Alternately, helium may be used with resultant low consumption per sample.
X-Ray Investigations on Some Salts of Hydrazine and Hydrazine Derivatives
Authors: Stammler M. , Orcutt D.
Published: March 2019

The salts of hydrazine or methyl derivatives of hydrazine were prepared by neutralization of the base with inorganic acids, for instance, HBF4, HClO4, H SO4, and HCl. Upon recrystallization of the product from a suitable solvent, X-ray diffraction patterns were obtained. Hydrazine tetrafluoborate H2N-NH2·HBF4 was found to crystallize in the monoclinic system. Cell dimensions and possible space groups were determined. The corresponding perchlorate salt crystallizes in two forms, one of which is isomorphous with hydrazine tetrafluoborate. The second form seems to be stabilized by small amounts of water.

The tetrafluoborate salt was prepared from the 1,1-dimethyl hydrazine. It was found to crystallize in the tetragonal system with a primitive unit cell. The perchlorate salt of this base is isomorphous with the fluoborate but with a slightly larger unit cell. Both materials undergo plastic-like deformation. The general appearance and mechanical properties are similar to those of a hydrocarbon wax. The 1,1-dimethyl hydrazine sulfate and the 1,1-dimethyl hydrazine hydrochloride have a lower symmetry than the HBF4 salt and do not show the wax-like properties of the latter. Based on the study of these chemically related compounds an explanation is offered for the properties of 1,1-dimethyl hydrazine tetrafluoborate in terms of crystalline structure.
A High-Temperature X-Ray Diffractometer Specimen Holder
Authors: Dreikorn R. E.
Published: March 2019

A high-temperature X-ray diffractometer specimen holder that fits on a standard General Electric diffractometer is described. The thermal expansion of iridium from 23 to 1720°C is reported as 7.5 • 10−6−6 per °C and diagrams made at 2000°C are shown.
A Weighted Least-Squares Parametric Method of Reducing Nuclear-Reactor Gamma Spectral Data
Authors: Whiton J. C. , Gamble R. L. , Thornton R. M.
Published: March 2019

A mathematical method has been developed which reduces nuclear-reactor gamma pulse-height spectral data to the form of differential energy spectra through the use of a high-speed computer machine. In essence, the method consists of a least-squares fit of weighted multichannel analyzer data and the utilization of curve-smoothing parametrization. The least-squares approach tends to reduce the magnitude of data that must be handled, i.e., reduces the order of matrix involved. Weighting is used to obtain fractional deviations for minimization by lease squares and thus obtain a satisfactory fit throughout the entire channel range. The parametrization smoothes the reduced data by making use of the fact that reactor gamma spectra can be represented by the product of an exponential and a polynomial. Difficulties that arise when pure matrix inversion is applied have been obviated, and the advantage of high-speed data reduction is gained through the use of an IBM 704-7090 computer program. Error analyses have been undertaken, and data have been reduced for comparative purposes. Results are included in the presentation of the investigation.
X-Ray Absorption-Edge Determination of Cobalt in Complex Mixtures*
Authors: Hakkila E.A. , Waterbury G.R.
Published: March 2019

The application of the X-ray absorption-edge technique was extended to the determination of cobalt in aqueous and alcoholic solutions containing a wide variety of impurity elements. In the procedure developed, secondary radiation from a 50% copper-nickel alloy is passed through an absorption cell filled alternately with the solvent and the sample solution. The transmitted Intensities of the Kα lines for copper and nickel are measured, and the concentration of cobalt is determined using accepted absorption principles. The K absorption edge for cobalt occurs at 1.604 A, restricting cell construction materials and solvents to those containing light elements with low X-ray absorption characteristics and also limiting the path length of the cell.

Cells of 0.16- and 0.34-cm path length were used in the analysis of aqueous and alcoholic solutions, respectively. With the 0.16-cm path-length cell, relative standard deviations of 4.6 to 0.5% were obtained for cobalt concentrations ranging from 1.00 to 10.00 mg/ml for known aqueous solutions that contain various known concentrations of nitric acid. With the longer path-length cell, relative standard deviations from 1.8 to 0.46% were obtained for cobalt concentrations in the same range in known alcoholic solutions containing various known concentrations of nitric acid. The standard deviation of determining the blank is 0.043 mg of cobalt per milliliter for the 0.16-cm cell and 0.016 mg of cobalt per milliliter for the longer cell.

