A model for the long awaited crystal structure of metastable NaAlF4 is established from the powder diffraction pattern of a partly disproportionated sample. Orthorhombic, Cmcm, a=3.6121(3), b=14.952(1), c=5.2692(4) Å, Z=4, V=284.58(4) Å3. Sodium atoms are in NaF6 trigonal prisms interconnected by edges in compact layers. AlF6 octahedra are both cis- and trans-corner connected forming a layer structure similar to that observed in the NaNbO2F2 (P21/c) and BaZnF4 (Cmc21) structure types. NaAlF4 is ideally simple and symmetrical, isostructural with BiReO4 (Cmcm), representing the aristotype of the NaMIIIF4 and BaMIIF4 series.

Phase transformation temperatures of a polycrystalline Ni-rich Ti49.86Ni50.14 shape memory alloy were investigated using a differential scanning calorimeter. In situ structural and texture analyses of the monoclinic Ti49.86Ni50.14 were investigated using neutron powder diffractometer technique. Differential scanning calorimeter results showed that this Ni-rich alloy has a one-step cubic to monoclinic martensitic phase transformation on cooling and a one-step monoclinic to cubic transformation on heating. In situ high-resolution neutron powder diffraction data of the monoclinic phase from low temperatures to room temperature on heating are consistent with the differential scanning calorimeter’s heating results. In addition, the refined monoclinic crystal structure parameters for all neutron diffraction data sets agree satisfactorily with single-crystal X-ray diffraction results. The multiple-data-set capabilities of the GSAS Rietveld refinement program, with a generalized spherical-harmonics description was used successfully to extract the texture description directly from a simultaneous refinement using 52 time-of-flight monoclinic neutron diffraction patterns, taken from a polycrystalline sample held in 13 orientations inside the diffractometer.

A comparison of different methods of X-ray diffraction analysis for the determination of crystallite size and microstrain; namely, line profile analysis, Rietveld refinement, and three approaches based on the variance method, is presented. The analyses have been applied to data collected on a ceria sample prepared by the IUCr Commission on Powder Diffraction. In the variance method, split Pearson VII, the Voigt function, and its approximation pseudo-Voigt function were fitted to X-ray diffraction line profiles. Based on the fitting results, the variances of line profiles were calculated and then the crystallite size and root mean square strain were obtained from variance coefficients. A SS plot of Langford as well as a Fourier analysis and Rietveld refinement have been carried out. The average crystallite size and microstrain were determined. The values of area-weighted domain size determined from the variance method are in agreement with those obtained from line profile analysis within a single (largest) standard uncertainty, and the volume-weighted domain sizes derived from the SS plot, Fourier size distribution, and Rietveld refinement agree within a single standard uncertainty. The results of rms strain calculated from variance and Pearson VII shape function and those from Rietveld refinements fall within a single esd. However, the variance method in conjunction with pseudo-Voigt and Voigt functions produce rms strains substantially larger than those determined from line profile analysis and Rietveld refinements.

A method to characterize iron oxide microparticles by microquantity X-ray powder diffraction is presented. The method employs small sections of acrylic tubing and double sided Mylar® tape that fits over a standard 170 mm collimator for a Bruker-AXS SMART 1000 or APEXII three-circle single-crystal diffractometer (Mo X-ray tube). The tubing will hold and position a sample that is placed on the double-sided Mylar® tape and allow for rapid specimen mounting/dismounting and data collection. The method is simple, portable, and readily adapted to a variety of single-crystal X-ray diffractometers.

The successful synthesis of ZnS hollow microspheres by a solvothermal route is reported. The synthesis was achieved by a proper selection of a sulfur source, i.e., Na2S2O3⋅5H2O or (NH2)2CS, to react with Zn(CH3COO)2⋅2H2O in mixed solvents of ethylene glycol and deionized water. The ZnS products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence spectroscopy. XRD identified the ZnS products to have either zinc blende or wurtzite structure. SEM images revealed hollow ZnS microspheres with 1 to 2 μm diameters and 100 to 200 nm shell thicknesses. TEM images confirmed that the hollow ZnS microspheres were assembled by ZnS crystalline nanocrystallites. The room-temperature photoluminescence spectrum of the zinc blende hollow microspheres showed a strong green emission at 514 nm and weak emission at 379 nm.

