Using X-ray grazing incidence diffraction (GID) it is possible to perform a nondestructive analysis of the heterogeneous stress field for different volumes below the surface of the sample. The stress can be measured at very small depths, of the order of a few μm. The penetration depth of radiation is almost constant in a wide 2θ range for a given incidence angle α. It can be easily changed by an appropriate selection of α angle (or also by using a different type of radiation). There are, however, some factors which have to be corrected in this technique. The most important is the refraction of X-ray wave: it changes the wavelength and direction of the beam. Both effects modify a pick position. A corresponding correction was calculated and tested on ferrite powder and on 316L austenite stainless steel sample.

Rietveld refinement using neutron, laboratory X-ray, and synchrotron powder diffraction data of NIST SRM clinker 8488 was performed. Quantitative phase analysis (QPA) results were compared between data, and with other studies. QPA results for the main phases in the clinker were found to be in agreement between the different data used here, and in and other studies, although the QPA of the tricalcium silicate polymorphs was shown to be inconsistent. The QPA results for the tricalcium aluminate phase varied between data types, and the neutron data were unable to distinguish this phase.

The modal analysis of samples belonging to the zeolite-rich pyroclastic formation named “Neapolitan yellow tuff” (Central and Southern Italy) has been determined by full-profile refinement of X-ray powder diffraction (XRPD) data using a combined Rietveld–RIR method. The quantitative analysis and especially the zeolite content is a profitable source for geo-petrographic and genetic considerations and as well an essential source to assess the physical and chemical properties of the bulk material for a feasible use in industrial applications. Albeit a wealth of methods are used for the quantitative determination of zeolite content in pyroclastites they all fail for lack of accuracy as far as concerns the absolute standard deviation of the quantitative data. The outstanding outcomes achievable by using the Rietveld method make it as the most promising technique to fulfill this lack. The glass content in each sample is calculated by a combined Rietveld–RIR method in which a known amount of an internal standard is added to the mixture to rescale the Rietveld refined weight fractions into absolute values. Then, it is reasonable to designate this method as an external method according to the definition given by Hill and Howard (1987). Its counterpart is the internal method developed by Riello etal. (1995a,b). Other techniques such as the addition method and the background scattering volume calculation are developed to accomplish a further determination of the glass content. The results are compared to the values obtained from the Rietveld–RIR analysis. These experimental methods yield an over-estimation of the amorphous phase because the incoherent scattering contribution (air, absorption, sample holder, Compton scattering) is accounted for as the amorphous fraction itself. The glass content of each sample acquired from the Rietveld–RIR refinement on the “raw data” is compared to that accomplished from the refinement of incoherent scattering subtracted data. In addition, some largely used XRPD quantitative techniques such as the external standard and RIR (reference intensity ratio) and the influence of the sample loading method are accounted for in an internally consistent comparison among different procedures of analysis.

A new classification of opals through X-ray powder diffraction (XRPD) methodology, by analysing 75 new samples of opal came from different worldwide areas, is introduced. A brief historical summary of the application of XRPD analysis on opals and the most important XRPD results reported in literature were compared with the newly obtained XRPD data. A simple method for the classification of opals on the basis of their degrees of structural order-disorder calculated from the diffraction data is proposed. In addition, a clear boundary, which has not been previously described by others in literature, related to the presence (or absence) of two-peak characteristic of the cristobalite phase is identified. This boundary allows for a discrimination of opals C from CT.

Characterization of semi and noncrystalline materials, monitoring structural phase transitions in situ, and obtaining structural information together with spatial distribution of the investigated material are only a few applications that hugely benefitted from the combination of high-energy X-rays and modern algorithms for data processing. This work examines the possibility of advancing these applications by shortening the data acquisition and improving the data quality by using the new high-energy PILATUS3 CdTe detector.

An additional statistical calibration for the Bruker D8 Discover microdiffractometer is necessary to obtain accurate reproducible 2θ data for cell-refinement work. This new approach uses a graphical mapping method of the 2θ error versus the location of a selected diffraction peak on the detector surface to describe the separate roles of different calibration procedures (rebiasing, flood field, and spatial corrections) and parameters (sample-to-detector distance, x-y center coordinate) in minimizing the error. Optimized parameters are used to obtain the lowest achievable Δ2θ with this setup. Intensity error relative to the position of the diffracted line on the detector was found to be consistent at up to 20% and could not be reduced using any of the investigated techniques and parameters.