A Norelco X-ray spectrograph with a three-position head was used in these analyses. Less than 5 min is required to convert this instrument from normal fluorescence operation to absorption-edge analysis. Approximately 15 to 20 analyses can be performed daily.
Surface Preparation of Solid Metallic Samples for X-Ray Spectrochemical Analysis
Authors: Michaelis R.E. , Kilday Betty Ann
Published: March 2019

In X-ray spectrochemical determinations, the surface preparation of metal samples is important since the emitted secondary radiation is absorbed except for that emerging from the immediate surface. Surface preparation also has been found to be a critical factor in eliminating or at least in minimizing the effects of certain metallurgical changes among or within samples on the X-ray determinations. For example, a change of particle size of an undissolved constituent, or a change in grain size, may markedly influence the X-ray analysis, depending on the surface preparation. A metallographic polishing technique, whereby the sample surfaces were finished with ¼μ diamond dust, was reported for the determination of lead in leaded steel (Kilday and Michaelis, in press). This investigation has been extended to other materials such as hypereutectic silicon-aluminum alloy and white-cast iron. A comparison is made of the effects of different surface preparations on X-ray determinations.
Diffraction Effects from Irradiated Aluminum Single Crystals*
Authors: Kissinger H. E.
Published: March 2019

The effect of substructural perfection on the accumulation of irradiation damage in aluminum was examined. Large single crystals with extensive substructure and crystals essentially free of substructure, all with faces cut parallel to crystal planes, were subjected to neutron irradiation. Subsequent examination by X-ray diffraction revealed pronounced changes in integrated intensity and Debye-Waller temperature factor for the substructure-free crystals; these effects disappeared upon re-etching of the surface. Laue photographs showed that the normal single-crystal pattern was partially obscured by a polycrystalline effect which also disappeared upon etching. Crystals with extensive substructure showed no such effects.

This diffraction evidence supports the view that irradiation-induced defects in aluminum migrate to and collect at the crystal surface if no internal trapping sites exist.
Low-Temperature Transitions of Some Ammonium Salts
Authors: Stammler M. , Orcutt D. , Colodny P. C.
Published: March 2019

X-ray diffraction studies were performed on ammonium fluoroborate [NH4BF4], ammonium perchlorate [NH4ClO4], ammonium chloride [NH4CI] and ammonium phosphate [(NH4)H2PO4] within a temperature range of ambient to −190°C. For these experiments a specimen holder was designed to effect rapid cooling of the sample. Results indicate that the fluorob orate and perchlorate salts undergo a polymorphic transition at −190°C. The decreasing intensities of the (011) and (112) reflections of the orthorhombic modification indicates a firstorder reaction. No transition was observed when these salts were cooled to −40°C. The ammonium chloride shows a transition at about −30°C which confirms the results obtained by G. H. Goldschmidt and D. G. Hurst. The ammonium phosphate (NH4)H2PO4, which is tetragonal at ambient temperature also undergoes a transition if cooled to −190°C. The kinetics of this reaction are discussed.
Some X-Ray Generator Characteristics to Consider in Order to Realize the Optimum Stability and Reproducibility of Intensity Measurements
Authors: Torkildsen R.
Published: March 2019

This paper presents some of the physical considerations which must be considered in operating an X-ray generator to obtain maximum stability and reproducibility of intensity measurements. In addition, a typical X-ray generator will be discussed from the standpoint of enabling the user to realize all of the stability and reproducibility capabilities which were designed into the equipment.
Determination of Aluminum in Iron-Aluminum Alloys by Vacuum X-Ray Fluorescence
Authors: Wagner J. C. , Bryan F. R.
Published: March 2019

Aluminum, is determined within the range 2-16% in iron. Repeatability of X-ray determinations is within a standard deviation of 0.07 % aluminum for a sample containing 10.2% aluminum. The standard deviation of the chemical values from the straight line calibration curve is 0.3% aluminum. X-ray analytical time is approximately 5% of the time required for chemical analysis. Peak-to-background ratio is improved by using a chromium-target thin-window X-ray tube instead of a tungsten tube.
Design Considerations for On-Stream X-Ray Analysis
Authors: Kiley W. R. , Deichert R. W.
Published: March 2019

