bluuebunny/crossref_metadata_2025_split huggingface dataset:
Particle Statistics and Whole-Pattern Methods in Quantitative X-Ray Powder Diffraction Analysis
Authors: Smith Deane K. 
Published: March 2019

AbstractModern powder diffraction employing computer-controlled diffractometers now allows quantitative analytical methods to use the whole diffraction trace rather then only individual peaks. Two such methods are in common use the Rietveld method which refines the crystal structures of the component phases as part of the matching calculation, and the patternfitting method which uses reference patterns from a database. Potential accuracies of these methods seems to be around 1 % absolute. The most severe limitation on the potential accuracy of these methods is particle statistics, which has been reviewed in considerable detail.
Grazing-incidence X-Ray Analysis of Surfaces and Thin Films
Authors: Huang T. C. 
Published: March 2019

AbstractGrazing-incidence X-ray analysis techniques which are commonly used for the nondestructive characterization of surfaces and thin films are reviewed. The X-ray reflectivity technicue is used to study surface uniformity and oxidation, layer thickness and density, interface roughness and diffusion, etc. The grazing-incidence in-plane diffraction technique is used to determine in-plane crystallography of epitaxial films. The grazing-incidence asymmetric-Bragg diffraction is used for surface phase identification and structural depth profiling determination of polycrystalline films. Typical examples to illustrate the types of information that can be obtained by the techniques are presented.
Powder X-Ray Diffraction Characterization of Laser Deposited Ferroelectric Thin Films
Authors: Wong-Ng W. , Huang T.C. , Cook L.P. , Schenck P.K. , Vaudin M.D. , Chiang C.K. , Robins L.H. , Brody P.S. 
Published: March 2019

AbstractThin films of BaTiO3and Pb(Zr53Ti47)O3(PZT) have been deposited on Pt and Pt-coated silicon substrates using both Nd-YAG and excimer lasers. The BaTiO3films were prepared using heated substrates and were crystalline. The PZT films were deposited at room temperature and were amorphous; on annealing, they crystallized and gave rise to well-defined powder x-ray diffraction patterns.To compare and correlate the properties and processing conditions of these thin films, characterizations were performed using a variety of analytical techniques including x-ray diffraction, TEM, SEM/EDX and ferroelectric and dielectric property measurements. The x-ray diffraction technique was used for identifying the various phases formed and also for analyzing the profiles of the diffraction peaks. Both the PZT films annealed below 800°C and the BaTiO3 films typically show polycrystalline x-ray diffraction patterns corresponding to a pseudo-cubic structure (i.e no peak splitting) instead of the tetragonal patterns characteristic of the target materials. It was found that for the BaTiO3films the pseudosymmetry was due to crystallographic alignment of the longer c-axis In the substrate surface to relieve strain. In the FZT films annealed below 900°C, it is suggested that the residual surface strain and/or small crystallite size of these materials may have precluded the peak splitting; at higher annealing temperatures, the tetragonal symmetry was recovered.
Characterization of Perovskite-Like Substrates for Thin Film Superconductors using Synchrotron X-Ray Topography
Authors: Yao G.-D. , Hon S.Y. , Dudley M. , Phillips Julia M. 
Published: March 2019

AbstractThe characterization of defect configurations in various perovskite-like substrate materials for high Tc superconductor epitaxial films has been conducted using white beam synchrotron X-ray topography. The substrates were found to contain crystal lattice defects such as twins, dislocations and grain boundaries. It is shown that characterization of substrates can potentially afford insight into factors controlling the properties of the high Tc superconductor tilms supported on them. This can help in the selection of optimum substrate material. Defect formation mechanisms in individual materials as well as their respective influences on the films are discussed. Comparisons between the physical and chemical properties of several potential substrate materials are presented.
Preferred Orientation Analysis in Textured Materials
Authors: Bunge H.J. 
Published: March 2019

