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  • Wiley-Blackwell  (52.677)
  • Molecular Diversity Preservation International
  • International Union of Crystallography (IUCr)
  • 1985-1989  (58.927)
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  • 1
    Digitale Medien
    Digitale Medien
    Structure of crystalline polymers edited by I. H. Hall (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 53-54 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009797
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  • 2
    Digitale Medien
    Digitale Medien
    Dry etching for microelectronics edited by R. A. Powell (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 54-54 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009815
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  • 3
    Digitale Medien
    Digitale Medien
    Molecular beam epitaxy of III-V compounds: a comprehensive bibliography, 1958-1983 edited by K. Ploog (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 54-54 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009803
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  • 4
    Digitale Medien
    Digitale Medien
    Relationship between counting modes, absolute noise term and the errors of structure functions in the interpretation of small-angle X-ray scattering data (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 55-60 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The requirements imposed on the magnitude of the noise in a scattering curve in order to minimize the corresponding error in the structure functions are estimated for a given value of the time T in which the scattering curve is recorded. Typical small-angle X-ray scattering (SAXS) curves have been used to check how these conditions are fulfilled when different counting modes are applied for the measurement. It is shown that fixed-time counting is the most practical technique and produces error bands in the structure functions with magnitudes close to the smallest values attainable in SAXS investigations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009827
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  • 5
    Digitale Medien
    Digitale Medien
    Incoherent scattering corrections for forward scattering of neutrons by aqueous buffers. Temperature dependence and influence of absorbing salts (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 61-64 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Following the procedure suggested by May, Ibel & Haas [J. Appl. Cryst. (1982), 15, 15–19] for the correlation of transmission data with the level of neutrons scattered incoherently into the full solid angle 4π measurements have been made of the transmission and incoherent scattering intensities of aqueous buffers of different H2O/D2O ratios at temperatures between 280 and 343 K. That it is possible to extend the proposed calibration procedure to absorbing-ions-containing buffers is also shown.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009839
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  • 6
    Digitale Medien
    Digitale Medien
    The inverse contrast variation in small-angle neutron scattering: a sensitive technique for the evaluation of lipid phase diagrams (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 65-70 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Small-angle neutron scattering experiments have been performed with aqueous dispersions of binary lipid mixtures. One component was protonated, the other was partly deuterated. By varying the mole fraction of the deuterated species the mean scattering-length density of the lipid lamellas and hence the contrast between liposomes and the solvent was changed. It is shown that this inverse contrast variation has the advantage of (i) a simpler data analysis, (ii) an increased resolution of homogeneous and heterogenous lipid distributions and (iii) a considerably increased sensitivity for the evaluation of phase diagrams in segregated lipid mixtures. Phase boundaries can now be determined to an accuracy of better than 1 mol%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009840
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  • 7
    Digitale Medien
    Digitale Medien
    Borrmann effect for alignment of a four-circle diffractometer (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 71-74 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A very simple method is described to align accurately any full four-circle diffractometer with respect to the incident beam. This method relies on anomalous transmission measurements. It has been found that the centroids of the Ge 220 anomalous transmission intensity distributions measured at the four main positions of the χ circle, that is 0, 90, 180, and 270°, not only provide an accurate determination of the reference angles for ω and φ, but also provide an accurate method to align the χ circle with respect to the direction of the incident beam. This procedure promises to be even more helpful for diffractometers installed at synchrotron radiation laboratories than for in-house installations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009852
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  • 8
    Digitale Medien
    Digitale Medien
    ABSORB: An absorption correction program for crystals enclosed in capillaries with trapped mother liquor (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 75-79 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A computer program to calculate the contributions of crystal, capillary and a simple model of mother liquor to the overall absorption of X-rays has been written. It is based on the Gaussian quadrature method of integration; the crystal is described by the polyhedral faces bounding it, the capillary by its diameter, thickness and orientation with respect to the diffractometer axes and the mother liquor by the crystal faces that trap it between crystal and inner capillary wall. The program is written in Fortran for a VAX 11/780 computer and incorporates tables of mass absorption coefficients for silver, molybdenum and copper radiations for easy calculation of linear absorption coefficients.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009864
