An analysis of the microstructure of nanocrystalline cerium oxide produced by thermal decomposition of cerium (IV) oxide nitrate at temperatures in the range 230° to 960 °C is described. Parameters describing the breadths and shape of X-ray diffraction line profiles were obtained by means of pattern decomposition and a method based on the Voigt function was used to obtain information on the temperature dependence of the microstructure. No marked anisotropy in size and strain broadening was observed. It was found that the crystallites are on average spherical, the dimensions increasing significantly with formation temperature, while microstrains decrease with annealing temperature. The results of size determinations were compared with SEM measurements. They suggest a competition between the crystallite growth and “particle” growth processes in the initial sintering of the loosely packed cerium oxide powder.

The systems PbO–Bi2O3–P2O5/As2O5/V2O5 have been studied with respect to their compounds and solid solutions. A number of new compounds, particularly with high-Bi contents were found. Most of them are structurally closely related to the CaF2 and δ-Bi2O3 structures. Several binary and ternary solid solutions with P/As/V substitutions were investigated.

The incommensurately modulated structure of Bi2Sr2Eu1.3Ce0.7Cu2O10.17, with a = 5.4752(4) Å, b = 5.4522(3) Å, c = 17.860(1) Å, Z = 2, was refined by the GJANA program [Gao et al., Acta Cryst. A 49, 141 (1993)] from X-ray powder data in C:C2mb: 111 four-dimensional space group (Rov = 0.064, Rm = 0.041, Rsat = 0.202, Rp = 0.049, Rwp = 0.065). Displacive modulation parameters of all cations and oxygen atoms in the Bi-layer were involved in the refinement. Obtained results including the modulation parameters are in agreement with those found for the similar phase Bi2Sr1.7Nd1.8Ce0.5Cu2O10+δ from single-crystal data [Mironov et al., J. Solid State Chem. 109, 74 (1994)].

A method is described to determine the standard deviation of a peak position due to counting statistics. In this method, the statistical noise for a peak is first simulated based on the model of Poisson distribution and then imposed on the peak. The peak position is then determined by a profile fitting routine. By repeated application of these processes on a given peak, one obtains a number of slightly different peak positions and hence their corresponding standard deviation. This method can be applied to a peak described by any analytical function or a set of any number of digitized points. Investigation of the precision of peak positions was carried out by applying this method on various analytical peaks located at low, medium, and high 2θ angles. The results showed that the standard deviation of a peak position decreases with increasing P/B and P/σ, where P is the net peak count above the background B and σ=(P + B)½ is the estimated standard deviation for noise. It increases with increasing peak width and Δ2θ, the step size used to digitize the peak profiles. It decreases as the 2θ range of simulation and fitting increases up to 2θ=3 FWHMs (full width at half maximum) and remains at a constant value thereafter. The standard deviation of the position of a real peak obtained by ten repeated measurements is 0.0034°; the corresponding result obtained by the current method is 0.0035°. This peak is best fitted by a Pearson-VII function and the standard deviation obtained by this method is 0.013° when only the head portion with intensity ≥85% maximum net intensity is simulated and fitted. The corresponding result obtained by the traditional method of parabola fitting is 0.0055°. Therefore, the precision of a peak position also depends on the peak shape.

Ammonium nickel phosphate monohydrate (NH4NiPO4·H2O) crystal data were obtained by X-ray powder diffraction. Ammonium nickel phosphate monohydrate is orthorhombic with unit-cell parameters a = 5.566 (1) Å, b = 8.760 (2) Å, and c = 4.742 (1) Å.

The structures of two high-pressure tungsten oxides, previously studied by high-resolution electron microscopy, were confirmed by Rietveld refinement based on X-ray powder diffraction data. The phases have identical stoichiometry, W3O8, and extremely narrow 00l reflections in common. The microstructure of the dominant phase was investigated by means of X-ray powder diffraction pattern decomposition. A Williamson–Hall plot revealed that all lines, except the 00l reflections, were broadened solely due to the crystallite size effect. A cylindrical model is used to describe the average form of the coherently diffracting domains. The height of the cylinder, whose axis is colinear with the crystallographic c parameter of both phases, is considered “infinite,” and the average diameter of the cylinder model is 655(22) Å. A quantitative confirmation is obtained from electron microscopy.

The synthesis at 850 °C and the structural characterization of the elpasolite structure compound Cs2NaCeCl6 is reported space group Fm3m, a = 10.943(2) Å, V = 1310.4 (Å)3, Z = 4, M = 641.64, Dx = 3.252, and Dexp = 3.21. Powder diffraction data from a Rietveld structure refinement, are reported.

A resident powder diffractometer control program is described, which allows independent use of the PC for other programs during data collection. The control program and a simple interface card were developed for the case when a PC is used to automate the DRON type diffractometers.

Ab initio structure determination of new compound (Pb0.6Cu0.4)Sr2PrCu2O7−x was obtained at 300 and 100 K from X-ray powder diffraction data and refined by Rietveld technique. (Pb0.6Cu0.4)Sr2PrCu2O7−x has an isotypical structure with TlBa2CaCu2O7 (1212) at both 300 and 100 K. At 300 K, crystal data: (Pb0.522Cu0.4)Sr2PrCu206.53, Mr=681.293, tetragonal system, space group P4/lmmm, a = 3.8631(5)Å, c= 11.9134(2)Å, V= 177.79Å3, Z= 1, Dx, = 6.3631 g/cm3, μ=1036.549 cm−1 (λ=1.54051 Å), F(000) = 299.6, the structure was refined with 31 parameters to Rwp = 4.02%, Rp=2.96% for 3379 step intensities and Rb = 4.80%, Rf=5.17 for 143 reflections, “goodness of fit” S = 2.20. At 100 K, crystal data: (Pb0.547Cu0.4)Sr2PrCu2O6.89, Mr=692.232, tetragonal system, space group P4/mmm, a = 3.8580(2) Å, c= 11.8898(5) Å, Z=1, Dx = 6.4953 g/cm3, μ= 1053.235 cm−1 (λ=1.54051 Å), F(000) = 304.6, the structure was refined with 32 parameters to Rwp = 5.53%, Rp=4.22% for 2574 step intensities and Rb = 6.11%, Rf=5.31% for 111 reflection, “goodness of fit” S= 1.79. Moreover, the composition of Pb was refined to 0.522 at 300 K and to 0.547 at 100 K as compared with the stoichiometric composition 0.6.