AbstractPolycrystalline materials may either be compact such as metals, ceramics, or some polymers or they may be powder samples. In both cases preferred orientation of the crystallites must be taken into account. In compact materials, texture formation by solid state processes and the texture-property relationship are the main purposes for texture investigations. In powder diffraction, texture correction can increase the accuracy of the results. Also strongly textured samples may be used in order to seperate diffraction peaks which are coincident in random powders.
Texture Characterisation in X-Ray Powder Diffraction using the March Formula
Authors: O'Connor B.H. , Li D.Y. , Sitepu H. 
Published: March 2019

AbstractTexture, i.e. preferred orientation (PO), of crystallites can cause serious systematic errors in quantitative analysis of crystalline materials using x-ray powder diffraction (XRPD) data. The singleparameter model of March (1932), proposed by Dollase (1986) for use in powder diffractometry is a promising mathematical formalism for correcting PO in XRPD analysis of uniaxially-oriented specimens. O'Connor et al. (1991) successfully applied the March formula in applying preferred orientation corrections for gibbsites, Al(OH)3, using Rietveld pattern-fitting and a line ratio method in which corrections are determined according to the intensity ratios of selected lines. The paper gives an appraisal of the general applicability of the methods considered by Li and O'Connor with particular reference to powder diffraction data for gibbsite, molybdite (MoO3), calcite (CaCO3) and kaolinite specimens. It is shown that some caution should be exercised when using the March formula to describe PO in Rietveld analysis.
Texture Development in Powder Mixtures
Authors: Gao B. , Bunge B. J. , Fantner C. J. , van der Veen R. A. 
Published: March 2019

AbstractThe development of preferred orientation, by powder compaction was studied in several single phase, two-phase and three-phase powders. It was found that texture formation depends strongly on the properties of the powder particles and the preparation technique. In powder mixtures strong interaction effects were observed which either enhanced or reduced the degree of the preferred orientation. The required degree of series expansion of the texture function ranged from zero up to about fourteen.
Opportunities for Materials Analysis with Next Generation Synchrotron Sources
Authors: Hart Michael 
Published: March 2019

AbstractPolycrystalline and powder diffraction is the most commonly practised method of x-ray analysis. During the last decade the construction of dedicated synchrotron radiation sources has resulted in the renaissance of these x-ray analysis methods; ab initio structure analysis and refinement, quantitative analysis of the structure, composition and stress in thin films and on surfaces, have all been improved. New techniques providing extremely high resolution, using anomalous dispersion, diffraction and scattering at grazing incidence to control x-ray penetration depth, have been developed. This brief review of work with W. Parrish at Stanford Synchrotron Radiation Laboratory and R. J. Cernik at the Daresbury Synchrotron Radiation Source is extended to indicate how third generation sources might be exploited in materials science.
2θ/α Scan X-Ray Powder Diffractometer
Authors: Kobayashi Yuji 
Published: March 2019

AbstractThe Bragg-Brentano focussing method (2θ/θ scan) is widely used in X-ray powder diffractometers. We have recently manufactured a diffractometer (2θ/α scan) whose incidence and reflection sides are asymmetrical. This report describes the optical system, including evaluation and application. The present method enables the following benefits to be obtained by simply changing the sample-to-receiving slit distance b without changing the X-ray source-to-sample distance a: (1) enhanced angular resolution, (2) increased diffracted X-ray intensity, and (3) variable asymmetrical angle. The experimental results show that the focussing condition of this optical system was satisfied. It also shows that the intensity of diffracted X-rays could be increased by approximately 1.4 times at b = 100 mm when the intensity at a = 185 mm and b = 185 mm was assumed to be 1. Furthermore, it was verified that FWHM can be reduced by making sample to receiving slit distance greater.
Recent Developments in Stress Analysis by Diffraction Methods
Authors: Hauk V. 
Published: March 2019

AbstractStarting in Germany (Garmisch Partenkirchen, 1986) we had the 1st ICRS (Int. Conf. on Residual Stresses). The second was held in France (Nancy, 1988), the third in Japan (Tokushima 1991). In all areas, the diffraction measurements furnish exceptional contributions, and in many cases they are the only methods capable of solving problems. Because of the importance of the diffraction methods, the literature on residualstress analysis (RSA) has enlarged in the last years, Figure 1.
A Comparison of X-Ray and Neutron Diffraction Measurement of Lattice Parameters for the Determination of Residual Stress and Chemical Composition in Zirconium Alloy Tubes
Authors: Griffiths M. , Winegar J.E. , Mecke J.F. , Holden T.M. , Holt R.A. 
Published: March 2019

