The calculated XRD profiles of alite (impure Ca3SiO5, the major phase in Portland cement) derived from seven postulated crystal structures for alite were compared with a measured alite profile, extracted from the XRD pattern of a standard Portland cement. Only two of these profiles were found suitable for multiphase Rietveld phase quantification, namely those given by the monoclinic superlattice and triclinic models. These, however, gave very slow computing times because the large low-symmetry structures generated many X-ray reflections over the pattern. Also tested was an “observed” standard profile for alite, derived from experimental alite profiles, and generated using the (hkl) file feature of the SIROQUANT P.C. quantitative analysis system. This file was based on rhombohedral pseudosymmetry and contained very few (hkl) reflections, compared to the low-symmetry models (64 reflections instead of 951 for the monoclinic and 1691 for the triclinic models, respectively). The latter standard profile gave the best fit to the known phase concentrations and gave computing times which were shorter by factors of 2.5 and 4.9 than those for the monoclinic and triclinic standard profiles, respectively.

Five structurally related compounds, TlMgAsO4, TlMgPO4, TlZnAsO4, TlZnPO4, TlZnVO4, have been synthesized by solid-state reaction. Single crystals have been grown by various methods. Space group and unit-cell parameters were determined. Powder diffraction data for each phase are reported.

Complete sets of correction factors for absorption and air scattering effects in X-ray powder diffraction are reported. Both symmetrical reflection and transmission techniques are considered and boundary conditions to be tested for any given value of scattering angles are listed. This may prove particularly useful on coding computer programs for correction of raw intensity data files. Effects of interstitial volume on correction for absorption and subtraction of air scattering were investigated. For samples of high interstitial volume, like loosely packed powders or aerogels, the contribution from air trapped inside the specimen is significant and leads to expressions of the air scattering correction factors different from those commonly reported in the literature.

Eight phosphates and arsenates of manganese have been synthesized and examined using powder X-ray diffraction in order to update or extend the current powder diffraction data files. The studied compounds are MnPO4·H2O, MnAsO4·H2O, LiMnPO4(OH) LiMnAsO4(OH), LiMnAsO4, Mn2As2O7) MnAsO4, and Mn(PO3)3. The powder patterns have been indexed and the cell data are reported.

An Excel command macro has been developed which directly transforms X-ray powder diffraction data to a spreadsheet format. This spreadsheet format offers a number of data reduction and plotting capabilities not available in a diffractometer's software. The conventional approach uses computer programs to transform the data outside a spreadsheet. The development of these programs is not a simple process, and requires the user to be familiar with computer programming and the software of a diffractometer. Furthermore, these programs are diffractometer-specific. A different approach is followed in which an Excel macro transforms the data within a spreadsheet. This macro, with minor modifications, can be applied generally to treat data from any diffractometer. A copy of the macro and an example illustrating its working principle are included.

Precise X-ray powder diffraction patterns for the tetragonal form of Li3B5O8(OH)2 were obtained using a Huber camera; photographs were taken at 22 °C with CuKα1 radiation (λ =1.5406 Å) and with Si as internal standard (a = 5.4308 Å). Refinements of indexed reflections yielded the following parameters: a = 6.8455(4)Å, c = 14.551(1)Å, space group P41212, Z = 4, Dx = 2.31, and Dm = 2.28 g/cm3. The Smith–Snyder figure of merit of F30 = 97(O.OO7,45) compares to that of F30 = 2.6(0.206,57) reported for the existing pattern in the Powder Diffraction File (34-1070).

Crystal data and results of structure refinements for ScPO4 are reported. The material is tetragonal, I41/amd, with a = 6.5787(2) Å, c = 5.7963(2) Å, Vd = 250.86(2) Å3, Z = 4, Dx = 3.704 Mg/m3. Intensity data were obtained from a Stoe transmission type diffractometer equipped with a position sensitive detector. CuKα1 radiation, λ = 1.5405981 Å was employed. Silicon, SRM 640b (a = 5.43094 Å) was used as an internal standard. The structure was refined by the Rietveld method by aid of three different programs.

