The analysis of mixtures of phases which produce complicated composite x-ray powder patterns is greatly facilitated by use of our profile fitting method and the technique of applying it is illustrated with a five-compound mixture. Profile fitting gave higher precision in the determination of the reflection angles and Intensities and resolved overlaps in a much shorter time than with other methods. If the reference standards are obtained with the same precision, a smaller error window width can b e used in the search/match procedure.

The phase and elemental distributions on zirconium alloys containing 5, 10, 25, 35, and 50 at.%. yttrium, oxidized in dry air at 1200 and 1600°C, have been studied by X-ray diffraction, fluorescence, and electron-microprobe techniques. Zirconium-yttrium alloys, which are entirely solid at 1200°C, and zirconium 5 and 25 at.% yttrium alloys, which aire two-phase solid plus liquid at 1600°C, form a multiphase scale of ZrO2, Y2O3, and ZrN. The phase distribution varies with yttrium content, while the average metal composition remains constant throughout the oxide scale and base metal. In contrast, zirconium 35 and 50 at.% yttrium alloys, which are entirely liquid at 1600°C, form a single-phase Y2O3 layer.

The mechanism of air oxidation of solid zirconium-yttrium alloys, up to 50 at. % yttrium, is one of anion diffusion to the oxide-metal interface with little or no diffusion of the metallic elements. The oxidation of liquid alloys differs in that, as a result of yttrium diffusion to the oxide-liquid interface, Y2O3 is the only oxide formed. Ternary Zr-Y-O isotherms are presented to illustrate the phase distribution and mode of formation.

A novel windowless sample preparation method is described which allows for X-ray fluorescence analysis of light elements (Z = 13 to 20) in coal or oil-tar pitches, asphalts and other bituminous compounds. The article also discusses blending and spiking of pitches with suitable organometallic compounds in order to prepare a range of trace-element calibration standards. The general instrumental conditions, recommended peak counting times and detection limits are also discussed.

The angular dependence of Total-reflection X-Ray Fluorescence intensities can behave in various ways. The variety is discussed by examining the x-ray intensity distribution in the material under investigation. It is shown that for thin layers on solids, interference fringes are present due to x-ray standing waves. This phenomenon is exploited to determine the depth distribution of elements in layered specimens.

Computational methods for determining precision lattice parameters based on extrapolation, lattice refinement, least squares and trial and error indexing, with intermediate corrections for peak positions using external and internal standards, have been evaluated with respect to the ICDD published values for zincite. Lattice parameters can be routinely determined to an accuracy of one part in ten thousand without the use of external or internal standards, by using computational extrapolation on data with a well aligned and maintained diffractometer. Lattice refinement determination of lattice parameters was only effective, with respect to the ICDD values, when used in conjunction with external and internal Standards. Least squares yielded results with low standard deviations, but the use of standards did not reduce the refined sample displacement or zero angle errors, and gave an increased error in lattice parameters with respect to the ICDD values. The trial and error indexing, which can only be used with peak positions corrected with respect to both external and internal standards, gave relatively low de Wolff and Smith-Snyder figures of merit, but nevertheless yielded lattice parameters of the highest accuracy of one part in twelve thousand, with respect to the ICDD values.

Two principal mathematical methods are used for quantitative XRFA: fundamental parameter calculations and the evaluation of empirical parameter equations. A comprehensive computer program based upon fundamental parameter equations was introduced in 1976 by D. Laguitton and M. Mantler (LAMA-I) and improved by T. C. Huang in 1979 (LAMA-II). The present paper describes the features of the theoretical background of a computer program using a new type of empirical (alpha*-) parameter equations. It is essentially designed for convenient analysis of compounds including those containing chemical elements, that cannot be directly measured by conventional X-ray spectrometers, such as oxides, nitrides, and others. The program also communicates automatically with LAMA in order to establish theoretical tables of alpha*-coefficients as well as conventional alpha-coefficients.