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  • 9
    Digitale Medien
    Digitale Medien
    Semiquantitative X-ray diffraction method for phase analysis using additions of a foreign component (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 80-84 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A method is described for semiquantitative X-ray diffraction phase analysis, which involves the addition to the investigated multicomponent system of known large (about 80–95%) amounts of a crystalline substance originally not contained in the system. This results in a decrease of the diffraction line intensities of the components to be measured to small but detectable values. The weight fraction of a component is related to the added fraction of the doping substance and to the fraction of that component remaining in the doped sample. The method is very simple and yields the weight fractions of the major components in the system with a typical error of a few percent. The weight fractions of the minor components cannot be determined with fair accuracy in this way. The method is appropriate in cases where only a small amount of the investigated system is available. Optimum conditions to attain maximum accuracy of the method are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009876
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  • 10
    Digitale Medien
    Digitale Medien
    The use of an array processor for the simulation of X-ray topographs (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 85-92 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The use of a varying-step algorithm now allows the simulation of traverse topographs and of section topographs taking into account the real width of the incident beam. However, computation time remains a critical factor in practical use. With an array processor it is possible to decrease the computation time significantly. It is shown that pictures of good quality may be obtained in a reasonable time using local facilities. The influence of various parameters on the accuracy of the simulations is discussed. It is demonstrated that local machines can be more useful, in crystallography, than giant computers often difficult to reach through the network of communications.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009888
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  • 11
    Digitale Medien
    Digitale Medien
    In situ alignment procedure for X-ray topography (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 106-109 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A simple method for in situ alignment of samples in a double-crystal X-ray topography system is described. This method permits a specific crystallographic axis to be made coincident with the sample rotation axis used to set the Bragg angle. Surface reflections from approximately orthogonal crystallographic planes are required and tables of such planes suitable for alignment of cubic crystals are given. This procedure allows rapid setup for the other accessible surface reflection or transmission topographs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009906
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  • 12
    Digitale Medien
    Digitale Medien
    Detectability of two overlapping Pearson VII peaks in simulated X-ray diffraction patterns (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 114-119 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: This article presents mathematical methods for calculating the shoulder limit and detection limit for two merging Pearson VII functions. Results are given for the particular case of the modified Lorentzian (n = 2). The modified Marquardt algorithm of the data reduction program used by the authors is briefly discussed. Synthetic diffraction patterns are used to determine a practical detection limit for this program that compares favourably with the theoretical detection limit.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988500992X
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  • 13
    Digitale Medien
    Digitale Medien
    Large-angle convergent-beam electron diffraction; a simple technique for the study of modulated structures with application to V2D (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 110-113 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: With a highly convergent electron beam entering a small crystal area, the Bragg condition may be fulfilled simultaneously for many diffraction orders along a reciprocal-lattice direction, and reflections with (sin θ)/λ 〉 2 Å−1 are accessible. Considerations based on the dynamical theory of electron diffraction suggest that for Bragg reflections with (sin θ)/λ 〉 1 Å−1, 100 keV electrons can be treated quasi-kinematically when the crystal thickness is less than 1000 Å, and this is supported by experiments. This simple approach has been used to determine the D-induced static displacement modulation δ of V along the a axis (monoclinic indexing) in the β phase of V2D. From visual inspection of the Bragg intensities for large diffraction orders, up to (sin θ)/λ = 2.35 Å−1, it is concluded that δ = 0.070 (5) Å.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009918
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  • 14
    Digitale Medien
    Digitale Medien
    A two-crystal X-ray interferometer from different pieces of silicon material (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 120-122 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: It is shown that an X-ray interferometer consisting of two crystals cut from different pieces of silicon material can be successfully operated. The dependence of the visibility of the interference pattern on different thicknesses of beam splitter and analyzer is investigated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009931
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  • 15
    Digitale Medien
    Digitale Medien
