X-ray powder diffraction pattern for InN synthesized using a microwave plasma source of nitrogen is reported. The data were obtained with the help of an automated Bragg-Brentano diffractometer using Ni-filtered CuKα radiation. The lattice parameters for the wurtzite-type unit cell are ao=3.5378(1) Å, co=5.7033(1) Å. The calculated density is 6.921±0.002 g/cm3.

The compounds BaR2O4, (R = Pr, Tb), where R are two of the less frequent trivalent lanthanides, have been prepared under reducing atmosphere from mixtures of BaO2, the R metals, and the oxides Pr2O3 and Tb4O7, respectively. The crystal structure of BaR2O4 have been refined from X-ray powder diffraction data by the Rietveld method of profile analysis using 31 parameters in each case. Both oxides are orthorhombic, isotypic with SrY2O4, of the perovskite-related CaFe2O4 structure type, S.G. Pnma (No. 62), Z = 4, a = 10.6113(8), b = 3.6303(3), c = 12.485(1) Å, and V = 480.93(5) Å3 for R = Pr; and a = 10.4282(8), b = 3.4893(3), c = 12.1809(6) Å, and V = 443.22(3) Å3 for R = Tb. The R–O distances vary between 2.15(6) to 3.40(6) Å for R = Pr, and between 2.15(3) to 2.91(5) Å for R = Tb.

Palladium tetrammine dichromate, [Pd(NH3)4]Cr2O7, was obtained by precipitation from [Pd(NH3)4]Cl2·H2O and (NH4)2Cr2O7. The X-ray diffraction pattern of this compound corresponds to a new phase, which was indexed in the triclinic system, but on a cell that should be considered as preliminary. From the chemical analysis and the X-ray absorption experiments at both K-edges of Pd and Cr, we conclude that the surrounding of these atoms is kept during formation.

Gamma-phase lithium aluminate (LiAlO2) is a ceramic powder used in molten carbonate fuel cells (MCFCs) and in other nuclear and ceramic applications. Upon exposure to water vapor and carbon dioxide at 25 °C, we have observed that gamma-LiAlO2 converts to lithium aluminum carbonate hydroxide hydrate, Li2Al4(CO3)(OH)12·3H2O(LACHH) and Li2CO3. The conversion was observed by X-ray diffraction (XRD) and carbonate analysis. An equation for the conversion is given, and the morphology is determined by scanning electron microscopy. A high-temperature XRD study and thermogravimetric/differential thermal analysis (TGA/DTA) showed that LACHH decomposes at 250 °C. The decomposition products of LACHH and Li2CO3 react to form first alpha-LiAlO2 and then gamma-LiAlO2 at temperatures of 650 and 1000 °C, respectively.

Ba2NaNb5,O15 and eighteen additional compositions in the NaNbO3-BaNb2O6 system from 60 to 85 mole % BaNb2O6 have been prepared and studied by X-ray powder diffraction. A calculated pattern has been used to aid in indexing the powder pattern of stoichiometric Ba2NaNb5O15(BNN-S). The lattice parameters of BNN-S have been determined from repeated measurements of 2 higher order reflections and are a=b=17.5994(8)Å and c=7.9771(9)Å. A comparison with the Powder Diffraction File (PDF) 34-210 indicates that the present data provide a more precise match to the unit cell, include additional weak reflections and cover a greater 2θ range. There is a tungsten bronzetype solid solution range from 60 to 75 mole % BaNb2O6.

X-Ray powder diffraction data and unit cell parameters of industrially produced, as well as bench scale prepared, ammonium paratungstate tetrahydrate are reported and compared with current Powder Data File (PDF) (1989) patterns. A least-squares refinement resulted in two slightly different unit cells. Both cells are monoclinic with S.G. = P21/n(14), Z = 2. The density, 4.639(2)kg/m3, calculated from one of these unit cells corresponds reasonably well with a measured value of 4.61 (2). It has, however, not been possible to determine at present why ammonium paratungstate tetrahydrate has two unit cells. No relation between the crystalline form and the method of preparation nor the exact water content could be established.

Arsenic molybdate, As4Mo3015, has been investigated by means of X-ray powder diffraction. The diffraction data were collected with a focussing (Guinier-type) transmission diffractometer equipped with a primary-beam monochromator (Ge 111) for CuKα radiation and a scanning position-sensitive detection system. A monoclinic unit cell was determined using an indexing program.

The crystal structure of Cr2[Ni(CN)4]3·10H2O has been determined on X-ray diffraction powder data by means of the Rietveld method. The starting model was based on the isomorphic, disordered structure of Mn3[Co(CN)6]2·12H2O. At room temperature the crystal is cubic, F4¯3m, a=10.097(6) Å, V=1029.4(5) Å3. The structure is disordered and contains 1.33 formula weights per unit cell. The Ni and Cr ions are coordinated by N and C atoms, respectively, forming octahedra linked by CN groups. The water molecules replace partly the chromium, carbon, and nitrogen positions in the crystal. The final R values are: Rwp=0.032 (Rexp=0.023), RB=0.088, and DW-Stat.=1.31 (DWexp=1.8).

Measurements of X-ray diffraction patterns of high-Tc superconductor and tungsten–carbide powder samples using a Bragg–Brentano diffractometer showed systematic variations of the intensities for different preparation conditions. For specimens with high surface roughness, an angle-dependent decrease of the intensities is observed which is caused by the microabsorption of the X-rays due to the microstructure of the powder sample. In Rietveld analysis, the thermal parameters are strongly influenced by this effect and may tend to negative values. A realistic description of the surface structure of flat powder samples is proposed. Using an analytical approximation for the microabsorption effect and its dependence on the microstructural parameters the Rietveld refinement yields reasonable values for the thermal parameters.

High quality powder diffraction data were obtained from a specimen containing inseparable impurities, by using single crystal precession photographs to explore all possible reflections for the mineral being studied. In this manner it is acceptable to ignore weak reflections that do not index on the unit cell and that are not observed on the single crystal photographs. Triphylite is given as an example.

A commercially available photoconductor material, p-diethylaminobenzaldehyde diphenylamine hydrazone, C23H25N3, has been purified and recrystallized from an absolute alcohol solution. The triclinic compound has been characterized by X-ray powder diffraction. Experimental 2θ values corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 74 observed reflections with 2θ up to 30.5° are reported. The powder diffraction data have been evaluated, and figures of merit are reported. Unit-cell parameters least-squares refined from the 74 observed reflections of the triclinic compound are in good agreement with those obtained from the single-crystal structure analysis.

New powder X-ray data for cancrinite [ideally Na8Si6Al6O24 (CO3)2·2 H2O] are reported along with in-situ real-time thermal processes recorded using energy dispersive X-ray diffractometry (EDXD). A completely anhydrous phase is obtained after heating the sample up to 600 °C and quickly cooling it to room temperature, as shown by means of both Rietveld analysis and IR spectroscopy. The anhydrous phase does not show any tendency to re-acquire molecular water. During the heating process, at around 450 °C, a peak splitting is observed, possibly due to a reversible phase transition.