The method of intensity ratios can be used for quantitative x-ray diffraction analysis even when none of the diffraction peaks of any phase can be individually resolved. The method uses intensity values from a finite number of discrete integration intervals and appropriate reference-intensity-ratios measured on a set of reference samples to yield a best fit composite pattern that is matched to the unknown by least-squares refinement. Solid-solution phases are analyzed by using multiple reference patterns and determining the best choice during the pattern matching procedure. The method may be extended easily to employ whole diffraction traces by using a large number of small intervals.

As part of a program studying the effects of large strain deformations resulting from multiaxial loading to a variety of materials, a thin walled tube (0.46” O.D. x 0.02” wall thickness) of 70-30 Brass was subjected to strain deformation in the following directions 1) along the tube axis, εz = 0.3393; 2) circumferential around the tube surface, εθ = -0.0121; 3) perpendicular to the wall thickness, εR = 0.3514. This report describes the results of an x-ray examination of the external surface of the tube by the line broadening technique.

Enhanced solid state reactivity of materials both during and after shock compression has been attributed to the introduction of large numbers of defects into the crystalline lattices and to reduction in the particle and crystallite size of powders [1,2]. Line broadening of x-ray diffraction profiles provides a means to determine the residual lattice strain resulting from such defect concentrations as well as a means to determine the coherent crystallite size. Various diffraction studies on shock-loaded powder materials have previously been reported and much of this work primarily by Soviet and Japanese scientists has recently been reviewed [2]. Cohen has reported results on shock-loaded copper [3]. In prior work, however, shock, pressures have not typically been quantified and there are few detailed line broadening investigations of refractory inorganic powders [1,4,5]. The present study on shock-loaded alumina powders is a detailed investigation of the influence of shock loading on residual lattice strain and coherent crystallite size.

Enhanced solid state reactivity of materials both during and after shock compression has been attributed to the introduction of large numbers of defects into the crystalline lattices and to reduction in the particle and crystallite size of powders [1]. In particular, orders of magnitude increases in the catalytic activity has been observed In shock-modified TiO2 [2]. Line broadening of x-ray diffraction profiles provides a means to determine the coherent crystallite size and the residual lattice strain resulting from defect concentrations. The present study on shock-loaded rutile is a detailed Investigation of the influence of shock loading on residual lattice strain and coherent crystallite size. Annealing of shock-modified rutile powders is also studied.

There is a great deal of interest by the electronics Industry in understanding the reactions occurring at the interface between a solid metal and a liquid solder or braze. This is due to the complex nature of current microelectronics Packaging, where soldering or brazing operations often involve complex metallurgies and tightly controlled furnace profiles. However, to date only a few studies have been carried out on the reaction kinetics at a liquid metal-solid metal interface. This is due in part to the difficulty in carrying out such , experiments. In the past, two main techniques have been used to obtain solid-state kinetic data. The first, quantitative metallography, is slow and tedious to perform, and generally of limited accuracy. The second technique involves measuring the change of some property, such as electrical resistivity, that is a function of the concentration of one of the phases. The main disadvantages of these techniques are that absolute values of concentration are not obtained, and that the relationships between a property and constitution are rarely available. In addition, most physical properties are sensitive to factors other than constitution, and interference from these factors can often result in erroneous data.

A computer-controlled high temperature Guinier diffractometer system for accurate determination of lattice thermal expansion is described. A critical test of the system using α-Al2O3 (0.3μ polishing alumina) showed close agreement with the single crystal expansion data of Wachtman et al. Lattice thermal expansion of cordierite doped with the following dopants: Ge+4, P+5, Zn+2, Li+1 and Ca+2 was investigated. Of these the Li+1 at the 5% level (5% of Si+4 replaced by Li+1 + Al+3) produced the largest decrease in mean lattice expansion.

The continuing development in recent years of mercuric iodide room temperature x-ray spectrometers has led to steady improvment in the spectral energy resolution capability of these systems. This has been due largely to the continuing reduction in the electronic noise level of the associated preamplification electronics. It has been demonstrated that a system consisting of a mercuric iodide detector in combination with a pulsed-optical feedback preamplifier provides superior energy resolution performance in x-ray spectrometry in comparison to the other types of preamplification. Previously, results have been reported by us of the energy resolution of such systems with both the detector and input FET of the preamplifier at room temperature and with the input FET cooled by liquid nitrogen and the mercuric iodide x-ray detectors lightly cooled.

Improvements in x-ray tube technology for the low-power tubes used in energy-dispersive XRF systems can provide better performance. These improvements are occurring in six areas: thin-window tubes, lower kV capability, higher kV and mA capability, pulsed tubes, smaller focal spots, and miniaturization. These improvements will lead to better excitation of the light elements, analysis of low-mass samples, higher count rates, small spot analysis, and smaller systems.

While x-ray fluorescence spectrometry is a highly sensitive and highly repoducible method of analysing samples, its one weakness is its relatively low sensitivity for light elements. This is mainly due to two problems: firstly the low fluorescent yield of the low atomic number elements, and secondly to the inherent inefficiency of exciting these elements. While it is not possible to improve the fluorescent yield, considerable improvements in light element sensitivity can be achieved by improvements in x-ray tubes.

We have previously reported in these proceedings on the automation of Wavelength-Dispersive X-ray Fluorescence arid X-ray Diffraction Spectrometers using stepping motors, either installed in place of existing synchronous drive motors, or attached to existing gear or belt drive mechanisms that control the theta/two-theta positioning of the spectrometer. This technique is applicable to most types of instruments (successful adaptations to Philips, Siemens, GE/Diano, and Rigaku systems are working routinely at this writing).

