The relative intensities ratios for the determination of the relative amounts of alpha and beta phases in silicon nitride and the relative amounts of delta yttrium disilicate (Y2Si2O7) and nitrogen apatite [Y5(SiO4)3N] are reported. These constants were determined using an iterative method applicable when the pure phases are not easily prepared. In addition, a calibration curve was obtained for the quantitative measurement of free silicon in silicon nitride over the range 0 to 0.3% by weight of Si.

Ba2NaNb5,O15 and eighteen additional compositions in the NaNbO3-BaNb2O6 system from 60 to 85 mole % BaNb2O6 have been prepared and studied by X-ray powder diffraction. A calculated pattern has been used to aid in indexing the powder pattern of stoichiometric Ba2NaNb5O15(BNN-S). The lattice parameters of BNN-S have been determined from repeated measurements of 2 higher order reflections and are a=b=17.5994(8)Å and c=7.9771(9)Å. A comparison with the Powder Diffraction File (PDF) 34-210 indicates that the present data provide a more precise match to the unit cell, include additional weak reflections and cover a greater 2θ range. There is a tungsten bronzetype solid solution range from 60 to 75 mole % BaNb2O6.

That very large famous and infamous borough of New York City, namesake of one of the country's most graceful bridges, Brooklyn, was perhaps the least likely of places for the development of a teaching center of international brilliance – and, at that, in the then little known field of X-ray diffraction. Such was the case, however. Where else, it has been asked, could a visiting lecturer on X-ray technique look out at his audience and, to his dismay, find in the front row, Paul P. Ewald, Herman Mark, Isidor Fankuchen and David Harker – respectively, a founding father of X-ray diffraction, a founding father of polymer chemistry, an entrepreneur par excellence in X-ray crystallography, and a major player in macromolecular (proteins) analysis. Only there at the Brooklyn Polytechnic Institute. It was unique in its time and function as the pre-eminent school of learning for the rapidly evolving practices of polymer science and X-ray diffraction.

The crystal structure of metastable Li2Si2O5, Fw = 150.05, has been refined by the Rietveld method using high resolution X-ray powder diffraction data recorded at the Daresbury Synchrotron Radiation Source on the new 8.3 diffractometer. Li2Si2O5, in keeping with many compounds of interest to the materials scientist, exhibits relatively broad diffraction peaks. It is important to establish the quality of crystal structure data that may be obtained from such materials on this new instrument. Various functions were used to model the peak shape from this instrument; a split-Pearson VII function appeared to be marginally superior to Pearson VII or Pseudo-Voigt functions. Refinement was carried out using the split-Pearson VII in the space group Pbcn (60) and terminated with a = 5.6871(6), b = 4.7846(5), c = 14.645(1) Å, V = 398.50 Å3, Z=4, Dc= 2.502 gcm−3, Rwp = 17.06, Rex = 14.48 and Χ2 = 1.39. The refined parameters are compared with those obtained from a previous single crystal X-ray determination.

A program has been written for rapid lattice parameter refinement which is designed to be applied to components in a mixture. This FORTRAN program employs a linear least-squares technique and is applicable to crystal systems with symmetry orthorhombic or higher. In addition to lattice parameters, a 2θ-zero can also be refined. Either approximate lattice parameters or a minimal set of indexed lines can be used as input. An example is given of its application to a AuMn two phase system.

Use of the program NBS*AIDS83 to modify data in the ICDD Powder Diffraction File (PDF) has led to substantial changes in card entries for Sets 1-33, in contrast to the previous policy of the International Centre for Diffraction Data of republishing cards where data has been significantly altered. Further changes to data have been revealed in the use of the database with the Philips PLUS 37 search and retrieval system.

The temperature dependence of the cell parameters is given for Bi2Mo3O12, Bi2Mo2O9, γ-Bi2MoO6 and γ'-Bi2MoO6, and the volume expansion coefficient is derived. A description is given of a high-temperature diffractometer (HTD) for temperatures up to about 1600°C in controlled atmospheres.

A powder X-ray diffraction technique has been developed to quantify the relative amounts of α-carbamazepine (A) and β-carbamazepine (B) when they occur as a mixture. The theoretical basis of this technique was developed in 1948 by Alexander and Klug (Anal. Chem., 20:886-889). The powder X-ray diffraction patterns of A and B revealed that the line with d-spacing of 10.1 Å was unique to A. The ratio of the integrated intensity of the 10.1 Å line in a mixture of A and B, to the intensity of the 10.1 Å line in a sample consisting of only A, was calculated as a function of weight fraction of A in the mixture. These ratios were also experimentally determined, and there was a good agreement between the theoretical and experimental intensity ratios. The particle size of the samples, the sample preparation technique and the experimental conditions were controlled so as to eliminate the major sources of error in powder X-ray diffractometry. In order to minimize preferred orientation of the particles, a sample holder was specially fabricated.

X-ray powder diffraction analysis of Diltiazem Hydrochloride C22H26N2O4S·HCl reveals that the compound crystallizes in an orthorhombic unit cell with the powder data unit cell parameters of a=9.08(1), b=42.09(4), c=6.03(1) Å, V=2305 Å3. The unit cell dimensions determined by single crystal diffraction analysis agree well with those of powder diffraction analysis. Samples prepared under different crystallization conditions yielded the same powder patterns.

Barium titanyl oxalate tetrahydrate, Ba(TiO)(C2O4)2.4H2O, has been investigated by means of X-ray powder diffraction. Precise powder diffraction data were obtained by a conventional diffractometer with strictly monochromatic radiation. Unit cell dimensions were determined by an indexing program based on the variation of parameters by successive dichotomies. A monoclinic cell was found, a=14.044(2)Å, b=13.812(2)Å, c=13.382(2)Å, β=91.48(1); V=2594.9Å3, which is characterized by the figures of merit M20=46.5 and F30=107(0.0056, 50). The complete powder pattern was reviewed by means of the program NBS*AIDS83 and the 81 first lines were indexed. Structural imperfections were not detected from the diffraction line widths, which are comparable to the instrumental resolution.

Powders of Al and Ti were blended and compacted, the compact then melted in an attempt to produce single phase Al3Ti. Optical microscopy of the cast and homogenized specimen revealed an almost single phase microstructure with minor amounts of a second phase. The composition of the matrix was measured using fully quantitative energy dispersive X-ray analysis. By use of X-ray diffractometry, the interplanar spacings and the associated integrated peak intensities were experimentally measured for the binary DO22 compound, Al3Ti. Using standard structure factor equations, the intensities were calculated for the various reflections. Good agreement was obtained between calculated and observed intensities.

X-Ray powder diffraction data and unit cell parameters of industrially produced, as well as bench scale prepared, ammonium paratungstate tetrahydrate are reported and compared with current Powder Data File (PDF) (1989) patterns. A least-squares refinement resulted in two slightly different unit cells. Both cells are monoclinic with S.G. = P21/n(14), Z = 2. The density, 4.639(2)kg/m3, calculated from one of these unit cells corresponds reasonably well with a measured value of 4.61 (2). It has, however, not been possible to determine at present why ammonium paratungstate tetrahydrate has two unit cells. No relation between the crystalline form and the method of preparation nor the exact water content could be established.

Arsenic molybdate, As4Mo3015, has been investigated by means of X-ray powder diffraction. The diffraction data were collected with a focussing (Guinier-type) transmission diffractometer equipped with a primary-beam monochromator (Ge 111) for CuKα radiation and a scanning position-sensitive detection system. A monoclinic unit cell was determined using an indexing program.