Exact is a mini-computer based fundamental parameters program which is utilized for matrix corrections in energy-dispersive X-ray analyses. We have previously shown this technique to work well with radioactive sources. However, due to the limited selection of isotopic sources available and their inherent low X-ray flux, we have investigated the use of Fe, Sn, and Dy secondary-targets as sources of monochromatic X-rays. Results to date indicate that the secondary-targets provide X-ray radiation which has sufficient monochromaticity for our technique to remain valid.

Many advanced semiconductor device designs require the growth of heteroepitaxial layers with lattice parameters differing by up to a few percent with respect to the substrate. X-ray diffraction offers a nondestructive method of determining the extent of relaxation. This paper discusses the sensitivity of x-ray techniques to small amounts of relaxation, describes how relaxation is measured in cubic materials for layer on (001) substrates and suggests nomenclature for the case of asymmetric relaxation.

An x-ray fluorescence analysis method applicable to the case of fluorescent spectra excited with monoenergetic x-rays has been developed. The technique employs a minimum number of calibration steps using single element thin film standards and depends upon theoretical cross sections and fluorescent yield data to interpolate from element to element. The samples are treated as thin films and corrections for absorption effects are easily determined- Enhancement effects, if not negligible, are minimized by sample dilution techniques or by selective excitation.

The application of x-ray topographic techniques to the measurement of stress in thin, films is discussed. Quantitative measurements of stresses in thin films deposited on semiconductor substrates, such as silicon, are also discussed. Double crystal and single crystal techniques are used for such measurements. Both techniques are applied to the measurements of stress in silicon oxide, silicon nitride and polycrystalline silicon films on silicon. The doubly crystal technique is useful for measurements of stresses as low as 109 dynes/cm2 in films only 1000A thick. The single crystal technique is less sensitive by one order of magnitude. The advantage of the single crystal technique is its simplicity and speed. It is useful for large scale measurements as encountered in the manufacture of silicon integrated circuit.

Residual strains and stresses were determined in both phases of a hot pressed α-Al2O3 composite containing 25 wt % β (cubic) SiC whiskers using conventional x-ray diffraction and profile analysis. Both phases in this composite were randomly oriented as confirmed by back reflection pinhole photographs. The reflections found most useful with Cu Kα radiation were: 511 + 333 for β-SiC at -134° 2θ and 146 for α-Al2O3 at -136° 2θ. The peak shift and broadening observed in these reflections, relative to the starting powders, were largely due to the two phases mutually constraining each other elastically. This was confirmed by the reversal of the peak shift and most of the broadening in the SiC reflections when the Al2O3 matrix was etched away. Using the method of Cohen and Noyan, it was found possible to separate the macrostresses from the microstress components in each phase. The microstresses were largely hydrostatic; of the order of 895 MPa (130 ksi) compressive in the whiskers and 370 MPa (54 ksi) tensile in the matrix. The macrostresses were ~79 MPa (11.5 ksi) tensile.

A precise and practical method for the determination of d-values and lattice parameters from digital diffraction data is described. Systematic errors are corrected mathematically during a d-spacing / lattice-parameter least-Squares refincment process making it unnecessary to use internal standards. X-ray and synchrotron diffraction data of an ICDD alumina plate obtained with a wide variety of experimental conditions and analysis parameters were used to study the precision in the derivation of d-values and the accuracy in the determination of lattice parameters. Results showed that the precision in determining d-values was high with |Δd/d|avg ranging from 2x105 to 4x10-5. Using the results obtained from the high precision XRD analysis as a reference standard, the accuracy in the lattice parameter determinations from the synchrotron diffraction data reached the l-2x10-6] range. Lattice parameters, with an accuracy in the high 10-5 range, were also obtained using parameters commonly used in a routine XRD analysis such as a wide RS (0.11°) for high intensity, peaks only in the front reflection region, no Kα2 stripping, and a Single 2θo parameter for systematic error corrections.

Three new mixed oxides having the nasicon structure and containing arsenic(V) as tetrahedral ion were prepared and X-ray analyzed. The stoichiometry of the three phases can be expressed by the comprehensive notation MeZr2As(3−x)PxO12 where Me stands for Na+ or K+, x equals to 0 and 1.5 when Me=Na, while x equals to 1.5 when Me=K. For two other compositions of the above series, the powder patterns were calculated on the basis of the structural data from single crystal determinations, thus permitting us to complete the characterization of the solids, with nasicon framework, deriving from MeZr2P3O12 (Me=Na+, K+) by partial (50%) or complete (100%) substitution of As for P.