The hydration of ordinary Portland cements (OPC) was investigated with X-ray powder diffraction (XRPD) technique, mainly using synchrotron radiation. In situ experiments were performed during the first hours of hydration to study the evolution of the crystalline phases in the system. The hydration was carried out with pure water and in the presence of additives such as superplasticizers and setting accelerating agents. As soon as water is added to the cement, ettringite crystallizes. Its evolution appears to be very complex, and lattice parameters change as a function of setting time, indicating a possible chemical evolution of ettringite with time and as a function of pH. CSH (Ca-Si-hydrate) forms after a few hours from the beginning of hydration. CSH can be indirectly quantified and its evolution studied.

Quantification of potentially toxic single mineral phases in natural dusts of heterogeneous composition is critical for health hazard assessment. For example, crystalline silica, a human carcinogen, can be present as respirable particles in volcanic ash such as quartz, cristobalite, or tridymite. A method to rapidly identify the proportions of crystalline silica within mixed dust samples, such as volcanic ash, is therefore required for hazard managers to assess the potential risk of crystalline silica exposure to local populations. Here we present a rapid method for quantifying the proportions of single phases in the mineral assemblage of mixed dusts using X-ray diffraction (XRD) with a fixed curved position-sensitive detector. The method is a modified version of the whole-pattern peak-stripping (PS) method (devised by Cressey and Schofield [Powder Diffr.11, 35–39 (1996)]) using an internal attenuation standard (IAS) but, unlike the PS method, it requires no knowledge of other phases present in the sample. Ten synthetic sample mixtures were prepared from known combinations of four pure phases (cristobalite, hematite, labradorite, and obsidian), chosen to represent problematic constituents of volcanic ash, and analyzed by XRD. Results of the IAS method were directly compared with those of the PS method. The proportions of cristobalite estimated using the methods were comparable and accurate to within 3 wt %. The new IAS method involved less sample preparation and processing and, therefore, was faster than the original PS method. It therefore offers a highly accurate rapid technique for determination of the proportions of individual phases in mixed dusts.

X-ray powder data and refined cell parameters for two titanium carbonitride solid solutions are presented. Some deviations from Vegard's law were observed.

A monochromatic source of X rays for sample excitation permits the use of pure elemental standards and relatively simple calculations to convert the measured fluorescent intensities to an absolute “basis of weight per unit weight of sample. Only the mass absorption coefficients of the sample for the exciting and the fluorescent radiation need be determined. Besides the direct measurement of these absorption coefficients in the sample, other techniques are considered which require fewer sample manipulations and measurements, These fundamental parameters methods permit quantitative analysis without recourse to the time consuming process of preparing nearly identical standards.

With the explosive growth in the number of highly automated powder diffraction systems, many types of analyses which were previously considered a specialty analysis are now performed on a routine basis. Algorithms have been developed for measuring peak profiles from which crystallite sizes, residual microstrain, and X-ray crystal structure (Rietveld techniques for example) can be determined. However, these techniques require an instrumental peak profile calibration standard to correct the experimental data for instrumental broadening due to the system optics.

Significant problems are encountered when laboratories try to cross-correlate or reproduce published data due to the lack of a common reference material for instrumental calibration. This is particularly distressing in microstrain and crystallite size calculations which can be dramatically affected by a poor choice of standard materials. Microstrain and crystallite size measurement are becoming increasingly important for the characterization of advanced materials and catalysts.

The structure of TeO3, first published by Dumora and Hagenmuller (1968), was redetermined from new X-ray data collected with a powder diffractometer using space group R3̄c with a = 4.901(2), c = 13.030(4) Å, V = 271.05(8) Å3 and Z = 6. Intensity data were obtained with CuKα, radiation (λ = 1.540598 Å). Structure refinement was performed with 49 reflections and led to R = 0.058. The material is isostructural with FeF3. Powder data are given.

Weld residual stress (RS) measurements are often undertaken on test-pieces which have been cut out from large components, yet it remains unclear to what extent the RSs in test-pieces are representative of those present in the original component. Similarly weld mechanical performance tests are frequently undertaken on cross-weld test-pieces without a proper understanding of the level or influence of retained RS. We present a systematic study of the relaxation of longitudinal RS in thin-plate butt welds produced using different materials and welding methods (FSW, laser-MIG, and pulsed-MIG). In each case the RSs were measured repeatedly in the same location as the welds were progressively and symmetrically cut down. Although cutting inevitably leads to stress redistribution, significant relaxation of the longitudinal RS was only observed when the weld length or width was reduced to below a certain value. This critical value appears to correlate with the lateral width of the tensile zone local to the weld-line and may be considered to be the characteristic length as defined in St. Venant’s principle. Further, it was found that the level of stress relaxation as a function of weld length for all the welds studied could be collapsed onto a single empirical curve using a simple approach based on the characteristic length scales of the weld. Given the range of materials and welding methods used, this relation appears to be of general use for thin-plate welds although further work is required to test the limits of its applicability.

