bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Epitaxial Films by X-Ray Diffraction
Authors: Segmüller Armin 
Published: March 2019

AbstractIn this paper, the application of recently developed x-ray diffraction techniques to the characterization of thin epitaxial films will be discussed. The double-crystal diffractometer, with high resolution in the non-dispersive arrangement, enables the materials scientist to study epitaxial systems having a very small mismatch with high precision. A key part of the characterization of an epitaxial film is the determination of the strain tensor by measuring lattice spacing! in various directions The determination of strain and composition profiles in ion-implanted films, epitaxial layers and superlattices by rocking-curve analysis will also be reviewed. Grazingincidence diffraction, an emerging new technique, can be used to obtain structural details parallel to the interface on films with thicknesses ranging down to a few atomic layers. The synchroton has now become increasingly available as a powerful source of x radiation which will facilitate the application of conventional and grazing-incidence diffraction to ultra-thin films.
Resolution of Overlapping X-Ray Fluorescence Peaks With the Pseudo-Voigt Function
Authors: Huang T. C. , Lim G. 
Published: March 2019

AbstractA method for resolving overlapping X-ray fluorescence spectra by curve fitting is described. The profile shape of an experimental fluorescence line obtained by wavelength dispersive method is represented by a simple pseudo-Voigt function, i.e. a sum of an asymmetric Gaussian and Lorentzian, each of equal width. Results showed that the pseudo-Voigt function matched the experimental profiles with high reliability. The relative Gaussian and Lorentzian contents and the asymmetry of the profiles depended upon the analyzing crystal, coliimating system and the 2θ peak position. For fixed crystal and collimator the smaller the 2θ, the larger the Gaussian content and the lower the asymmetry. The original Gaussian and Loretzian components of the exact Voigt function calculated from the parameters of the fitted pseudo-Voigt function explain the broadening effects of the X-ray emission lines and the instrumental aberrations on observed spectra. Curve fitting method with the psuedo- Voigt function has been used successfully to analyze overlapping fluorescence spectra. Examples and applications include a thin film sample where the Kα and the Kβ lines of adjacent transition elements overlap, and a strontium zirconium oxide specimen where the Zr Kα and the Sr Kβ lines strongly interfere. Concentrations obtained from the resolved individual peak intensities of Zr and Sr Kα lines are within ±1% of the true values.
Determination of Nickel and Vanadium in Crude Oil Using Wavelength Dispersive X-Ray Fluorescence Spectrometry and a Tight Standardization Method*
Authors: Mansour S. , Abu-Dagga F. , Sabri R. 
Published: March 2019

AbstractMetallic impurities present in crude oils lead to the rapid deactivation of catalysts used in refineries and a drop in the yield of oil products. The determination of these impurities is therefore of primary importance. The conventional and most widely used methods to determine trace metals in oils and petroleum products are chemical analysis methods such as atomic absorption spectrometry (AAS) and inductively coupled plasmaoptical emission spectrometry (ICP-OES). Sample preparation for these methods includes decomposition of the crude sample by dry ashing and combustion of the oil sample followed by chemical treatment of the dry ash residue (ASTM, 1983; Fassel et al., 1976). Major drawbacks of chemical analysis methods are the length of time required to prepare the sample and the possibility of losing trace metallorganic compounds in the form of volatile compounds.
A Modular Automatic X-Ray Ahalysis System
Authors: Slaughter M. , Carpenter Davis 
Published: March 2019

