bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Temperature Furnaces for X-Ray Diffractometers
Authors: Campbell William J. , Stecura Stephan , Grain Clark 
Published: March 2019

AbstractThis paper summarizes developments in the field of high-temperature X-ray diffractometers through 1959, evaluates various furnace designs, and describes briefly the X-ray diffraction facilities of the Federal Bureau of Mines.X-ray optics, for those furnaces that have precision sample movements, are equivalent in resolution and line profile to conventional X-ray techniques. There is a 10-25% loss of intensity due to absorption of X-rays in the furnace windows, magnitude of which depends on wavelength and type of window used, and a reduction (5–40° 2θ) of useful angular range from limiting X-ray windows, radiation shielding, or the viewport for an optical pyrometer. In oxidizing atmospheres, temperatures up to 1500°C were obtained with furnaces wound with platinum—20% rhodium wire. Under nonoxidizing conditions temperatures of 1800 to 2000°C were obtained with both tantalum-foil and tungsten-wire heaters.Accurate temperature measurement over the area and depth of samples being studied is the most difficult problem in high-temperature X-ray diffractometry. Below 500°C, there are several furnace designs which are reported to reduce thermal differentials to less than 1°C across the sample. However, at temperatures around 1000°C, there are thermal gradients of 20-30°C/cm across the sample and 100–600°C/cm through the sample holder, making thermocouple location critical. Secondary standards have been used extensively to calibrate the furnaces; however, there is disagreement concerning which are the most reliable data to use. For these reasons, plus others discussed in this report, there is a probable error in the temperature determination of ±10 to 20°C at 1000°C, with the error increasing with temperature.
Alignment Device and Thermal-Control System for High-Temperature X-Ray Diffractometry
Authors: Corvin I. , Schossberger F. , Ticulka F. 
Published: March 2019

AbstractA high-temperature high-vacuum X-ray diffractometer attachment was constructed to observe formation of materials at elevated temperatures. The device consists of a conventional water-cooled compartment, a resistance-type furnace for heating samples to 800°C, and inlets and outlets for gaseous reactants and evacuation. Two sources are available for evaporation of materials which may react with or coat the sample. The sample is aligned by a two-part sample-slit system. The sample temperature is regulated by means of a current-adjusting control unit and a self-saturating reactor with suitably positioned thermocouples. Temperature distribution and constancy over the sample surface were determined.
Heterogeneity Effects in X-Ray Analysis*
Authors: Claisse Fernand , Samson Claude 
Published: March 2019

AbstractA fundamental quantitative treatment of the heterogeneity effects in X-ray fluorescence has been made. The theory predicts that the grain-size effect appears only in a limited region of grain sizes which depends on the wavelength of the primary radiation and the nature of the compounds in the mixture. With monochromatic radiation, the fluorescence intensity showed increase or decrease by a factor of a few units as grain size is decreased, A factor as large as 12, the theoretical value, has been observed in one particular experiment. Usually the grain-size effect can be eliminated by intensive grinding. For the light elements fine grinding is disastrous if long wavelengths are used. By an appropriate choice of the wavelength it is possible to eliminate the effect even without grinding. The mathematical treatment also predicts, but less rigorously, a grain-size effect in X-ray diffraction.The effect on the fluorescence intensities by changes in the chemical composition of the grains that contain the fluorescent element is predicted by the theory.These findings are discussed in relation to the analysis of elements when polychromatic beams are used.
Some Special Sample-Mounting Devices for the X-Ray Fluorescence Spectrometer*
Authors: Bertin Eugene P. , Longobucco Rita J. 
Published: March 2019

