Crystallographic structures of two new orthophosphates Ca0.50SbFe(PO4)3 and CaSb0.50Fe1.50(PO4)3 obtained by conventional solid state reaction techniques at 900 °C, were determined at room temperature from X-ray powder diffraction using Rietveld analysis. The two compounds belong to the Nasicon structural family. The space group is R3 for Ca0.50SbFe(PO4)3 and R3c for CaSb0.50Fe1.50(PO4)3. Hexagonal cell parameters for Ca0.50SbFe(PO4)3 and CaSb0.50Fe1.50(PO4)3 are: a=8.257(1) Å, c=22.276(2) Å, and a=8.514(1) Å, c=21.871(2) Å, respectively. Ca2+ and vacancies in {[Ca0.50]3a[◻0.50]3b}M1SbFe(PO4)3 are ordered within the two positions, 3a and 3b, of M1 sites. Structure refinements show also a quasi-ordered distribution of Sb5+ and Fe3+ ions within the Nasicon framework. Thus, in {[Ca0.50]3a[◻0.50]3b}M1SbFe(PO4)3, each Ca(3a)O6 octahedron shares two faces with two Fe3+O6 octahedra and each vacancy (◻(3b)O6) site is located between two Sb5+O6 octahedra. In [Ca]M1Sb0.50Fe1.50(PO4)3 compound (R3c space group), all M1 sites are occupied by Ca2+ and the Sb5+ and Fe3+ ions are randomly distributed within the Nasicon framework.

The measurement of lattice parameters using the Le Bail method was shown to be inappropriate for a complex, low symmetry, structure, even with high resolution synchrotron diffraction data. The method failed as a result of ambiguous indexing in the absence of constraints on diffraction intensities, that arise when a structural model is used, combined with the large number of reflections. A caution for the use of the Le Bail and other whole-powder pattern decomposition methods is presented, particularly for high reflection density data.

In this study, the effects of growth interruptions on the formation of the interfaces in GaAs∕AlAs multilayers are investigated. For that purpose, a series of different samples has been manufactured with molecular-beam epitaxy. The introduction of growth interruptions of 50 s after the deposition of the layer leads to a change in the morphological properties of the interfaces, in particular their correlation length. These modifications due to the growth interrupt are analyzed with diffuse X-ray scattering. As a result of the measurements, an extension of the lateral correlation length can be proved. By contrast, the vertical correlation of the interfaces is not affected.

Structural characterization from powder diffraction of compounds not containing isolated molecules but three-dimensional infinite structure (alloys, intermetallics, framework compounds, extended solids) by direct space methods has been largely improved in the last 15 years. The success of the method depends very much on a proper modeling of the structure from building blocks. The modeling from larger building blocks improves the convergence of the global optimization algorithm by a factor of up to 10. However, care must be taken about the correctness of the building block, like its rigidity, deformation, bonding distances, and ligand identity. Dynamical occupancy correction implemented in the direct space program FOX has shown to be useful when merging excess atoms, and even larger building blocks like coordination polyhedra. It also allows joining smaller blocks into larger ones in the case when the connectivity was not a priori evident from the structural model. We will show in several examples of nonmolecular structures the effect of the modeling by correct structural units.

Trigonal rare-earth dioxymonocyanamides Ln2O2CN2 (Ln=Dy, Ho, Er, Tm, Yb) were synthesized by the modified solid-state metathesis (SSM) method, in which Ln2O3 and melamine C3N6H6 were mixed and heated at 850 °C in vacuumed silica ampoules. Possible chemical reaction pathways are proposed. X-ray diffraction (XRD) patterns of Ln2O2CN2 were refined using the Rietveld method. Compounds Ln2O2CN2 crystallize in the trigonal system with space group P3m1, Z=1, and cell parameters of a and c varying from 3.7267(1) to 3.6407(1) Å and from 8.1848(3) to 8.1152(3) Å, respectively, as Ln atoms change from Dy to Yb. These compounds have stacking structures of Ln2O22+ and CN22− layers, similar to those of previously reported compounds Ln2O2CN2 (Ln=Ce, Pr, Nd, Sm, Eu, Gd). The presence of CN22− ions has been confirmed by infrared spectroscopy, with two characteristic peaks in the vicinity of 651 and 2075 cm−1.

The compound Na2ZnV2O7 with an åkermanite-type structure has been synthesized. It has a tetragonal unit cell, a=8.2711(4), c=5.1132(2) Å, and crystallizes with P-421m symmetry, Z=2. Its crystal structure has been refined from a combination of X-ray and neutron powder diffraction data. The structure contains layers of corner-sharing VO4 and ZnO4 tetrahedra, the former in pairs forming pyrovanadate V2O7 units. The sodium atoms are positioned between the layers, with a distorted antiprismatic coordination of oxygen atoms.

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.

In this study, we use X-ray diffraction (XRD) and micro-Raman spectroscopy (MRS) to measure internal strains in sensors embedded in polymer matrix composites. Two types of strain sensors embedded in either chopped graphite fiber∕epoxy matrix composite (MRS) or unidirectional graphite fiber∕polyimide matrix composite (XRD) were investigated. For XRD measurements, the sensors were in the form of spherical aluminum inclusions with diameters ranging from 1 to 20 μm. Due to large cross section area of an incident X-ray beam, only average stresses are reported using the XRD approach. Complementary to XRD experiments, MRS was pursued to measure internal strains in Kevlar-49 fibers embedded in chopped graphite fiber∕epoxy matrix composite. In recent years, MRS as an experimental tool for microstrain measurements has drawn considerable attention mostly due to its excellent spatial resolution. The resolution of MRS typically ranges between 1 and 10 μm, which means that strains can be measured in individual sensors. The principle of this method relies on a change of certain molecular vibration frequencies as a result of an applied stress. Several examples are presented and discussed to demonstrate the potential of combining micro and macrostrain measurements and modeling to capture the stress distribution in heterogeneous materials.

