In X-ray diffraction techniques intensity of radiation is an important factor. In addition, when high resolution is required, the usual collimating system restricts the width of focus that can be effectively used. Accordingly, a prime requirement is that the target loading shall be high to give the greatest possible brilliance at the focus. An X-ray unit designed to achieve these qualities will be described. Its use with a spectrometer and with a number of cameras for differing crystallographic studies will be illustrated.

The tube operates with alternative electron guns, one of them to provide a circular focus of 40 microns in diameter and the other to provide a line focus of 1.4 millimeters in length and 0. 1 millimeter in width.

Spray drying is shown to be an effective and rapid method for preparing samples for quantitative analysis by x-ray powder diffraction. Previously intractable problems like the simultaneous analysis of multiple phases in orientation prone systems can be carried out. Using this method, and a computer controlled diffractometer, five and six phase analyses of Devonian shales can be accomplished in approximately forty minutes. A rapid and convenient method for using the absorption diffraction technique for x-ray quantitative analysis is described.

The sources of raw materials used in the manufacture of Portland cement include pure to argillaceous limestones, shale and clay, plus minor quantities of sand, iron ore, fly ash, coal ash and suitable industrial wastes. To ensure a high quality product, rapid - precise - reproducible and practical analytical techniques are required. Quantitative XRF analysis techniques meet those demands.

For this comparative technique, the instrument used is a wavelength dispersive sequential spectrometer. The advantages and the drawbacks of the technique are discussed, along with the procedure of the specimen fused bead preparation. The importance of calibration standards and unknown samples being prepared in an identical manner, and being presented to the instrument under similar conditions, is stressed. International and synthetic standards, concentration ranges for the five major elements, mathematically generated coefficients to correct absorption and enhancement effects, and a summary of the standard error of estimates are examined and discussed.

The accuracy of the method is verified by the analysis of known standard reference materials such as obsidian rock, coal fly ash, argillaceous limestone and blastfurnace slag. The values are compared with the known certified values.

The electron probe microanalyzer has found numerous applications in physical metallurgy. Some recent problems which have been studied with the microanalyzer constructed by the author at the California Institute of Technology include (1) determination of the penetration of chromium in chromized iron, (2) determinations of the concentration of nickel in taenite bands occurring in a fragment of meteorite from Canyon Diablo, (3) identification of intermediate phases in the as-cast structure of an alloy of titanium and copper, (4) identification of phases in the titanium—silver binary system, (5) determination of concentration fluctuations in a gold—copper alloy resulting from slow solidification, and (6) determination of the diffusion profile of nickel in single crystal sapphire.

The mass absorption coefficient (μ) of a weakly absorbing solid material may be measured by either the transmission or the reflection method. The latter typically employs a crystalline substrate and the diffraction method, measuring the transmission of the diffraction peak(s) of the substrate through the analyte. Compressing or compacting a powdered sample is not required when the reflection method is used.

This report will describe scientific activity in XRF as well as some practical application topics for Japan and China.

An X-ray fluorescence analysis unit has been automated with a multi-position sample changer, a stepping motor to position the spectrometer, and computer addressable switches to control the selection of crystal, detector, collimator, and beam filter. The unit can be controlled off-line through a Teletype or on-line with a computer. This computer utilizes a multi-user program for the simultaneous operation of the fluorescence analysis unit and two diffractometers. Programming the system for any desired analytical or research procedure is accomplished using an expanded version of BASIC.

Recently synchrotron radiation (SR) sources have been extensively used for the study of materials science. The high intensity of tunable monochromatic X-rays from SR facilitates many types of spectroscopic/ diffraction studies which have otherwise not been possible. Regarding the X-ray fluorescence technique, significant improvement of the minimum detection limit has been performed and has enabled trace element analysis in the order of tens of ppb or 10-12 g.3-8 SR microanalyzers and near surface analysis using grazing incidence geometry are also attractive applications of synchrotron X-ray fluorescence technique. From a point of materials characterization, chemical state analysis is not less important than ordinary element analysis.

The authors previously reported stress measurement in stainless steel by the use of monochromatic Cr-Kβ X-rays and a position sensitive proportional counter. Results indicated that a stress value can be obtained with high precision on account of the subtraction of background and the elimination of αFe(211) peak by Cr-Kα X-rays. The major disadvantage of this method, however, is that the intensity of Kβ X-rays monochromatized is essentially weak and it is complicated to eliminate Kα X-rays for practical use.

Both double-crystal and triple-axis x-ray diffraction techniques have been used to study complex SiGe/Si structures. A novel method for measuring the nucleation activation energy of dislocations in strain relaxed SiGe/Si structures is presented to illustrate the usefulness of these techniques.