AbstractVarious sample-mounting devices are described for use with a commercial flat-crystal X-ray fluorescence spectrometer having conventional (i.e., not inverted) geometry: (1) a sample drawer with two sample “spinners,” one for rotation of flat samples in their own plane, the other for rotation of cylindrical or filamentary samples about an axis normal to the plane defined by the directions of the primary and secondary X-ray beams; (2) rotatable mounting stages for filter paper disks and various very small samples; (3) a sample drawer for selected area operation with pinhole or slit apertures in the primary beam or pinhole apertures in the secondary beam; (4) a liquid cell with 0.00025-in. Mylar window (the cell is inexpensive, easily filled and rinsed, and usable 20-50 times before the window must be replaced); (5) three types of cell for powder samples (one has a 0.00025-in, Mylar window and is filled through a port in the top; the other types are open on both sides and are filled by placing them on glass plates and introducing the powder from the back; one of these back-loading cells permits rotation of the powder sample); (6) rotatable stages for briquetted powder samples; (7) mounting devices for wire samples on small spools (one of these devices permits rotation of the spool).These devices were designed and made at the X-ray laboratory of the RCA plant at Harrison, N. J., and have been used there successfully with a wide variety of samples for several years.
Vacuum X-Ray Instrumentation and its Application to Mill-Products Control
Authors: Dryer H. T. , Davidson E. , Andermann G. 
Published: March 2019

AbstractWith the introduction in 1960 of the first commercial multichannel vacuum X-ray spectrometers, ARL opened the way for greater economy of operation for light-element analysis over conventional helium-path instrumentation. The design concepts and features of these instruments are discussed, including the adaptability to “on-stream” or continuous analyzer programs. The successful application of vacuum X-ray equipment for the analysis of ores, concentrates, and slags will be presented. Factors relating to sample preparation, precision, and accuracy are given and analytical sensitivity and speed are covered.
X-Ray Probe with Collimation of the Secondary Beam
Authors: Heinrich Kurt F. J. 
Published: March 2019

AbstractAn attachment to a commercial flat-crystal X-ray fluorescent goniometer permits analysis of small areas. The selection of the sample area is achieved by collimating the secondary beam. The geometry of the probe, its stage, and counting statistics applied to the probe are discussed. Experimental data are shown referring to determination of spot size, counting rates obtained, and both qualitative and quantitative applications.
X-Ray Measurement of the Static Lattice Distortion in the Solid Solution of Oxygen in Titanium*
Authors: Schoening F. R. L. , Witt F. 
Published: March 2019

AbstractOxygen was introduced into a single crystal of titanium in successive stages. The intensities of the h00 and 00l reflections were measured with a single-crystal diffractometer. The observed variation of the intensities with oxygen concentration was attributed to three factors: (1) the additional scattering from the oxygen atoms, (2) a change in the Debye-Waller factor, and (3) an exponential factor originating from the distortion around the oxygen atom. The theory of X-ray scattering from crystals containing centers of distortion was applied to the hexagonal titanium containing interstitial oxygen atoms. Using the variation of the lattice constant with oxygen concentration, it was possible to predict the intensity reduction due to lattice strains. It was concluded that it would have been possible to obtain an estimate of the defect concentration from the X-ray measurements of lattice expansion and intensity reduction.
Measurement of the Lattice Constants of Neon Isotopes in the Temperature Range 4–24°K
Authors: Bolz L. H. , Mauer F. A. 
Published: March 2019

AbstractUsing an X-ray diffractonieter cryostat, the lattice constants of the isotopes20Ne and22Ne as well as the naturally occurring mixture have been measured throughout most of the temperature range in which they exist as solids (0 to approximately 24°K), The heavier isotope has the smaller lattice constant, the values obtained at 4.2°K being:20Ne—4.4624Å,22Ne—4.4540Å, and11Ne—4.4622Å. The absolute error in these values is believed to be no greater than 0.001 A. The volume expansion coefficient, which does not appear to differ significantly in the three cases, increases to a value of 6.3 × 10−3/°K at 24°K.
Recent Advances in Electron-Probe Analysis
Authors: Long J. V. P. 
Published: March 2019

