Recent developments at synchrotron X-ray beamlines now allow collection of data suitable for structure determination and Rietveld structure refinement at high pressures and temperatures on challenging materials. These include materials, such as dolomite(CaMg(CO3)2) that tends to calcine at high temperatures, and Fe-containing materials, such as the spinel MgFe2O4, which tend to undergo changes in oxidation state. Careful consideration of encapsulation along with the use of radial collimation produced powder diffraction patterns virtually free of parasitic scattering from the cell in the case of large volume high-pressure experiments. These features have been used to study a number of phase transitions, especially those where superior signal-to-noise discrimination is required to distinguish weak ordering reflections. The structures adopted by dolomite, and CaSO4, anhydrite, were determined from 298 to 1466 K at high pressures. Using laser-heated diamond-anvil cells to achieve simultaneous high pressure and temperature conditions, we have observed CaSO4 undergo phase transitions to the monazite type and at highest pressure and temperature to crystallize in the barite-type structure. On cooling, the barite structure distorts, from an orthorhombic to a monoclinic lattice, to produce the AgMnO4-type structure.

The recent advances in levitation methods for materials processing now enable structural, thermo-physical property, and phase transition studies to be made on high temperature solids and liquids without container contamination. These studies have led to new insights into the liquid state and have revealed how local order in the liquid can dictate phase formation. In this article, levitation techniques are briefly discussed, focusing most on electrostatic levitation. Recent synchrotron studies of electrostatically levitated undercooled Ti–Zr–Ni liquids are presented, which demonstrate that developing icosahedral short-range order in the liquid causes the nucleation of a metastable icosahedral quasicrystal instead of the stable tetrahedral Laves phase. In addition to providing the first experimental proof of a half-century-old hypothesis linking the order of the liquid with the nucleation barrier, these data raise new questions about the general applicability of the thermodynamic model assumed in the classical theory of nucleation. The combination of electrostatic levitation and synchrotron high-energy x-ray diffraction also allows rapid and accurate determinations of phase diagrams for high temperature materials. This is demonstrated usingTi–Fe–Si–O as a case study. This new technique, then, is of practical as well as basic importance.

In situ high-temperature X-ray diffraction (XRD) data have been collected for silver behenate, CH3(CH2)20COOAg. In the absence of development chemistry silver behenate exhibits four phase transformations when heated from room temperature to 200°C. Combining XRD and differential scanning calorimetry (DSC) results, the phase transformation temperatures and phase types have been determined. Types I, II, and III forms of silver behenate are found to be crystalline phases, whereas Types IV and V forms are liquid crystal phases.

Phase composition estimates by X-ray powder diffraction and Rietveld analysis are becoming more widely used in the cement industry. The ASTM C01.23 Compositional Analysis subcommittee developed test method C 1365, “Standard Test Method for Determination of the Proportion of Phases in Portland Cement and Portland-Cement Clinker Using X-Ray Powder Diffraction Analysis.” A round-robin analysis involving 11 laboratories was initiated to assess the precision and bias of this approach and to develop guidelines for Rietveld analysis of hydraulic cements. Four cements were prepared using NIST SRM clinkers spiked with known amounts of one or more of the following minerals: gypsum, bassanite, anhydrite, and calcite. Specimens were provided with instructions that laboratories analyze the whole cement, collect data in triplicate, and repack the specimen for each run. The results of the round robin were used to estimate interlaboratory and intralaboratory precision and bias of phase abundance determinations. The results show an improvement over previous cement round-robin studies utilizing traditional internal-standard-based, peak-area-measurement methods.

The solid-state phase transitions of the KNO3–NH4NO3 solid solutions have been determined by high temperature X-ray diffractometry, and lattice parameter calculation has also been performed. Ammonium nitrate (AN) is of great use for gas generators of automobile air bag systems. The X-ray diffraction results showed the single (AN) phase III from 5% to 20% KNO3 in NH4NO3 and up to 373 K, which is the important temperature range for the air bag gas generator applications. The X-ray diffraction patterns of the low temperature KNO3 phase (KN II) are from 92% to 100% KNO3 composition range and up to 393 K temperature. The high temperature KNO3 phase (KN I) showed very broad composition range from 20% up to 100% KNO3 at various temperature ranges. The lattice parameters of the NH4NO3-rich (AN III) and KNO3-rich (KN II and KN I) solid solutions have been calculated at different temperature range. The volumes of AN III phase decrease from 0.3201(4) to 0.3166(1) nm3 at room temperature and from 0.3250(6) to 0.3215(3) nm3 at 373 K as the compositions increase from 5% to 20% KNO3. The lattice constants of the hexagonal KN I phase show that there is no significant change in a direction when the temperature increases. Details of X-ray results, lattice expansions, and equations during heating are presented.