Several design concepts were evaluated for on-stream X-ray analysis, chief among which were: (1) sample presentation, (2) X-ray spectrograph and (3) data handling. The sample is presented to the X-ray spectrograph through a vertical cell having a mylar window and a device to measure variations in sample density. The X-ray spectrograph is of fixed-channel, modular design, with a capacity of up to six channels, and is designed for use in industrial environments. The complete spectrograph can be translated in a horizontal plane to position itself and determine the elemental composition in a series of sample cells. The data handling uses digital circuitry to permit normal use of analog readouts or digital data logging systems. Operational data are given for on-stream analysis.
The X-Ray Diffraction Measurement of Residual Stresses in Aluminum Alloys
Authors: Larson Ronald C.
Published: March 2019

This paper presents the theoretical and practical aspects of measuring residual stresses by X-ray diffraction with emphasis on the analysis of aluminum alloys. The theoretical considerations of radiation) beam geometry, and peak location will be discussed in regard to establishing optimum analysis techniques. The precision and reproducibility of this technique have been investigated so that results can be applied accurately. The approach, however, is basically a practical one, with the intent of studying residual stress systems as they affect engineering applications. Residual stress systems produced by thermal and mechanical treatments have been determined and the effect of treatment modifications and variations on the resultant stress system have been analyzed. The effect of operational variables such as time and temperature on the developed stress system are shown. From this, the merits of a particular treatment can be determined with respect to its intended application.

Analysis of solution heat-treated and quenched 2014 aluminum has shown a significant effect of the quench temperature on the resultant residual stress system. The results obtained from shot-peening this alloy are presented, as well as the effect of time and temperature on the shot-peened stress gradient.
Analysis of the Broadening of Powder Pattern Peaks from Cold-Worked Face-Centered and Body-Centered Cubic Metals
Authors: Wagner C. N. J. , Aqua E. N.
Published: March 2019

The broadening of powder pattern peaks of metals is normally caused by small crystallite size and by distortions within the crystallites as a consequence of dislocation configurations. In addition, the experimental diffraction geometry contributes to the line broadening. Using Cu Kα radiation, we recorded the peak profiles of the cold-worked and annealed filings of tungsten, niobium, aluminum, and silver-indium alloys with a standard focusing diffractometer. The Rachinger method was applied to separate the Kα1 and Kα2 peaks, and the Kα1 peaks were subjected to a Fourier analysis. Elimination of the instrumental broadening was carried out by the Stokes method, which does not require any assumptions concerning the mathematical description of the diffraction peak profile.

The Fourier coefficients, AL, were separated into the fraction produced by particle size, ALFF, and by strains, ALe, by the Warren-Averbach method and plotted as a function of the distance L = ndhkl, normal to the reflecting planes (hkl) of spacing dhkl. The negative, reciprocal initial slope of the ALPF vs. L curve is equal to the effective particle size Deff, which contains the effects of the true crystallite size and faulting. The coefficients ALβ = AL/ALPF are used to calculate the root mean square strain <∊L2>1/2. The sum of the ALPF, which is proportional to a reciprocal integral breadth, leads to a different particle size, DWAPF, which is also dependent upon the crystallite size and faulting. The sum of the AL6 values is a measure of the strain ƐWA.

The integral breadths bst, corrected by the Stokes method, i.e.,

are separated into a particle size term bstPF and distortion term bSts using the relations . It is found that only the first relation leads to particle sizes DG,StPF and strains ∊G,st similar to those obtained by the summation of the ALPF and AL6, i.e., DWAPF and ∊wA, respectively. The integral breadths of the cold-worked peaks Bew and of the annealed standards bA. were also calculated, using the Lauc definition of B equal to area per peak maximum. A comparison of the values of bst/Bcw with bA/Bew for bA/Bew < 0.6 shows that all data follow the parabolic relation b/Bew = 1 − bA2/Bew2. The maximum deviation of bst/Bew from the parabola is less than 10%.
Dependence of Lattice Parameters on Various Angular Measures of Diffractometer Line Profiles*
Authors: Parrish W. , Taylor J. , Mack M.
Published: March 2019

When the accuracy of a lattice parameter determination is carried beyond about 0.01 % it becomes of special importance to consider the equivalence of λ and θ in solving the Bragg equation for d. A reference angle on the observed diffractometer profile must be identified with the corresponding wavelength, of the incident X-ray spectral distribution. Exact identity is not possible because the diffractometer profiles are broadened, distorted asymmetrically, and displaced from their correct positions by amounts dependent on the shape of the incident spectral lines, the angular separation of the Kα1,2 doublet lines, and the specimen, instrumental, and geometrical aberrations innerent in the experimental method. The aberration functions vary with the experimental conditions and are Bragg-angle-dependent, thereby introducing systematic errors which are not eliminated by extrapolation procedures.

