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  • 1985-1989  (13)
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Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Calcium niobium oxide, Ca0.75Nb3O6: a novel metal oxide containing niobium-niobium bonds. Characterization and structure refinement from synchrotron powder x-ray data (1987)
    s.l. : American Chemical Society
    Inorganic chemistry 26 (1987), S. 2389-2391 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00262a011
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The synthesis and structure determination from powder diffraction data of LaMo5O8, a new oxomolybdate containing Mo10 clusters (1988)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 110 (1988), S. 3295-3296 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00218a047
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Synchrotron X-ray and neutron powder diffraction studies of the structure of α-CrPO4 (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 452-457 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The crystal structure of α-CrPO4, previously solved from high-resolution synchrotron powder X-ray data, has been refined by the Rietveld method. The peak shape variation is well fitted by a convolution of Gaussian and Lorentzian terms, which incorporate both instrumental and sample-broadening contributions. The structure has also been refined using medium-resolution neutron diffraction data, and the results of the two experiments are compared with a reported single-crystal study. The three sets of coordinates are found to be in good agreement, demonstrating the potential of structure determination and refinement using powder data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889888004625
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    High-resolution synchrotron X-ray powder diffraction with a linear position-sensitive detector (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 905-910 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: X-ray synchrotron powder data were collected from a capillary sample of a small-molecule organic peptide compound, glycylglycine (NH2CH2CONHCH2COOH) by step-scanning at 1° intervals with a linear position-sensitive detector covering an angular range of 2.7° in order to test the feasibility of recording a high-resolution pattern and using the data for Rietveld analysis. Appropriate corrections for detector linearity and position were implemented, and comparison with a diagram recorded with a single scintillation detector and a crystal analyser system showed similar quality for the two sets of data. A detailed comparison of the refined atomic coordinates and those of an earlier X-ray single-crystal study showed the estimated standard deviations to be significantly underestimated in both refinements. A linear detector should be particularly useful for small samples and capillary specimens of moderately absorbing materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889888007253
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    ADPD: a new approach to shared-site problems in crystallography (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 206-208 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: From the anomalous dispersion of X-rays close to the Zr and Y absorption edges it has been found that individual cation B factors can be determined independently in a refinement of the structure of an yttria-stabilized zirconia ceramic material with composition Zr0.81Y0.19O1.90. With X-ray powder data collected at a single wavelength this is not possible because of the high correlations. Simultaneous refinement of data collected at three different X-ray wavelengths [0.7726(1), 0.7283(1) and 0.6892(1) Å] has allowed the determination of separate mean-square displacements for each atom, the respective values are 0.045(2) for Zr4+, 0.024(6) for Y3+ and 0.098(2) Å2 for O2−. The results indicate that the structural configuration of Zr4+ is significantly different from that of Y3+. This anomalous-dispersion powder diffraction (ADPD) technique should be of general application to similar shared-site problems of this kind.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889887010422
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  • 6
    Electronic Resource
    Electronic Resource
    Powder diffraction with synchrotron radiation. II. Dispersion factors of Ni (1985)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 41 (1985), S. 417-420 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Accurate values of the absolute integrated reflections from a powder sample of Ni have been determined from measurements with synchrotron radiation as a function of scattering angle over a range of energies from 290 to 3 eV below the Ni K-absorption edge, 8332 eV. From these values, the dispersion factor f' has been determined by comparison of the experimental scattering factors with the theoretical values of Wang & Callaway [Phys. Rev. B. (1977), 15, 298- 306] based upon a LCAO calculation with the KSG (Kohn & Sham and Gaspar) approximation for exchange [Kohn & Sham (1965). Phys. Rev. 140, A1133-1138; Gaspar (1954). Acta Phys. Acad. Sci. Hung. 3, 263-286]. The values obtained for f' as a function of energy are within about 0.2 electron units of those calculated from measured and tabulated absorption coefficients by Bonse & Hartmann-Lotsch [Nucl. Instrum. Methods (1984), 222, 185-188] and within about 0.5 electron units of their direct measurements by interferometric techniques in the range 30 to 3 eV below threshold. The variation of f' with scattering angle is negligibly small (less than 0.2 electron units on average). The present experiment demonstrates that powder techniques provide a simple and convenient method for the measurement of f' for many materials that are not available in forms suitable for the application of other techniques such as interferometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767385000897
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Powder diffraction with synchrotron radiation. I. Absolute measurements (1985)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 41 (1985), S. 413-416 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Accurate measurements of the integrated intensities of several reflections from a standard powder sample of Ni have been made using monochromatic synchrotron X-ray radiation of wavelength 1.5413 Å from a perfect double-crystal Si(111) monochromator. A perfect Ge(111) analyzer crystal was mounted on the detector arm of the diffractometer to serve as a narrow 'angular' receiving slit. The intensities were placed on an absolute scale by application of the appropriate powder diffraction expressions, which require the incident photon counts, the axial and equatorial openings of the receiving 'slit', and the polarization factor to be known. The procedure for evaluating these instrumental parameters is described in some detail. The quantitative agreement between these and previous absolute measurements on a standard Ni sample with Cu Kα radiation demonstrates that the synchrotron technique can be used for absolute measurements of high accuracy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767385000885
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Synchrotron X-ray and neutron powder diffraction studies of the structure of α-CrPO4. Erratum (1989)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 22 (1989), S. 70-70 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Owing to a printer's error, the equation given in the Discussion of the paper by Attfield, Cheetham, Cox & Sleight [J. Appl. Cryst. (1988). 21, 452–457] is incorrect. The correct equation is (Δρ/σ(Δρ)) = (1/P) \sum_{P}|p2 − p1|/(σ21 + σ22)1/2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S002188988801386X
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  • 9
    Electronic Resource
    Electronic Resource
    Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al2O3 (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 79-83 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The application of the Rietveld refinement technique to synchrotron X-ray data collected from a capillary sample of Al2O3 in Debye–Scherrer geometry is described. The data were obtained at the Cornell High Energy Synchrotron Source (CHESS) with an Si(111) double-crystal monochromator and a Ge(111) crystal analyzer. Fits to a number of well resolved individual peaks demonstrate that the peak shapes are very well described by the pseudo-Voigt function, which is a simple approximation to the convolution of Gaussian and Lorentzian functions. The variation of the Gaussian and Lorentzian half widths, ΓG and ΓL, with Bragg angle can be approximated quite closely by the functions V tan θ and X/cos θ which represent the contributions from instrumental resolution and particle-size broadening respectively. Rietveld refinement based on this model yields generally satisfactory results. The refined values of V and X are consistent with the expected vertical divergence (∼0.1 mrad) and the nominal particle size (∼ 0.3μm). In particular, the use of a capillary specimen virtually eliminates preferred orientation effects, which are highly significant in flat-plate samples of this material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889887087090
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  • 10
    Electronic Resource
    Electronic Resource
    Absence of magnetic order in (Ba, K)BiO 3 (1988)
    [s.l.] : Nature Publishing Group
    Nature 335 (1988), S. 151-152 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Muon spin precession signal observed a, in a non-superconducting specimen of (Ba, K)BiO3 at T = 3.4K by applying a transverse external magnetic field Hext= 125 G, and b, in an anti-ferromagnetic YBa2Cu3C〉6 18 at T = 276 K with Hext = 100 G. The muon decay-time histogram is given as N(t) = ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/335151a0
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