Solid solutions are pervasive in minerals and in industrial inorganic materials. The analyst is often called upon to provide qualitative and quantitative X-ray phase analysis for specimens containing solid solutions when all that is available are Powder Diffraction File (PDF) data or commercial standards for the end members. In an earlier paper (1) we presented several examples of substantial errors in accuracy of quantitative analysis that can arise when the crystallinity and composition of the analyte standard do not match those of the analyte in the sample of interest. We recommended that to obtain more accurate quantitative analyses, one should determine the analyte composition (e.g., from XRF on grains seen in a SEM or from comparison of cell parameters with those of the end members) and synthesize an analyte standard with this composition and with a crystallinity approximating that of the analyte (e.g., as determined from peak breadth or α1/ α2 splitting).

X-ray diffraction and electron microprobe analysis were used in combination to identify reaction phases that formed on the surfaces of low-carbon steel specimens reacted with a 75% basalt-25% bentonite mixture and anion-doped water in sealed pressure vessels at 100°C and 250°C. Reaction phases on specimen surfaces and in adhering geologic material were identified by conventional X-ray diffraction scans of entire specimens with intact reaction layers. Comparison of results from adhering geologic material and scans of selectively removed layers allowed establishment of approximate reaction gradients in the adhering packing material. Electron microprobe analysis of specimens in cross-section provided quantitative chemical analyses of adhering reaction phases, and identification of reaction layer composition gradients and thicknesses. Magnetite formed on the surface of specimens reacted at 250°C for 4 weeks. Iron-enriched clay was also observed on specimen surfaces and in the adjacent basalt-bentonite mixture. The 100°C experiments yielded surface films of a siderite-structure phase, (Fe,Ca,Mn)CO3, that were not observed in previous experiments with synthetic ground-water. Less extensive iron enrichment of the adjacent clays compared to that seen in the 250°C experiments was observed. The siderite-structure phase generally formed when no carbonate ion was present in the initial solution, implying dissolution of impurity calcite in the bentonite as the controlling factor in the reaction. The results demonstrate the utility of combining X-ray diffraction and electron microprobe analysis for characterization of reaction phases on alloys reacted with complex geologic materials.

The development of intense synchrotron radiation sources during the last twenty years has enabled several types of x-ray spectroscopy and scattering techniques to come into practical use. One of the most significant methods for the characterization of extremely dilute samples is high resolution x-ray absorption-edge spectroscopy. The technique is usually divided into two separate methods according to whether the x-ray absorption near edge structure (XANES) or the extended x-ray absorption fine structure (EXAFS) is analyzed. XANES features are due mainly to bound-state electronic transitions just below, and on the low energy side of the edge, and to multiple scattering resonances on the top of the edge and at somewhat higher energies. EXAFS features are oscillations due to ejected photoelectron back scattering interference processes in the close vicinity of the absorber atom. XANES analysis is used to determine atom valence, atom site distortion from regular geometries, and other details of the atom site. EXAFS features can be analyzed to recover interatomic distances between the absorber atom and its first few shells of neighbors, as well as the number and types of these neighbors. Together these techniques can provide an atomspecific probe of die short-range structure within almost any type of condensed matter.

Ten compounds are found in the Ba0-Y203-CuOx system. High temperature (≈950-1000°C) phases identified as Ba4Y2O7 , Ba2Y2O5 , Ba3Y4O9 , BaY2O4 , Y2Cu2O5 , BaCuO2+x, Ba3YCu2OZ BaY2Cu05 and BazYCu306+x are formed in this temperature range. In addition, a new compound with composition of 2BaO:CuO, which possibly has a melting point below 950°C, was prepared at 850°C. A summary o£ the crystallographic data of these 10 phases is given. In particular, results of x-ray studies pertaining to four compounds, BazYCu306+x, which is currently the most promising high To' superconductor material, Ba2Cu03 , BaY2Cu05 , and Ba3YCu20Z are reviewed.

Quantitative analysis by x-ray powder diffraction methods has become increasingly important in recent years with the availability of computer-controlled automatic powder diffractometers. All data gathering techniques require suitable reference standards to scale the measured data properly. One means of achieving this scaling is through the reference Intensity ratio which is defined as the intensity ratio of the strongest diffraction maximum of a substance to the strongest maximum of a reference material in a 1:1 mixture “by weight. These ratios may he measured or they may he calculated if the crystal structures of the materials are accurately known.