Key words: nasicon, ionic conductors, phosphates, arsenates

The Pd2HgSe3 phase was synthetized from individual elements by the silica glass tube technique and its crystal structure has been refined by the Rietveld method. The Pd2HgSe3 phase crystalizes in P$\bar 3$m1 space group with the unit-cell parameters a = 7.3096(2) Å, c = 5.2829(1) Å, V = 244.45(1) Å3, Dc = 8.84 g/cm3, and Z = 2. In its layered crystal structure, the [PdSe6] octahedra share opposing Se–Se edges with adjacent [PdSe4] squares forming layers parallel with the (001) plane. The layers show AA type stacking along the c-axis. Hg atoms occupy the anti-cubooctahedral voids between two consecutive layers. Pd2HgSe3 is isostructural with Pt2HgSe3 and Pt4Tl2X6 (X = S, Se, or Te) phases. The structure can be viewed as a 2a.2a.c superstructure of PtSe2.

Two selected members of the homologous series An+2BBn′O3n+3 (A=Sr and Ca; B and B′=Co) have been investigated for their crystal structures because of their potential applications as thermoelectric materials. A combined Rietveld refinement and spin-polarized magnetic geometry optimization technique was employed for the structural studies. Both the n=3 member, (Sr0.8Ca0.2)5Co4O12, and the n=4 member, Sr6Co5O15, have distorted hexagonal perovskite-related structures that possess one-dimensional cobalt oxide chains separated by alkaline-earth cations. The linear chains consist of one unit of CoO6 trigonal prism alternating with n units of CoO6 octahedra. Crystal structures and reference powder X-ray diffraction patterns of (Sr0.8Ca0.2)5Co4O11 [P3c1, a=9.4196(2) Å, c=19.9857(6) Å, V=825.83 Å3, and Dx=5.358 g/cm3] and Sr6Co5O15 [R32, a=9.497 64(12) Å, c=12.3956(2) Å, V=968.34 Å3, and Dx=5.455 g/cm3] are reported.

Compound from the solid-solution NdSrNi1−xCrxO4−δ, 0≤x≤1, has been prepared using conventional solid-state method and was characterized by X-ray powder diffraction. The NdSrNi0.5Cr0.5O4−δ sample shows the adoption of the K2NiF4-type structure based on the tolerance factor calculation. X-ray diffraction analysis using the Rietveld method was carried out and it was found that NdSrNi0.5Cr0.5O4−δ compound crystallizes in tetragonal symmetry with space group I4/mmm. The lattice parameters are found to be at room temperature, a=3.8012(3) Å and c=12.4812(1) Å. For X-ray diffraction data, the reliability factors are RB=0.034, Rwp=0.089, , and χ2=1.17. Bond-valence sum calculations were performed for nickel and chromium. The changes in unit-cell parameters are discussed in terms of oxygen stoichiometry and transition metal (3d) oxidation state from the perspective of the Brown bond-valence sum calculation theory.

Neutron diffraction studies were carried out to ascertain the structural details of the composition Ce0.5Nd0.5O1.750. The structure was unequivocally found to be that of C-type cubic. The refinement on an F-type cubic lattice was found to be unacceptable because of high R values. Selected bond distances are also being reported. In addition, the neutron diffraction studies on a typical defective F-type composition Ce0.75Nd0.25O1.875 were also carried out.

Strain field distribution in a naval platform under dry-dock conditions is complex and represents the cumulative response from residual stress (“locked in” during fabrication of materials and formation of the structure) and static loading stress (e.g., dry-dock loading). The magnitude and distribution of stress fields are a significant concern for the Canadian Navy, where the superposition of applied stresses on residual stresses may adversely affect the performance, safe operational envelope, and service life of naval platforms. Stress analysis was conducted on Canada’s VICTORIA Class submarines using a portable miniature X-ray diffractometer (mXRD) under dry-dock conditions. This paper introduces the concept of “residential stress” as it applies to submarine platforms and discusses the methodology for performing stress analysis with a portable mXRD. The evolution of residential stress during routine pressure hull repairs to Canada’s VICTORIA Class submarines is discussed. In particular, the recent replacement of the diesel exhaust hull and back-up valves on one of the submarines, as well as a pressure hull plate extraction-insertion-weld procedure on another, is discussed.

Crystal data for RuIn3 are reported. The material is tetragonal, , with a = 6.9983 (3), c = 7.2440 (4) Å, Vol = 354.78 Å3, Z = 4, Dc = 8.34 gm/cm3. It is isostructural with the compound CoGa3. The crystals of RuIn3, which form long needles, display electrical resistivity characteristics of a typical metal.

Intensity data were obtained from a diffractometer trace taken with CuKα radiation, λ = 1.54178 Å. The structure was refined by least-squares calculations to R1 = 0.116 with 53 observed reflections. Powder pattern data are also given.

