A direct method for determining powder diffraction data from a range of depths is described, where the linear absorption coefficient may vary with depth. A series of traditional data collections with varying angles of incidence are required, and the X-ray diffraction data arising from specific depths will be calculated by the transformation of these measured, angle-dependent spectra. These may then be analysed using any conventional method in order to gain information about characteristics of the sample in question at specific depths. Regularisation techniques have been used to solve the governing Fredholm integral equation to determine the depth-dependent diffractograms. The method has been validated by the use of simulated data having known model profiles, and has also been applied to experimental data from polycrystalline thin film samples.

The presence of strain distributions within semiconductor features influences many aspects of their behavior. For example, microelectronic technology that incorporates strained silicon improves device performance by increasing carrier mobility in the Si channels. Because current semiconductor fabrication contains multiple levels of metallic and dielectric structures, an understanding of the mechanical response of the constituent elements is critical to the prediction of the overall device performance. In addition, the interaction of strain fields between adjacent structures becomes greater as feature sizes decrease and the corresponding feature density increases. The use of synchrotron-based X-ray methods allows one to determine the interaction between strained features and their environment at a submicron resolution. Real-space mapping of strain distributions in pseudomorphically strained, raised SiGe structures revealed that elastic relaxation extends approximately 20 times the feature thickness from their edges. X-ray topographic methods were also applied to map the substrate deformation induced by overlying SiGe features. A formulation based on the classical Ewald-von Laue theory of dynamical diffraction was derived to match the measured diffraction profiles.

A general expression is proposed for the peak profile produced by a system of simple-shape crystalline domains (sphere, cube, tetrahedron, octahedron) whose size is dispersed according to a gamma distribution. The analytical expression obtained is particularly suited to “on the fly” pattern simulation or profile fitting for nanocrystalline materials. An advantage of using the proposed profile expression is that it always corresponds to a physically meaningful, though a priori fixed, size distribution, whereas the traditionally employed Voigtian profiles can produce unphysical negative size distributions for certain combinations of profile parameters. The peak profile depends on the distribution mean and variance instead of the more common empirical parameters of peak width and shape.

The crystal structure of La2SiO5 was refined from laboratory X-ray powder diffraction data (CuKα1) using the Rietveld method. The crystal structure is monoclinic (space group P21∕c,Z=4) with lattice dimensions a=0.93320(2) nm, b=0.75088(1) nm, c=0.70332(1) nm, β=108.679(1)°, and V=0.46687(1) nm3. The final reliability indices were Rwp=7.14%, RP=5.52%, and RB=3.83%. There are two La sites in the structural model, La1 and La2. La1 is ninefold coordinated to oxygen, forming a tricapped trigonal prism with a mean La1-O distance of 0.263 nm. The La2O7 coordination polyhedron is a distorted capped octahedron with a mean La2-O distance of 0.251 nm. The La1O9 polyhedra share faces and the La2O7 polyhedra share edges, forming two sets of sheets that alternate parallel to the (100) plane. These sheets are linked through SiO4 tetrahedra and non-silicon-bonded oxygen atoms to form a three-dimensional structure. This compound is isomorphous with the low-temperature (X1) phases of R2SiO5 (R=Y and Gd). The volumes of RO9 polyhedra steadily increase with increasing ionic radius of R, from Y3+ to Gd3+ to La3+, which causes substantial volumetric expansion of the crystals.

We discuss the impact of strong absorption for thermal neutrons on data analysis and compare absorption corrections in the GSAS and MAUD Rietveld codes for texture and structural parameter refinement. Diffraction data were collected on the neutron powder diffractometer HIPPO at LANSCE from dysprosium and erbium, which are moderate-to-strong absorbers for thermal neutrons with absorption cross sections of 159 barns for Er and 994 barns for Dy at λ=1.8 Å. Both elements have hexagonal-close-packed (hcp) crystal structures, and the samples were various thicknesses of rolled foils. The orientation distribution functions (ODF) were fit to the same neutron time-of-flight data sets using two very different full pattern Rietveld analysis procedures. Spherical harmonics functions were fit to the textured data using GSAS. These data were also analyzed by the modified direct method E-WIMV using MAUD. The resulting pole figures from the ODFs determined by both Rietveld analysis packages are qualitatively similar, and the textures were confirmed by X-ray diffraction. Additionally, data from orthorhombic dysprosium and erbium fluoride powders show that atomic positions are not sensitive to absorption. We address inconsistencies and methodologies in data analysis when strong absorption is present.

Powder diffraction data for five three-layer Aurivillius ceramics of the form Bi2Sr2−xAxNb2TiO12 (A=Ca,Ba,x=0,0.5,1) have been determined from specimens that were characterized using both X-ray and neutron diffraction. Full Rietveld analysis demonstrated that the crystals were all tetragonal (space group I4∕mmm, #139), with highly aniostropic layered structures with lattice parameters on the order of a=3.9 Å and c=33 Å, and densities on the order of 7 g∕cm3

X-ray imaging techniques based on Compton backscatter permit inspection and screening of sea containers, a wide variety of vehicles, luggage, and even people. In contrast to more commonly used transmission images, backscatter imaging involves positioning both source and detection apparatus on only one side of a target object. This presents the user with inspection opportunities in situations that may be extremely difficult, if not impossible, for transmission systems that require access by the detector subsystem to the opposing side of the target. The backscatter image is somewhat akin to a photograph of the contents of a closed container, taken through the container walls. Techniques for producing X-ray images based on Compton scattering will be discussed, along with wide-ranging examples of how systems based on these principles are used to perform inspections for both security applications and for the detection of contraband materials at ports and borders. Potential applications in the area of nondestructive evaluation will also be considered. Differences in the type of information displayed by transmission and backscatter images will be highlighted, and tradeoffs between backscatter image quality and interpretability, scan speed, effective penetration, and X-ray tube voltage will also be discussed. The method used in scanning the target object results in an extremely low radiation dose, a result that significantly broadens the application spectrum for this imaging technique.