    Experimental and computer simulation study of the variation with depth of the X-ray section topograph images of a dislocation (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 93-105 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A systematic study of the variations of the contrast of a dislocation in silicon on section topographs with the depth of the line was performed both experimentally and with computer simulations. Mo Kα1 radiation and 33{\bar 3} and {\bar 3}{\bar 3}3 symmetric reflections were used. The crystal thickness was 440 μm so that the value of μt was 0.64. The influence of the orientation of the dislocation was studied for values of the angle between the line and its Burgers vector ranging between 60 and 90° in the glide plane. It was observed that when the dislocation lies close to the entrance surface, whatever its orientation, its image is centred around the trace of the plane of incidence passing through the intersection of the dislocation with the direct beam while when the dislocation lies close to the exit surface its image is centred around the projection of the dislocation on the section pattern. The variation of the orientation of the image for intermediate depths of the dislocation is interpreted by means of the geometrical construction of the dynamical image. The values of the orientation of the image calculated according to this simple model are in good agreement with those measured on both experimental and simulated topographs. The same geometrical model enables the difference in the relative positions of the direct and dynamic images of stereo pairs to be explained. A new feature was observed in the simulated images and several of the experimental ones, namely a concentration of intensity along the projection of the dislocation in the reflected direction. Slit width was taken into account in the simulations for a better fit with experimental topographs but not polarization, which was taken to be normal to the plane of incidence. Because of the small value of the crystal thickness and of μt, the variation of the contrast with the Burgers vector is very small, making its determination very difficult.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988500989X
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  • 16
    Digitale Medien
    Digitale Medien
    Electro-optical and magneto-optical properties of liquid crystals by L. M. Blinov (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 130-130 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009967
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  • 17
    Digitale Medien
    Digitale Medien
    Computer program for the evaluation of radial distribution functions in Rayleigh scattering of Mössbauer radiation experiments (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 122-125 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The Rayleigh scattering of Mössbauer radiation has recently been applied to the study of disordered macromolecular systems. A general program has been developed for the analysis of the scattering intensities obtained with this technique. The methodology, which follows the line of the X-ray analysis of disordered systems, has been improved and it can provide information on the static and dynamic structures from the Fourier transform of the total and elastic scattering intensities. A flow-chart of the whole program with its main features and the organization of input-output are also described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009943
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  • 18
    Digitale Medien
    Digitale Medien
    Computer simulation of convergent-beam electron diffraction patterns from bicrystals (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 126-130 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A computer program for simulating convergent-beam electron diffraction patterns from single crystals and bicrystals is described. The program is based on the dynamical theory of electron diffraction, and the intensity of a convergent-beam disc is constructed from the individual intensities of a number of plane waves incident on the specimen. For the bicrystal case, this program allows the influence of parameters such as the location of the boundary plane and a rigid translation at the boundary to be investigated. These effects are discussed for a horizontal (111) twin boundary in silicon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009955
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  • 19
    Digitale Medien
    Digitale Medien
    Multiple scattering in neutron polarization analysis experiments (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 131-134 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A simple analytic method to correct the experimentally observed spin-flip and non-spin-flip scattering cross sections in neutron polarization analysis experiments for the effects of multiple scattering is presented. From known parameters of the constituent elements of a specimen and from the measured experimental cross sections the single scattering cross sections can readily be determined. This is particularly useful in situations where the scattering is isotropic or exhibits only slight angular dependence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009979
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  • 20
    Digitale Medien
    Digitale Medien
    An experimental test of a double-crystal monochromator for thermal neutrons based on two bend silicon crystals (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 135-140 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Reflecting properties of a double-crystal (DC) monochromator consisting of two elastically bent perfect silicon crystals in the parallel non-dispersive (1, −1) setting were experimentally treated. Using an unconventional fully asymmetric geometry, the effective mosaicity may be significantly enhanced up to the value of about 10−2 rad. Test experiments were performed on the 111 and 400 reflections for wavelengths of 0.2 nm and 0.157 nm, respectively. The experimental results obtained are found to be in good agreement with the theoretical predictions published in a previous paper [Mikula, Kulda, Vrána & Chalupa (1984). J. Appl. Cryst. 17, 189–195].