A modular x-ray and electron beam system has been constructed to accomplish most standard types of x-ray analysis automatically. The system includes a vertical powder diffractometer, a vacuum spectrograph, a four-axis single-crystal diffractometer and an electron microprobe with four spectrometers. The system is controlled by a single computer with auxilliary drum storage. The powder diffractometer has automatic goniometer drive, automatic sample changing with computer cataloging of samples and automatic variable divergence slit. The x-ray spectrograph is a standard unit with added 100 KV capability, automated goniometer drive, eight or 32 position sample changer, six-analyzing-crystal changer, collimator changer, and detector changer. All functions including sample number cataloguing are computer controlled. The four-axis single crystal diffractometer has all functions computer controlled and includes peak search option. The electron microprobe/scanning electron microscope has all spectrometers, x, y, z stage motions and sample changer controlled by computer. X-Ray channels, beam current and sample current are automatically read-out. Control of probe functions and correction of mechanical errors in stage operation, are aided by a digital beam scanner with a light pen. Counting channels and computer interfacing are modular, and channel components are interchangable by the operator. Computer hardware may be expanded and the software is modular. Any combination of instruments up to eight may be operated.The computer operates all instruments simultaneously in a time-sharing mode. Programs consist of operating system programs, individual instrument programs and data processing programs. The operating system drives all x-ray hardware, fetches programs and data from the drum, allocates data storage, queues final results for printing and performs other necessary executive functions. For qualitative analysis, spectra for each instrument are collected automatically in several modes and are stored on the drum. A variety of methods are used to remove background, strip unwanted peaks and find peak position and intensity. A.S.T.M. diffraction, spectrographic and special files are maintained on the drum. Quantitative analysis is executed automatically using a version of "MAGIC" on the electron microprobe and a multiple linear regression method for the spectrograph and diffractometer.
Energy Dispersive Analysis for Adjacent Elements Using Two Single Channel Analyzers
Authors: Chow Hubert K. 
Published: March 2019

Energy dispersive x-ray analysis has become an extremely useful analytical tool. The technique provides for the direct observation of x-ray emission spectra, eliminating the need for a dispersive crystal. The purpose of this reported investigation was to study the use of the technique with a simple pulse height analyzing system and to develop a routine method for correcting Interferences due to adjacent element spectral overlap and matrix effects.The analyzing system consists of a radioisotope source, a lithium drifted silicon detector, a preamplifier, an amplifier, two single channel analyzers and two digital ratemeters. In order to obtain results suitable for quantative measurement, a two-step empirical method was employed for the correction of peak overlapping and matrix effects. If two peaks in a spectrum overlap at their tails, one can set up a channel width of the analyzer to a region where there are no overlapping pulses. It is then possible to calibrate the ratio of the intensity obtained from this channel to that obtained from the whole peak in its pure state, i.e. without the appearance of a neighbor peak. The actual intensity of the peak in the overlapping spectrum is, therefore, the observed counts multiplied by the ratio. The next step is the correction of matrix effect by means of conventional empirical methods using standard samples. Two types of the samples, Zn-Cu powder mixtures and Ee-Cu in aqueous solutions, were studied to illustrate this method. The usefulness of applying the analyzing system and technique to industrial measurements, either on-line or batch, will also be discussed.
Rapid Recording of Powder Diffraction Patterns With Si(Li) X-Ray Energy Analysis System: W and Cu Targets and Error Analysis
Authors: Sparks Cullie J. 
Published: March 2019

X-ray diffraction patterns using continuous radiation from copper and tungsten target x-ray tubes and detected with a Si(Li) energy analysis system are presented. Errors caused by a misaligned diffractometer and x-ray penetration into the sample are shown to be more difficult to correct and larger in magnitude than errors arising from energy calibration. All these errors can be minimized by mixing a standard with the unknown sample.The energy resolution of the detector influences the breadth of the diffraction peaks more strongly than the standard slit systems available with commercial diffractometers. Thus, to reduce the recording time and maintain the same standard deviation for the data, one should increase the sizes of the front and receiving slits including the Soller slits. X-ray energy diffraction patterns can be recorded with standard deviations less than +0.001 Å in the d spacing with only 200 sec measurement time using the standard diffractometer slit system. Copper targets are probably as useful as tungsten even though the continuous intensity is about three times.less. Copper has fewer interfering characteristic lines, and its use permits convenient conversion to normal θ scanning diffractometer operation.
A Computerized Technique of Plotting a Complete Pole Figure by an X-Ray Reflection Method
Authors: Klappholz J. J. , Waxman S. , Feng C. 
Published: March 2019

