Methods of the structure analysis were used to determine the incommensurate structure modulation in a sample of hauyne from Laacher Lake, Germany. The modulation parameter n=0.145, determined using single-crystal patterns, was refined using powder data. An indexing technique for additional reflections (satellites) using a parameter subcell and Miller index main reflections was suggested. Crystallographic characteristics of the hauyne of Laacher Lake are compared with that of hauyne from Sacrafano (Italy) and with lazurtes from Baikal, Pamir, and Afghanistan. We found that the crystal structure modulation can serve as a source of paragenesis information on sulphate bearing sodalte group minerals.

2,4,6-Trimercapto-s-triazine, trisodium salt (ideally, Na3S3C3N3·9H2O), also known as TMT-55, is a white powder that is used to precipitate heavy metals from contaminated waters. Chemical analyses confirmed the nominal composition. TMT-55 crystals are uniaxial negative with indices of refraction (25 °C) of nε=1.520 and nω=1.675. The structure was determined by single-crystal methods at 25 and −110 °C. A powder pattern was determined and compared to a simulated pattern based on the 25 °C structure data. Crystal data at 25 °C are: R3;Z=6; a=17.600(1) Å and c=9.720(2) Å; V=2607.5(5) Å3; Dx=1.55 g/cm3.

The activity of the high Tc task group of the ICDD Ceramic Subcommittee is described. This activity includes the compilation of X-ray powder diffraction patterns of the high Tc superconductors and related phases identified from the International Centre for Diffraction Data/Powder Diffraction File (ICDD/PDF). The coverage of this ICDD/PDF Superconductor SubFile (SC) includes high Tc phases and their structurally related phases, products of elemental substitution in the high Tc phases, phases found in the phase diagrams containing the high Tc phases, as well as potential reaction products with commonly used sample containers, and potential conventional low-temperature (metallic and nonmetallic) superconductors.

Two compounds with compositions around n=14 and n∼5.4 (n=Bi/Mo molar ratio) have been prepared by solid-state reaction with five heating/grinding cycles at 800 °C. The lattice constants of both compounds can be related to the fluorite-type structure of δ-Bi2O3. Bi14MoO24 has been indexed as an orthorhombic pseudotetragonal (√2×√2×1) superstructure: a=7.812 (±0.005) Å, b=7.762 (±0.005) Å, c=5.7716 (±0.0007) Å (but a+b=15.5750±0.0020). For orthorhombic (3×5×3) Bi38Mo7O78: a=16.8236 (±0.0027) Å, b=28.6182 (±0.0045) Å, c=16.9082 (±0.0027) Å.

Ammonium manganese phosphate monohydrate (NH4MnPO4.H2O) has been investigated by means of X-ray powder diffraction. The title compound is orthorhombic with unit-cell parameters a=5.7289(11), b=8.8167 (12), and c=4.9098 (8) Å.

New ternary compounds of Ca14Al10Zn6O35 and Ca3Al4ZnO10 compositions have been synthesized in the CaO–Al2O3–ZnO system. Single crystals of the new compounds have been grown, and crystal structures and crystallochemical properties were established. The phenomenon of heterovalence isomorphous statistical substitution of aluminium for zinc in alumino-oxygen tetrahedra has been established. It is now possible to synthesize a large group of new ternary compounds, the compositions of which are similar to that of spinels. The structure and properties of the new phases are presented.© 1997 International Center for Diffraction Data.

The crystal structure of cobalt(II) acetate tetrahydrate, Co(C2H3O2)·4H2O, has been refined using single-crystal, laboratory powder, and synchrotron powder diffraction data, both individually and in various combinations. The compound crystallizes in the monoclinic space group P21/c, with a=4.80688(3), b=11.92012(7), c=8.45992(5) Å, β=94.3416(4)° at 27 °C, and Z=2. The crystal structure consists of discrete centrosymmetric trans-Co(C2H3O2)(H2O)4 complexes, linked by a three-dimensional network of hydrogen bonds. Each complex participates in 14 hydrogen bonds, 12 intermolecular, and 2 intramolecular. Compared to the single-crystal refinement, refinement of laboratory powder data yielded an average difference in bond distances of 0.02 Å, in bond angles of 3°, and in root mean square atomic displacements of 0.07 Å. The standard uncertainties of the bond distances were 0.01 Å, compared to the 0.001–0.002 Å in the single-crystal refinement. Refinement of the synchrotron powder data yielded improved accuracy and precision. It proved impossible to locate or refine hydrogen positions using a single-powder dataset, but the hydrogens could be refined using rigid groups in a joint refinement of the two powder datasets. Even from powder refinements, it is possible to obtain suitable accuracy and precision to distinguish C–O and C=O bonds, and to examine details of chemical bonding.

Standardized experimental and calculated X-ray powder diffraction data for a new synthetic zeolite, cesium titanium silicate, CsTiSi2O6.5, are reported. In addition, a structure model in space group Ia3d (230), which is isomorphous with the mineral pollucite (CsAlSi2O6·xH2O), is proposed for CsTiSi2O6.5. This structure model is the basis of the reported calculated X-ray powder diffraction data for CsTiSi2O6.5. The experimental pattern for CsTiSi2O6.5 shows this compound crystallizes in a body-centered cubic (BCC) unit cell with a=13.8423 (1) Å. The measured value of the reference intensity ratio (I/Ic) of CsTiSi2O6.5 is 2.37, while the contrasting calculated value of I/Ic is 4.45. The experimental density (Dm) of CsTiSi2O6.5 is 3.48±0.09 g/cm3, in agreement with the calculated density (Dx) of 3.42 g/cm3. Chemical analysis of CsTiSi2O6.5 by atomic absorption spectroscopy gives its composition as 54±2 wt% Cs; 23±2 wt% Ti; 23±2 wt% Si, which compares favorably with the theoretical composition of 56 wt% Cs; 20 wt% Ti; 24 wt% Si.

A nonlinear optical material, o–chlorobenzol–benzoyl thiourea (C14H11ClN2OS), 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 78 observed reflection with 2θ up to 72° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The unit cell parameters least-squares refined from 28 nonoverlapping peaks of the monoclinic compound with a P2 space group are a=13.2797(4) Å, b=12.4058(8) Å, c=8.1561(2) Å, β=95.398(1)°, V=1337.7(4) Å3, Z=4, Dx=1.444 g/cm3. © 1997 International Centre for Diffraction Data.

The crystal structures of solution-grown and melt-grown polycrystalline samples of n-hexatetracontane (n-C46H94) in the temperature range 293–359 K have been investigated by X-ray powder diffraction. The solution-grown sample has an orthorhombic structure, with space group Pbc21 and cell dimensions a=4.952 Å, b=7.424 Å, and c=120.95 Å. While heating this sample a gradual transition to a monoclinic phase takes place, with onset temperature 335 K. At temperatures close to the melting point two configurations of the ab plane have been observed. Cooling a sample from the melt results in a mixture of a monoclinic and an orthorhombic structure. Rietveld refinements of the structures of solution-grown and melt-grown samples at 293 K have been performed.