The reflection shift δ2Θ caused by a radial shift δr of the sample away from its tangential position at the focusing circle is examined for grazing incidence diffraction and grazing excidence diffraction. Experimental results for residual strain/stress evaluation on thin films using a Bragg–Brentano diffractometer with a grazing incidence equipment are presented. Grazing excidence diffraction is less sensitive to δr than grazing incidence diffraction.

More isostructural compounds would have the same Pearson Symbol Code (PSC) if the hydrogen atom is not counted in computing the numeric portion of the PSC.

A computer program is presented that allows for the analysis of powder X-ray diffraction (XRD) patterns. Some peculiar features of the program are: the aptitude for dealing with diffractograms obtained from semicrystalline polymer samples and the ability to evaluate XRD patterns collected with CPS 120 detectors. The program is available as freeware via anonymous ftp at: ftp.cc.uniud.it under the directory/pulwin/.

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 low-temperature oxidized form of Sr49.5Ca16.5Bi34O151 has been determined using a combination of neutron, synchrotron, and laboratory X-ray powder diffraction data. The structure is pseudo-orthorhombic; systematic absences and successful refinement indicated the true structure to be monoclinic, with space group P2l/n. Structural refinement using only neutron powder data yielded the lattice parameters a=8.38 898(29) Å, b=5.99 334(21) Å, c=5.89 586(20) Å, β=89.997(8)°, and V=296.43(3) Å3. This compound is a distorted perovskite phase [described in the perovskite ABO3 formula as Sr(Bi0.7Ca0.3)O3] with ordering of the M-site cations, resulting in the formula A2MM′O6. In this ordered structure, the A sites are solely occupied by Sr, the M sites mainly by Bi, while on the M′ sites Bi and Ca are distributed in an approximate ratio of 2:3. The MO6 and M′O6 octahedra share corners, and are tilted with respect to the neighboring layers with an angle of ∼15° around all three axes. The tilt system symbol is a+a−a− according to Glazer notation. All Bi ions are in the 5+ oxidation state.

Two new solubility-limiting phases relevant to nuclear waste disposal are reported, namely CeSiO4 and Ca2Ce8(SiO4)O2, produced by hydrothermal synthesis at 180 °C. X-ray diffraction data are presented for both compounds. Rietveld refinement was performed for each of these phases. CeSiO4 was confirmed to be a zircon structure type, with space group I41/amd, unit cell type="bold">abold=6.9564(3), type="bold">cbold=6.1953(4) Å. Bond lengths for SiO4 are in excellent agreement with published values; Ce4+ is coordinated to eight oxygen atoms with four regular and four short bonds. Ca2Ce8(SiO4)O2 was shown to have an apatite structure, with space group P63/m and unit cell type="bold">abold=9.4343(3), type="bold">cbold=6.8885(4) Å. The unit cell and bond lengths were found to be slightly smaller than would be expected from other lanthanide-containing analogs; possible reasons for this are discussed.

Arsenic molybdate, As2MoO7, produced by phase transformation of As4Mo3O15, has been analyzed by X-ray powder diffraction. The powder diffraction data were collected with a focusing (Guinier-type) transmission diffractometer equipped with a primary-beam monochromator (Ge 111) for Cu Kα radiation and a scanning position-sensitive detection system. A monoclinic unit cell was determined using an indexing program and compared with calculated single crystal data.

A complete set of d spacings, intensities, and h, k, l indexes for Ti2AlN has been determined from X-ray powder diffraction. The lattice parameters are a=2.989(2) Å, c=13.614(5) Å; in good agreement with previous work. The new set of results comprises seven reflections not present in the current Ti2AlN PDF card No. 18-70. Furthermore, a new set of relative intensities are reported that are in better agreement with the calculated values than they are with those listed in the PDF card.