Most of the published diffractometer measurements of lattice parameters have used as the reflection angle, 28, of the diffractometer profile the peak P(2θ) or the midpoint of chords at various heights above background M1/2(2θ), M2/3(2θ), etc., of the Kα1 line. The relationship between these various angular measures of the line profile is not constant; P(2θ) may be equai to, greater than, or less than M1/2(2θ), depending on the asymmetry of the line profile. The X-ray wavelengths currently used in diffractometry refer to the peak P(λ) of the spectral distribution. The use of P(λ) with different angular measures of the diffractometer profiles results in a range of d's from which different values of the lattice parameters are calculated. The selection of arbitrary methods of defining 2θ does not take into account the significant aspects of the diffraction process, nor does it facilitate the correction of the data for systematic errors inherent in the experimental measurements.
Prealloyed Iron-Nickel Powders by an Amalgamation Process
Authors: Peavler R. J. , Ananthanarayanan N. I.
Published: March 2019

X-ray studies indicate that mixed iron and nickel “amalgams” are reactive even at room temperature. By distilling off the mercury from these amalgams at temperatures between 400 and 100°C, ultrafine iron-nickel alloy powders are readily obtained. X-ray studies show that these powders possess equilibrium structures corresponding to the temperature of preparation. Alloy powders belonging to many alloy systems and having controlled composition, purity, and particle size may be prepared by this process. One special use of the process is in the preparation of homogeneous alloy powders for studying solid state equilibria below 400°C, particularly in alloy systems with sluggish transformations, the process being invaluable in the temperature range between 200 and 100°C, Another is in the preparation of ultrafine metal and alloy powders with equally fine, if not finer, dispersions of other phases, suited for studying dispersion-strengthening. Both of these special uses are currently under investigation,
A Study of Solid-Solution Formation in the Milling of TiCl3—AlCl3 Powder Mixtures
Authors: Wilchinsky Zigmond W. , Looney Ralph W.
Published: March 2019

Solid solutions of AlCl3 and TiCl3 were formed in all proportions by milling together dry powders of AlCl3 and TiCl3 (delta crystalline modification). For each composition, X-ray diffraction showed a single phase having a high degree of layer stacking disorder. These materials, including milled AlCl3, were isomorphous with the so-called delta modification of TiCl3.

The presence of solid solutions was investigated primarily by lattice parameter measurements made with a diffractometer and carried out with the aid of internal standards. For the milled materials, lattice parameter changes were observed not only with changes of composition, but also with the crystallite size. In terms of the system of hexagonal axes used for α TiCl3, the a parameter for the milled samples decreased with decreasing crystallite size, whereas the c parameter increased. In the samples examined, this effect was about the same order of magnitude as that due to changes in composition. In order to evaluate the effects due to composition alone, a correction was made for the effect of crystallite size, and the lattice parameters were then expressed as the limiting values one would obtain for very large crystals.

With increasing AlCl3 content, the a parameter decreased from 6.168 Å for no AlCl3 to 6.162 Å for 20 mol.% AlCl3. For higher AlCl3 content, a showed a relatively rapid and almost linear decrease to 5.921 Å for 100% Aids. The c parameter decreased from 17.73 Å for no AlCl3 to about 17.61 Å for 35 mol.% AlCl3, and thereafter decreased slowly to 17.58 Å for 100% AlCl3. The layer stacking disorder appeared to increase the lattice parameters in solid solutions containing less than 25 mol,% AlCl3. However, at 25% and 100% AlCl3, no significant effect was observed.
New Technique for Quantitative SiO2 Determinations of Silicate Materials by X-Ray Diffraction Analysis of Glass
Authors: Nash Douglas B.
Published: March 2019

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

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

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

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

In interpreting X-ray intensity data from electron probe microanalyzers, the simplest approximation that can be made is that the X-ray intensity is a linear function of concentration. This linear relationship has been found to hold only in very limited cases. Where this simple relationship does not hold, it is generally assumed that increased concentration of an element is reflected in increased intensity of its characteristic X-ray lines. This assumption, which is always valid for binary samples, has been extremely useful, particularly for the interpretation of X-ray scanning pictures. However, in analyses based solely on observed X-ray intensities, large deviations from the linear relationship can make semiquantitative results misleading.