Mechanical sensitivity of energetic materials is discussed as a function of particle size and lattice defects. Therefore an approach is made to quantify and characterize lattice defects of the energetic powders RDX and HMX using X-ray diffraction. The mechanical properties of these cyclic nitramines are supposed to be dominated by different defect mechanisms—deformation twinning and dislocation slip. The energetic powders and the line-shape standard SRM 660a (NIST) were measured on a Bragg-Brentano diffractometer D5000 (Bruker-AXS), and the diffraction patterns were evaluated by Rietveld- and peak-profile analysis using Williamson-Hall plots. Additionally, preparing samples as thin powder layers was tested in order to reduce line broadening due to low absorption. The investigations reveal interesting details. Characteristic line broadening was found for RDX and HMX pointing to a comparably higher microstrain in HMX. Anisotropic line broadening was found for RDX and discussed in terms of strain fields of dislocations.

The microstructure evolution in pure copper deformed by rolling at liquid nitrogen temperature was determined by using X-ray diffraction peak profile analysis. The crystallite size distribution and defects evolution were determined as a function of different reduction levels (e.g., 67%, 74%, 87%, and 97%). By using the Multiple Whole-Profile fitting procedure the Fourier transforms of the experimental X-ray peak profiles were fitted all at once by theoretical calculated functions. Here it is assumed that the crystallites are spherical shape and have a log-normal size distribution. It is also supposed that the strain broadening of the profiles is caused by 〈110〉 {111}-type dislocations. The results show that the median and the variance of the crystallite size distribution decreases as the deformation reduction increases. The dislocation density has a minimum value at 74% reduction. The increase of the dislocation density at higher deformation levels is due to the nucleation of new generation of dislocations from the crystallite grain boundaries. It was found that the edge dislocation type dominate, the dislocation network formed during the deformation process.

We present a review of the application of diffraction stress∕strain analysis to small volumes. For cases in which the material properties and∕or the stress state are not homogeneous, traditional approaches may yield erroneous stress results. On the other hand, with proper care, relevant mechanical information about the system can be obtained. Through the use of conventional and synchrotron-based X-ray methods, we can determine the amount of strain transfer between thin film features that possess heterogeneous stress distributions and the underlying substrate. Two examples of such studies are presented. The resulting data are used to assess the validity of several models often used to predict the mechanical behavior in thin film∕substrate composites.

Round and spiral-shaped coil springs enable various peening angles that correspond to the surface location, and the directional shot angles may lead to a nonuniform residual stress on the coil spring surface. It is commonly known that a material under directional deformation exhibits a nonlinear 2θ-sin2ψ diagram (ψ split) due to the triaxial stress state. In this study, the residual stress distributions of spring materials deformed by shot peening at different angles were measured, and the microstructure for carbide precipitates was examined using a field-emission scanning electron microscope (FE-SEM). The nonlinearity in the 2θ-sin2ψ diagram for the shot peening samples was revealed. The extent of the ψ split increased with increasing shot peening angles, and was dependent not only on the mass fraction of carbide particles but also on the size distribution of the carbide particles.

The low-cycle fatigue behavior of a cobalt-based superalloy was studied in situ using neutron–diffraction experiments. The alloy exhibited stress-induced formation of a hexagonal-close-packed (hcp) phase within its parent face-centered-cubic (fcc) phase at ambient temperature under strain-controlled fatigue conditions with a total strain range, Δε=2.5%. The (101) hcp peak was first observed during the 12th fatigue cycle under the given conditions following a period during which no hcp phase was detected. Subsequently, the intensity of the hcp peaks increased as fatigue progressed. Furthermore, within a single fatigue cycle, the intensity of the (101) hcp peak decreased during the compression half-cycle and increased again when the specimen was subjected to a subsequent tensile strain. The result suggests that the fcc to hcp transformation is partially reversible within one fatigue cycle.

A commercially available solid-state multiple strip detector was successfully used to perform reciprocal space mapping and to significantly reduce the data collection time as compared to conventional setups. The quality of the data benefits from the detector’s unique properties such as a high local linearity range and high dynamic range. This paper describes maps of symmetrical and asymmetrical reflections taken on different kinds of samples. A quasiperfect AlGaAs∕GaAs Multiquantum Well Structures (MQW) was used to evaluate details about the instrumental function. The main application of the proposed setup is for less perfect materials similar to GaN-based structures. A study of the thermal stability of a metal-organic chemical-vapor deposition grown InGaN∕GaN MQW by means of in situ temperature-dependent reciprocal space mapping demonstrates the possibilities of the new setup.

CheMin is a miniature X-ray diffraction/X-ray fluorescence instrument that is included in the payload of the Mars 2009 Mars Science Laboratory mission. A portable CheMin prototype was built to test the capability of the instrument for remote in situ mineralogical characterization of geological materials. The instrument was successfully deployed at a variety of Mars analog sites in Death Valley, CA, in May 2004.

Microcalorimeter X-ray detectors using a transition edge sensor depend for their linearity and energy scale on the stability of the operating point on the transition curve. We report on some sources of energy scale drift in microcalorimeter X-ray detectors and the manner in which they have been addressed. Previously observed drifts of >10 eV∕h have been reduced to 1–2 eV∕h. This improved stability has resulted in the observation of X-ray fluorescence linewidths of ⩽12 eV over 6 h of counting time.