The technique of plotting a complete pole figure composed of data points in both longitude and latitude from 0 to 180 degrees by a computer program is described. X-ray data were obtained by a reflection method from a specimen cut into three sections mutually perpendicular to one another. The computer program calculates each position in the pole figure based on the time rate of change of the tilt angle ϕ and the spin angle α which are transformed into rectangular coordinates.The advantage of the present technique is to minimize the x-ray intensity loss due to geometric defocusing, since each section of a given specimen is required to tilt not more than 55 degrees. Due to the fact that a complete pole figure is plotted, one is allowed to examine the symmetry or lack of symmetry in a given specimen with respect to a set of references axes.
Application of the X-Ray Two-Exposure Stress Measuring Technique to a Carburized Steel
Authors: MacDonald Bruce A. 
Published: March 2019

X-ray stress factors for a carburized steel were determined experimentally as a function of tempering temperature from loaded cantilever specimens . The standard X-ray stress expressions were modified to account for both the applied calibrating stresses and the biaxial residual stresses present in the surface of these specimens. The resulting equations permitted calculation of the ﹛ 211 ﹜ stress - free interplanar spacing, elastic modulus and Poisson's ratio from the X-ray data.Tempering to higher temperatures reduced significantly the surface residual compressive stresses and stress - free spacing. The change in spacing with tempering of these specimens must be considered when determining elastic stresses by the one-exposure X-ray technique. Tempering also produced a linear relationship between the tempered hardness and ﹛ 211 ﹜ interplanar spacing.
Chemical Analysis of Nickel Oses by Energy Dispersive X-ray Fluorescence
Authors: Wheeler Bradner D. , Bartell Daniel M. , Cooper John A. 
Published: March 2019

Chemical analysis of geological materials such as nickel ores has been accomplished by atomic absorption (1,3) x-ray fluorescence (11,14) and conventional wet methods (10). Procedures utilizing these techniques are capable of producing excellent results but are often difficult and time consuming.Minerals often present serious problems in chemical analysis by wet methods. X-ray analysis can therefore offer the analyst considerable savings in time providing the obstacles which exist are understood and minimized or eliminated. The most serious problems to solve are absorption and enhancement effects, mineralogical differences among samples, sample preparation, and particle size effects which often influence the intensities of the analytical lines. In addition, the element of interest may be of low concentration in a variable and unknown matrix.
Comparison of the Hanawalt and Johnson-VAND Computer Search/Match Strategies
Authors: Cherukuri Satyam C. , Snyder Robert L. , Beard Donald W. 
Published: March 2019

Over the past fifteen years two basic computer search/match strategies have evolved. The exhaustive search approach of Johnson and Vand (1) uses a sequential file structure whereas Nichols (2) developed a strategy which uses an inverted file, examining only those patterns containing lines of interest. Frevel (3) was the first to attempt to relate the quality of the reference patterns to the search strategy using a very restricted data base. These “first generation” search/match algorithms were forced to use very wide d and I windows due to the poor quality of the unknown and reference patterns.Snyder (4) wrote the first “second generation” search/match procedure which takes advantage of high quality of data in the JCPDS data base when it is present. Recently, a minicomputer optimized version of the Johnson-Vand strategy has been incorporated into this search system enabling a chance to compare these two strategies under similar conditions.
XRD Quantitative Phase Analysis Using the NBS*QYANT82 System
Authors: Hubbard Camden R. , Robbies Carl R. , Snyder Robert L. 
Published: March 2019

X-ray powder diffraction (XRD) is widely used for qualitative analysis of the phases in multiphase mixtures. To extend the characterization to the level of quantitative analysis (QA) requires solution of many challenging problems such as elimination of preferred orientation (1,2,3); selection of an appropriate reference standard which closely matches the analyte phase in crystallite size, thermal history, stoichiometry etc. (4); effectively collecting the experimental intensities (5,6); and finally, performing the data reduction and analysis.The desire to solve the last problem in a general way and to incorporate the “best” procedures developed in several laboratories into one package was one of the stimuli for developing the NBS*QUANT82 system of programs. This system is integrally coupled with the data collection system AUTO (6,7).
X-Ray Diffraction Observation of Fracture Surfaces of Ductile Cast Iron
Authors: Yajima Zenjiro , Hirose Yukio , Tanaka Keisuke 
Published: March 2019