The previous LAMA I and II programs have been completely rewritten in this new version. Better precision and an order of magnitude increase in speed were achieved with a different numerical method and more efficient code. Fundamental parameters and/or empirical parameter calculations can be used. New routines for the analysis of oxides and other compounds of light elements, and multiple thin film layers with secondary enhancement factors are included.

Several literature references address the relationship between the reciprocal of the absorption coefficient and the Compton scatter peak, intensity. Most workers use a Compton scattered tube line in the calculation of background; however, use of Bremsstrahlung scatter in the present work is also valid for this calculation. Background calculation for a fixed-angle monochromator is desirable since the background cannot be measured off peak. A method for calculating background for fixed-channel instruments by summing the calculated Rayleigh and Compton scatter intensities is presented in this paper.

Equations for computing sample absorption coefficients and matrix corrections from fundamental parameters require measurement or prior knowledge of all bulk element concentrations for samples of finite thickness. Uses of these equations in commercial software have thus required either 1) “similar” standards, 2) limited applications to metal alloys, oxides or specially-prepared matrices of known composition, or 3) user supplied definitions of bulk light element concentrations. A fourth option, which provides superior analytical flexibility, is the use of backscattered x-ray intensities with element scatter cross-sections to define the unmeasured light-element component of the sample matrix. Backscatter intensities constitute the only spectral basis for routinely characterizing the light-element component of geological, biological and other materials which contain significant H, C, N, O, etc. They thus offer a unique basis for utilizing fundamental-parameter matrix corrections in the general case of unknown samples without standards.

The classification of obsidian artifacts has been receiving considerable attend of changes in obsidian trace element composition can now be identify ancient trade routes. The classification of this glassy volcanic material has been attempted using a variety of elemental analysis technique. The most successful and most widely employed method of non-destructive analysis has been that which employs X-ray fluorescence analysis (XRF); either wavelength dispersive (WDS), or energy dispersive (EDS).

The National Enforcement Investigations Center of the EPA provides support services for the enforcement activities of the Agency. Recently, we have analyzed hazardous wastes as part of efforts to enforce the Resource Conservation and Recovery Act and the Superfund Act. Sample preparation for inorganic elemental analysis is a difficult and time-consuming step. Thus, it would be desirable to be able to use x-ray fluorescence methods which require relatively little sample preparation for the analysis of solid hazardous wastes. A major problem to be overcome is the need to calibrate for a large variety of samples. However, a compensating factor is that the error will be largely determined by the sampling error and the measurement accuracy is not quite so critical.

The laterite material (geological) from Cerro Impacto was first studied by air radiometric techniques in the 1970's and was found to have an abnormally high radioactive background. Further studies showed this deposit to be rich in thorium, columbium, barium and rare-earth elements (mostly La, Ce, Pr and Nd). A similar work (1) has been reported for the analysis of Brazil’s lateritic material from Morro do Ferro to determine elemental compositions (including barium and rare-earth elements) and its relationship to the mobilization of thorium from the deposit using a Co-57 radioisotope source.

For more than a decade the Institute of Geological Sciences has carried out large-scale geochemical analysis in pursuit of mineral exploration and regional geochemical reconnaissance programmes for the Department of Industry. Over this period an XRF analytical system has been developed to meet part of this requirement for multielement data. The elements of interest range from the fourth period to uranium, and have become more numerous as exploration and analytical techniques have expanded. In particular, additions have been made of those elements such as arsenic, molybdenum and tungsten which are more difficult of determination by conventional methods.

Sodium silicate solutions have been manufactured commercially for over one hundred years. Such solutions have been used in the past as major constituents in waxes, polishes and adhesives, and in detergents. A current additional use is their application in enhanced oil recovery. In many uses of sodium silicate solutions trace metal levels adversely effect performance. Depending on the source of the raw materials used in the silicate production and on processing conditions iron and vanadium in particular may be found at the 50-200 ppm level. X-ray fluorescence is used as a rapid method for analysis of iron in sand, one of the raw materials used in silicate manufacture. In order to use an instrument already at the plant site, we decided to develop an XRF method for metals analysis in the silicate solutions as well.

This study compares the quality of the fused samples obtained by three separate methods. The first set of samples was prepared by the method used at USGS in Denver and reported by Taggart and Whalberg (1). The second set was fused by our manual method and cast in graphite molds. The third set was fused in the Herzog HAG-12 automated fusion device.

The manual fusion technique requires the use of a muffle furnace capable of 1100°C (2100°F) and graphite molds. No release agents such as KBr and LiBr are required since the disks release easily from the graphite. The 25mm diameter center of the “fire-polished” upper surface of the disk is used for analysis without further surface preparation. This method has been shown to be suitable for preparation of a wide variety of glasses and raw materials including burned dolomite, silicates* high zircon materials such as BCS-388, calcined alumina and alumina refractories.

The disposal of fly ash from coal burning power plants is rapidly becoming an environmentally complex problem. Recently though, the attitude towards fly ash use has been changing from a disposal oriented point of view to a more rational position which considers fly ash as a resource to be recycled. One major hinderance of fly ash use has been the extreme variability of composition that exists between fly ashes produced at different power plants. This variability makes the analysis of fly ash very important.

The most common methods currently used for fly ash analysis are atomic absorption or wet chemistry methods defined in ASTM C311. Both methods tend to be expensive, time consuming, and sample preparation is both tedious and critical for some elements. In this study X-ray fluorescence (QXRF) is used for the quantitative analysis of the major and minor elements found in “typical” fly ashes. The method, which is computer controlled, is quick, reliable, and requires minimal sample preparation.