Recently aluminum nitride (A1N) has been intensively studied as a promising material for production of hybrid integrated circuit substrates because of its high thermal conductivity, high fjexural strength, and nontoxic nature. The estimated theoretical value of its thermal conductivity at room temperature is 320 W/mK, but it is strongly degraded by the introduction of oxygen. The measured values vary from 30 to 260 W/mK, Therefore, in production of this material the reduction of oxygen contamination is of paramount importance.

The progressive ordering of a single crystal of Ni4Mo by isothermal ageing at 650°C (transformation temperature = 868°C) has been studied by x-ray line broadening techniques using the Warren- Averbach method employing computer techniques. The long-range-order parameter, antiphase domain size, and internal strains were measured as a function of ordering time and compared with those previously obtained at 700°C. The activation energies for domain growth and ordering were found to be 91 kcal/mole and 44.5 kcal/mole respectively. The rms strain developed during ordering was found to be dependent on the degree of tetragonality of the structure.

Analysis of serai conductor material and associated integrated circuits (IC) is imperative for ensuring quality products. Currently, routine circuit testing is dominated by measurement of the optical and electrical material/device properties through final device performance and parametric testing.

Characterization of the crystal microstructure still is not considered a routine process test. Structural characterization usually is based on double-crystal rocking curves, x-ray topography, or a combination of these techniques.

Texture means the orientation distribution of the many crystallites in a polycrystalline sample with respect to a reference system on the sample, for example the rolling direction in steel. Texture has to be distinguished from preferred orientation observed in laboratory-made powder samples. Preferred orientation is just a nuissance in the experiment and must be corrected in the ensuing analysis, for example by the formula given by March and published by Dollase Preferred orientation we find commonly in samples containing plate-like crystal flakes. This is again to be distinguished from a non-random particle distribution in the powder samples prepared for diffraction experiments. This effect is always present, also for example in NBS silicon, even if only to a. very small degree (see for example Will et. al). It must and can easily be corrected for in the final least-squares calculation.

It is shown that the integrated intensities of diffraction lines from calcite and aragonite powders prepared by precipitation vary markedly, due to variations in sample packing efficiency arising from different degrees of polydispersity in the particle size distributions. Since prolonged grinding to equalize initially divergent distributions changes the polymorph composition, the packing effect imposes the principal limitation on the precision of the x-ray method for certain types of calcium carbonate preparations.

X-ray spectrochemical analysis is a versatile technique that can be used to determine considerably more than just the elemental composition of a sample. X-ray lines and bands are, in many cases, influenced by the state of chemical combination of the element whose spectrum is being investigated. Significant effects due to changes in bonding are seen in the K and L spectra of the low atomic number elements which fall in the 20 to 90 Å region. Results using primary excitation, a stearate crystal, and a flow proportional counter are shown for the K spectra of boron, carbon, and nitrogen. Chlorine and sulfur L spectra from some simple metal compounds of these elements are also shown.

By collecting the diffracted X-rays in a focussing powder diffractometer with a linear position-sensitive detector (PSD), the data accumulation time can be widely reduced. Due to the focussing properties of the geometrical arrangement good resolution can be simultaneously achieved over a few degrees of the diffraction angle 2 Theta. The full pattern is collected by scanning the PSD along the entire 2 Theta arc. Scanning speeds of several hundred degrees per minute are possible and still yield well plotted diagrams.

This work demonstrates the performance of the system in different tasks of X-ray powder diffraction such as identification of unknown materials, quantitative analysis, determination of lattice constants and microcrystalline properties. The results, evaluated by parts of the program system DIFFRAC 11, show that the accuracy and resolution of the continuously scanning PSD technique match these tasks without difficulty and reach the precision limits of powder diffractometry itself. It is demonstrated that the data collection velocity, which matches well the data evaluation times, is not the only advantage compared to conventional diffractometets.

There are several methods for the measurement of retained austenite in steels, which influences mechanical behavior and corrosion resistance of steels. Among them, X-ray diffraction methods using a wide angle goniometer or X-ray stress analyzer are commonly used because the methods are non-destructive, giving useful information about residual stress or lattice strain as well.

