X-ray powder diffraction data for the spinels CoAl2O4 and CoGa2O4 were measured with synchrotron radiation using λ = 1.2033 Å, determined with Si as a standard (a = 5.4305 Å). The two blue compounds prepared hydrothermally are cubic with space group Fd3m. Profile refinements gave the results: CoAl2O4 had a = 8.0968(1) Å and composition (Co0.71Al0.29]Al1.71Co0.29]O4 and CoGa2O4 had a = 8.3229(1) Å and composition Ga[CoGa]O4. The degree of inversion is thus 0.29 for CoAl2O4 and one for CoGa2O4.

Powder X-ray diffraction data are reported for La0.6Sr0.4Co1−yFeyO3 (y=0.1, 0.25, 0.4, 0.6, 0.8, 1.0). The powders were prepared by thermal decomposition of metal-containing complex solutions. All compositions have rhombohedral unit cells. In hexagonal setting, the cell parameters are a=5.4388 Å, c=13.2355 Å for y=0.1; a=5.4427 Å, c=13.2542 Å for y=0.25; a=5.4530 Å, c=13.2838 Å for y=0.4; a=5.4769 Å, c=13.3175 Å for y=0.6; a=5.5057 Å, c=13.3918 Å for y=0.8; and a=5.5278 Å, c=13.4368 Å for y=1.0. The space group is probably R3c (167) for all compositions. The observed trends in the change of the pseudocubic cell parameter ac with increasing iron content can be explained in terms of substitution of Co4+ by Fe4+ when y<0.4, and substitution of Co3+ by Fe3+ when y≳0.4.

An indexed powder diffraction pattern and related crystallographic data are reported for secnidazole [C7H11N3O3, IUPAC name: 1-(2-hydroxypropyl)-2-methyl-5-nitroimidazole], which is not represented in the Powder Diffraction File. The unit cell dimensions were determined from diffractometer methods, using monochromatic CuKα1 radiation, and evaluated by indexing programs. The monoclinic cell found for 1-(2-hydroxypropyl)-2-methyl-5-nitroimidazole is: a=12.426(2) Å, b=12.173(2) Å, c=6.656(1) Å, β=100.19(1)°, Z=4, space group P21/c (No. 14), Dx=1.271 g/cm3. Crystallization of an anhydrous powdered sample of secnidazole in a buffer solution of Na2B4O7 and NaOH (pH 10.4) resulted in crystals that contained water of crystallization, as shown by single crystal structure determination. Secnidazole exhibits crystal pseudopolymorphism, because the experimental powder pattern of the anhydrous form and the calculated pattern from the structure determination of the hydrate form are similar. Observed powder diffraction data for this drug were interpreted with the aid of a calculated pattern based upon the crystal structure determined. The cell found by TREOR90P for anhydrous secnidazole is in good agreement with that of the hemihydrate form determined from single crystal diffraction: a=12.424(2) Å, b=12.187(2) Å, c=6.662(1) Å, β=100.9(1)°; Z=4.

A new, convenient program has been designed and implemented on a VAX computer to facilitate the use of the Johnson/Vand program (Version 21) for identifying components in crystalline mixtures by X-ray diffraction. (The data base of references is distributed solely by the JCPDS – International Centre for Diffraction Data.) This new program uses an easy-to-follow conversational mode of communication for setting up the input file for the identification program from a remote terminal. The program is menu driven with screens for input of sample information, for change of default computational parameters, and for handling the experimental diffraction data. Many of the input screens can be readily bypassed when the default parameters are acceptable. An editor feature is provided for viewing the final input file and for correcting the diffraction data.

This paper contains a review and explanation of the super conducting Ruddlesden-Popper phases in the systems Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O. Calculated powder X-ray patterns for the phases Bi-2201, 2212, 2223, and 2234 (where the numbers refer to the stoichiometric ratios of Bi:Sr:Ca:Cu) and Tl-1201, 1212, 1223, 1234, 2201, 2212, 2223, and 2234 (here the numbers refer to the molar ratios of Bi:Ba:Ca:Cu) generated from the reviewed crystal structures are presented. Observed powder patterns for Tl-2201, Tl-2212, Bi-2201 and Bi-2212 are included and compared to the calculated patterns of these phases.