A PDF 15/40 computer wich ADC and CAMAC interfaces is used to control data collection apparatus, acquire data, and reduce data to determine the elemental composition of aerosol samples. The background is subtracted from each energy spectrum, peak centers are located automatically using a Gaussian correlation technique, peak multiplets are resolved with Gaussian fits, peak energies are compared with entries in a table of x-ray lines for possible identification, multiple identification of peaks and line interferences are resolved, and the elemental amounts are determined from the areas of the Gaussian fits.

The use of the computer controlled powder diffractometer for the qualitative and quantitative analysis of multi phase powder mixtures is becoming relatively common place, and we ourselves have described in some detail the hardware and software components of typical systems 1,2) of which the AFD 3600 is the latest version 3). Although great success has been achieved in the use of the minicomputer for machine control, data acquisition and display, plus some degree of data workup, less success has been gained in search/matching of unknown powder patterns, although computer programs have been available for a number of years which utilize relatively large computers for automatic search/matching e.g. 4,5) the success with which these programs have been applied has been somewhat disappointing. Much of the difficulty arises from the marginal quality of data in the JCPDS index and from uncertainties in the accuracy of the experimental patterns.

A general computer program has been written in basic Fortran language and tested for computing average particle size, strain, and particle size distribution according to the Fourier method of B. E. Warren.

The program provides such optional features as input data and Fourier coefficient print out, automatic background correction, the choice of fixed count or fixed time input mode, the synthesized diffraction peaks deconvoluted with respect to the instrumental diffraction peak, and a variable amplification range of particle Size. Included in the analysis is a polynomial fitting procedure for the scattering factor. The authors have attempted to write this computer program to be as self-explanatory as possible for general applicability. This program is available on request.

This Fourier analysis program has been tested using known distribution functions, and has been used for measuring average particle size, particle size and strain distribution in heattreated boron-doped graphite samples.

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.

Energy dispersive X-ray fluorescence (EDXRF) analysis is finding increasing application in field assay of soils and stream sediments for geochemical prospecting; in borehole logging and core analysis for formation evaluation in mine control, and in on stream analysis for process control.

The analytical capability of the method is determined by the choice of source, the energy of the exciting radiation and the energy resolution of the detector. The nature of the samples, their atomic number and concentration are also important. However, the most dominant constraints on limits of detection are often imposed by the environment at the region of measurement: by the borehole condition, the nature of the rock face or the form of the particulates and stability of the fluid in a process stream.

The analysis of dry powder samples for magnesium, sodium, and fluorine by X-ray and electron excitation has been studied. As in the case of heavier elements, the form of chemical combination influences the elemental sensitivity; sensitivity changes due to self-absorption can be adequately predicted using published absorption coefficients. Where both absorption and enhancement effects are possible, selection of X-ray target or excitation potential can. eliminate the enhancement problem. Matrix effects were found to be extremely variable and unpredictable. Finally, X-ray and electron excitation results are compared for the three elements in a series of geological samples. Efficiency of excitation was far better for electron excitation, but limits of detectability were lower for X-ray excitation due to significantly lower backgrounds.

Two strategies are at present commonly used in studying and refining crystal structures from powder diffraction data: the total pattern refinement proposed by Rietveid (1969) and the two-step method originally proposed and applied by Will (Will et al., 1965). The latter one works by separating-the intensity determination of the individual peaks from the actual structure refinement, structure analysis or any structural calculation (tor example based on line broadening). Both methods have their merits, and their drawbacks.

A series of nanostructured Fe/Ag metal films were produced at various substrate temperatures to determine their magnetic characteristics. The magnetic coercivity was found to increase with the diffracting-particle size which is process controlled. The films produced at low substrate temperature (<200°C) consisted of small metallic clusters of Ag (<100 Å). As the substrate temperature was increased, the films exhibited increased crystallinity and larger diffracting-particle size. The position of the maximum in the particlesize distribution function and the width of the function increased with substrate temperature.

The amphibole mineral, cummingtonite-grunerite, has been used as a tracer for taconite tailings discharged into Western Lake Superior. The discovery of many asbestiform amphibole fibers in the tailings and Western Lake Superior water lead to concern over fiber concentrations in municipal water supplies using this water. This concern was based on the association between human asbestos exposure and increased rates of cancer of the gastrointestinal tract and peritoneum. An x-ray diffraction external standard technique has been developed for rapid, inexpensive, semi-quantitative determinations of amphibole mass concentration in water. The average amphibole mass concentrations for different Western Lake Superior water intakes compare very well with the average electron microscope fiber counts for the same samples. Daily amphibole analysis of the Duluth water supply indicates an average amphibole concentration of 0.19 milligrams per liter.

A new method for the collection and analysis of high temperature Guinier x-ray data has been devised at The Dow Chemical Co. This technique can be used to monitor various types of structural transformation and thermal expansions up to 900°C. The thermal expansions of α-Al2O3 and two TiO2 structures, anatase and rutile, have been characterized for their use as high temperature internal standards.