Residual strains and stresses were measured in hot-pressed α-Al2O3 composites containing 25 wt% β (cubic) SiC whiskers with and without a 50-100Å thick carbon coating. X-ray diffraction methods were used including the separation of macrostresses from the microstresses in the -Al2O3 and SiC phases by the method of Noyan and Cohen. The presence of the carbon coating on the whiskers reduced the magnitude of the residual microstresses in the whiskers by ˜13% and in the matrix by ˜10%. The measured residual stresses in the whiskers and the reduction due to the carbon film were in good agreement with calculations from recent models proposed by Hsueh, Becher and Angelini, and by Li and Bradt.

Zn-Ni-alloy electroplated steels are used for the parts of automob iles because of their high corrosion resistance. in the x-ray stress measurement of this material, some unique experimental results were observed: (i) The sin2Φ diagrams were severely curved, and (ii) the influence of the wave length of x-ray radiations upon the shape of the d-sin2Φ diagram was very slight. As no strong texture or the gradients of composition were observed in this material, the above experimental results suggested the existence of steep stress gradients in the direction of depth, and a theoretical problem on the difference in the effective penetration depth of x-rays and the weighted mean of the lattice strain between thin films and ordinary thick materials.

Errors pertinent in dual beam absorptiometry have been studied. Five areas are given in detail: 1. Scattering, in which a computer analysis of multiple scattering shows little error. 2. Geometrical configuration effects, in which the shape of the sample influences accuracy. 3. Poisson variations, in which dosage and statistical error are minimized. 4. Absorption coefficients, in which variations in compilations are examined. 5. Filtering, wherein is shown the need for Kβ filtering. A zero filter system is outlined.

The fundamental parameter method for x-ray spectrometry has been used most commonly for bulk samples, because it permits an analysis utilizing a minimum number of standards, even for samples with complicated matrices. The need for the analysis of thin film materials, which includes multi-layer films, has been increasing in recent years along with the rapid progress of high technologies. However, there have been few reports that deal with the application of fundamental parameter methods to multi-layer thin films. There may be two situations in the analysis of thin films. In routine analysis of quality control applications, they usually require precise analysis. Fortunately, it is possible to prepare well characterized standards similar to the unknowns.

Two kinds of improved techniques are described for precise measurement of lattice parameters with an accuracy of 1 ∼7x10-5, in both of which a differenoe of Bragg angles between two X-ray beams such as K α1 and K β1 is measured.

In the first technique, which was applied to relatively imperfect crystals such as gallium arsenide, gallium arsenide phosphide, and gallium phosphide, two different diffraction planes were utilized for two radiations such as CuK α1 and CuK β1 in order to reduce the difference of the Bragg angles to the order of several minutes of arc.

In the second technique, which was applied to a nearly perfect crystal such as silicon, a double crystal arrangement of parallel setting was used, where lattice parameter of the specimen was relatively measured in comparison with the one of the first crystal which was known beforehand.

A flow proportional counter for ultrasoft x-ray applications has been constructed and used to measure proportional counter parameters in the ultrasoft x-ray region at atmospheric and subatmospheric pressures for counting gases of P-10 and methane. We find that at atmospheric pressures the parametrization given by Zastawny for describing gas amplification in proportional counters applies and have measured values for the parameters for P-10 and methane. For subatmospheric pressures the Zastawny parameters are inadequate. A new parametrizatlon is required. In addition, the linearity of the detector for x-rays of energies of 15 KeV to 0.5 KeV was measured for pressures ranging from 750 Torr to 150 Torr and found to be excellent in all pressure regions.

Total reflection X-ray fluorescence (TXRF) analysis of “low Z” elements, Ti, Fe, Ni, Cu, Zn and “high Z” elements, Zr, W, Au, Pb, are required for micro scale semiconductor device production processes. In the past, the W–Lβ X-rays have been used for the analysis of S to Zn.

This paper describes a new three crystal monochromator coupled with a gold direct-drive rotating anode target. This development has produced significant improvements in the sensitivities and LLD's for all measured elements. The monochromator makes the Au Lα (9.71 keV), Au Lβ (11.44 keV) and Au Lγ (13.33 keV) available for routine use in TXRF analyses. The Au Lα X-ray is best used for the lower Z elements, Na to Cu. The best result for W, Cu and Zn are obtained with the Au Lβ X-ray. This is the result of both increased peak intensity and lower background. For the heavier elements, such as Au and Pb, the Au L X-ray yields intensities 100 times higher than what has been achieved in the past.

