A lattice metric singularity occurs when unit cells defining two (or more) lattices yield the identical set of unique calculated d-spacings. The existence of such singularities, therefore, has a practical impact on the indexing of powder patterns. For example, when experimental data from ζ-LiBO2 were indexed, two solutions (a rhombohedral and a monoclinic lattice) with approximately the same figure of merit were found. These two lattices yield the same set of unique d-spacings even though they are characterized by different reduced cells with cell volumes in the ratio 2 to 1. From the indexing point of view, both answers are correct. A singularity of this type is common and not a mathematical rarity. In fact, any rhombohedral cell of this kind has a derivative monoclinic subcell, each of which gives the same set of unique calculated d-spacings. In actual cases like this, one can run into a trap. Due to experimental error and input parameters, an indexing program may determine only one of the cells with a high figure of merit. When this happens, it is critical to recognize that another solution exists, especially if one has determined the lower symmetry lattice.

The capability of whole-powder-pattern decomposition in the quantitative phase analysis (QPA) of natural products was investigated using three- to six-component mixtures and pottery bodies. Here, the term pottery body means plastic clay suitable for making pottery and it is compounded of ceramic raw materials. Average errors of the weight fractions for each phase were within 1 weight percent in each mixture of natural products. The amounts of reduced oxides in pottery bodies derived from the X-ray diffraction technique were in good agreement with results obtained by X-ray fluorescence analysis. The present procedure does not require knowledge of crystal structures; it appears adequate for the QPA of natural products.

The crystal structure of the new ternary phase CuSnTi is determined by full profile Rietveld analysis of the powder diffractogram. 104 reflections were refined to a final RBragg value of 5.60%. CuSnTi crystallizes with the spacegroup P63/mmc and is isostructural to InNi2. The lattice parameters are a=0.439 555(5) nm and c=0.601 505(9) nm.

The principal aim of this study was to assess a new approach to the characterization of uroliths using synchrotron radiation. To achieve this, a detailed investigation of the crystalline nature of a human bladder urolith has been undertaken. Changes in the phase composition and crystalline mineral nature have been measured from the urolith core center to its outer surface. Data were collected using a microbeam, synchrotron probe, and image plate. Rietveld analysis has enabled us to determine that the unit cell dimensions of the majority phases (anhydrous uric acid and calcium oxalate monohydrate) are significantly greater in the core region but become progressively smaller from the outer to inner regions. The crystallites of both phases are also shown to possess significant radial orientation which varies through the urolith and reaches a maximum at a point of principal fracture. The analysis has also allowed us to study the change in average crystallite morphology; the crystallites of both phases are shown to decrease in size toward the outer parts of the urolith although this is in a nonuniform fashion. Evidence of calcium oxalate dihydrate was also found, but only within the outermost region of the urolith.

A cover for Scintag's six and twelve-position sample changers was designed and constructed to provide an inert atmosphere for samples during diffraction batch runs. The cover is equipped with inlet and outlet gas ports and fits over the top of the sample changer. Using dry nitrogen gas fed into the inlet of the cover, a sample of lithium bromide was protected from atmospheric moisture for greater than 18 h. The cover uses a thin Mylar window that gives greater than 95% transparency for copper K-alpha X-rays. The cover is a simple device that allows our lab to run multiple moisture-sensitive samples in a batch mode. The simple approach and materials used in the construction of the cover could be applied to other brands of powder diffractometers.

Aluminum borate (9Al2O3·2B2O3) whiskers were chemically synthesized in potassium sulphate flux by using the starting chemicals of aluminum sulphate and boric acid. The synthesis temperature of 1075 °C was found to be the optimum with respect to whisker morphology. A tentative X-ray diffraction (XRD) pattern was suggested for the whiskers produced after heating at 1150 °C. The product purity, phase composition, and whisker morphology were investigated by XRD, energy dispersive X-ray spectroscopy, and scanning electron microscopy, respectively.

Powder X-ray diffraction data of melatonin C13H16N2O2 were collected on a conventional X-ray powder diffractometer: the monoclinic cell parameter are a=7.7416(8) Å, b=9.2897(9) Å, c=17.1444(16) Å, β=96.756(9)°, volume 1224.4(3) Å3 (space group P21/c). The strongest lines are (d (Å), I/I0) 8.161 (100), 5.411 Å (46), 3.412 Å (34), 4.668 Å (33), 4.645 Å (25), 3.554 Å (22), 3.668 Å (16), and 4.483 Å (14). Reported intensities are validated by Rietveld analysis. The data consist of measured positions and intensities and cover an angular range up to 60° 2θ: experimental, calculated, and difference patterns are also reported.