AbstractIntergranular residual stresses can exist in zirconium alloys, especially when there is a large distribution of grain orientations. The stresses result from the anisotropic plasticity and thermal expansion of the hexagonal close-packed crystal structure of α-zirconium. Apart from complicating the characterisation of materials using lattice parameter measurements, the intergranular stresses can significantly affect material behaviour, especially in nuclear reactor environments, and there is therefore a great deal of interest in their measurement.The effects of specimen preparation and surface relaxation on X-ray diffraction measurements of lattice parameters of zirconium alloys have been investigated by comparing bulk neutron diffraction with X-ray diffraction on identical materials. The results show that: (i) intergranular or interphase residual stresses exist in dual-phase Zr-2.5Nb pressure tubes; (ii) the stresses normal to the surface of an X-ray diffraction specimen are not relieved completely when there are intergranular residual stresses in the material. One can conclude that intergranular stresses have to be considered when determining chemical compositions from lattice parameter measurements and also when measuring macroscopic residual stress using X-ray diffraction.
Profile Fitting by the Interference Function
Authors: Lutterotti Luca , Scardi Paolo 
Published: March 2019

AbstractOn the basis of the “column-like” powder model of Warren and Averbach, a profile fitting procedure was devised to obtain microstructural disorder parameters. The interference functionwhere d is the interplanar distance, λ the wavelength, θ the diffraction angle and N the number of cells within a column, was used to model experimental profiles taking into account the column-like crystallite size and r.m.s. strain distributions. The procedure can be applied both to single peak and to two or more peaks of multiple order of reflection. The method was tested on several samples, also having a bimodal size distribution, and the results compared with those obtained by the well-established Warren-Averbach analysis.
X-Ray Diffraction from a 28 Attoliter Crystal Volume
Authors: Skelton E.F. , Ayers J.D. , Qadri S.B. , Hu J.Z. , Finger L.W. , Mao H.K. 
Published: March 2019

AbstractMetallic filaments with sub-micrometer diameters have recently been fabricated using novel materials fabrication techniques at NRL. The specimens are enshrouded in a glass sheath and all efforts to obtain structural information from these samples with conventional x-ray sources have been negative. By using synchrotron radiation on a wiggler beam line, x-ray diffraction data have been obtained from samples with diameters of 0.22, 0.09, 0.07, and 0.04 μm. The two thicker samples were found to be single crystals with a structure consistent with that of normal Bi. Single crystal diffraction peaks obtained from the 0.07 μm sample are incompatible with the Bi-1 or any other known structure of Bi. We have provisionally identified this as Bi-X.
Performance Characteristics of a High Resolution Si(Li) Detector Using a Time Variant Amplifier and a Pulsed Source of X-Rays
Authors: Short M. A. , Gleason T. G. 
Published: March 2019

Two recent improvements in energy dispersive spectrometry are the development of time variant amplifiers and the introduction of pulsed X-ray sources. Either pulsed X-ray tubes or electron beams with fast beam blanking may be used.Time variant amplifiers designed by Kandiah (1 ,2) used control logic to co-ordinate charge restoration of the detector preamplifier, pole-zero cancellation and baseline restoration. In the pulse shaping circuit, time constants are switched during the processing of each pulse to optimize throughput, baseline stability and pileup rejection. Pulse processing techniques have been discussed by Statham (3) .
The Use of Polarized X-Rays for Improved Detection Limits in Energy Dispersive X-Ray Spectrometry.
Authors: Ryon Richard W. , Zahrt John D. , Wobrauschek Peter , Aiginger Hannes 
Published: March 2019

AbstractThe use of polarized x-rays to excite fluorescence spectra with decreased backgrounds and improved detection limits is reaching a mature state of development. With bulk, low-Z specimens, polarized x-ray sources have produced detection limits which are ~℩ to 3 times lower than are obtained with the best unpolarized photon sources. Based upon experience and the known properties of larger solid angle geometries, further significant to dramatic improvements are anticipated.
Feasibility Study for On-Stream X-Ray Analysis of Barite
Authors: Gurvich Yury M. 
Published: March 2019