Strain field distribution in a naval platform under dry-dock conditions is complex and represents the cumulative response from residual stress (“locked in” during fabrication of materials and formation of the structure) and static loading stress (e.g., dry-dock loading). The magnitude and distribution of stress fields are a significant concern for the Canadian Navy, where the superposition of applied stresses on residual stresses may adversely affect the performance, safe operational envelope, and service life of naval platforms. Stress analysis was conducted on Canada’s VICTORIA Class submarines using a portable miniature X-ray diffractometer (mXRD) under dry-dock conditions. This paper introduces the concept of “residential stress” as it applies to submarine platforms and discusses the methodology for performing stress analysis with a portable mXRD. The evolution of residential stress during routine pressure hull repairs to Canada’s VICTORIA Class submarines is discussed. In particular, the recent replacement of the diesel exhaust hull and back-up valves on one of the submarines, as well as a pressure hull plate extraction-insertion-weld procedure on another, is discussed.

Time-resolved synchrotron powder diffraction was used to follow the thermal transformation of cement-asbestos. Thermal transformation of asbestos fibers into nonfibrous crystalline phases is a promising solution for the elimination of these hazardous minerals. Time resolution offered by the use of an imaging plate detector with a high-brightness X-ray source allowed for the observation of metastable phases, commonly not detectable with conventional instrumentation. In addition, the use of a closed capillary as a sample holder mimicked the real, novel industrial reactor where cement-asbestos slates are sealed in a tunnel kiln. The changing gas atmosphere in the closed system was shown to affect the final composition of the recrystallized product. This study demonstrates the importance of advanced powder diffraction techniques in this field of applied research.

Sr0.5Zr2(AsO4)3 arsenate was prepared and structurally characterized by powder X-ray diffraction and by Raman and infrared spectroscopies. Its structure, which belongs to the Nasicon-type family, was refined by the Rietveld method in the R-3 space group, from X-ray powder diffraction data. The hexagonal unit-cell parameters were determined to be ah=8.965(2) Å, ch=23.955(6) Å, V=1667.43(6) Å3, and Z=6. The structure is formed by an ionic three-dimensional network of AsO4 tetrahedra and ZrO6 octahedra linked by corners with Sr2+ ions occupying half of the M1 sites in an ordered manner. Raman and infrared spectra were recorded and assignments of the stretching and bending vibrations of the AsO43− tetrahedra were made. The number of the peaks observed is in good agreement with that predicted by the factor-group analysis of the R-3 space group.

This manuscript describes the construction, testing, and use of a simple side-loading air-tight specimen holder for use with Bruker X-ray powder diffractometers.

Rietveld refinement using synchrotron powder X-ray diffraction data of the ranciéite, Ca0.19K0.01(Mn4+0.91◻0.09)O2⋅0.63H2O, crystal structure reveals significant differences from that reported previously. The interlayer H2O molecules occupy sites halfway between the Mn,O octahedral sheets. The Mn sites in the octahedral sheets have 10% vacancies, and the mean Mn–O distance indicates that all Mn is tetravalent (Mn4+). The interlayer Ca cations are located above and below the Mn vacancies and are octahedrally coordinated to three O2 atoms in the octahedral sheet and three H2O molecules in the interlayer.