AFeTi(PO4)3 (A=Ca,Cd) materials were obtained by solid state reaction in air at 1000 °C. Structures of the two compounds were determined from X-ray diffraction data using Rietveld analysis. Both phases exhibit the Nasicon-type structure (R3¯c space group) with a statistical Fe(Ti) distribution within the framework. Their hexagonal cell parameters are a=8.518(1) Å, c=21.797(2) Å and a=8.534(1) Å, c=21.416(2) Å, for CaFeTi(PO4)3 and CdFeTi(PO4)3, respectively. Cd atoms occupy the M1 site in CdFeTi(PO4)3. From XRD data, it is difficult to distinguish without ambiguity between Ca2+ and Ti4+ ions in CaFeTi(PO4)3. Nevertheless from the cation–anion distance found after the structure determination, Ca2+ distribution within the M1 site of Nasicon structure are validated.

The crystal structure of SiAl5O2N5 was characterized by laboratory X-ray powder diffraction (CuKα1). The title compound is hexagonal with space group P63/mmc (Z = 2). The unit-cell dimensions are a = 0.303153(3) nm, c = 3.28153(3) nm, and V = 0.261178(5)  nm3. The initial structural model was successfully derived by the direct methods and further refined by the Rietveld method. The final structural model showed the positional disordering of two of the four (Si,Al) sites. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were R wp = 5.00%, S (=R wp/R e) = 1.25, R p = 3.76%, R B = 1.26%, and R F  = 0.90%. The disordered crystal structure was successfully described by overlapping four types of domains with ordered atom arrangements. The distribution of atomic positions in each of the domains can be achieved in the space group P63 mc. Two of the four types of domains are related by a pseudo-symmetry inversion, and the two remaining domains also have each other the inversion pseudo-symmetry.

A method is presented for correction of integrated X-ray intensities for preferred orientation of crystallites in a spinning specimen. It is based upon direct integration of the data obtainable from pole distribution of a single crystallographic plane. This pole distribution can be determined from measurements on a texture goniometer or, in special cases, from an ω-scan or from intensities of all reflections measured on a powder diffractometer only. The method was tested on four samples of magnesium and magnesium cadmium alloys and applied to hexagonal BN and α-Ti(N) surface layers. The method was developed with regard to application in phase analysis and thin film studies.

A series of synthetic calcium silicates has been produced comprising nano-sized plates. The starting calcium silicate referred to as nano-structured calcium silicate, NCS, appears itself X-ray amorphous but contains impurities of calcite. These impurities decompose during the dry thermal conversion of the material into wollastonite. NCS can be enriched with calcium or silicon, respectively. The silicon enriched NCS can be hydrothermally transformed into a sheet material related to Ca7Si16O38(OH)2. The X-ray pattern of this material was sufficient to allow the calculation of its unit cell with a comparatively high figure of merit. The calcium enriched NCS can form two very distinctly different ceramic materials upon hydrothermal treatment, one a band material (formed below 200 °C) and the other a rose petal shaped material (formed above 210 °C). The X-ray diffraction patterns could not be resolved. The fit between the observed and calculated patterns was less than 50% as expressed in comparatively low figures of merit (unusually <20), which is attributed to calcium carbonate impurities in the samples disrupting the long range order. The patterns of these calcium enriched samples could be best compared to those of tobermorite or truscotite.

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.

We use density functional theory meta-generalized gradient approximation TPSS + D3(BJ) + U + J calculations to investigate the energetics and geometry of water molecules in the flexible metal-organic framework material Materials of Institut Lavoisier (MIL)-53(Cr) as a function of cell volume. The critical concentration of water to cause the transition from the large pore (lp) to the narrow pore (np) structure is estimated to be about 0.13 water molecule per Cr. At a concentration x = 1 water molecule per Cr, the zero-temperature np and lp configurations each have a hydrogen bond between the H of each framework hydroxyl group and water oxygen (OW). At intermediate volumes, water dimer-like configurations are observed. A concentration x = 1.25 leads to hydrogen bonding between water molecules in the np phase that is absent for x = 1. Our results suggest possible mechanisms for pore closing in hydrated MIL-53(Cr).

The crystal structure of the third polymorph of dibenzylsquaramide (Portell, A. et al., 2009), (fig. 1) has been determined from laboratory X-ray powder diffraction data by means of direct space methods using the computing program FOX. (Favre-Nicolin and Černý, 2002) The structure resolution has not been straightforward due to several difficulties on the indexing process and in the space group assignment. The asymmetric unit contains two different conformers, which has implied an additional difficulty during the Rietveld (Rietveld, 1969) refinement. All these issues together with particular structural features of disquaramides are discussed.