X-ray diffraction observation of metal fractures provides fracture analysists with useful information on the mechanisms and mechanical conditions of fracturing. This method is called “X-ray fractography” and has been developed especially in Japan as a new engineering tool for fracture analysis.In the present paper, X-ray fractography is applied to fracture surfaces of ductile cast iron (JIS FCD 60) which are widely used as machine parts. The fracture toughness tests were conducted at ambient and low temperatures by using compact tension (CT) specimens with blunt notches and three-point bending (TPB) specimens with fatigue pre-cracks. The line broadening of X-ray diffraction profiles was measured on and beneath fracture surfaces of fracture toughness specimens.
A New Technique for Radioisotope-Excited X-Ray Fluorescence
Authors: LaBrecque J.J. , Parker W.C. 
Published: March 2019

SummaryIn this work we plan to describe a new simple technique for exciting characteristic X-rays for X-ray fluorescence. This technique was originally designed for use with β-emitting radioisotopes (1) but now has been extended to other types of isotopes.The technique involves mixing directly with the sample (about 20mg) a small amount of a radionuclide (about 100 μCi). An equal atomic mixture of the following elements was prepared: Ti, Mn, Zn, BrfAg, Sn,and Ba. This mixture was investigated with the following isotopes: Ni-63, S-35, Pm-147, Na-22, Co-137, I-125, Co57, Cd-109, Zn-65, Fe-55 and Am-241. A composite table of the corrected integrated Kα—lines of the elements in the mixture and Graphs showing the ratio of the Ka line intensity of the element of interest divided by the Kα line intensity of Ti will also be presented.
Elemental Analysis of Geological Samples Using a Multichannel, Simultaneous X-Ray Spectrometer
Authors: Cross J. B. , Wilson L. V. 
Published: March 2019

X-ray spectrometry has been used successfully for major and trace element analysis of geological samples (e.g. reference 1). Its advantage is providing accurate and precise results in a rapid manner: a key factor in selecting analytical methods for mineralogical studies involving large numbers of samples. All elements with atomic numbers greater than 9 (fluorine), except noble gases, can be determined with sensitivities ranging down to ppm levels.The analytical method described in this report is for the determination of the major elements (i.e. Na, Mg, Al, Si, P, K, Ca, Ti, Mn and Fe) in geological samples. Commercially available automated fusion devices are used for sample preparation.
Chemical Analysis of Coal by Energy Dispersive X-Ray Fluorescence Utilizing Artificial Standards
Authors: Wheeler Bradner D. 
Published: March 2019

AbstractAccurate determinations of the elemental composition of coal by classical methods can be quite difficult and are normally very time consuming. X-ray fluorescence utilizing the powder method, however, has the ability of providing accurate and rapid analyses. Unfortunately, well characterized standards, although available, are not plentiful. In addition, the durability or stability of ground and pelletized coal samples is poor resulting in deterioration with time. As a result, artificial coal standards were prepared from certified geological materials by fusing in lithium-tetra-borate in percentages approximating expected ash contents and compositions in coal. Since the lithium-tetra-borate comprises about the same percentage of the standard as does the carbon, hydrogen, and oxygen in coal, the ground and pelletized coal sample can be assayed against the fused calibration curves by compensating for the differences in the mass absorption coefficients of the two matrices.
Variability of Crystal Performance in X-Ray Fluorescence Spectrometers
Authors: Dubrawski Jules V. , Turner Ken E. 
Published: March 2019

