The structure of the Ba5R8Zn4O21 series (R=lanthanides) was investigated using X-ray Rietveld refinements. The compounds were successfully prepared for R=Eu, Gd, Dy, Ho, Er, Tm, and Yb. Ba5R8Zn4O21 crystallizes in the tetragonal space group I4/m; for R=Yb to Eu, a ranges from 13.635 02(5) to 13.960 62(9) Å, c from 5.658 46(3) to 5.784 83(5) Å, and V from 1051.987(8) to 1127.459(14) Å3. The Zn2+ ions adopt a fivefold distorted square pyramidal coordination. The seven-coordinate R3+ reside in monocapped trigonal prisms. These prisms share edges, and form layers stacked along the c axis. There are two types of BaO polyhedra: bicapped square prisms (BaO10), and irregular BaO10 polyhedra. For larger R, Ba5R8Zn4O21 was not stable, and tetragonal BaR2ZnO5(La, Nd) and orthorhombic BaR2ZnO5(Sm) phases were observed instead.

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. Lattice metric singularities often involve lattices that are in a derivative relationship one to another. A variety of types of singularities are possible depending on the number of different lattices involved (i.e., binary, ternary, quaternary), on the nature of the derivative lattice relationship (i.e., subcell/supercell, composite), on the Bravais type of each of the lattices, and on the the volume ratio(s) of primitive cells defining the lattices. In the laboratory, an encounter with a singularity can lead one into a trap; viz., the investigator using an indexing program, or by other means, may determine only one of the lattices with a high figure of merit. When this happens, it is critical to recognize that there exists more than one indexing solution. In a previous work, a binary singularity was described involving a monoclinic and a rhombohedral lattice. In the present work, we describe a second type of singularity—a ternary singularity—in which the two of the three lattices are in a derivative composite relationship.

The characteristics of the (101) peak of α-quartz and the (104) peak of the NIST SRM 1976 alumina flat plate standard have been measured in dependence of time for 60 h with Cu-Kα1 radiation in Bragg-Brentano geometry with a Philips X’Pert diffractometer equipped with a primary Ge(111) monochromator. It was found that the reproducibility of the peak position and the peak shape falls well in the ±3σ range, whereas the peak intensity strongly depends on the power history of the X-ray generator and the temperature of the diffraction system. The effects on Rietveld refinements are discussed and recommendations are given for optimized data collection.

In this work, zinc oxide samples were obtained from hydroxycarbonate by thermal decomposition at 300 °C. Zinc hydroxycarbonate samples were produced by homogeneous precipitation over different periods of time. The method used to obtain zinc oxide produces different morphologies as a function of the precursor precipitation time. Among the obtained particle shapes were porous spherical aggregates, spherulitic needle aggregates, and single acicular particles. This work investigated spherulitic needle-aggregate formation and the correlation among morphology, domain size, and microstrain. Transmission electron microscopy data revealed that the acicular particles that form the spherulitic needle aggregates consist of nanometer crystallites. Apparent crystallite size and microstrain in the directions perpendicular to (h00), (h0l), (hk0), and (00l) planes were invariable as a function of precursor precipitation time. From the results, it was possible to conclude that the precursor precipitation period directly influenced the morphology of the zinc oxide but did not influence average crystallite size and microstrain for ZnO samples. Therefore, using this route, it was possible to prepare zinc oxide with different morphologies without microstructural alterations.

A new zinc phosphate was synthesized by the hydrothermal reaction of zinc oxide and phosphoric acid in the presence of 1,4-diaminebutane. The formula of the product is (ZnPO4)4(H3PO4)2(C4N2H14)2 and crystallizes in the triclinic system with a=8.6590(3) Å, b=10.3467(3) Å, c=8.3910(3) Å, α=102.180(2)°, β=93.676(2)°, and γ=88.203(2)°.

Powder X-ray diffraction data for methionine sulfoxide, C5H11NO3S, obtained from the commercial amino acid, are presented in this work. Monoclinic cell parameters are: a=15.500 Å; b=3.820 Å; c=13.490 Å; β=97.300 °.

An organic adduct nonlinear optical material m-nitrobenzoic acid⋅diethanolamina (C11H16N2O6) 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 56 observed reflections are reported. The powder diffraction data have been evaluated, and the figure of merit was found to be F30=57.9 (0.0108, 48). The unit cell parameters were refined by a least-squares fit with a Cc space group and a=22.973(5) Å, b=4.6657(6) Å, c=15.023(3) Å, β =124.45(1)°, V=1327.75 Å3; Z=4, Dx=1.37 g/cm3. The powder diffraction results are in agreement with those obtained from single crystal structure data.

Two adducts (NH2CH2COOH)3⋅H2BeF4(TGFb) and (NH2CH2COOH)3⋅H2SeO4(TGSe) were obtained and characterized by X-ray powder diffraction. The samples were indexed using the TREOR program [Werner, Z. Kristallogr. Kristallogeom. Kristallphys. Kristallchem. 120, 375–387 (1964)] on a monoclinic unit cell. The lattice parameters of adducts TGFb and TGSe were refined by a least-squares method using the Lattice Constant Refinement Program of the Rikagu software. The refined lattice parameters are a=9.1589(9) Å, b=12.6204(13) Å, c=5.6966(8) Å, β=105.451(9)° for TGFb. The Smith and Snyder figure [Smith and Snyder, J. Appl. Crystallogr. 12, 60–65 (1979)] is F30=39.4(0.0141,54). The refined lattice parameters a=9.5063(11) Å, b=12.8281(10) Å, c=5.8682(7) Å, β=110.353(77)° for TGSe. The Smith and Snyder figure is F30=39(0.0106,73). The powder diffraction results are in agreement with those obtained from single crystal structure data.