AbstractThe electron-pro be analyzer has been developed in a period of thirteen years to a point where several different instruments are commercially available and about one hundred are already in use. At the present time it is possible to analyze volumes of about 1 μ3 at the surface of a specimen for elements above sodium in the periodic table with a concentration sensitivity of the order of 0.1-0.01%. New developments in the field include efforts to extend the range of Z to lower atomic numbers and to increase the spatial resolution of the method so that smaller volumes niay be analyzed. Progress in the analysis of the light elements centers at present mainly on the use of nondispersive detectors and. computer techniques for the resolution of overlapping pulse-height distributions. With such methods qualitative detection of elements down to beryllium has been achieved in the presence of their near neighbors. Efforts to increase the spatial resolution of the probe have led to the use of thin specimens which are partially transparent to electrons. Partly as a consequence of this approach, apparatus has been developed in which an electron microscope with facilities for selected area diffraction has been combined with an electron-probe analyser. The ever-widening range of application of the electron-pro be technique has inevitably disclosed problems in the interpretation of quantitative data, and it is clear that at the present time more information on the process of X-ray production by electrons is required before semi-empirical methods can be entirely eliminated. Examples of the use of the method in metallurgical and mineralogical studies illustrate some of the current trends in the refinement of measurement technique and interpretation of experimental data.
The Use of X-Ray Emission Spectrography for Petroleum Product Quality and Process
Control
Authors: Caley J. L. 
Published: March 2019

AbstractA Norelco Autrometer (automatic multielement X-ray spectrograph) is being used by a petroleum refinery control laboratory for process control and product quality control. As many as 100 analyses covering 13 elements are run per day. Concentrations range from a few ppm to 25%.The instrument has reduced the elapsed time for many analyses from 8 hr to 5 min, made possible in many cases greater accuracy than previously used wetchemical methods, reduced laboratory manpower and increased refinery production efficiency in many instances.
The Debye Temperature of Iron-Manganese Solid Solution Alloys
Authors: Gazzara Charles P. , Middleton Raymond M. 
Published: March 2019

AbstractValues of the Debye temperature 0 for iron-manganese solid-solution alloys have been determined from X-ray diffracted intensity measurements of powder specimens at ambient temperatures of 310, 239, and 98°K. Corrections to 0 were made with respect to the temperature-dependence of Θ, temperature diffuse scattering, dispersion, volume expansion of the alloy, and the temperature gradient through the specimen. The variation of Θ with temperature has been found to be approximately linear, the value of Θ decreasing 3 % between 98 and SICTK. for a nominal Fe–4%Mn alloy.Increasing the concentration of manganese in an iron-manganese solid-solution alloy decreases Θ in qualitative agreement with Lindemann's equation. The values of Θ for other s olid-solution alloys computed using Lindemann's equation also agree with reported experimental values of Θ. The Debye temperature of a nominal Fe-3%Mn alloy annealed for 2 hr at 300, 600, and 700°C has not been found to maximize at 600°C as has been reported by Il'ina et al. On the contrary, Θ decreases with increasing annealing temperature until, in the range 600 to 700°C, it reaches its true value; and at these temperatures the powder was found to be fully annealed.
Relation Between Ionic Radii and Transformation Temperature in Rare Earth Niobates
Authors: Gingerich K. A. , Bair H. E. 
Published: March 2019

AbstractIn this work a detailed X-ray powder diffraction study of the reversible temperature transformation has been undertaken in several rare earth niobates MNbO4 M being lanthanum, cerium, neodymium, gadolinium, holmium, thulium, ytterbium, and yttrium. Both high-temperature diffractometer and film techniques were used. It was shown for the substances investigated that the low-high transformation is a continuous transition over the wbole temperature range from monoclinic at room temperature to tetragonal at the transition temperature. It was found that the rate of the overall transition is rapid, and also that the transition between any intermediate state occurs reversibly within minutes or seconds. The continuous transition and the rapid rate of attainment of equilibrium in the solid, even between intermediate states of the transformation, support the earlier assumption that it is a displacive-type order-disorder transition.
Quantitative Determinations and Descriptions of Preferred Orientation*
Authors: Holland J. R. 
Published: March 2019