The room temperature powder pattern of abacavir hemisulfate (anti-HIV reverse transcriptase compound) was indexed using 2θ values obtained from a powder pattern spiked with an internal standard. The resulting unit cell values for the monoclinic I2 cell [nonstandard setting of C2 (No. 5)] are a=13.278(1) Å, b=8.437(1) Å, c=14.259(2) Å, β=93.87(1)°. There are two formula units [(C14H16N6O)2.H2SO4] per unit cell and Dx=1.390 g∕cm3.

Structure determination of 3,5-dimethoxybenzyl bromide and 3,4,5-trimethoxybenzyl bromide has been carried out from laboratory powder X-ray diffraction data using the direct-space Genetic Algorithm technique for structure solution followed by Rietveld refinement. These two compounds are of interest for their potential use as building blocks for the synthesis of dendritic materials. Although the two molecules differ only in the presence/absence of the methoxy group at the 4-position of the aromatic ring, the structural properties of the two materials are significantly different.

Potassium tetraperoxomolybdate (VI) K2[Mo(O2)4] was prepared, and its X-ray powder diffraction pattern was recorded at low temperature (258 K). The unit cell parameters were refined to a=10.7891(2) Å, α=64.925(3)°, space group R−3c (167), Z=6. The compound is isostructural with potassium tetraperoxotungstate (VI) K2[W(O2)4] (Stomberg, 1988). The sample of K2[Mo(O2)4] was characterized by analytical investigations, and the results of crystal structure refinement by Rietveld method are presented; final RP and RWP are 9.79% and 12.37%, respectively.

Materials in the Ti–Al–C ternary system commonly contain three coexisting phases, Ti3AlC2, Ti2AlC, and TiC. Quantitative phase analysis in this ternary system was investigated using X-ray diffraction. First, nonoverlap diffraction peaks were selected: the (002) peak at 2θ=9.5° for Ti3AlC2 (I∕I0=26.5), the (002) peak at 2θ=13.0° for Ti2AlC (I∕I0=39), and the (111) peak at 2θ=35.9° for TiC (I∕I0=78), respectively. Then, based on the mixing-sample method without internal standards, a set of equations was derived for determining the amounts of Ti3AlC2, Ti2AlC, and TiC in a sample using the intensities of the selected diffraction peaks. Finally, the applicability and error sources for this method were investigated. The method is simple and straightforward, and is applicable to the entire Ti–Al–C ternary system, since the derivation of this equation group is self-checking.

Numerous methods are available to forensic scientists for detecting fingerprints in which the prints are treated with various agents to enhance the visual contrast between the print and the surface. In the present work, the spatial elemental imaging capabilities of micro-X-ray fluorescence (MXRF) were used to visualize fingerprint patterns based on inorganic elements present in the prints. A major advantage of using MXRF is that the prints are left unaltered for other analyses, such as deoxyribonucleic acid extraction or for archiving. Most of the fingerprints which were examined were imaged from the potassium and chlorine present in the print residue. Among the various prints studied, lower count rates were also observed in the elemental maps of Ca, Al, Na, Mg, Si, P, S, and the X-ray source scatter. A sebaceous oily fingerprint left by one subject was successfully imaged by MXRF, but sebaceous prints left by a different person were undetectable, indicating that print elemental composition may be person and/or diet dependent. Prints containing substances that might be found in real-world cases were also visualized including sweat, lotion, saliva, and sunscreen.

This paper reports the results of crystallography and crystal chemistry investigation of the (Ba1−xSrx)Y2CuO5 (“green phase”) solid solution series by X-ray powder diffraction (XPD) and neutron powder diffraction techniques. The single phase regions for (Ba1−xSrx)Y2CuO5 were determined to be 0⩽x⩽0.3 for samples prepared at 810 °C in 100 Pa pO2, and 0⩽x⩽0.7 for samples prepared at 930 °C in air. All single phase (Ba1−xSrx)Y2CuO5 samples are isostructural to BaY2CuO5 and can be indexed using an orthorhombic cell with the space group Pnma. Lattice parameters, a,b,c and the cell volume, V, of the (Ba1−xSrx)Y2CuO5 members decrease linearly with increasing Sr substitution (x) on the Ba site. The general structure of (Ba1−xSrx)Y2CuO5 can be considered as having a three-dimensional interconnected network of [YO7],[(Ba,Sr)O11], and [CuO5] polyhedra. The copper ions are located inside distorted [CuO5] “square” pyramids. These pyramids are connected by the [Y2O11] groups that are formed from two monocapped [YO7] trigonal prisms sharing a triangular face. The Ba2+ ions are found to reside in distorted 11-fold coordinated cages. The oxygen sites are essentially fully occupied. XPD reference patterns of two members of the series, (Ba0.3Sr0.7)Y2CuO5 and (Ba0.7Sr0.3)Y2CuO5, were prepared for inclusion in the powder diffraction file.