A minicomputer program system for phase Identifications in x-ray powder diffraction is described. The routines written in FORTRAN comprise the users’ special purpose standard-file management (creation of microfiles from the complete JCPDS-data base or own standards, as well as utility routines for corrections, supplements and bookkeeping) and the measured data processing, including raw data acceptance, data reduction by two selectable peak-search routines (trendoriented or 2nd derivative) and an exhaustive search/match procedure through selected microfiles. The data reduction and analysis programs have manifold graphical displays allowing manual interference. In one run up to five phases can be matched. The weight portion of every phase is estimated, using I/I (corundum)- values, Hie whole analysis (in automatic operation) consumes about 1 or 2 minutes of the processor time on a pdp 11/34 minicomputer. This matches well to the data collection times accessible for fast powder diffraction systems /I/.

For many years the International Centre for Diffraction Data has sponsored round robins covering various aspects of X-ray powder Diffraction with the objective of illuminating and understanding current practices and problems associated with, the analysis of diffraction data. As computer analysis of diffraction data becomes ever more sophisticated, analytic capabilities are extended and the performance, not only of the instrumentation must be checked, but also that of the software which converts the measured data into useful results. In recent years, therefore, we have personally participated in a cell parameter round-robin, a d-spacing round-robin, a peak hunting round-robin, and, most recently, the present intensity round-robin and a line profile round-robin. Still others are in progress or being planned.

As the Environmental Protection Agency adds ever more sites to the National Priorities List for Superfund clean-up, there is a tremendous need for a fast method of screening for contaminants. In the case of inorganics, we can apply field-portable X-ray fluorescence technology.

With commercially available field-portable X-ray fluorescence equipment using in-situ measurements we can quickly screen a site (hundreds of measurements), input the data to a portable computer, process it, and print a colored concentration isopleth map of the contaminant of interest, all in realtime.

The in-situ measurement approach pioneered by Lockheed is the key to rapid screening capability. Problems arising from particle size distribution, soil heterogeneity, and bulk density are minimized by employing site-specific standards in the construction of our calibration curves. Inherent in these site-specific standards are all the matrix problems which occur in the routine samples.

The strength of field-portable X-ray fluorescence technology is the accuracy of analysis above the quantitation limits. The difficulty in measuring low concentrations near the detection limit is the weak point of field-portable units.

NOTICE: Although this research was funded in part by the U.S. EPA through Contract 68-03-3249 to Lockheed Engineering & Sciences Company, it has not undergone Agency review and does not necessarily reflect Agency policy.

The radiation from plasmas produced by the interaction of a pulsed laser and a solid target can be made to fall in the soft x-ray regime. The x-rays can serve as an alternative to the increasingly important synchrotron radiation facilities for a variety of techniques such as Extended X-ray Absorption Fine-Structure Spectroscopy and X-ray Lithography. In addition, the x-rays are of special interest for general microradiography of thin samples.

During the course of the past ten years the International Centre for Diffraction Data has sponsored a number of “Round Robin” tests to evaluate the quality of experimental X-ray diffraction data [1-5]. The latest of this series, called the Instrument Parameter Round Robin, was designed to evaluate, among other things, relative angularly-dependent sensitivity differences between diffractometers. Previous experiments have indicated that even perfectly aligned diffractometers of the same generic type, do not necessarily give the same set of relative intensities. One objective of the round robin was to quantify the magnitude of the experimental differences between data sets, and to demonstrate a means for external calibration of diffractometers, so that digitized diffraction intensity data obtained from different instruments could be directly compared.

The use of CaF2 (Dy) thermoluminescent dosimeters to diagnose the X-radiation from 1.06 μ laser-produced plasmas is described. The TLD's have been used in various cassettes to measure total X-ray yield and the X-ray continuum out to ∼100 kev. Described are experiments pertaining to maintenance and recovery of TLD soft X-ray response, their linearity, insensitivity to 1.06 μ laser light, and energy calibration. Also, described are the TLD attenuation experiments in the “soft” and “hard” components of the laser plasma X-ray spectrum.