AbstractThe problems associated with quantitative determinations and descriptions of preferred orientation are discussed and a method proposed to yield quantitative descriptions. A means of obtaining representative quantitative data using reflection techniques is described. The position of intensity minima in quantitative pole figure descriptions of preferred orientation is equal in importance to intensity maxima. Hence, rate-meter counting of diffracted intensity as the sample is continuously or semicontinuously rotated in a given spatial relationship is not satisfactory. Instead, sealer counting by fixed counts at a given spatial position yields more meaningful results; however, fixed-time sealer counting is used to reduce the time for data collection. The data are plotted in the form of normalized pole figures and analyzed.To determine the relative volume of material associated with a given-texture component and an index of preferred orientation, the data are integrated. This is done by numerical integration or, alternatively, by graphical means. Integrating over the interval from ϕ = 0 to ϕ = π/2 and α = 0 to α = n/2 (where ϕ and α are spherical coordinates) will give the pole concentration per unit area for an ideally randomly oriented specimen for an octant of the sphere of projection. The relative volume of material associated with a given set of intensity maxima can be determined by integrating the intensity over the area of the maxima, summing these values, and dividing by the multiplicity to obtain the total intensity, It. The relative volume can be expressed as a ratio of It divided by random intensity. The texture strength can be expressed as the standard deviation from the random condition. Such information is vital to quantitative predictions of the anisotropy of properties
Vacancy Related Defects in Antimony-Doped Silicon
Authors: Howard J. K. , Miller D. P. 
Published: March 2019

AbstractHelical dislocations and vacancy aggregates have been reported in lithiumdoped germanium and in diffused silicon. In the present study, defects related to an excess vacancy concentration are examined in as-grown silicon. X-ray topography, etch techniques, and Hall effect are used in determining the conditions of formation of these imperfections. Two distinct types of defects are observed: (1) helical dislocations and (2) dislocation loops. The helical dislocations are identified in the X-ray topographs and correlated to their etch figures. The diameters of the helices in various crystals range from less than 10 to 100 μ. The largest concentration of helices are observed in the initial growth, but prismatic loops or helical segments are also present in the low dislocation density regions of some crystals. The dislocation loop image consists of a pair of opposed arcs. The lengths of images vary from 30 to 400 μ, and the axis of the loop is usually parallel to <110> linage contrast changes with changes in sample orientation, but conclusive Burgers vector determinations are incomplete.The formation of these defects is shown to be directly related to the heat treatment during crystal growth. The total acquisition of vacancies during growth is quite high and is attributed to the “orbital” growth process. In the “orbital” method, the seed check rotates 8-9 rpm about the center of the crucible as the growing crystal rotates 50-60 rpm. A linear relationship exists at room temperature between the vacancy concentration and the antimony impurity concentration. Impurity concentrations were determined independently by chemical and mass spectrograph techniques. A defect complex involving V− and Sb+ in thermal equilibrium is employed to explain this effect.
Preferred Orientation in Ceramic Materials Due to Forming Techniques
Authors: Pentecost Joseph L. , Wright Charles H. 
Published: March 2019

AbstractAccurate measurement of the electrical and mechanical properties of polycrystalline oxide ceramics has revealed anisotropy in a number of properties. The source of this anisotropy may be attributed to a number of causes, however, with oxides having anisotropic crystals, preferred orientation of the crystallites may be suspected. Aluminum oxide and beryllium oxide ceramics samples of high purity and density were formed by slip casting, dry pressing, isostatic pressing, and extrusion. Pole figures for the (113), (110) and (030) planes in aluminum oxide and (100) and (103) planes in beryllium oxide were prepared by using a Siemens automatic pale figure goniometer.It was found that both slip-cast oxide samples and dry-pressed aluminum oxide samples and dry-pressed beryllium oxide samples showed sufficient preferred orientation to prepare a pole figure from the data. The actual preferential orientation of the crystallites in these two oxides is discussed and the pole figure information presented. The effect of furnace atmosphere and surface contaminants on re crystallization at an exposed surface is covered briefly.
X-Ray Investigation of Aerosols from Wires Exploded in Nitrogen
Authors: Karioris Frank G. , Woyci Jerome J. 
Published: March 2019