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009980
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  • 21
    Digitale Medien
    Digitale Medien
    Neutron powder diffraction studies of two uranium–0.75 wt% titanium alloys (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 141-144 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Crystallographic properties of depleted uranium alloys (0.75 wt% Ti) with two different heat treatments were studied by neutron powder diffraction methods. The crystal structures are essentially the same as that of pure α-uranium metal, but with somewhat different unit-cell dimensions. The super-saturated Ti impurity in the quenched sample is primarily substitutional. Diffraction lines of the quenched uranium alloy showed a clear strain broadening. The r.m.s. strain obtained from the broadening was 0.0019.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885009992
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  • 22
    Digitale Medien
    Digitale Medien
    High-pressure single-crystal neutron diffraction (to 20 kbar) using a pulsed source: preliminary investigation of Tl3PSe4 (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 145-149 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new technique is described for performing high-pressure single-crystal neutron diffraction [up to 20 kbar (2 GPa) at room temperature], using a BeCu pressure cell, an area detector and the Los Alamos National Laboratory pulsed neutron source. Success of this method depends on the increase in information available with a multi-wavelength pulse neutron source, a novel orientation of a cylindrically symmetric pressure cell with its axis coincident with the neutron beam and a specific crystal orientation within the pressure cell. Bragg scattering from the pressure cell is avoided and background for a given 2θ is constant. For a crystal of orthorhombic or higher symmetry oriented with the incident beam passing midway between the major lattice vectors, it will be possible to refine a complete three-dimensional structure with data collected from only one pressure loading. Preliminary investigations of Tl3PSe4 lattice parameters (space group Pcmn) at 15(1)kbar yielded linear compressibilities (× 1000 in kbar−1) of Ka = 1.05(8), Kb = 1.50(10), Kc = 1.20(8). The anisotropic compressibility is explained by examination of the ambient-pressure room-temperature structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010007
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  • 23
    Digitale Medien
    Digitale Medien
    X-ray powder diffractometric procedure for lattice parameter determination for long-chain molecules (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 150-155 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An X-ray powder diffractometric procedure has been developed to determine the lattice parameters of long-chain hydrocarbons and mixtures thereof. Useful information was limited to low diffraction angles owing to the large size of the unit cell. Intensities were measured in the reflection mode for thick samples with low absorption. Centroids of the diffraction profiles were corrected for axial beam divergence, sample flatness, displacement and transparency and goniometer scale zero position. An internal Si standard was mixed with the sample to determine the displacement of the sample surface from the goniometer axis. The values of a, b and c for the orthorhombic structures n-tricosane (n-C23H48) are 4.965(3), 7.462(4) and 62.12(2) Å and for n-pentacosane (n-C25H52) are 4.964(3), 7.450(4) and 67.21(2) Å. The values agree well with earlier single-crystal studies except for c for which a larger value is reported in the earlier work, probably due to sample impurity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010019
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  • 24
    Digitale Medien
    Digitale Medien
    Lattice paramters of solid solutions of long-chain n-alkanes (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 156-158 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Crystal lattice parameters of mixtures of the normal alkanes n-C23H48 and n-C25H52 have been determined by X-ray powder diffractometry. The c-axis length increases nearly monotonically with increasing C25H52 content, a and b are larger for the mixtures than for the pure substances with maximum values at 15% n-C25H52. The small but significant increases in a of 0.6% and b of 0.9% have not been previously reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010020
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  • 25
    Digitale Medien
    Digitale Medien
    An interactive program for crystal orientation and martensitic transformation investigations: COATI (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 159-164 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An interactive program for comparison of experimental with theoretical martensitic transformation data and for orientation determination from Laue and zero-layer reciprocal-lattice photographs is described. The program can generate orthographic, gnomonic, Laue and zero-layer reciprocal-lattice projections of lattice vectors, circles and latitude-longitude nets. A utility for habit-plane calculation from surface trace data and its diagrammatical representation is provided. Drawings before and after transformation can be superimposed. Output from program MRTNST [Ledbetter & Wayman (1971). Mater. Sci. Eng. 7, 151–157] (altered to handle triclinic lattices) can be read directly by COATI, which also facilitates the graphical method of martensitic calculations. A lucid command language allows easy manipulation of previously complex procedures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010032
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  • 26
    Digitale Medien
    Digitale Medien
    A group refinement procedure in protein crystallography using Fourier transforms (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 165-169 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A rigid-body refinement method and program for crystallography of macromolecules is described. Orientational and translational parameters are refined by fitting the molecular Fourier transforms to the observed structure-factor amplitudes. The range of convergence of the method has been tested on four examples with known crystal structure: PTI, chymotrypsinogen and two forms of α1 anti-trypsin. It was successfully applied in the structure solution of two unknown crystal structures: a third form of α1 anti-trypsin and C-phycocyanin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010044
