A polycrystalline single-phase sample with nominal composition Bi24PbO37 was synthesized from Bi2O3 and PbO by a high-temperature solid state reaction at 690 °C for 1.5 h. The compound adopts Bi12SiO20-type structure [cubic, space group I23 (No. 197); a = 10.24957(3) Å] and was refined to Rp = 7.96%, Rwp = 10.4%, Rexp = 8.43%, RB = 3.06%, and S = 1.23. The distributions of Pb2+ and Bi3+ over cationic sites based on the X-ray powder diffraction data were determined using a combination of the Rietveld refinement and bond valence calculations. The results showed that the asymmetric unit contains two mixed cation sites: the fully occupied 24f site and the partly occupied 8c site, with the unit-cell content (Bi23.68Pb0.32)(Bi1.28Pb0.72)O38.48. The structural constraints favor a preference of Pb2+ ion for the 8c site, i.e. only 1.3% of Bi3+ is substituted by Pb2+ at the 24f site and 36% at the 8c site. At the 24f site, the cations are surrounded by 5 + 2 or in a very small amount by 5 + 1 + 2 oxide ions, forming a base bicapped square pyramid or a bicapped highly deformed octahedron, respectively. At the 8c site, the cations with three oxide ions form a trigonal pyramid with the cations at the apex.

A new hydrate of magnesium chromate is synthesized by quenching aqueous solutions of MgCrO4 in liquid nitrogen. MgCrO4·11H2O is isostructural with the rare mineral meridianiite (MgSO4·11H2O) being triclinic, , Z = 2, with unit-cell parameters a = 6.811 33(8) Å, b = 6.958 39(9) Å, c = 17.3850(2) Å, α = 87.920(1)°, β = 89.480(1)°, γ = 62.772(1)°, and V = 732.17(1) Å3 at −15 °C. The difference in unit-cell parameters between SO4- and CrO4-bearing species is only partially accounted for by the difference in S–O and Cr–O bond lengths; the remainder of the difference (over 90% in the cell volume) is attributed to weakening of the interpolyhedral hydrogen-bond network.

Crystalline silica is known for its health hazards, and since 1997 has been listed as Group 1, Carcinogenic to Humans, by the International Agency for Research on Cancer. This issue is particularly important in the industrial environment, and there is still no method that allows quantification of the different polymorphs of crystalline silica. Many analytical methods have been proposed, and the major problem in almost all cases is attributable to the very large variety of matrixes encountered. This study evaluates the potential of X-ray diffraction techniques and an automated Rietveld analysis in order to overcome this problem and to adapt the quantitative analysis of quartz, the most prevalent crystalline silica polymorph, to routine analysis in the health and safety environment. Matrix simulations are done and many parameters are optimized. Sample preparation, the acquisition program, pattern treatment, and Rietveld refinement are evaluated, and a general procedure is determined. Automation of Rietveld refinement leads to a significant reduction in analysis time, but cannot be applied to every type of sample.

An experimental X-ray powder diffraction pattern was produced and analyzed for imipenem monohydrate, an antimicrobial pharmaceutical agent. Although there are no experimental powder patterns in the ICDD PDF-4/Organics Database, there is one powder pattern calculated with single-crystal X-ray diffraction data from the Cambridge Structural Database. Here, we report the refined experimental powder diffraction data for imipenem monohydrate. These data for imipenem monohydrate are consistent with an orthorhombic crystal system having reduced unit-cell parameters of a = 8.2534(3) Å, b = 11.1293(4) Å, and c = 15.4609(6) Å. The resulting unit-cell volume, 1420.15(15) Å3, indicates four formula units per unit cell. Observed peaks are consistent with the P212121 space group.

The crystal structure of type I clathrate Ba8Ni4Ge42 has been determined using neutron powder diffraction, transmission electron microscopy (TEM, for possible superlattice), and extended X-ray absorption fine structure (EXAFS) measurements. Ba8Ni4Ge42 is cubic with the space group Pmn and unit-cell parameter a = 10.6769(2) Å (Dx = 5.988 g cm−3). The structure combines two different types of polyhedra: the dodecahedron (Ge20, 20-atom cage with 12 pentagonal faces) and the tetrakaidecahedron (Ge24, 24-atom cage with 12 pentagonal and 2 hexagonal faces). Each unit cell contains two Ge20 dodecahedra and six Ge24 tetrakaidecahedra. The Ge20 dodecahedra are linked via the interstitial 6c positions. The framework structure is formed by a tetrahedrally bounded network of Ge atoms, whereas Ba atoms reside inside the Ge20 and Ge24 cavities at the 2a and 6d crystallographic positions, respectively. Ni atoms exclusively occupy the 6c positions located on the hexagonal faces of the larger tetrakaidecahedra; no Ni atoms are found in the smaller dodecahedra that consist of pentagonal faces. A local structure study using EXAFS supports the coexistence of Ge and Ni on the 6c site. Electron diffraction in TEM reveals no detectable Ge/Ni ordering.

Methods of chemical preparation and XRD data are reported for four cyclotriphosphates associated with barium alone and with ammonium and thallium. These phosphates are Ba3(P3O9)2·4H2O, BaNH4P3O9·2H2O, BaTlP3O9·2H2O, and BaTlP3O9·Ba3(P3O9)2·4H2O was prepared by the direct method of chlorures, BaNH4P3O9·2H2O and BaTlP3O9·2H2O by the method of ion-exchange resin, and BaTlP3O9 by total dehydration of BaTlP3O9·2H2O. Ba3(P3O9)2·4H2O is monoclinic, space group P21/n, Z = 4, with a = 7.546(3), b = 12.105(4), c = 11.649(4) Å, β = 100.340(3)°, V = 1046.8(2) Å3, M(20) = 81, and F(20) = 117(0.003 419, 50). BaNH4P3O9·2H2O is monoclinic, space group P21/n, Z = 4, with a = 7.547(1), b = 12.065(1), c = 11.697(1) Å, β = 101.111(1)°, V = 1045.1(3) Å3, M(20) = 9 (AV.EPS = 0.000 116 9), and F(20) = 14(0.0287 06, 53). BaTlP3O9·2H2O is monoclinic, space group P21/n, Z = 4, with a = 7.546(3), b = 12.105(4), c = 11.649(4) Å, β = 100.340(3)°, V = 1046.8(2) Å3, M(20) = 81, and F(20) = 117(0.003 419, 50). BaNH4P3O9·2H2O and BaTlP3O9·2H2O are isostructural. BaTlP3O9 is orthorhombic, space group P212121, Z = 4, with a = 11.086(2), b = 12.283(2), c = 5.786(1) Å, V = 787.9(4) Å3, M(20) = 10 (AV.EPS = 0.000 116 9), and F(20) = 14(0.026 955, 56).

The International Centre for Diffraction Data has a colorful history, starting as a small task group of involved and interested scientists and progressing through a number of evolutionary steps that were required to deliver scientific products and services globally. The results of these efforts can be found in numerous scientific publications that focus on basic physics, method development, and analyses of the material identification of solid-state materials. This article examines the evolution of the organization through its members and employees.