This paper presents Monte Carlo simulations considering all stages of the creation process of two-dimensional projections in a computed tomography (CT) device: excitation of angle dependent X-ray spectra within the X-ray tube using results from a previous study [Chyba et al. (2008). Powder Diffr. 23, 150–153]; interaction of these X-rays and secondary photoelectrons with a simple inhomogeneous sample; and interaction of X-rays and photoelectrons with the components (thin layers) of a matrix scintillation detector. The simulations were carried out by using custom software running on up to 50 nodes of a computer cluster. Comparative calculations were also made by using the software package MCNP [Booth et al. (2003). MCNP—A general Monte Carlo N-particle transport code, Report LAUR 03-1987, Los Alamos National Laboratory, Los Alamos, NM]. Tube spectra were calculated with algorithms proposed by Ebel [(2006). Adv. X-Ray Anal. 49, 267–273]. Measurements for the chosen setup made with an available CT device were in relatively good agreement with calculated results. It was shown that good knowledge of the tube spectra is of importance, but most differences between resulting projections and measurements are caused by uncertainties concerning detector response due to light yield of the scintillator and to internal scattering effects within the thin detector layers which lead to spreading of a detected point signal within the detector matrix into neighboring matrix elements.

New bismuth yttrium gadolinium oxide, Bi1.8Y0.1Gd0.1O3, synthesized from a stoichiometric mixture of Bi2O3, Y2O3, and Gd2O3, was characterized by X-ray powder diffraction. The compound was determined to be tetragonal, with space group P421c (114), unit-cell parameters of a=7.793 08(29) and c=5.665 71(40) Å, and the number of formulas per unit cell Z=4. Bi1.8Y0.1Gd0.1O3 is isostructural with β-Bi2O3.

Biaxial residual stress in a 〈111〉 textured cubic TiN polycrystalline thin film was analyzed by linear least-squares refinement using the method proposed by Yokoyama and Harada [J. Appl. Crystallogr. 42, 185–191 (2009)]. Values of the unstressed (or stress-free) unit-cell parameter a0=4.2332±0.0006 Å and the stress components of σ11=397(88), σ22=401(88), and σ12=−110(100) were obtained. The values of the in-plane stresses σ11 and σ22 presented in the TiN film are practically the same, while σ12 is relatively small. The results obtained in this study confirm that the above theoretical prediction by Yokoyama and Harada can be used to obtain reliable values of stress-free unit-cell parameter and three biaxial stress components of a textured cubic thin film.

θ-KAlF4 is a new nanosized potassium tetrafluoroaluminate metastable polymorph (13×18×55 nm3). The crystal structure is solved ab initio from X-ray powder diffraction data in direct space [orthorhombic unit cell with a=8.3242(3) Å, b=7.2502(3) Å, c=11.8875(4) Å, V=717.44(5) Å3, Z=8, and space group Pnma]. This new structure type, unique in the whole AIMIIIF4 family, is related to the fluorite structure and consists of AlF6 octahedra linked via a common edge forming a bioctahedral motif which is trans-connected through the corner-shared fluorine, resulting in the formation of infinite ladderlike double file of octahedra ([Al2F8]2−)n running along the b axis.

Crystal structure of 4H-SiC was refined from room-temperature X-ray powder diffraction data using the Rietveld refinement method. The refined lattice constants were determined to be a=b=3.079 93(0) Å, c=10.082 22(2) Å, and the refined overall temperature factor B=0.383(3) Å2. Using the Debye approximation, the Debye temperature was successfully determined to be 1194.8 K.

Due to the extraordinary beam characteristics of the new PETRA III synchrotron, i.e., the high brilliance, the extremely low emittance of 1 nm rad, and the high fraction of coherent photons even in the hard X-ray range, the imaging beamline (IBL) at PETRA III will provide state of the art imaging and tomography capabilities with resolution well into the nanometer range. Novel applications of tomographic techniques allow for high speed in situ measurements as well as highest spatial and density resolutions. Additionally, the highly coherent beam enables the application of phase contrast methods in an exceptional way. Since the focus is on the energy range between 5 and 50 keV, the IBL will among others be ideally suited for microtomography and nanotomography on small engineering materials science samples as well as for studying soft matter, bones, medical implants, and biomatter.