X-ray fluorescence spectroscopy is new becoming a tool in research and. industry. Semiconductor detectors are proving valuable in measuring fluorescent X rays, and so are providing a versatile tool for rapid multielement analysis of many types of samples. This paper will mainly be concerned with, different types of copper ore. An experimental setup has been designed to determine Cu, Fe and Pb of concentration ranging from 0.1 to 20, to 5, and to 4 percent, respectively, with analytical precision of 20% relative at 0.1% Cu, and 3% relative at 20% Cu. For excitation a 100 mCi Pu-238 source and/or a low power air-cooled X-ray tube were used. Data acquisition and “on-line” evaluation for each sample takes about 100 seconds. Electronics blocks and sub-systems used In the set-up are available commercially. The most important benefit to be obtained from the setup is the ability to provide precise, reproducible determinations of large numbers of samples day after day.

Moderate counting rates, in excess of 400 cps at a signal/noise ratio of 18 on 3.5% NaaO in rocks, permit high-precision quantitative analysis for light elements in silicates. Special advantages of fluorescence analysis in the 10 A region, with adequate excitation provided by an aluminum target tube, will be described. These advantages include an ease of discrimination by excitation potential and by high dispersion using large 2d space crystals. Minor and simple modifications of the optic path combined with electronic discrimination make the method ideal for sodium and magnesium. Routine runs over periods of days have been made possible by a new technique of calibration involving computer corrections for systematic drift from any source. Repeated tests show that the total analytical error, including specimen preparation, closely approaches that of the counting statistics used, and that the drift corrections are complete. In granitic rod; analyses resulting precisions (standard deviation/mean) are 1% for 2-5% Na2O and 2% for 0.25-1.0% MgO.

Stresses in polymeric materials can be measured by diffracting X-rays from embedded crystallites that yield suitable powder diffraction lines. An appropriate technique for this has been, reported by C. S. Barrett and Paul Predecki elsewhere and is reviewed here with additional details. It is based on a diffractometer modified so as to operate at very high 26 angles, with specimens prepared in various ways. Results show that adequate precision is reached by scanning Ka doublet in a few minutes and simply noting any displacement of peaks compared with peaks from an unstressed specimen; higher precision can be reached with slower scans or more detailed analysis of the peaks. Tests with embedded metallic particles were successful when the particles were (A) distributed throughout a moulded polymethyl methacrylate (Lucite) sheet of the order of a millimeter thick, alone or sandwiched between layers of particle-free material, or (B) embedded in polyester resin applied to a surface of Plexiglas bars, or (C) embedded in graphite-fiber epoxy composites in a layer at a chosen position within a specimen.

Characteristic soft x-ray emission lines created as a result of low energy (10-100keV) positive ion excitation of a target material has been applied to the study of thin films of oxygen that form naturally on metal surfaces. The specific metals investigated were aluminum and nickel aa well as a number of their corresponding alloys.

Low energy positive ions are well suited as projectiles for the study of thin films in that they have low penetrating powers, yet produce high x-ray yields for K-, L-, and M-shell elemental x-ray lines. Perhaps the most important feature is the fact that no background bremsstrahlung continuum x-radiation is generated in the slowing processes of the ions. Exploiting the advantages of these facts, a special high sensitivity detection technique has been developed for the soft x-ray analysis of the constituents that make up a particular thin surface film.

The physical basis for thickness and atomic density measurements of thin surface films by positive ion excitation are discussed. Calibration data are presented for thin films of known thickness and composition establishing the sensitivity of the method for the measurement of the elemental atomic densities of thin films down to a few monolayers or approximately 10 Å in thickness. Finally, the results of the analysis of oxide surface films of aluminum, nickel and some of their alloys are presented and discussed.

The objective of this continuing program is to gain an understanding of the mechanisms and principles governing the formation of oxide surface films on metals with the basic goal of producing new alloying techniques for metal passification in a saline environment.

This paper describes the imaging of fossils using elemental x-ray area mapping (EXAM). The technique utilizes a commercially available instrument originally designed for the silicon chip industry. The EXAM data are processed digitally with imaging software to remove surface irregularities and enhance specimen details. Applications of this technique to specimens with irregular surfaces are described.

For phase analysis of small amounts of material in an x-ray powder diffractometer the sample is often spread on a sample mounting plate or support plate. Different types of plates on which thin samples can be mounted are:

• - silver membrane filters

• - metal or other polycrystalline plates

• - polymer membrane filters, for example PVC, polycarbonate, cellulose nitrate

• - glass slides

• - single crystals; cut so that no diffraction lines occur.

Filters are often used to collect environmental dust; these samples can be analysed “as received,” Glass slides are inexpensive, flat, and readily available. Polycrystalline filters and plates have the disadvantage of possible line overlap with lines of the sample material (refer to figure 1), Glass plates or polymer filters have the high and curved background due to amorphous scatter as shown in figure 2.