Modern on-stream X-ray equipment for slurry analysis is now used in hundreds of mines throughout the world. This technique provides valuable information for process control which cannot be achieved by other analytical methods. One of the most recent successful examples is the Brenda Mines, in Canada, where the ARL Process Control X-ray Quantometer (PCXQ) is used for ten different streams in a Cu-Mo concentrator.The success of slurry analysis is highly dependent upon the analytical method selected, based on the following factors: (i) the features of the analyzed materials, (ii) the concentration ranges, (iii) percent of solids, and (iv) requirements of analytical accuracy and precision. A preliminary investigation of methods and of analytical conditions can be done on a laboratory X-ray spectrometer using solid models of slurry. Such preliminary work significantly simplifies the introduction of the new technology and helps in the preparation of proper specifications.
A Second Generation Automated Powder Diffractometer Control System
Authors: Snyder Robert L. , Hubbard Camden R. , Panagiotopoulos Nicolas C. 
Published: March 2019

AbstractThe real-time x-ray powder diffractometer control system AUTO incorporates several advances in data collection and analysis. Counting procedures for selected area data collection are optimized to achieve either a preselected statistical error in minimum time or a minimum error in fixed total time. Run files are employed to greatly simplify quantitative analysis procedures and for controlling repetitive runs. External calibration curves for 20 are used to eliminate all but sample dependent aberrations to peak positions. A generalized data file structure is used to document the instrumental variables and sample parameters.
The Application of X-Ray Diffraction for Glass Batch Homogeneity Determination
Authors: Kim H. S. , Cohen C. I. 
Published: March 2019

AbstractAn X-ray diffraction (XRD) technique is employed to determine the presence or absence of crystalline phases in glass batch and to determine its homogeneity qualitatively and quantitatively.Sample preparation problems are discussed, and promising techniques for sample preparation are presented. Qualitative batch homogeneity determination is accomplished by comparing the integrated intensity of a particular reflection of the reference sample to that of the unknown sample. Quantitative batch determination is accomplished by using the internal standard method. Three replicated data sets indicate that the standard deviation of kaolinite and colemanite are higher than those of quartz and calcite. However, the overall data from the quantitative analyses lie within an acceptable range of precision and accuracy.
Neutron Powder Diffraction at a Pulsed Neutron Source: A study of Resolution Effects
Authors: Faber J. , Hitterman R. L. 
Published: March 2019

AbstractThe General Purpose Powder Diffractometer (GPPD), a high resolution (∆d/d=0.002) time-of-flight instrument, exhibits a resolution function that is almost independent of d-spacing. Some of the special properties of time-of-flight scattering data obtained at a pulsed neutron source will be discussed. A method is described that transforms wavelength dependent data, obtained at a pulsed neutron source, so that standard structural least-squares analyses can be applied. Several criteria are given to show when these techniques are useful in time-of-flight data analysis.
Recognition and Treatment of Background Problems in Neutron Powder Diffraction Refinements
Authors: Baur W. H. , Fischer R. X. 
Published: March 2019

AbstractIrregular backgrounds in time-of-flight neutron powder diffraction data and nonlinear backgrounds in angle dependent neutron powder diffraction data. were corrected by fitting fifth degree polynomials to those portions of the data most affected. The anomalous background intensities were in both cases due to non Bragg scattering. The polynomial fitting was carried out over a sufficiently widerange of the profile to avoid interfering with the Bragg peaks. The corrected data gave internally consistent results for the crystallographically nonequivalent (Si,Al) -0 (1) and(Si, Al) -0 (2) bond lengths in zeolite rho and compare favorably with previous refinements of this Zeolite in space group Im3m. Internal and external in consistencies of bond lengths are just as diagnostic of refinement difficulties as negative isotropic temperature factors or non positive definite an isotropic temperature factors are.
Lattice Thermal Expansion Effects in Pure and Doped Cordierite by Time-of-Flight Neutron Diffraction*
Authors: Predecki F. K. , Haas J. , Faber J. , Hitterman R. L. 
Published: March 2019