A new micro-X-ray flourescence (XRF) instrument was developed in combination with an atomic force microscope (AFM). A small pinhole of 5 or 10 μm was made on the AFM cantilever. The center of the micro-X-ray beam generated by a polycapillary X-ray lens was passed through the pinhole. The present experiment demonstrated that the size of the original X-ray beam of 48 μm produced by the polycapillary lens was reduced to about 10 μm. This instrument enables both observation of the surface morphology by the AFM and elemental analysis by micro-XRF.

Total reflection X-ray fluorescence analysis (TXRF) is an established technique for trace element analysis in various sample types. Restricted in the past to expensive large-scale systems, in this study the capability of a benchtop system for trace element analysis is reported. By analysing various heavy metals in raw and digested sewage as well as mercury in recycling glass, the suitability of the TXRF system for these kinds of applications could be proven. Based on this data, the benefits, disadvantages, and restrictions of the benchtop system in comparison to other trace element techniques like inductively coupled plasma optical emission spectroscopy (ICP-OES) and atomic adsorption spectroscopy (AAS) are evaluated.

The Monte Carlo—Library Least-Squares (MCLLS) approach has now been developed, implemented, and tested for solving the inverse problem of EDXRF sample analysis. It consists of a linear library least-squares code and a comprehensive Monte Carlo code named CEARXRF that is capable of calculating the unknown sample spectrum, all the elemental library spectra in the sample, and the differential operators for each library spectrum with respect to each element. Two codes with graphical user interface have been designed to implement the MCLLS approach and benchmark results are presented for the two stainless steel samples; SS304 and SS316. The results are accurate, the system is easy to use, and all indications are that this approach will be very useful for the EDXRF practitioner.

The analysis of the distribution of pharmaceutical materials in tablet formulations, such as drugs and matrix elements, is critical to product performance and is used in such areas as quality control, impurity testing, and process monitoring. Recently imaging techniques, such as Raman, near-IR, and fluorescence imaging, have become popular for “visualization” of pharmaceutical formulations, allowing for spatial and chemical composition information to be obtained simultaneously. These methods have been primarily focused on molecular imaging, or spatial analysis of the molecular characteristics of the tablet formulation. However, elemental species are also an important part of pharmaceuticals. Micro X-ray fluorescence (MXRF) elemental imaging offers complementary information to molecular imaging techniques. In this study, MXRF was used for the elemental imaging of various commercial pharmaceutical drug and vitamin supplements. Specifically, elemental composition and heterogeneity were monitored for each different tablet.

Cognitive deficits are repeatedly described with Pb exposure, but little is known about the distribution of lead in brain. To determine the local distribution of lead (Pb) and other trace elements, X-ray fluorescence spectroscopy measurements have been performed, using a microbeam setup and highest flux synchrotron radiation. Experiments have been carried out at ID-22, ESRF, Grenoble, France. The installed microprobe setup provides a monochromatic beam (16 keV) from an undulator station focused by Kirkpatrick-Baez X-ray optics to a spot size of 5 μm×3 μm. Brain slices from frontal cortex, thalamus, and hippocampus have been investigated (20 μm thickness, imbedded in paraffin and mounted on kapton foils). In general no significant increase in fluorescence intensities could be detected in one of the investigated brain compartments. Pb and other (trace) elements such as S, Ca, Fe, Cu, Zn, and Br could be detected in all samples and showed strong inhomogeneities within the analysed areas. While S, Ca, Fe, Cu, Zn, and Br could be clearly assigned to brain vessel structures (blood vessels, plexus choroidei), Pb was very inhomogeneously distributed. The local distribution of the detected elements in various brain structures will be discussed.

As complementary metal oxide semiconductor devices continue to scale along the rapid pace of Moore’s law, gate dielectric materials with significantly higher dielectric constant (k=10–25) are being evaluated as replacements for conventional silicon dioxide, SiO2 (k=3.9), and silicon oxynitride. This allows for the introduction of a physically thicker film with lower leakage current and with capacitance equivalent to a thinner (1.0 nm and below) SiO2 layer (Schlom and Haeni, 2002; Wilk et al., 2001; Kingon et al., 2001). Although binary metal oxide films such as HfO2 and ZrO2 exhibit higher permittivity than their corresponding silicates and aluminates, alloyed with various molecular percents of SiO2 or Al2O3, respectively, they are compromised by lower onset of crystallization temperature which contributes a higher degree of interfacial microroughness and increased gate leakage current due to dislocations and oxygen vacancies generated along grain boundaries. Accordingly, development of hafnium silicate has been the subject of intense investigation as an advanced gate dielectric thin film designed to meet the device manufacturing requirements of thermal stability in direct contact with substrate silicon and metal gate electrode materials. In this paper, we present results corresponding to the utilization of total reflection X-ray fluorescence spectroscopy (TXRF) as a quick, accurate, nondestructive technique for hafnium silicate composition determination based on detection of the Hf:Si ratio of (HfO2)x(SiO2)1−x, where x varies over the range 0.2–1.0.