Precise X-ray powder diffraction patterns of two isostructural triborates, CsB3O5(CBO) and TlB3O5(TBO), have been collected on a D5000 diffractometer with a primary monochromated beam (λ CuKα1=1.5406 Å). Refinement of indexed reflections in the space group P212121 led to: a=6.201(1) Å, b=8.514(2) Å, c=9.176(2) Å, Z=4, Dx=3.363 for CBO and a=5.2156(4) Å, b=8.2659(6) Å, c=10.2240(9) Å, Z=4, Dx=4.773 for TBO. The Smith–Snyder figures of merit are F30=53.0 (0.0101, 56) for CBO and F30=112.9 (0.0074, 36) for TBO. These values are much better than the previous ones published in Powder Diffraction File.

Two compounds of the elpasolite family (A2BLnX6), Cs2KTbCl6 and Cs2KEuCl6, were obtained {by evaporating to dryness a hot aqueous HCl solution of the appropriate chlorides [Morss etal., Inorg. Chem. 9, 1771 (1970)]} and characterized by powder X-ray diffraction. Title compounds are isostructural with cubic Rb2NaTmCl6 and correspond to the perovskite related structure with space group Fm3m, cell parameters 11.1294(6) and 11.1618(4) Å, V=1378.5(2), and V=1390.5(1) Å3, respectively.

We report precision X-ray powder-diffraction (XRD) data of single phase pure Ti2ZrAl. Ti2ZrAl samples were prepared by an arc melting method and annealed at 1000 °C for 30 days. XRD analysis was carried out on these samples and it was found that Ti2ZrAl has a DO19 structure (space group P63/mmc, No. 194). The lattice parameters are found to be a=5.961±0.001 Å and c=4.793±0.001 Å.

The powder diffraction pattern of the perovskite AgNbO3 has been measured using CuKα1 radiation with an incident beam focusing monochromator to eliminate the Kα2 component. Indexing the pattern shows that the multipartite cell is 2×2×4 times that of the pseudocubic subcell. Comparison is made with the diffraction pattern of NaNbO3, which has a similar multipartite unit cell. There are strong similarities, but close inspection shows that the structures are not isomorphous. The paper concludes with a discussion of the figure of merit FN for pseudosymmetric structures. It is suggested that two figures of merit be reported. The first should be the standard one using either all measured reflections or just the first 30. The proposed second figure of merit does not include any superlattice reflections. These superlattice reflections tend to be very weak, resulting in a low completeness factor and relatively large error in the measurement of their position. This effect produces an unrealistically low value of the standard figure of merit. By including only “main” reflections, i.e., those reflections that are common to both the low-symmetry and high-symmetry parent phase (if it exists), a much better estimate of the quality of the fitting of the measured diffraction pattern is obtained.

Recipes are given to assist in setting up rigid bodies for common molecules and coordination polyhedra, to define satellite groups, to perform rotations around arbitrary axes through the origin of the rigid body, and to refine intramolecular degrees of freedom under consideration of the special needs of powder diffraction. To the greatest possible extent, the notation follows that of the well known Rietveld refinement program GSAS (Larson and Von Dreele, 1994).

The variables of reflection overlap, crystallinity and crystallite size, primary extinction, microabsorption, chemical substitutions, preferred orientation, and analytical procedures affect quantitative analysis by powder X-ray diffraction. The intensity of the strongest reflection (I) of 39 minerals from a typical sedimentary environment divided by the intensity of the strongest reflection (Ic) of corundum, I/Ic, may be used to determine mineral percentages. Because of the numerous variables mentioned above, the I/Ic ratios used should be taken from multi-mineral specimens that occur either in the same geological formation for quantitative analysis (±7%) or in a similar geological formation for quantitative analysis (±30%).

An X-ray powder diffraction quantitative analysis has been developed to determine the relative amounts of the principal crystalline phases (α-Li2SiO3, α-Li2Si2O5 and the α-cristobalite form of SiO2) contained in selected Li2O–SiO2 glass-ceramics. The analysis was extended to estimate the amorphous-to-crystalline content ratio of individual samples. The method utilized is an external-standard intensity ratio technique that employs cristobalite, a component common to each sample, for a standard.

In the framework of the study of the relationship between crystal packing of solid dyes and their visible reflectance spectra, the crystal structure of 3-methoxy-7H-benz[de]anthracen-7-one (Disperse Yellow 13, C18H12O2) has been determined using a combined set of Bragg–Brentano diffractometer and Guinier–Johannson photographic data with the grid search procedure. Parameters of the orthorhombic cell (P212121, No.19, Z=4) at 295 K are a=15.265(9) Å, b=20.524(9) Å, c=3.990(2) Å. Rietveld refinement gave Rp=0.085, Rb=0.135. The molecules form stacks along [001] with an interplanar spacing of 3.46 Å.