Total-reflection X-ray fluorescence spectrometry, abbreviated as TXRF, is known for its high sensitivity down to the low pg-level or sub-ppb level, respectively, and its wide dynamic range of about three to four orders of magnitude (Yoneda and Horiuchi, 1971, Wobrauschek and Aiginger, 1980; Knoth and Schwenke, 1978 and 1980, Aiginger and Wobrausohek, 1985, Michaelis et al., 1985, Prange, 1987). Meanwhile several laboratories have purchased commercially available TXRF spectrometers and have started to report favourable about this technique. Applications have been reported from various disciplines: These are estuarine and marine water quality management and research, air pollution studies, mineralogical investigations, biology and medicine (Prange, 1987, Prange et al, 1985; Prange and Kremling, 1985, Prange et al., 1987, Stöβel and Prange, 1985, Michaelis, 1986, Ketelsen and Knöchel, 1985, Leland et al., 1987, von Bohlen et al., 1987, Junge et al., 1983, Hentschke et al., 1985, Hentschke et al., 1985, Gerwinski and Goetz, 1987, von Bohlen et al., 1987), In spite of its close kinship to conventional EDXRF , TXRF is quite different with respect to operation and performance and provides complementary capabilities.

The effect of temperature on nucleation and growth of Ti3Al precipitates in two Ti-Al alloys was determined using sensitive X-ray diffraction techniques. The X-ray peaks arising from the ordered Ti3Al phase were compared with the fundamental peaks of the matrix. Peak broadening due to particle size resulted from the small Ti3Al precipitates and this was analysed using Fourier methods to determine a mean particle size and particle size distribution. The two alloys used for this investigation were Ti-8.5 wt.% Al and Ti-8%Al-1%Mo-1%V (8-1-1) alloy. The precipitate size in Ti-8.5 wt% Al was considerably more dependent on temperature than the precipitate size in 8-1-1 alloy, achieving a size of 190Å after 20 hrs at 650°C. The solvus temperature for precipitation was the same for both alloys, vis, 675°C to 700°C. These results compare favorably with transmission electron microscopy of thin foils prepared from the same samples.

A formalism which was proposed by Ruppersberg (1992) for a self consistent evaluation of stress gradients in the case of strongly varying σ33(T) stresses is applied for studying the variation of the stress components with distance z from the irradiated surface of a ground hardened steel plate.

X-ray diffraction analyses were applied to various pure nickel substrates while exposing them to oxygen at temperatures up to 800 °C. Coefficients of thermal expansion (CTE) were calculated from lattice parameters for both the nickel and the growing surface oxides. Behaviors more complex than the case for single phase bulk solids were observed due, in part, to oxidationinduced strains. The CTE values for such dynamic composite systems are not the same as those for the bulk solids. Thus, for example, the CTE values were found to be dependent on substrate metal thickness. In addition, discontinuities in the CTE's of both nickel and NiO occurred at or near their respective second order phase change temperatures.

This 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.

Rietveld X-ray powder diffraction (XRD) and uniaxial stress measurement procedures are being evaluated as a means of correlating the crystalline structure properties of zinc-nickel electroplate with observed plating properties. The study is being performed on a suite of six samples of varying composition (6 to 20%Ni) electrodeposited on mild steel. Rietveld refinement of the XRD data (Rietveld, 1969) has been performed on a specially prepared ingot (9%Ni:91%Zn) to determine the structural parameters and relative abundances for the γ(Ni4Zn22), δ(Ni3Zn22) and η(Zn) phases which could possibly be present in the electroplate. Relative phase abundances were verified by Atomic Absorption Spectrometry (AAS) and electron probe microanalysis (EPMA) image mapping techniques.

The structural parameters for the ingot zinc-nickel phases were subsequently used as initial parameters in Rietveld calculations for the six electroplate samples. Structure refinement of the electroplate XRD data was hampered by extremely high preferred orientation and the corresponding lack of quality diffraction peaks. However, Rietveld refinements produced accurate cell dimensions (which correlate linearly with nickel composition), a means of quantifying the degree of preferred orientation, and crystalline phase verification. For residual stress determination, d-sin2ψ plots were produced for each electroplate sample. The plots were found to be linear for Ni < 12%, allowing calculation of residual stress, and distinctly curved for Ni > 12%.

I report the experimental setup to obtain an x-ray beam from germanium monocrystal of unusually small angle of vertical divergence of the order of 2 sec. of arc without using any collimator. The production and the properties of the highly collimated beam of x-ray will be described. A rectangular piece of germanium 1” × 1” and of thickness 0.5 mm has been cut with specific orientation of crystallographic planes (111) and (110). The 1” × 1” surface is parallel to (111) planes and the surface of one edge is parallel to (110) planes suitable for Borrmann channelling via (220) planes.