Gamma-phase lithium aluminate (LiAlO2) is a ceramic powder used in molten carbonate fuel cells (MCFCs) and in other nuclear and ceramic applications. Upon exposure to water vapor and carbon dioxide at 25 °C, we have observed that gamma-LiAlO2 converts to lithium aluminum carbonate hydroxide hydrate, Li2Al4(CO3)(OH)12·3H2O(LACHH) and Li2CO3. The conversion was observed by X-ray diffraction (XRD) and carbonate analysis. An equation for the conversion is given, and the morphology is determined by scanning electron microscopy. A high-temperature XRD study and thermogravimetric/differential thermal analysis (TGA/DTA) showed that LACHH decomposes at 250 °C. The decomposition products of LACHH and Li2CO3 react to form first alpha-LiAlO2 and then gamma-LiAlO2 at temperatures of 650 and 1000 °C, respectively.

A nonlinear optical material, o–chlorobenzol–benzoyl thiourea (C14H11ClN2OS), has been characterized by X-ray powder diffraction. Experimental values of 2θ corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 78 observed reflection with 2θ up to 72° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The unit cell parameters least-squares refined from 28 nonoverlapping peaks of the monoclinic compound with a P2 space group are a=13.2797(4) Å, b=12.4058(8) Å, c=8.1561(2) Å, β=95.398(1)°, V=1337.7(4) Å3, Z=4, Dx=1.444 g/cm3. © 1997 International Centre for Diffraction Data.

Hydrothermally altered rocks hosting precious metal deposits frequently contain stacking disordered layer silicates. X-ray diffraction analysis using the Rietveld method can be used to determine mineral abundances in these rocks if suitable disorder models are applied. It is shown here that disorder models of kaolinite and pyrophyllite can be described by a recursive calculation of structure factors. This permits the physically sound refinement of real structure parameters of these disordered minerals and the determination of mineral abundances. Even mixtures containing two disordered Si–Al layer silicates can be quantified reliably. The developed disorder models can now be implemented in routine phase analysis, allowing the quantification of large numbers of samples to identify mineralogical gradients surrounding ore deposits.

Crystal structure of the skutterudite-related phase has been refined by the Rietveld method from X-ray powder diffraction data. Refined crystallographic data for CoSn1.5Te1.5 are a=12.9063(2) Å, c=15.7837(3) Å, V=2276.89(4) Å3, space group R3 (No. 148), Z=24, and Dx=7.50 g/cm3. The crystal structure of the title compound can be viewed as a modification of the skutterudite structure (CoAs3)—it is isostructural with CoGe1.5Te1.5 and IrSn1.5Te1.5. In the structure of CoSn1.5Te1.5, the Sn and Te atoms exhibit long-range ordering, which results in lowering of the original cubic symmetry of the skutterudite structure to the trigonal one.

Stress in the early stages of growth has been measured in α-Al2O3 (alumina) scales formed on FeCrAl- and NiAl-based alloys during heating in air at 1000 °C to 1200 °C. Scale thickness ranges from 0.5 to 5 μm, times from 5 to 720 min. Stress was measured using the multiple-tilt method. In order to measure the thinnest scales at the earliest times, focused, monochromatic synchrotron radiation was used for high intensity, and a fixed, small angle of incidence was used along with an appropriate wavelength to maximize scattering from the film relative to the background from the substrate. Depending on the composition, transient tensile stresses of up to 1.2 GPa were observed, with maximum stress at times ranging from >10 h at 1000 °C to <10 min at 1200 °C. Thermal stresses induced by an abrupt temperature change were found to relax much more quickly, suggesting that the kinetics observed during isothermal growth reflect a dynamic competition between stress generation and stress relaxation. These results challenge commonly accepted models of growth stress in scales that predict that a compressive stress will be generated as the metal converts to a larger-volume oxide in a constrained location such as an interface. The observed tensile stress may be due to another mechanism altogether (e.g., grain coalescence), or to the conversion of a transitional Al2O3 to the equilibrium α-Al2O3 phase. For one composition, transitional Al2O3 is observed during the period of tensile stress

Doubly curved crystal (DCC) X-ray optics provide an enabling technology for new portable, remote, and in situ applications of monochromatic X-rays for composition and structure analysis of amorphous, polycrystalline, and crystalline solids. Femtogram sensitivity for surface contamination, parts-per-billion (ppb) impurity levels for solids, and composition, structure and uniformity of thin films with compact, low power (20–50 W) source optic combinations are possible.