For multielement systems, the deviations from linearity result in ranges of concentration for each element within which increased concentration of the element does not result in an increase of its characteristic X-ray intensity. The magnitude of these deviations, and. hence the ranges of concentration, is related to the X-ray absorption and secondary fluorescence in the sample, which are in turn dependent on instrumental parameters such as X-ray take-off angle. Such inversions in the normal intensity-concentration relationship can result in gross misinterpretation of X-ray scanning pictures on even a qualitative basis. The various factors that lead to deviations from linearity are evaluated, and methods are given for correctly interpreting X-ray intensity data on a qualitative and semiquantitative basis.
The Applicability of Theoretically Calculated Intensity Corrections to Practical Metallurgical Problems in the Electron Probe
Authors: Moll Sheldon H.
Published: March 2019

Recent studies have indicated only limited agreement between theoretically calculated X-ray absorption, fluorescence, and electron penetration correction factors and calibration curves obtained from alloy standards in binary systems. For some practical metallurgical problems, including diffusion gradient studies, intermediate phase identifications, etc., where analytical precision is required, alloy standards must be employed.

Most metallurgical investigations, however, are concerned with alloys containing a variety of elements. The use of theoretical calculations in these analyses is severely limited. At present, the precision of analyzed chemistries in such systems is somewhat poorer than the precision of the measured X-ray intensity values. Methods for applying combinations of theoretically calculated corrections, extrapolations from nominal alloy chemistries, etc. have been employed which yield reasonable analytical precisions but at best are first-order approximations. Approximate calculations for use in determining the chemistries of fine precipitates or inclusions where matrix excitation is unavoidable are also discussed.
Standards in Electron Probe Analysis of Minerals*
Authors: Adler Isidore
Published: March 2019

The application of electron probe analysis to complex mineral systems has pointed out the great need for suitable standards. It is often difficult to obtain highly accurate analytical results on these complex systems using pure end members because of the large number of correction factors involved, particularly since some of these factors are not well known.

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

A technique has been developed for quantitative analysis of the major constituents in small samples (less than 0.1 g) of corrosion products found On various missile parts. The technique was developed primarily to aid in interpretation of X-ray diffraction patterns of multicomponent corrosion products. The corrosion sample is mixed with KBr and the mixture is pressed into a disk in the same fashion commonly used in infrared work. The Br Kβ1 line serves as an internal standard. Intensities of the element's Kα line and the internal standard are established by scanning through the appropriate Bragg angle and recording peak heights on a strip-chart recorder. A xenon-filled proportional detector and a pulse-height analyzer were used.

The percent of an element is determined by references to calibration curves which relate intensity ratios to weight ratios for the 3-d transition metals. The oxides of the metals were used in the preparation of the calibration curves. The weight ratio vs. intensity ratio relationship is linear over the weight ratio range 0.01 to 0.11. Data were collected using an air path and a helium path; the higher intensity ratios obtained with, the helium path, and the dependence of intensity on atomic number are illustrated. A comparison is made between the intensity ratios in a KBr matrix and in a NaBr matrix. The technique developed requires about 15 min sample preparation time.
X-Ray Fluorescence Analysis of Niobate-Tantalate Ore Concentrates
Authors: Rose Harry J. , Brown Robena
Published: March 2019

An X-ray fluorescence method is described for the analysis of niobotamalate concentrates, bringing speed and accuracy to determinations that are difficult chemically. Many of the problems inherent in the X-ray fluorescence analysis of powdered samples are eliminated by fusion of the sample in a mixture of Li2B4O7 and La2O3. Absolute amounts can be determined without reliance on chemically analyzed standard concentrates. Standards in a wide range of concentrations are readily prepared from pure chemicals. La2O3 plays a dual role, aiding in the fusion of highly refractory oxides and minimizing absorption differences between samples. In addition to niobium and tantalum, elements commonly present in niobate-tantalate ore concentrates, such as titanium, iron, tin, and manganese, are readily determined.