AbstractWires of 18 different metals were exploded in nitrogen by the discharge of a 20-μF capacitor bank charged to 10 kV. The resulting aerosols were collected under nitrogren on membrane e filters, which were mounted on glass slides and used directly in the sample holder of a recording X-ray diffractometer. The X-ray data were analyzed to determine the composition and approximate crystallite size of the particulates produced by the wire explosions in nitrogen and subsequent exposure to air.Nitrides are found as reaction products from the explosion in nitrogen of aluminum, iron, indium, tantalum, thorium, uranium, tungsten, and zirconium. No nitrides were detected in the samples from cadmium, copper, magnesium, molybdenum, lead, and tin explosions, although such nitrides are known to exist; and the aerosols produced in nitrogen by the explosion of silver, gold, molybdenum, platinum, and tin consist almost entirely of metal particles. Oxides are attributed to contamination of the nitrogen or exposure of the samples to air.Most of the crystallites observed are less than 1000 Å as determined from X-ray line broadening find confirmed in some instances by electron microscopy. For the UN2 and ThO2, crystallite sizes of the order of 130 Å and 50 Å, respectively, are observed. In samples comprised of a mixture of phases, the constituents usually have different mean crystallite sizes. The crystallite size is not affected dramatically by the ambient nitrogen pressure or voltage used.
Technique of Measuring Low Percentages of Retained Austenite using Filtered X-Ray Radiation and an X-Ray Diffractometer*
Authors: Erard H. Robert 
Published: March 2019

AbstractThis paper describes a technique of measuring the volume percent retained austenite in steel using ordinary filtered X-radiation and an X-ray diffractometer. As compared with conventional rate-meter recordings or microphotometer traces of diffraction peaks, the subject technique extends the range of austenite determinations from the usual 7 % down to 1 %. It markedly improves over the entire range of measurement.Essentially, the technique consists of step scanning the profile of each selected martensite and austenite diffraction line and recording the corresponding intensity within a known probable error. The step-scanning, fixed-count, and counting-rate, recording operations are performed automatically by a counting-rate computer. The integrated intensity of each diffraction line is obtained by summation of intensity increments above background in accordance with the “trapezoidal rule.” For hardened steel, the best peak-to-background ratio is secured using filtered Cr Ka radiation with the vanadium filter located in the diffracted beam. The volume percent retained austenite is determined by direct comparison of the integrated intensity of an austenite line with the integrated intensity of a marten site line and from the relationships between intensity and concentration for the martensitic and austenitic phases.An application of the subject technique was its use in determining the retained austenite behavior of carburized 9310 steel. The volume percent austenite retained on the surfaces of as-quenched specimens was determined as a function of carburizing potential. The amount of retained austenite subsequently transformed by various combinations of tempering, refrigerating, and retempering treatments was successively ascertained. The amount of retained austenite determined using the subject technique compared closely with the amount of retained austenite measured by metallographic examination. However, the reproducibility of results was better for the X-ray method as compared to metallographie examination. The nondestructive nature of the X-ray method permitted successive measurements on the same surface following repeated thermal treatments.
Methods of Quantitative Electron Probe Analysis*
Authors: Wittry David B. 
Published: March 2019

AbstractMethods of quantitative electron probe analysis using empirical working curves have achieved only partial success because of variations in instrument design, analysis conditions, and homogeneity of standards. These problems have been solved for X-ray fluorescence analysis, but many of the more successful empirical methods cannot be used in electron probe analysis; instead, a more theoretical approach is indicated. In electron probe analysis quantitative results can be achieved with only pure elements as standards provided (1) the analysis conditions are carefully selected, (2) the observed intensities can be corrected to obtain the primary intensity actually produced in the specimen, and (3) the relationship of the primary intensity and concentration can be calculated. While present methods of making some of the corrections required improvement and a “universal” theory for relating the primary X-ray intensities to the concentrations still does not exist, the success achieved with this approach indicates that it should be used to the fullest extent before resorting to calibration curves. Moreover, as information is accumulated, the number of cases requiring the use of calibration curves should diminish, so that eventually it may be possible to perform quantitative analysis in any system with only pure elements as standards,