The compound DyNiSn has been studied by X-ray powder diffraction. The X-ray diffraction patterns for this compound at room temperature are reported. DyNiSn is orthorhombic with lattice parameters a=7.1018(1) Å, b=7.6599(2) Å, c=4.4461(2) Å, space group Pna21 and 4 formula units of DyNiSn in unit cell. The Smith and Snyder Figure-of-Merit F30 for this powder pattern is 26.7(0.0178,63).

An improved backloading method to determine the reference intensity ratios of sedimentary minerals is presented. More than 50 reference intensity ratios of more than ten types of minerals formed in typical sedimentary environments were measured. Quantitative tests were performed on those minerals. Comparison of the results show that this method minimizes preferred orientation and improves quantitative precision (absolute deviation is less than 3%) so that it is an acceptable specimen loading method.

An increasingly frequent used sample holder, the zero-background holder (ZBH), is evaluated for use in external standard calibration of powder patterns. The effectiveness of the ZBH calibration method is determined by comparison to the conventional internal- and external-standard calibration techniques. The three calibration methods are compared using the results of lattice parameter refinements of test powders, using Si as the standard. Several test materials were used in the evaluation which cover a wide range of absorption coefficients so sample transparency effects can be distinguished from sample displacement effects. Results of the calibrations clearly indicate that the ZBH method gives precision and accuracy comparable to the internal-standard method, and significantly better than the external-standard technique. In addition, the ZBH method yields substantially better results than the internal-standard method for materials with low absorption coefficients. Low-angle calibrations are also made on a ZBH using a proposed standard, silver behenate, which has peaks from 1.5° to 20° 2θ. These calibrations have shown that if care is not taken to establish a monolayer of powder on the ZBH crystal, significant errors in refined lattice parameters will result.

X-ray powder diffraction and optical data are presented for alkali-deficient schorls from two tourmaline-dumortierite deposits. The compositions of both schorls reflect the presence of an alkali-defect substitution, whereby the alkali cation deficiencies in the crystal structure are charge balanced by trivalent for divalent cation substitutions in the octahedral sites. Refined unit cell and optical data are as follows: a = 15.9523(15), c = 7.1466(2) Å, F30 = 104(0.009, 32), M20= 68, ε = 1.638(2), ω = 1.660(2), Dx= 3.12 for the schorl from Jack Creek, near Basin, Montana, U.S.A. and a = 15.9800 (15), c = 7.1504(2) Å, F30= 156(0.006, 32), M20= 152, ε = 1.642(2), ω = 1.668(2), Dx= 3.17 for the schorl from Ben Lomond, Hervey Range, North Queensland, Australia. Indexed X-ray powder diffraction patterns are also presented.

The systems PbO–Bi2O3–P2O5/As2O5/V2O5 have been studied with respect to their compounds and solid solutions. A number of new compounds, particularly with high-Bi contents were found. Most of them are structurally closely related to the CaF2 and δ-Bi2O3 structures. Several binary and ternary solid solutions with P/As/V substitutions were investigated.

The structure of the oxyphosphate Ni0.50TiO(PO4) has been determined ab initio from conventional X-ray powder diffraction data by the “heavy atom” method. The cell is monoclinic (space group P21/c, Z=4) with a=7.3830(5) Å, b=7.3226(5) Å, c=7.3444(5) Å, and β=120.233(6)°. Refinement of 46 parameters by the Rietveld method, using 645 reflexions, leads to cRwp=0.152, cRp=0.120, and RB=0.043. The structure of Ni0.50TiO(PO4) can be described as a TiOPO4 framework constituted by chains of tilted corner-sharing TiO6 octahedra running parallel to the c axis, crosslinked by phosphate tetrahedra and in which one-half of octahedral cavities created are occupied by Ni atoms. Ti atoms are displaced from the center of octahedra units in alternating long (2.231) and short (1.703 Å) Ti–O bonds along chains.

Error quantities, defined earlier to estimate the accuracy of texture measurement, are used to define a probability criterion for correct indexing of powder diffraction diagrams. The criterion is based on the compatibility of pole density distribution functions of different (hkl) depending on the directions {θ,γ}(hkl) of the reciprocal lattice vectors r*(hkl). The criterion was applied to permutation of the indices and variation of the angles {θ,γ}(hkl) in the vicinity of the correct values. In fortunate case, these angles can be determined within a few degrees by minimizing the error quantities. The method works very well with strong textures but it is still applicable if only weak textures can be achieved. The method was tested with different crystal symmetries including cubic, hexagonal, orthorhombic, and monoclinic. It is concluded that the criterion can be successfully applied to all crystal symmetries. If a measuring technique based on a position sensitive detector is used, even multifold peak superpositions in tilted sample orientations can be resolved. The method can also be applied if some (hkl) cannot be separated experimentally.

X-ray powder diffraction data for the compound 2-nitro-l-phenyl-prop-l-ene, C9H9NO2 are reported. The crystals are orthorhombic and the space group is Pbca[61], with a = 7.576(2), b = 19.452(5), c = 11.269(4)Å, Z = 8 Dx = 1.305, Dm = 1.300(2) g/cm3.