The fusion mixture consists of 80 mg of sample, 120 mg of La2O3 and 800 mg of Li2B4O7. The fusion is made in graphite crucibles at 1100°C for 15 min. The cooled bead is ground in a mixer-grinder and pressed into a pellet. X-ray fluorescence measurements yield linear calibration curves for each of the elements over a wide range of concentration.
Improved Trace Analysis with the Use of Synchronized Electronic Discrimination in an X-Ray Scanning Procedure
Authors: Salmon Merlyn L.
Published: March 2019

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

The field of electron probe microanalysis has rapidly spread from metallurgy, geology, and biology to many allied fields. It is the purpose of this discussion to cover an application that has not received much attention—namely, the study of relay contact surfaces with this technique.

In this case, many of the problems encountered are somewhat different, but the ultimate results are quite gratifying. Sample preparation is greatly simplified inasmuch as the surface condition is of prime interest and absolutely no preparation is a prerequisite. Unfortunately, this does lead to some problems of sample mounting and makes the interpretation of results more difficult. Examples are given of the types of information that can be obtained on the substrate materials as well as the finished plated contacts.
The Effect of Valence and Coordination on K Series Diagram and Nondiagram Lines of Magnesium, Aluminum, and Silicon*
Authors: Baun William L. , Fischer David W.
Published: March 2019

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

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

The preparation of semiconductor materials by epitaxial deposition has rapidly gained prominence in recent years. GaAs(1-x)Px alloys of variable composition, deposited on GaAs substrates, have been prepared in an open-tube reactor using H2, AsCl3, and PCl3 with GaAs source material, The deposits ranged in composition from GaAs to GaAs0.5P0.5 and were 10-30 microns thick.

X-ray diffraction topography was employed to evaluate the structural perfection of the monocrystalline GaAs substrates and the perfection of the deposited Ga(As, P) films. A scanning-reflection technique was developed to study the concentration, type, and spatial distribution of imperfections over large areas (∼8 cm2) to depths of 25 microns. Some areas of investigation included (1) the poly cry stallinity of some deposits, (2) the effect of substrate perfection on the film quality, (3) the depth of mechanically induced damage, and (4) the structural perfection of magnesium-diffused GaAs and Ga(As, P).
The Application of Cylindrical Geometry for the Determination of Crystal Orientation
Authors: Forest Robert D. , Barton Richard J. , Schieltz N. C.
Published: March 2019

A procedure for conveniently determining the orientation of noncubic crystals is presented. The methods usually employed for cubic crystals, flat-film backreflection Laue patterns interpreted with the aid of a table of interplanar angles, is not readily adaptable to noncubics. In general, tables of interplanar angles for noncubics do not exist and if the effort is expended to generate them, such a vast array of angles result that they are virtually impossible to use. It is thus necessary to use the symmetry of the pattern to identify the low-index planes. However, on flat-film geometry, due to the small angular range of the data, insufficient low-index points are present to permit orientation.

In order to alleviate this problem we have developed the necessary techniques for the interpretation of back-reflection Laue patterns employing cylindrical-film geometry. The necessary overlays and their use are presented along with some of the results obtained.
Substructure Measurements by Statistical Fluctuations in X-Ray Diffraction Intensity
Authors: Sturcken E. F. , Gettys W. E. , Bohn E. M.
Published: March 2019

The substructures of a bet a-quenched and a recrystallized form of high-purity uranium were measured by a method based on statistical fluctuations in X-ray diffraction intensity. For these measurements, Warren's statistical equation for determining grain size was modified to make the equation applicable to materials with high absorption coefficients or moderate-to-large grain size ( > 20 microns) or both, since many metals fall into this category, and to allow for defocusing of the X-ray beam which occurs as a natural consequence of the experiment.

The beta-quenched uranium was found to have numerous subgrains with a range of misorientation angles that was smaller and larger than the limits of the X-ray measurements (Ω = 10−4 to 10−2 steradians). The presence of the large subgrains was corroborated by optical microscopy. The presence of very small subgrains was corroborated by transmission electron microscopy which showed 0.1- to 1-micron subgrains relatively free of dislocations bounded by dense dislocation networks, and by micro Laue diffraction patterns (30-micron beam diameter) which showed partial rings similar to a powder pattern.

