The crystal structure of four cyanometallates has been determined from X-ray powder diffraction data using the Rietveld method. The variously hydrated compounds Cu3[Co(CN)6]2, Mn3[Co(CN)6]2 and KNi[Fe(CN)6] crystallize at cubic symmetry (Fm3m) with lattice parameters 10.032(2), 10.413(3) and 10.234(5) Å, respectively. The crystal of KMn[Fe(CN)6]·2H2O shows a monoclinic structure (P21/c) with the lattice parameters a=10.108(2) Å, b=10.104(3) Å, c=10.114(3) Å, β=92°, 93°. The starting model was based on an isomorphic Mn3[Co(CN)6]2 single crystal structure, where Co and Mn ions are octahedrally coordinated by C and N atoms, respectively, forming three-dimensional bimetallic networks with the C≡N groups as bridging ligands.

Improvements of standard X-ray powder diffractograms of two Y-type hexagonal ferrites (Ba2Co2Fe12O22, Ba2Zn2Fe12O22) are reported.

The title materials are stuffed cristobalites possessing moderate to extreme pseudosymmetry. On the bases of their X-ray powder diffraction patterns, the Mg, Zn, and Cd compounds had been previously reported as cubic and, more recently, the Zn phase as orthorhombic. Newly measured X-ray powder diffraction data demonstrate that all (including the hitherto unknown Co analog) have the Pca21 structure of Na2BeSiO4 at room temperature, but with a widely variable degree of cubic pseudosymmetry. Observed X-ray diffraction data are in good agreement with those calculated by the Rietveld method using a constrained model with Pca21 M2+/Si site occupancy and pseudocentrosymmetric Pcab atom locations. For the most nearly cubic phase, the Cd compound, there is too little deviation in the pattern from cubic symmetry to support atom coordinate refinement even with the constrained model. In these derivatives of the stuffed cristobalite structure family, M2+ and Si atoms form an ordered tetrahedral array which avoids M2+–O–M2+ connections. Potassium atoms fill all of the intervening large cavity sites.

A technique is described for the preparation of Guinier camera samples which are permanent and can be stored indefinitely in microslide file cases.

The Powder Diffraction File (PDF) X-ray diffraction pattern for SnO2 (cassiterite, syn), determined in the early 1950's at the National Bureau of Standards, was evaluated using the NBS*AIDS83 editorial review program and a calculated powder pattern. Systematic errors in d-spacings and relative intensities were attributed to the lack of an iterative least-squares refinement of unit cell parameters, to inadequate precision in reporting d-spacings, to poor sensitivity to high angle reflections, and to detector dead time. A new SnO2 pattern was prepared and used to illustrate criteria for evaluation of powder patterns. An R-Factor for quantifying agreement between observed and calculated relative intensities was utilized. The systematic errors in the earlier pattern occurred at higher angles and did not hinder its usefulness for identification purposes.

A systematic survey of phase formation in the Na2O-ZrO2-SiO2 system has revealed inconsistencies in the number and identity of ternary phases, and of their X-ray powder data. The phases Na2ZrSiO5, Na4Zr2Si3O12, Na2ZrSi2O7 and Na2ZrSi4O11 were prepared by solid-state reaction and their experimental X-ray diffraction patterns measured. Calculated X-ray diffraction patterns were generated by computer, using published crystallographic data, and critically compared with the experimentally observed values. The unit-cell constants were redefined to a greater accuracy than the presently accepted values published in the Powder Diffraction File. Only Na4Zr2Si3O12 produced an X-ray diffraction pattern which agreed with that previously published; those from the other phases were significantly different in both the intensities and positions of the reflections. Data for synthetic Na2ZrSi4O11 identical to the mineral vlasovite are reported.

A new compound [Mn(H2O)]0.25(VO)0.75PO4·2H2O was prepared by the reaction of V2O5 with the boiling aqueous solution of H3PO4 and KMnO4. The reaction product is a yellow-brown powder, stable in air. The tetragonal unit-cell parameters (298 K) are a = 6.2034(2)Å, c = 13.814(1)Å, V = 531.59Å3, Z = 4, Mr = 194.94, Dx = 2.493 g/cm3, Dexp = 2.52 g/cm3. X-ray (CoKα radiation) powder diffraction data (35 lines) are reported. The compound's structure is probably derived from the VOPO4·2H2O layered lattice by substitution of [Mn(H2O)]3+ ions for a quarter of the vanadyl groups VO3+. Practically the same powder data and unit-cell parameters were found for [Mn(H2O)]x(VO)1−xPO4·2H2O, where x ranges from 0.185 to 0.25.