New powder X-ray diffraction data of adenosine C10H13N5O4 were reported: cell parameters are a=4.8386(4) Å, b=10.2919(4) Å, c=11.8555(4) Å, β=99.298(5)°, volume 582.63(4)Å for the monoclinic space group P21. The strongest lines are: 7.723 (100), 5.085 (50), 5.851 (45), 4.710 (11), 3.881 (10), 3.899 (9), 3.292 (9), and 3.261 (9). Reported intensities are validated by Rietveld analysis. The data consist of measured positions and intensities and cover an angular range up to 75° 2θ and are significantly better than PDF 35-1977. Experimental, calculated, and difference patterns are also reported.

Powder X-ray diffraction data are reported for semimagnetic semiconductor Hg0.89Fe0.11S and Hg0.98Co0.02S crystals grown by the Bridgman method and for Hg0.80Mn0.20S crystal synthesized by a solid-state reaction method. The crystals have the sphalerite structure of metacinnabar (sphalerite-type high-temperature polymorph of HgS, space group F4¯3m). Phase analysis does not show any trace of other phases. The lattice parameters of the studied samples are a=5.803 20(5) Å, 5.8063(1) Å and 5.839 80(6) Å, respectively. The calculated density is reported.

Precise X-ray powder diffraction data are given for two germanides, CoGe and Co5Ge7. The refined unit cell parameters for CoGe are a=11.630(1) Å, b=3.8014(3) Å, c=4.9347(3) Å and β=100.889(8)° (space group C2/m, Pearson symbol mC16) with volume of the unit cell 214.24(2) Å3; the figures of merit are M20=96, F30=77 (0.0085, 46). The refined unit cell parameters for Co5Ge7 are a=7.6262(4) Å and c=5.8017(5) Å (I4mm, tI24) with volume of the unit cell 337.42(3) Å3; the figures of merit are M20=204 and F22=130(0.0068, 25). The dependence on composition of the unit cell parameters of CoGe is discussed in terms of specific defect structures.

Plant surfaces are mostly covered with microscopic layers of wax which exhibit characteristic morphologies, visible under high magnification. Waxes belonging to three different types were investigated. Powder data of seven natural and three recrystallised waxes as well as of two isolated compounds are presented. The mainly crystalline nature of the studied plant waxes is proved. The correlation between morphology, chemical composition, and powder patterns is discussed.

This paper presents the powder X-ray diffraction data of BaFI recorded using a Guinier diffractometer and Mo Kα1 radiation. BaFI stabilizes at standard temperature of 25 °C and standard-atmospheric pressure (STP) in the tetragonal structure (space group P4/nmm; No. 129) with lattice parameters a=4.660(1) Å and c=7.960(5) Å. Our observed pattern is different from the existing observed powder diffraction data reported in the PDF files 34-716 (Beck, 1976) and 31-139 (), but matches almost perfectly with the pattern calculated by us from the reported single crystal data ( and with the calculated data available in PDF file 70-0481. Further, our data provide a number of new Bragg peaks extending beyond the range of d values available in the existing PDF files.

The crystal structure of the Aurivillius compound Bi2BaTa2O9 prepared via the chemical route was determined by direct methods using EXPO97, and refined using the Rietveld method with conventional X-ray diffraction data. The structure was found to be tetragonal (space group I4/mmm, number 139) and Z=2, isomorphic of the Bi2BaNb2O9 reported by Blake and co-workers in the literature (1997). Two refinements were performed using the two asymmetry functions of DBWS-9807 (release 20/May/99). The unit cell for each case are: a=3.932 22(6) Å, c=25.5053(6) Å (RA) and a=3.932 50(7) Å, c=25.5069(6) Å (RCF). The differences for atom positions, interatomic distances and angles are in the range of one standard deviation. Final agreements factors are: Rwp=7.97%, S=1.84, RBragg=4.28%(RA), Rwp=7.98%, S=1.84, RBragg=4.30%(RCF). The occupancies of Ba and Bi in site 2b were refined but constrained to have their summation equal to 1.00. The same constraints were applied to the Ba and Bi of the 4e site. The results show that on site 2b there are 70% of Ba and 30% of Bi and on the site 4e there are 82% of Bi and 18% of Ba. The charge equilibrium is maintained for one standard deviation of the site occupancies.© 2000 International Centre for Diffraction Data.

The X-ray powder diffraction data for δ-Na2Si2O5 are reported. The sample was prepared from water glass solution applied to pressed powder tablets of finely ground quartz using a heating program with a maximal temperature of 700 °C. The crystallographic data for δ-disilicate obtained from a Rietveld analysis are: space group P21/n, a=8.3818(4) Å, b=12.0726(5) Å, c=4.8455(2) Å, β=90.303(5)°, V=490.31 Å3, Z=4, and Dcalc.=2.468 g/cm3.