The crystalline structure of the M2CuWO6 phases with M = Ba or Sr was obtained from X-ray powder diffraction at room temperature with CuKα radiation. The phases are isostructural with tetragonal unit cells, space group I4/m and Z = 2. The parameters for the Sr2CuWO6 phase are: Mr = 518.6, a = 5.42693(5) Å, c = 8.4087(1) Å, V = 247.65(1) Å3, Dx = 6.954 Mg/m3, μ = 77.75 mm−1, F(000) = 454, R = 0.0375 for 24 reflections; the parameters for the Ba2CuWO6 phase are: Mr = 618.1, a = 5.56392(8) Å, c = 8.6274(1) Å, V = 267.08(1) Å3, Dx = 7.683 Mg/m3, μ = 157.0 mm−1, F(000) = 526, R = 0.0506 for 27 reflections. Cell parameters were obtained from Rietveld refinement. The crystalline structure is based on the perovskite structure. It is laminar with ordered alternating WO6 deformed octahedra and CuO2 planar squares along the [110] direction, joined by corners and rotated perpendicular to the [001] direction. The samples are electrica insulators.

Estimation of reference intensity ratios (ki or RIR) can be made on the basis of an atomic scattering function. Tests of regression equations for 50 compounds that predict an approximate reference intensity ratio from the easily computed scattering function have shown usefulness in multicomponent semiquantitative X-ray diffraction analysis. The method is best applied whenever only one or two minor components of a multicomponent sample have no readily measurable or calculable ki values and must be estimated. Where the difference between observed and predicted constants is large, these tests show that the ratios of true- to test-weight fractions are proportional to the corresponding ki ratios. The largest absolute errors occur whenever the ki must be predicted for components with medium weight fraction values. Estimation of ki for components of less than 10 weight percent results in only small errors in both predicted component and the other components of the sample. Where more than two components require predicted ki in a given sample, unacceptable errors for all components may result.

Line profiles of a powder diffraction pattern and the aberrations which affect the centroid and the variances of the peaks have been analyzed using the visualization in scientific computing (ViSC) systems. The constrained optimization of those aberrations has been derived from the theory developed by Wilson (1963). It allows the determination of systematic instrumental effects and gives indication of other diffraction effects related to the samples. The CuKβ radiation was used to process the experimental data directly as it is comprised of only one single wavelength.

Bafertisite, Ba(Fe, Mn)2Ti(Si2O7)O(OH, Cl)2, has been reported as belonging to three space groups, i.e., Pmmn, P21/m, and Cm. The samples of bafertisite from the original locality Bayan Obo, Inner Mongolia, and from Jiangsu Province, China, were reinvestigated by X-ray methods. On the basis of single-crystal photographs, Pmmn could be ruled out and the relationship between a subcell in P21/m and the true cell in Cm deduced. The transformation matrix from the subcell to the true cell is 002/02¯0/101¯. Using the X-ray powder data, the refined true unit cell parameters in space group Cm are: a=10.612(3), b=13.637(7), c=12.464(2) Å, β=119.49(2)° for Bayan Obo sample, and a=10.633(6), b=13.67(1), c=12.465(5) Å, β=119.55(4)° for the Jiangsu sample. The 00l-reflections, which are rather prominent due to preferred orientation, can only be explained by our new unit cell.

Ba0.5+x/2Zr2P3−xSixO12 or BaZPS compounds were synthesized by the sintering of powders formed by a solid-state reaction. The cell parameters of Ba0.5Zr2P3O12 and Ba0.5875Zr2P2.825Si0.175O12 were determined from X-ray diffraction (XRD) data based on the (#148) space group with hexagonal setting. The cell parameters were found to increase with increasing Si content in BaZPS.

As part of a study by high-resolution X-ray diffraction of chrome ores from the Great Dyke, Zimbabwe, powder data are reported for a well-crystallized ferroan magnesiochromite spinel, in which some Cr had been replaced by Al. Data were obtained by using CuKα1 radiation, with an incident beam focusing monochromator to eliminate the Kα2 component. The cell parameter is a0=8.3123(2) Å, the figures of merit are M17=383 and F17=182 (0.0055, 17) and the calculated density is 4.50(5) Mgm−3. A small amount of sample broadening was observed and this was attributed to a mean crystallite size of 259(1) nm. © 1997 International Center for Diffraction Data.