A FORTRAN 77 program to perform full matrix least-squares refinement of unit cell parameters from powder diffraction patterns showing incommensurate supercell reflections is described. The code is completely general, being applicable to any crystal system, and can refine all three unit cell edges and angles and, in the presence of an incommensurate supercell, can refine the components of the modulation vector along all three reciprocal axes. Estimated standard deviations on all the refined parameters are calculated analytically.

The lattice parameters of triammonium citrate, (NH4)3C6H5O7, were determined by X-ray single crystal and powder diffraction methods. The crystal structure is orthorhombic with a = 6.187 ± 0.001 Å, b = 14.803 ± 0.004 Å, and c = 10.826 ± 0.003 Å, and from the systematic absences, the space group is Pcc2 ().

Indexed X-ray powder diffraction data are reported for two organic salts with carbon rings having two quaternary nitrogens: diazonia-6,9 dispiro [5.2.5.2] hexadecane and diazonia-6,9 dispiro [5.2.5.3] heptadecane diiodides. For these compounds, which give solid electrolytes when associated with AgI, powder diffraction diagrams calculated by the Rietveld method from single crystal structure determinations are presented and are compared to the experimental diffraction data.

With a new emphasis on the control of polymorphism in pharmaceutical production, the need for methods to quantify polymorphic forms has arisen. Techniques using X-ray powder diffraction are increasingly being used to characterize the phases of drug substances that exist in multiple crystal forms. Current methods to identify the polymorphic phases in a drug substance include microscopy, infrared spectroscopy, thermal analysis (DSC/TGA), solid state NMR, and X-ray powder diffraction. Of the aforementioned techniques, X-ray powder diffraction provides the most effective approach to identify and quantify the different crystal phases of a pharmaceutical compound. This work is intended as a guide to the characterization and quantification of an organic crystalline system using X-ray diffraction. The approaches suggested are intended to provide assistance not only from an in-process pharmaceutical manufacturing standpoint, but also for routine quality assurance screening of polymorphic drug substances.

An Sb3Nb3O13 [Sb(III)2Sb(v)Nb(v)3O13] phase having a defect pyrochlore structure has been prepared by heating a sol–gel derived powder in oxygen. X-ray powder diffraction results indicate that Sb3Nb3O13 has a face-centered cubic structure, S.G. Fd3m(227), with a refined unit cell parameter a =10.4965(1) Å, calculated density Dx=4.893, four molecules per unit cell (Z), and a calculated figure of merit SS/FOM F30=92.4(0.009,38).

Substituting cations in materials with the formula Pb2B′B″O6 is more or less ordered on the B sites. High-quality single crystals of Pb2ScTaO6 (PST) and Pb(Sc0.5Nb0.5)O3 (PSN) were prepared from two thermal cycles. A stoichiometric mixture of the constituent oxides was prefired at up to 1000 °C, and then crystals were grown from a PbO–B2O3–PbF2 flux mixture, starting at a temperature of 1100 °C for PSN and 1200 °C for PST. At room temperature, X-ray examination showed that PSN had a perovskite structure with a cubic unit-cell and a refined parameter a = 4.080(1 ) Å, space group Pm3m and Z = 1, whereas PST formed a well-ordered superlattice with a = 8.136(1) Å, Z = 4 and space group Fm3m. In each case a fully indexed powder pattern is presented. The degree of order is estimated to be close to 80% for PST and less than 10% for PSN.

Indexed experimental powder diffraction patterns of Tl,Pb-1223 and Tl-1223 are presented with a method of determining good cell parameters for the former awkward case where c/a almost exactly equals 4. For Tl,Pb-1223, a = 3.814±0.001 Å, c = 15.267±0.005 Å, for Tl-1223, a = 3.814±0.001 Å, c = 15.302±0.005 Å, both tetragonal, space group P4/mmm.