A new ternary compound Gd117Fe52Ge112 has been successfully synthesized and studied by means of X-ray powder diffraction technique. Gd117Fe52Ge112 crystallizes in a cubic Tb117Fe52Ge112-type structure with space group Fm3m(#225) and lattice parameter a=28.7680(1) Å. Crystal structure of Gd117Fe52Ge112 has been successfully refined using the Rietveld method from X-ray diffraction data. The R-factors for the Rietveld refinement are Rp=0.099 and Rwp=0.128. X-ray powder diffraction data with the figure of merit F30 of 80.4(30) are also reported.

The diosgenin, (25R)-spirost-5-en-3β-ol, was isolated from rhizomes of dioscorea meridensis and characterized by X-ray powder diffraction, IR and MS. The diosgenin was found to be monoclinic, with refined unit cell parameters a=16.774(3), b=7.259(2), c=10.383(2) Å, β=92.74(2)°, V=1262.9(3) (Å3), Z=2, Dx(g∕cm−3)1.089, with space group P21 (No. 4).

Techniques for estimation of element levels directly in humans (noninvasive in vivo) or in samples (in vitro) from humans are reviewed. Toxic, nonessential, trace elements may cause temporary or permanent damage to various organs and tissues in humans. There is thus a need to control the concentrations. Knowledge of the relations between toxic effects and element concentration may be extracted from measurements in humans as well as in samples from humans and her environment. Applications traditionally include occupationally exposed subjects, but an increasing research area is studies of members of the general population and of patients undergoing therapy for malignant and other diseases. Most in vivo XRF studies deal with lead in bone and cadmium in kidneys. For retired lead workers, a clear association has been demonstrated between bone lead and blood lead, due to endogenous lead excretion from the skeleton. A study of mercury in vivo showed that the technique is capable of detecting mercury in heavily exposed worker’s kidneys. In vivo XRF in cancer and rheumatology patients has helped to understand how platinum and gold are retained in the human body. The newest in vivo applications include zinc in prostate gland and arsenic in skin.

Crystallite size determined by X-ray line profile analysis is often smaller than the grain or subgrain size obtained by transmission electron microscopy, especially when the material has been produced by plastic deformation. It is shown that besides differences in orientation between grains or subgrains, dipolar dislocation walls without differences in orientation also break down coherency of X-rays scattering. This means that the coherently scattering domain size provided by X-ray line profile analysis provides subgrain or cell size bounded by dislocation boundaries or dipolar walls.

A new Nasicon phosphates series [Na3+xCr2−xCox(PO4)3(0⩽x⩽1)] was synthesized by a coprecipitation method and structurally characterized by powder X-ray diffraction. The selected compound Na3.5Cr1.5Co0.5(PO4)3 (x=0.5) crystallizes in the R3c space group with the following hexagonal unit-cell dimensions: ah=8.7285(3) Å, ch=21.580(2) Å, V=1423.8(1) Å3, and Z=6. This three-dimensional framework is built of PO4 tetrahedra and Cr∕CoO6 octahedra sharing corners. Na atoms occupy totally M(1) sites and partially M(2) sites.

An analysis of the microstructure of nanocrystalline magnesium oxide produced by thermal decomposition of magnesium oxalate, in the temperature range 500 °C–1200 °C, is described. The study is based on diffraction line broadening analysis carried out with the integral breadth (Langford) and Fourier methods, combined with the pattern decomposition technique. Additionally, the whole pattern matching method is also applied. No marked line broadening anisotropy is observed in the patterns. It is shown that the nanopowders are characterized by minimal strain and that crystallites have an average spherical shape. Volume-weighted and area-weighted apparent sizes are in the ranges 98–480 Å and 72–282 Å, respectively, within the temperature range considered. The results obtained from line broadening analysis are compared to those observed with scanning electron microscopy and surface area measurements. A satisfactory agreement is found between sizes derived from the different techniques.

The crystal structures of ruthenium oxides with the general formula Nd2−xMxRu2O7−y, where M is Cu or Ag, 0≤x≤0.25, were investigated. All compounds that were prepared exhibit the pyrochlore structure with a cubic unit cell. The compounds were characterized by X-ray powder diffraction, and single-phase structures were found for Nd2−xCuxRu2O7−y, x=0.1, 0.2, 0.25, and for Nd2−xAgxRu2O7−y, x=0.1, 0.15, 0.2. The relative metal concentrations were verified by EDS. The cell parameters were determined by advanced peak-position analysis and calibrated by a Si internal standard. Atomic positions and oxygen occupancies where refined by the Rietveld method. It was found that the cell-size modifications agree with the relations between ionic sizes.

Li0.5M0.25TiOAsO4 (M=Mg,Co,Ni,Zn) oxyarsenates powders were prepared by coprecipitation method from dilute solution of Li2CO3,M(NO3)2×H2O (M=Mg,Co,Ni,Zn), (NH4)H2AsO4 and TiCl4 in ethanol. The resulting powders, obtained after drying at about 60 °C, were heated progressively with intermittent grindings at 200 °C–750 °C in air. These new compounds crystallize in the monoclinic system with space group P21∕c. Their parameters are functions of M2+ ion size.