A strategy for qualitative X-ray phase analysis of complex multiphase solids is illustrated through the analysis of eight fixed-bed gasification ashes. Coal from the same lignite formation was gasified in three different reactors. Despite the differences in gasifiers and their operating conditions, all of the ash specimens had the same basic crystalline phase assemblage: silicates and aluminosilicates (merwinite, dicalcium silicates, melilite, nepheline, carnegieite and a sodalite structure phase), oxides (ferrite spinels, hematite and periclase), calcite and residual lignite minerals (quartz, plagioclase). The identification strategy relied on a bulk chemical analysis of each ash and used manual methods with the JCPDS-ICDD search manuals for the Powder Diffraction File. Grain picking, size separations, magnetic enrichment, separation by hardness, dissolution of water soluble phases, and further crystallization of the ash through heat treatment all figured in the identification strategy. Identification of more than a dozen minor and trace phases resulted from these additional methods. Several trials with an automated search/match system demonstrated the difficulties of analyses of such complex phase assemblages. The need for SEM characterization of the ashes to accompany the XRD analyses is discussed.

The following article by L. L. Wyman is reprinted from Fifty Years of Progress in Metallurgical Techniques, ASTM STP 430, 1968, contains information on the early role of ASTM Committee E-4 in the publication of the early Powder Diffraction File data cards and in the formation of the Joint Committee on Powder Diffraction Standards. In fact, Roy Wyman was probably the single most instrumental individual in obtaining the sponsorship by ASTM for the continued publication of the PDF up to 1969 when JCPDS became an independent corporation. Roy was on the Board of Directors of JCPDS from the time of its incorporation until his death in 1976. He was Treasurer of JCPDS from 1971 to 1974 and Chairman from 1974 to 1975. Committee E-4 is still active and is the Committee within ASTM which maintains Cooperative Society status with the JCPDS-ICDD.

The titled compound, Hg2[Fe(CN)5NO], was synthesized and studied by X-ray powder diffraction, infrared spectroscopy, Mössbauer spectroscopy, and atomic force microscopy. The results arising from this study indicate that this compound is anhydrous and crystallizes in the P222 orthorhombic symmetry. The unit cell parameters were quantified as a=16.5905(9) Å, b=12.3145(8) Å, and c=8.7576(5) Å. The measured and calculated density values are Dm=1.149 g/cm3 and Dc=1.145 g/cm3, respectively, with Z=2.

The crystal structure of the two isostructural rare earth tungstates Ln6WO12 (Ln=Y, Ho) has been refined by the Rietveld method from X-ray powder diffraction data. They crystallize with a three-dimensional rhombohedral structure (S.G. R3¯ and Z=3 for the R-centered setting) closely related to that of the binary oxides Ln7O12 and deriving from the ideal fluorite structure. Final refinements, with isotropic thermal motion for each atom, resulted in profile and structure factors Rwp=0.166, RF=0.037 with Ln=Y and Rwp=0.121, RF=0.040 with Ln=Ho. The rare earth element is sevenfold coordinated with Ln–O bond lengths ranging from 2.19 to 2.70 Å for Y6WO12 and from 2.18 to 2.68 Å for Ho6WO12; the coordination polyhedron may be described as a monocapped trigonal prism. The tungsten atom is located at the center of a WO6 octahedron with a unique W–O distance of 1.98 and 1.92 Å for Y6WO12 and Ho6WO12, respectively.

The crystal structure of the rare earth (RE) compound CeFeGe3 has been studied by X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3-type structure, space group I4mm (No. 107) a=4.3294(1) Å, c=9.9444(3) Å, V=186.39 Å3, Z=2, and Dx=7.372 g·cm−3. The figure of merit FN for the powder data is F30=184.3(0.0037,44). The structure refinement was performed with 106 reflections and led to Rp=13.2% and Rwp=18.2%. Powder data are given.

By means of X-ray single crystal Weissenberg photographs, the crystal of the low-temperature solid form of 2-methyl-2-nitro-propanol, (CH3)2C(NO2)(CH2OH), has been determined and found to be of the monoclinic type, space group P21/c. The cell constants were refined from X-ray powder diffraction data: a=6.195(3) Å, b=19.116(7) Å, c=16.598(7) Å, and β = 90.12(2)° with Z = 12. The indexed pattern at 293 K is given.