In the last years Total Reflection X-Ray Fluorescence spectroscopy (TXRF) has shown to be an analytical technique for trace element analysis as well as surface quality control. Detection limits in the range of pg or ng/g (ppb) level in concentration values of aqueous solutions or 1011 -109 atoms/cm2 are achieved with new excitation sources. The range of detectable elements has been extended to low and high 2 elements. Instrumental developments and results of the Atominstitut as well as from some other working groups are presented.

The proton beam from the 4 MV Van de Graaff at the University of Florida has been used in conjunction with a 5 mm thick lithium drifted silicon, Si (Li), x-ray detector to do elemental analysis of biomedical samples by proton-induced x-ray emission (PIXE). Several hundred samples, mostly autopsy organs ashed at high, temperature, have been analyzed by this method. The main object of the research is the correlation between human diseases and trace element levels. The target mass has been determined by monitoring the elastically scattered protons from the sample. This technique considerably reduces the target preparation time by eliminating careful weighings or doping of each individual sample.

Residual stresses on the inner surface of stainless steel pipe used in nuclear reactors are of exceptional importance. Apparatus for measuring these in situ, in welded lengths of 10-inch diameter austenitic (304) stainless pipe has been developed at the University of Denver Research Institute under the sponsorship of the Electric Power Research Institute.

A Monte Carlo model that predicts the entire photon, spectrum for energy-dispersive X-ray fluorescence (EDXRF) analyzers excited by radio-isotope sources from multielement homogeneous samples is developed and demonstrated. The components of the photon spectrum include: (1) the and Kα and Kβ characteristic primary, secondary and tertiary X rays from both the unscattered and scattered source photons, (2) the characteristic X rays excited by other characteristic X rays that have been scattered, and (3) the scattered source photons from single, double, and multiple scatters in the sample.

The computer code NCSMCXF based on this model has been developed. It is capable of handling up to 20 elements per sample and provides a detailed account of the intensities of the X rays and backscattered source photons per unit source decay as well as a summary of the relative intensities from all elements present in the sample. Cubic splines are used within the code for photoelectric and total scattering cross sections and two-variable cubic splines for angular coherent and incoherent scattering distributions for efficiency in both computation time and storage. The code also provides the pulse-height spectrum of the sample by using the appropriate Si(Li) detector response function. The Monte Carlo predictions for benchmark experimental results on two alloy samples of known composition indicate that the model is very accurate. This approach is capable of replacing most of the experimental work presently required in EDXRF quantitative analysis.

A previous Monte Carlo model that uses the simple assumption of spherical homogeneous particles to approximate sample heterogeneities has been modified to improve the computer execution time requirements for the heterogeneous sample case. A new technique for photon tracking in this medium is used and reduces the computation time requirement by half.

Modern (>1950) data analysis techniques are commonly applied in many scientific fields but their careful application in other fields, including X-Ray diffraction, has been notably lacking or generally confined to the environment of university research. Perhaps this lack of widespread application in XRD can be blamed on the absence of sophisticated computer controlled instrumentation, and, if this is so, the situation should change rapidly, since today's automated diffractometers are driven by very powerful minicomputers with large firm disks and sophisticated operating systems. In such an environment it is entirely practical to implement, on-line, state-of- the-art data analysis techniques, and in this paper we present one such example.

The interfacing of both straight and curved Braun Position- Sensitive Proportional Counters (PSPC's) to a high resolution Huber-Guinier camera system has been accomplished, resulting in a 10 to 100-fold decrease in data collection times when compared to conventional Guinier (film or scintillation counter) detector techniques.

Various factors causing line broadening were evaluated for both PSPC Guinier systems. The depth of the PSPC gas chamber was found to Have the greatest influence on line profiles. An R0% increase in peak half-widths was observed for PSPC-Guinier data compared to our highest resolution Guinier film data, but still yielded significantly better resolution than conventional powder diffractometer data obtained in our laboratory.

The formation of the spherical Guinier—Preston zones in an aluminum-silver alloy is governed by a metastable miscibility gap, which consists of two different sections. The lower section occurs below 170°C (η state), the higher section up to 420°C (∊ state). The zones in the two sections differ in their silver concentration and in their atomic order. To prove the change in order, a combination of X-ray small-angle scattering and electric resistivity measurements was used. As the resistivity depends on the zone size and the atomic order, the change in order can be found when the zone size is known. This size was measured by the X-ray technique. To complete the results, X-rays ingle-crystal diffraction patterns with monochromatic radiation were taken at different stages. According to these patterns, three different states must be distinguished.