AbstractThe intensity performance of various common XRF crystals (LiF200, Ge, PET and LSM) has been investigated under fixed experimental conditions. Measured were the raw intensities of elements particularly suitable to a given crystal, and peak-to-background ratios at different elemental concentrations. Peak profiles for each crystal type were also recorded and analysed in terms of apparent crystallite size and mosaic spread. In general the LiF crystals showed least variability in performance, whereas the PET crystals demonstrated the most.
An X-Ray Spectrometer for Pixel Analysis of Art Objects
Authors: Mantler M. , Schreiner M. , Weber F. , Ebner R. , Mairinger F. 
Published: March 2019

AbstractAn x-ray spectrometer has been designed for pixel by pixel analysis along lines or across selected areas of paintings and other art-objects. Characteristic technical data are: 0.8mm2 pixel size, 800mm (vert.) by 1000mm (horiz.) by 200mm (perpendicularly to object) motion distances, ±20μm precision in positioning the system, 2x3m maximum object size (mounted vertically); 2.8kW x-ray tube; Si(Li)detector. PC's are used for instrument control and new, complex data evaluation software.
X-Spectrum Determination Applied to Flash Radiography
Authors: Le dain Loïc , Dinten Jean-Marc 
Published: March 2019

AbstractWe propose a method, by absorption [1,2,3,4], of determination of the X-ray spectrum emitted by a flash X-ray radiography generator. This approach leads to an ill posed inverse problem very sensitive to the measures precision.We improve the robustness of the method by introduction of a smoothness constraint on the X-ray spectrum to reconstruct. We also propose an automatic choice of the weight between the measurement and the constraint by using a cross-validation technique.We present an application on an unusual flash X-ray radiography generator - i.e. 75 ns of duration pulse, 6.5 MeV of maximum energy, 350 Rad for dose - for which an instrument of direct measure has not yet been found.
Recent Developments and Results in Total Reflection X-ray Fluorescence Analysis
Authors: Wobrauschek Peter , Kregsamer Peter , Streli Christina , Aiginger Hannes 
Published: March 2019

AbstractIn the last years Total Reflection X-Ray Fluorescence spectroscopy (TXRF) has shown to be an analytical technique for trace element analysis as well as surface quality control. Detection limits in the range of pg or ng/g (ppb) level in concentration values of aqueous solutions or 1011 -109 atoms/cm2 are achieved with new excitation sources. The range of detectable elements has been extended to low and high 2 elements. Instrumental developments and results of the Atominstitut as well as from some other working groups are presented.
Strategies for Preferred Orientation Corrections in Xray Powder Diffraction Using Line Intensity Ratios
Authors: O'Connor B.H. , Li D.Y. , Sitepu H. 
Published: March 2019

AbstractLi et al (1990) reported experiments with gibbsite powder specimens on the use of Rietveld pattern-fitting, involving the March preferred orientation model, to characterise preferred orientation according to the March r parameter. It was shown that intensity corrections may be applied with the March r parameter derived from Rietveld analysis or with the related line intensity ratio MR which is sensitive to preferred orientation. The present paper reports an analytic expression involving r and MR which has proved highly reliable for the correction of preferred orientation bias in quantitative phase analysis of gibbsite. Similar expressions may be readily derived for other materials for which the March model is appropriate. Therefore the line ratio approach has considerable potential for rapid correction of intensities for preferred orientation.
Residual Strains in Al2O3/SiC (Whisker) Composite from 25-1000°C
Authors: Ballard Benjamin , Predecki Paul , Hubbard Camden 
Published: March 2019

AbstractResidual strains in a hot-pressed α-Al2O3/25 wt % β-SiC (whisker) composite were determined at temperatures from 25 to 1000°C in 250°C increments. The data collected from the (146) reflections of Al2O3 and the (511+333) reflections of SiC whiskers indicates that residual strains in both phases decrease linearly with temperature; the composite's extrapolated zero-strain temperature is determined to be 1471°C and comparable to the value ~1350 °C obtained by Majumdar et al. from neutron data. The lattice thermal expansion of the whiskers agrees well with literature, data for the monolithic β-SiC form.