The recrystallized uranium had no misorientation within the grains greater than 5.5 × 10−3 steradians. In contrast to the beta-quenched case, no subgrains were found either by transmission electron microscopy (TEM) or micro Laue diffraction patterns. The TEM micrographs showed a uniform distribution of dislocation networks. Since no other substructural elements were observed, the dislocations are believed to be the cause of the misorientation within the grains for solid angles of less than 5 × 10−3 steradiflns.

These preliminary experiments show that the statistical method may be used in conjunction with transmission electron microscopy and micro Laue diffraction for the study of substructure. The statistical method gives quantitative data on “bulk” specimens that can be given a meaningful interpretation with the aid of the other techniques.
Generation of a Two-Dimensional Silicon Carbide Lattice*
Authors: Prickett R. L. , Hough R. L.
Published: March 2019

Silicon carbide vvas generated by pyrolysis of gas mixtures consisting of silicon tetrachloride, hydrogen, and organic vapors, such as acetone, on fine tungsten wires resistance-heated at 1500°C. Prominent two-dimensional structure was demonstrated for the 220 reflection. All other lines were of the normal threedimensional lattice type.

Elevation of less than 100° in the pyrolysis temperature eliminated the twodimensional reflection, and simultaneously changed the visible crystallite size.

Specialized techniques were used td generate the silicon carbide deposits and also to examine the structure of these deposits by X-ray diffraction to obtain lines from only the silicon carbide while ignoring the tungsten wire core. Diffraction techniques include offset collimation and vertical integration.
A Method for Trace Analysis with an Electron Microprobe
Authors: Fergason L. A.
Published: March 2019

A “chopped beam” system of analysis has been devised for a scanning electron microprobe equipped with a 400-channel analyzer. The system has been programed with circuitry which places a signal onto the X or Y scanning coils of the probe, so that the beam jumps back and forth between two analytical areas. The same signal is used to activate alternate halves or quadrants on the 400-channel analyzer in a synchronous manner. The analyzer accumulates X-ray intensity data in the appropriate halves and quadrants as the electron beam oscillates between sample and standard or, in the case of trace analysis, between the unknown and the pure major constituent for background correction. The probe may be left unattended while it is gathering information in this manner. The dwell time of the probe on a given analytical area is 6 sec “live” time.

Errors due to instrumental drift and sample contamination are nullified or minimized by this technique. Consequently, theoretical precision is closely approached for extended counting times. 100 ppm levels of aluminum, silicon, nickel, and iron in uranium have been determined to precisions as good as ± 10 ppm at the 95% confidence level.
Electron Probe Microanalysis of Zinc-Bearing Hexagonal Ferrites
Authors: Shappirio J. R.
Published: March 2019

The electron probe is shown to be an effective tool for the analysis of the series of ferrimagnetic oxides referred to as the hexagonal ferrites. This series of compounds) containing barium, Fe3+, and a divalent metal cation, is formed by an ordered stacking of basic structural units in varying ratios. The ideal, complex stoichiornewy of these polytype-like mixed-layer structures can be computed from X-ray unit cell data; the various structures and their predicted stoichiometry are reviewed. Results of electron probe analysis of zinc-bearing single-crystal hexagonal ferrites are compared with theoretical values, the various correction procedures applied to the probe data are presented, and the limitations of the method in the analysis of hexagonal ferrites are discussed. The information obtained from this study has laid the groundwork for the determination of chemistry in substituted members of the hexagonal ferrite group, and will contribute significantly to the interpretation of the magnetic properties exhibited by these compounds.
A Blazed-Grating Scanning Spectrometer for Ultrasoft X-Rays Suitable for Use in an Electron Microprobe
Authors: Nicholson J. B. , Hasler M. F.
Published: March 2019

The importance of operating within the blaze angle is emphasized by a series of measurements of ultrasoft X-rays obtained with a new grazing-incidence, grating spectrometer, A formula to maximize output intensity has been derived which predicts a variation of input angle with changes of wavelength. The spectrometer is designed to utilize this function. The grating spectrometer was installed into an Applied Research Laboratories Analyst's Microprobe. Since the AMX furnishes an utt.rasoft spectrometer with a fatty acid pseudocrystal as standard equipment, it is possible to compare the two systems simultaneously on the same sample at the same wavelength. The grating and crystal systems are compared for peak intensity and line-to-background ratio.