High-quality powder X-ray diffraction data for a well-characterised natural sample of natrolite (Na2Al2Si3O10.2H2O, space group Fdd2, Z = 8) are presented. Refined cell parameters were a = 18.2984±0.0007 Å, b = 18.6502±0.0008 Å, and c = 6.5589±0.0003 Å. The sample was characterised using thermogravimetric techniques (to determine water content), EPMA and ICP-MS (to determine composition). Available data suggest that the crystal matches the expected stoichiometry of natrolite. Our powder data show close similarity with the proposed structure of natrolite using the Rietveld method, giving R values of 8.54%, and suggest that preferred orientation is not present in the sample.

Reaction of tungsten (W) with SF6 has been studied using two types of samples. The first type (type I) consisted of rods fabricated by a drawing process and the second type (type II) consisted of square plates cut from a hot pressed billet. After the corrosion experiments, scanning electron microscopy (SEM) examination of the type I sample indicated the presence of deep pits parallel to the rod axis. X-ray analysis of these rods showed preferred orientation. Pole figure measurement was subsequently conducted to quantify the preferred orientation by using neutron diffraction. A significant orientation effect on the corrosion process was found, possibly originating from the considerable granular elongation parallel with the rod axis produced during the fabrication process. In contrast, the type II sample showed no directional corrosion and insignificant preferred orientation.

Y6Cr4+xAl43−x (x = 2.57); space group P63/mcm, a = 10.8601(1) Å, c = 17.6783(3) Å, V= 1805.7(1) Å3, Z=2; isostructural to Yb6Cr4+xAl43−x, (x=1.76) with two aluminium sites partially occupied by chromium (44% and 27% Cr). YCr4−xAl8+x (x=1.22); space group I4/mmm, a = 9.0299(2) Å, c = 5.1208(2) Å, V=417.55(3) Å3, Z=2, disordered variant of CeMn4Al8 with one chromium site (8f) partially occupied by aluminium (33% Al); X-ray powder diffraction data were collected on a well-crystallized multiphase sample containing 43 wt.% of Y6Cr4+xAl43−x, 27 wt.% of Y2Cr8−xAl16+x, 16 wt.% of Al, 13 wt.% of YAl3, and traces of Y2O3. Structure refinement converged at Rwp = 2.0% and RB = 3.5, 3.6% resp. for a total of 78 parameters and 1190 reflections.

A nonlinear optical material, 4-chlorocinnamylidenyl-4′ -phenylacetophenone (C23H17ClO), 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 94 observed reflections with 2θ up to 60° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The unit cell parameters least-squares refined from 30 nonoverlapping peaks of the orthorhombic compound with a P21212 space group are a =14.756(3) Å, b = 20.647(8) Å, c = 5.840(1) Å, V = 1779.3(9) Å3, Z = 4, and Dx = 1.287 g/cm3.

Improved powder X-ray diffraction (XRD) data for liottite and sacrofanite, two members of the cancrinite group of minerals, were obtained using a rotating anode diffractometer. The cell parameters of liottite are a = 12.8575(3), c = 16.0905(6) Å, and the space group is ; the strongest reflections are at 4.834(38), 3.783(12), 3.714(100), 3.312(91), 2.784(13), 2.682(26), 2.470(17), and 2.143(27) Å. The cell parameters of sacrofanite are a = 12.8945(4) and c =74.2128(37) Å, and the possible space groups are P63/mmc, P63mc, and ; the strongest reflections are at 11.18(23), 3.757(25), 3.723(100), 3.488(27), 3.302(62), 2.651(31), 2.645(30), and 2.149(18) Å. The new data include an increased number of indexed peaks and empirical formulae that differ from the reference data (PDF 29-1187 and PDF 35-653, respectively).

The structure of [Pd(NH3)4]Cr2O7 has been determined ab initio from conventional X-Ray powder diffraction data by the Patterson method. The cell is monoclinic (space group P21/c, Z = 4), with a = 7.771(3) Å, b=11.578(1) Å, c=11.852(4) Å, and β= 105.50(4)°. Refinements of 57 parameters by the Rietveld method, using 852 reflections lead to RB = 0.032, RP = 0.075, and Rwp = 0.092. The structure is built up from PdN4 square planes linked to Cr2O7 groups by hydrogen bonds. Hydrogen atoms could not be located.

A task group of the JCPDS—International Center for Diffraction Data (ICDD) was established with the charge of investigating the use of silver behenate, CH3(CH2)20COO·Ag, as a possible low-angle calibration standard for powder diffraction applications. Utilizing several data collection and analysis techniques, long-period spacing (d001) values with a range of 58.219–58.480 Å were obtained. Using the same collected data and one data analysis refinement calculation method resulted in dm values with a range of 58.303–58.425 Å. Data collected using a silicon internal standard and the same singular data analysis calculation method provided d001 values with a range of 58.363–58.381 Å.