The η′ state exists at room temperature after quenching from 550°C. The silver atoms prefer a layered arrangement in the zones, which is not very stable. It is destroyed after short annealings above 100°C. The η state is developed during annealing below 170°C. A three-dimensional atomic order is built up with increasing zone size, which results in a marked decrease in the resistivity. For the ∊ state (above 170°C), a nearly random atomic distribution exists. Step-quenching experiments prove that the ordered η state can also be developed at room temperature.

A ϕ-ψ diffractometer has been designed and constructed to evaluate residual stresses in polycrystalline samples by x-ray diffraction. It permits rotations of the x-ray diffraction apparatus, consisting of an x-ray tube and a position-sensitive proportional counter, about two axes ϕ and ψ. The ϕ-rotation from 0° to 360° is carried out about the normal to the surface of the stationary sample, whereas the ψ-motion consists of a rotation from -45° to +45° about an axis lying in the sample surface and the diffraction plane, but perpendicular to the diffraction vector. This ϕ-ψ diffractometer permits the application of the ϕ- and ψ-differential and integral methods for the evaluation of the strain tensor and its gradient averaged over the depth of x-ray penetration into the sample. Assuming that isotropic elasticity theory is applicable, the stress tensor can then be evaluated from the measured strain tensor.

A Warren-Averbach1-4 X-ray line profile analysis was applied to broadened X-ray diffraction peaks from copper deformed in fatigue. The copper specimens were fatigued by four-point bending at peak-strain amplitudes between 0.00105 and 0.00442 in./in., and measurements were made at various fractions of the total fatigue life. The analysis results in an estimation of (a) an average coherently diffracting domain size normal to the diffracting planes and (b) an rms strain distribution function where the strain normal to the diffracting planes is averaged over a given distance at all points in the diffracting crystals and expressed as a function of averaging distance.

Prior to fatigue cycling, the annealed copper exhibited extinction, which reduced the integrated intensity from the low-angle reflections. After fatigue cycling, the integrated intensity increased with increasing strain amplitude of fatigue. The integrated intensities and the rms strains were established during the first few percent of the fatigue life and were found to increase with fatigue strain amplitude. The measured strains were larger in the <100> direction than in the <111> direction, but the absolute values were small. On the basis of transmission electron microscopy of thin foils, these results may be explained by assuming the strains are due to the presence of numerous dislocation dipoles.

Accurate measurement of the electrical and mechanical properties of polycrystalline oxide ceramics has revealed anisotropy in a number of properties. The source of this anisotropy may be attributed to a number of causes, however, with oxides having anisotropic crystals, preferred orientation of the crystallites may be suspected. Aluminum oxide and beryllium oxide ceramics samples of high purity and density were formed by slip casting, dry pressing, isostatic pressing, and extrusion. Pole figures for the (113), (110) and (030) planes in aluminum oxide and (100) and (103) planes in beryllium oxide were prepared by using a Siemens automatic pale figure goniometer.

It was found that both slip-cast oxide samples and dry-pressed aluminum oxide samples and dry-pressed beryllium oxide samples showed sufficient preferred orientation to prepare a pole figure from the data. The actual preferential orientation of the crystallites in these two oxides is discussed and the pole figure information presented. The effect of furnace atmosphere and surface contaminants on re crystallization at an exposed surface is covered briefly.

The use of polarized x rays as the excitation source for x-ray fluorescence (XRF) measurements has been shown to significantly improve signal-to-background ratios. However, previous studies on polarized x rays applied to XRF techniques have concentrated on low-energy fluoresced x rays (<30 keV). In many cases strong matrix effects exist or the analyte is encased by a material that strongly attenuates low-energy x rays. These situations may preclude accurate assays based on L x-ray detection, and techniques based on the detection of higher energy K x rays may be more suitable because of the increased penetrability of higher energy x rays. The measurements and calculations reported in this work were made to assess the improvement in signal-to-background ratios and the increase in accuracy and detection sensitivity achievable by using polarized x rays as the excitation source for fluoresced x rays having energies between 25 and 110 keV.

An automatic time sequence filter sampler has been developed for atmospheric aerosol particle sampling of ambient air and subsequent analysis for elemental composition using the proton, beam of a Van de Graaff accelerator. Some features of the operation of the sampler are given, the retention of particles by the filter material are discussed, examples of the type of data obtained are presented, and some approaches to the numerical analysis of data for environmental interpretation are considered. Lines for further development and improvement in this type of sampler are indicated.

The mining industry uses coring as a standard method for the evaluation of ore deposits. Since coring is costly and time-consuming, increasing attention has been given to logging techniques capable of providing information about the orebody, thus allowing replacement of at least part of a coring program. An evaluation of the feasibility and potential for application of a variety of borehole logging techniques(l) concluded that X-ray diffraction (XRD) is one of the promising techniques for borehole assay, along with neutron activation analysis, X-ray fluorescence, photoluminescence, and infrared spectroscopy.