The purpose of this work was to develop accurate calibration standards which were fully characterized in terms of uniformity and concentration using fundamental measuring methods. Three similar sets of vacuum deposits were commercially made, each set containing the single deposits CuS, KCl, CaF2, Cr, Fe, Cu, RbNO3, SrF2, MoO3 , BaF2, and Pb. Thickness variations in each deposit were measured with PIXEA (proton induced x-ray excitation analysis) measurements taken at 6 to 8 positions along the deposit diameters. Relative elemental concentrations on corresponding deposits from each set were measured using multiple XRF intercomparisons. One set of deposits was destructively analyzed at the National Bureau of Standards with isotope dilution thermal ionization mass spectrometry (IDMS) in order to calibrate the remaining sets of vacuum deposits. The calibrated deposits were compared with standards from two commercial sources. For seven elements heavier than chlorine there was an average deviation of 13.5% between the calibrated deposits and the commercial standards. Disagreements as large as 15% were observed between standards from the two commercial suppliers.

To study the relationship between crystal growth conditions and resultant crystalline perfection, large nickel single crystals more than 12 cm long and 2 to 3 cm in diameter have been grown from the melt by the Czochralski method. Unlike semiconducting materials, one cannot easily thin metal crystals, without straining them, for the purpose of applying ordinary Lang topography with μL∼l where kinematical scattering in imperfect crystals is a good approximation. This situation with metal crystals necessitates the use of dynamical diffraction effects in imperfect crystals to permit sample crystals to be thick enough to demonstrate their imperfections as in the bulk.

The background to the use of the Pearson VII function as a model for powder diffraction profiles was summarised in connection with the fitting of data obtained essentially from Guinier patterns (1). The algorithm developed for modelling single-wavelength profiles was found to be less effective when applied to diffractometer data generated by the Kα doublet. Diffractometer, rather than Guinier film data are generally to be preferred, however, for profile measurements. A new approach was accordingly made to devising an algorithm for this particular application. Numerical features of the method highlighted by this task are described below. Attention is also drawn to problems encountered when profiles are measured using a diffracted-beam monochromator (DBM).

We describe an adaptation of photon excited x-ray fluorescence analysis which is optimized for the analysis of small samples. A fine focus x-ray tube is used in conjunction with small diameter detector collimators in order to focus on a small sample volume with as high sensitivity as possible. Sample areas of less than 1 mm diameter can be analyzed with ppm detectability. In applications involving the analysis of human hair samples, a minimum detectable limit of 10 ppm Hg can be realized in a 1 mm long segment of a single hair in a counting time of 200 seconds. Simultaneous measurements of the sample mass can be obtained from the intensity of the incoherent scattering. An automated x-ray fluorescence analysis system using the technique for the scanning of elemental profiles in such hair samples will be described.

A very accurate 8X8 matrix approach to dynamical theory of X-ray diffraction in which fewer approximations are made than in the classic vonLaue approach, is described here. The method is related to the very general matrix method of Kokushima and Yamakito, and is particularly suited to numerical solution with a computer. It can be used to solve problems in ideal, undistorted crystals with high precision even at near grazing incidence without special consideration of refraction or external reflection. It is also easy to apply to problems where periodicity of oblique Bragg planes varies in the direction normal to the surface. Such strain may be induced, for example, by variation of composition with depth. Certain problems wherein simultaneous diffraction by two sets of Bragg planes occurs can also be treated by this approach.

The relation of the X-ray small-angle scattering parameters to the results of transmission electron microscopy for spherical Guinier-Preston zones was investigated. Experimentally, the Guinier radius is found to equal (<R7>/<R5>1/2) and the Porod radius to equal <R3>/<R2>. These results were theoretically predicted by Baur and Gerold, A log normal distribution was found to be in close agreement with the experimental data. The use of this distribution allowed the size-distribution curve of spherical Guinier-Preston zones to be constructed from the X-ray parameters and from a knowledge of the metastable miscibility gap. This approach is used to follow the evolution of size distribution in both Al-Ag and Al-Zn alloys. The application of this approach to nncleation and growth as well as redistribution processes is discussed. Growth paths are established from the size distribution evolution curves through an Nv> construction. A brief discussion of the technique is included.