Interest in advanced thermoplastic composites for use in high performance structures stems from their order of magnitude improvement in fracture toughness and delamination resistance over epoxy based composites, their strong solvent resistance, and the possibility of dramatically lower fabrication costs through processing flexibility. The chemical and mechanical properties of semicrystalline thermoplastics depend on the morphology of the material, such as the crystallinity content and spherulite size. We describe here the use of x-ray diffraction to characterize the degree of crystallinity of the polyetheretherketone-graphite composite system, a leading thermoplastic candidate for use in aerospace vehicles. In reflection, diffraction from the microcrystalline graphite fibers dominates the scattered signal and must be adequately accounted for. The technique is useful on large samples and for quality control. In transmission, the graphite signal is weak, thus simplifying data analysis; however, sample thickness must be limited.

Emission-concentration proportionality Is one of the main features of electronprobe mlcroanalysis. It can be interpreted by taking simultaneously Into account the Z/A factor of Webster's law of deceleration and the variation with atomic number of the backscattering ratio. The baclcscattering ratio itself can be deduced approximately from experimental distribution curves of thecharacteristicemisslonjejqpertments on copper-gold alloys show good agreement with the theoretical predictions. An important practical consequence is that regulation of the electron beam falling onto the specimen leads to better results than regulation of the current passing through it. The different corrections are discussed, with special reference to the fluorescence induced by the general continuous spectrum. The case of insulating materials is considered separately; preliminary experiments seem to show that their behavior is not essentially different from that of conducting materials.

The diffraction, reflection, absorption, fluorescence, and the electronic emission that results from the interaction with ultrasoft X-rays (λ > 10 A) are presented as practical bases for microanalysis. Recent developments on sources and detectors for the ultrasoft X-radiations are described. A preliminary report on a current investigation on low-energy photo-Auger electron analysis and on a new type of low-energy electron spectrometer is also presented.

A modern analytical laboratory of a large corporation manufacturing paper, construction materials and chemicals must be sufficiently diversified in methodology to provide accurate results in the shortest possible time. Among other techniques the implementation of an automated “menu” driven wavelength dispersive spectrometer allowed for the setting-up of a variety of quantitative X-ray fluorescence methods.

Since the development of the first practical electron probe microanalyzer by Castaing and Guinier in 1951, approximately 14 such instruments have been placed in operation throughout the world and at least 15 more are under construction. All of the existing instruments contain the following basic components: (1) An electron beam system, (2) a movable specimen stage, (3) a means for viewing the surface of the specimen, and (4) an X-ray analyzer. The integration of these components into a practical instrument requires certain compromises in the performance capability of the instrument. A critical evaluation of the various approaches to this problem is given and a new electron objective lens is described which results in fewer restrictions on the over-all performance. The basic design of an instrument employing this lens, which will be manufactured by the Applied Research Laboratories, is discussed.

The state of stress in a material, as represented by the stress tensor, can be measured using x-ray or neutron diffraction techniques. A stress tensor measured using diffraction represents an experimental estimate of the true state of stress in the material. The measured stress tensor will include both instrumental and counting statistical errors. With careful measurement techniques, instrumental errors can be minimized, and accurate results can be obtained. The errors in the measured stress tensor that are due to counting statistics can be estimated using well established error propagation techniques. Unfortunately, these errors cannot be analytically propagated through the solution to the eigenvalue problem which yields the principal stresses and directions. Without estimates of the errors associated with the principal stresses and directions, the values determined for these quantities are of limited value.

The Fourier analysis of the broadened profiles in a powder pattern allows the determination of the effective particle or domain size and the microstrains within each domain in polycrystalline materials. In order to apply this method to the diffraction patterns of thin films and coatings, deposited on crystalline or amorphous substrates, special diffraction techniques must be employed for the registration of the relatively weak intensities. The fitting of the experimental profiles to pseudo-Voigt functions permits the recovery of the peak tails and a precise determination of the background. The positions of the peak maxima or centroids yield information about any compositional variations, and about the occurrence of stacking faults and residual stresses in thin films and coatings.

Due to the current high interest in characterizing epitaxially deposited thin films required by the electronics industry as well as the increased attention in elucidating reactions between solid surfaces and the environment (e.g., corrosion), investigators have increased their efforts in developing X-ray procedures for analyzing films and surfaces less than 2 μm thick. For example, an entire session of the 1985 Denver Conference on Applications of X-ray Analysis was devoted to this subject and an excellent review of X-ray diffraction techniques for characterizing thin films was recently published by Segmuller (1). Specific techniques include grazing incidence diffraction (2, 3), double crystal diffraction (3), and the use of the Seemann-Bohlin focusing geometry (4, 5).