An iterative external standard method of X-ray diffraction is presented to overcome the difficulties of preferred orientation and peak overlap encountered in quantitative phase analysis. Instead of using only a single line intensity in the traditional external standard technique, all the reflection data are used in the calculation. The accuracy and applicability of this method was tested on a series of two-phase powder mixtures with known composition. The results show markedly good agreement with the actual values. As an example, the analysis was applied to the data collected from an as plated electrodeposited Zn-Fe coating. The determined phase composition of the coating was found to be 88.2 +/− 5.3 wt % δ-phase and 11.8 +/− 0.7 wt % η -phase.

X-ray powder data and crystal data for acetaminophen, C8H9NO2, are reported and results are compared to existing PDF patterns.

Based on the crystal structure determination of orthorhombic Ba2CuF6 (space group Cmca), the previous X-ray powder patterns given for Ba2CuF6 (PDF 21-809) and Pb2CuF6 (PDF 22-654) are reindexed.

Yttrium aluminium garnet, Y3A15O12– YAG, has a powder diffraction pattern that is easy to analyse in principle, but shows very interesting problems. These problems are revealed using an interactive graphics system, UNIRAS, intregated with some of the usual procedures for crystallographic data processing. For example, indexing with the APPLEMAN procedure is improved when the high-angle peaks are properly identified, and the cell parameters then refine to a high precision. Iterations between refinements and graphical analysis allows the operator to identify even some of the very weak peaks in the pattern. Using the peak positions from the refinement, the experimental data can be analyzed for instrumental aberrations and corrections can be applied to improve the accuracy of the cell parameter.

The new diffraction patterns of the low- and high-temperature phases of Li0.87Hf2.032(PO4)3 and LiSn2(PO4)3 are given and indexed on the basis of a structure refinement from neutron powder data using Rietveld method. The two isotypic compounds present a reversible phase transition: triclinic (LT, space group P1¯) ⇄ rhombohedral (HT, space group R3¯c) which proceeds by topotactic distortion of the structural skeleton.

The temperature variation of the interplanar spacings (101), (112), and (211) of 325 mesh quartz was determined in the range 300–966 °K using X-ray powder diffractometry. The measured lattice parameters have been found to increase nonlinearly with temperature, and the dependence has been expressed by a polynomial of second degree from the least-squares fitting of the data, the results of which are presented herein. Values are given for the thermal expansion coefficients and Gruneisen parameter in the range 300 to 768 °K. In the range 768–966 °K, the expansion is zero. The derivatives dαa/dT, dαc/dT, and dαv/dT at ambient temperature are also given.

The superconductor related phases Ba3R3Cu6O14+x(or Ba2−zR1+zCu3O7+x, with z=0.5), where R = Pr, Nd, Sm, and Eu, have been prepared and characterized by X-ray powder diffraction, ac magnetic susceptibility measurement, resistivity measurement and thermogravimetric analysis (TGA). Attempts to make corresponding compounds with R = Gd, Dy, Y, Er, and Lu were not successful; they do not appear to form for rare-earth elements, R, with an ionic size smaller than Eu. The oxygen content of the successful materials was estimated by TGA. The Ba3R3Cu6Cu14+xcompounds which were sintered at 950°C and annealed in oxygen at 550°C were found to be nonsuperconducting above 10K. Previously reported results for the R=La compound have indicated that it was superconducting with a transition temperature of 15K The oxidation-reduction behavior of the Ba3R3Cu6O14+xmaterials is similar to that of the superconductor phases Ba2RCu3O6+x.

These present isostructural compounds are tetragonal with a space group of P4/mmm. The cell parameters range from a = 3.8612(4), c = 11.5624(14) Å, V = 172.38(4) Å3in the Eu compound to a = 3.8893(3), c = 11.6370(11) Å, and V = 176.03(3) Å3in the Pr compound. The standard X-ray diffraction patterns of these materials are given.