AbstractThe thermal expansion behavior of pure, Ge-doped and Li-doped hexagonal cordierites with respective compositions: 2MgO 2Al2O3 5Si02 2Mg0 2Al2O3 4Si02 Ge02) and 2MgO (2+x)AL203 (5-2x)Si02 xLi20 with x = .174, was investigated using time-of-flight neutron powder diffraction at temperatures from 22 to 750°C in vacuum. The data were refined in space group P6/mcc using the Rietveld method. The lattice thermal expansion curves of all 3 samples were quite similar. The negative axis expansion is associated with (1)displacement of the T2 cations generally toward the axis channels and (2) changes in the distortion of the coupled T1/M tetrahedra/octahedra in the structure. Both contributions were present in all 3 samples but the first was more dominant in the Ge doped sample. The nature and origin of the distortions in T1 and M are discussed.
Application of Quantitative X-Ray Diffraction Analytical Methods to the Study of High-Magnesium Phosphorites
Authors: Blanchard Frank N. , Goddard Robert E. , Saffer Barbara 
Published: March 2019

Phosphorite is a sedimentary rock with a high enough content of phosphate minerals to bo of economic Interest. Most phosphorites are composed predominantly of m1crocrystall1no to cryptocrystalline carbonate fluorapatlte thenceforth In this report referred to simply by the mineral group name apatite). Florida produces roughly 1/3 of the world's supply of phosphate rock, most of which is used 1n the fe rtiliz e r Industry.Long term continuation of phosphorite mining In Florida will require exploitation of the extensive hlgh-magneslum phosphorite deposits south of the present mining d istrict 1n central Florida, and this will require new technology In order to produce beneficlated concentrates with less than 1% MgO, a limit Imposed by fe r tiliz e r processing technology. In order to develop benefication methods applicable to these ores, it is essential to know how Mg occurs in phosphorites. Dolomite, CaMg(C03)2, is the chief host of Mg In phosphorites from Florida. Magnesium may also be present, however, as a substituent In apatite (the chief phosphate.mineral in these deposits), as a minor substituent 1n calcite (CaCO3), in certain clay minerals (particularly palygorskite and to a lesser extent in some smectites), and/or in organic matter within the apatite particles.
Instrumentation for Synchrotron X-Ray Powder Diffractometry
Authors: Parrish W. , Hart M. , Erickson C. G. , Masciocchi N. , Huang T. C. 
Published: March 2019

AbstractThe instrumentation developed for poly crystalline diffractometry using the storage ring at the Stanford Synchrotron Radiation Laboratory is described. A pair of automated vertical scan diffractometers was used for a Si (111) channel monochromator and the powder specimens. The parallel beam powder diffraction was defined by horizontal parallel slits which had several times higher intensity than a receiving slit at the same resolution. The patterns were obtained with 2:1 scanning with’ a selected monochromatic beam, and an energy dispersive diffraction method in which the monochromator is step-scanned, and the specimen and scintillation counter are fixed. Both methods use the same instrumentation.
Changes in the Unit Cell Dimensions of ZSM-5 Produced by the Adsorption of Organic Liquids*
Authors: Pollack S. S. , Gormley R.J. , Wetzel E. L. 
Published: March 2019

The adsorption of liquids in 2eolites has been a widely studied phenomenon, and with the development of ZSM-5, considerable work has been carried out on this zeolite, However, few articles have been published dealing with changes in the X-ray diffraction patterns when the zeolite pores contain adsorbed molecules. The purpose of this paper is to report changes in the X-ray diffraction pattern of ZSM-5 after mixing it with various organic solvents.This work began after studies of both deactivated and partially deactivated ZSM-5 catalysts showed that their X-ray diffraction patterns changed in intensities and peak positions after use in microreactor studies. If coke or hydrocarbons were causing the above changes, as postulated, would hydrocarbons adsorbed in ZSM-5 produce the same changes? Simpson and Steinfink showed that the low-angle lines of faujasite decreased in intensity after the adsorption of m-dichlorobenzene.