Detailed x-ray double-axis rocking-curve analysis has been made of a series of silicon wafers, polished using various colloidal silicas with a number of different conditions. Significant differences, attributable to the polishing conditions, were observed in the tails of the rocking curves, using a four-reflection, non-dispersive beam conditioner. These have been compared with theoretical simulations in order to deduce the strain profile near the surface.

X-ray diffraction observation of fracture surface yields useful information to analyze the cause of failure accidents of engineering structures. This experimental technique, named X-ray fractography, has been developed especially in Japan. The relationship between X-ray parameters and fracture mechanics parameters plays a key role in determinating the mechanical condition of fracture.

Chemical shifts of SKα, CrKβ1,3 and SnLβ2 were precisely measured with a two-crystal X-ray spectrometer (Toshiba AFV 701). Sulfur in the coke for iron smelting takes two oxidation states, i.e., S2− and S6+. Quantitative analyses of S2− and S6+ were performed by precisely measuring the profile of SKα and fitting the standard S2− of S6+ curve to the observed SKα profile with the non-linear least square method. Chemical shifts of CrKβ1,3 and SnLβ2 were utilized for the determinations of Cr6+, Cr3+, Sn4+ and Sn2+ in electro-plating solutions. Intensity ratio of IA to Ig was measured, where B means the point which showed an intensity independent of oxidation states. A means the point which showed the most dependent. Linear relations were found between intensity ratio IA/IB and Cr3+/Cr or Sn2+/Sn.

In this work experiments have been undertaken to determine the type of residual stresses of plastically deformed polycrystals of aluminum, copper, and nickel which cause a shift of the X-ray interference lines. In order to get accurate stress values, the lattice strain distribution has been measured in special planes of the deformed specimens, using the sin2 ψ technique. The surface stresses were determined as a function of the macroscopic plastic strain of cylindrical specimens. With increasing strain, the residual surface stress component parallel to the direction of deformation increases. The stresses observed are compressive ones after tension and tensile ones after compression.

The changes in the residual lattice strain distributions which arise on progressive thinning of the plastically deformed specimens have been measured. From the stress values determined in each new surface layer, the stress distribution originally present in the uodestroyed specimen was calculated. Tensile stresses in the interior of the specimens are in equilibrium with compressive stresses in the surface areas. The formation of residual stresses on specimens with a work-hardened surface layer is found to be quite different from that of well-annealed samples.

The results of this work seem to show that in uniaxially deformed cylindrical specimens, residual macrostresses arise which may be a consequence of a macroscopic inhomogeneity of work-hardening between the surface layers and the interior of the polycrystals.

A review of the crystal structures of the elements shows some prevailing tendencies of atomic arrangement. These are discussed as space, symmetry, and connection principles. Counteracting temperature and bond factors can be recognized.

The same principles and factors are responsible for the formation of alloy structures, taking into account additional factors due to the component's similarities and dissimilarities in size and electronegativity.

Similarity favors solid solution and dissimilarity favors compound formation. A q compound is here defined as a phase in a q-component system not connected with any other phase of the system by continuous solid solution. Similarly a q structure is defined as a structure type which needs only q components to be formed (considering present-day knowledge). For example, the binary compound Mg17Al12 has the elementary (1 ™) structure of α-manganese. As a rule, q compounds tend to form p structures with q > p.

A discussion of q structures with q = 1, 2, and 3 is given in some detail on the basis of known representatives to show: (1) the competition of geometrical principles and physicochemical factors in determining atomic arrangements of alloys; and (2) the value of rules for making guesses on the probable occurrence of compounds and their chemical composition in polycomponent systems yet unknown.

Objects of art and archaeology are relicts of the past, and art historians, archaeologists and conservators are constantly concerned with the questions of where, when or by whom such artifacts were made. Usually stylistic considerations can provide answers to these questions, but as styles were sometimes copied at locations and times quite different from those for which they were most characteristic, material analysis is often essential when one is attempting to infer how and of what materials an object was made. The use of several compounds e.g. as pigments in paintings, or the deliberate alloying of Cu with Sn, As, Sb and Pb, has varied greatly from region to region and from time to time and can be used to infer the geographic origin of an object or at least the origin of the materials, out of which it was made.

A numerical procedure is described and demonstrated for determining z-profiles from measured τ-profiles of diffraction data such as may be obtained by grazing incidence x-ray diffraction (GIXD). The z-profile was approximated by a piece wise linear function and the problem of solving the integral equation for the z-profile was thus converted to one of solving a set of linear equations. With a sufficient number of the linear pieces, the z-pTofile could be accurately determined. The procedure and its sensitivity to data errors was tested with several arbitrarily chosen known functions. It was found that when errors were introduced into either the τ-profile or the sample thickness D the resulting z-profiles become oscillatory.