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  • 27
    Digitale Medien
    Digitale Medien
    A time-resolved neutron powder diffraction investigation of the hydration of CaSO4.1/2D2O and of the dehydration of CaSO4.2D2O (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 170-172 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A chemical reaction, the hydration of CaSO4.½D2O, was followed in real time in an on-line neutron diffraction experiment at different temperatures. The results of the reactions are presented as diagrams showing the evolution of the intensities of CaSO4.2D2O in real time. The hydration passes through the formation of a gel interphase. The dehydration of CaSO4.2D2O was followed in the same way at temperatures up to 420 K.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010056
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  • 28
    Digitale Medien
    Digitale Medien
    Peak shape variation in fixed-wavelength neutron powder diffraction and its effect on structural parameters obtained by Rietveld analysis (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 173-180 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Analyses of high-resolution neutron powder diffraction data, using both the Pearson VII and pseudo-Voigt peak shape functions, have revealed a range of peak shapes from essentially Gaussian to Lorentzian and beyond. Moreover, the refinements show that the Lorentzian character of the peaks in each pattern increases with increasing diffraction angle. Both kinds of shape change are associated with varying relative contributions to the peak profiles of the instrumental resolution, isotropic crystallite strain and crystallite size effects. Rietveld analysis of powder data with the standard Gaussian form when the peaks have significant Lorentzian character has little effect on atomic positional parameters, but it leads to an overestimation of the thermal vibration coefficients and higher least-squares residuals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010068
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  • 29
    Digitale Medien
    Digitale Medien
    Determination of anomalous scattering factors for zinc and silver in Al–Zn–Ag alloys (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 181-183 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The anomalous scattering factors of zinc and silver in samples of Al-rich Al–Zn–Ag have been measured near their K-absorption edges. EXAFS spectra obtained from the Stanford Synchrotron Radiation Laboratory were converted to the imaginary part of the atomic scattering factor f′′ using the optical theorem. With a knowledge of f′′(E), f′, the real part of the atomic scattering factor, was determined from the Kramers–Kronig dispersion relation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501007X
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  • 30
    Digitale Medien
    Digitale Medien
    A micro-computer program to detect higher lattice symmetry (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 183-184 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: From a given initial unit cell the program generates new lattices that are distributed among crystal systems by a purely metrical criterion and sorted according to an empirical figure of merit. For each solution the output contains the new cell parameters along with the corresponding transformation matrix to be applied to the initial unit cell.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010081
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  • 31
    Digitale Medien
    Digitale Medien
    Crystallographers (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 188-189 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501010X
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  • 32
    Digitale Medien
    Digitale Medien
    New Commercial Products Section (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 190-190 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010123
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  • 33
    Digitale Medien
    Digitale Medien
    Treatment of intermolecular contacts in the restrained refinement program of Hendrickson & Konnert (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 185-188 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The restrained reciprocal-space least-squares refinement program of Hendrickson & Konnert [Computing in Crystallography, edited by R. Diamond, S. Ramaseshan & K. Venkatesan, pp. 13.01–13.25. (1980). Bangalore: Indian Academy of Sciences] has been modified to include non-bonded and/or hydrogen-bonded contacts between molecules related by symmetry operations and/or unit-cell translations. The modified program has been tested on an inhibited form of aspartate aminotransferase, which is an α2 dimeric enzyme with a crystallographic twofold axis relating the subunits. A number of heretofore unseen close contacts between atoms of separate subunits were located and correctly dealt with by the modified program.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010093
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  • 34
    Digitale Medien
    Digitale Medien
    Guidelines for Computer Program Abstracts (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 189-190 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010111
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  • 35
    Digitale Medien
    Digitale Medien
    Deformation of ceramic materials II (Materials Science Research 18) edited by R. E. Tressler and R. C. Bradt (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 190-190 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010135
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  • 36
    Digitale Medien
    Digitale Medien
    Calculation of intensity distribution in the case of oblique texture electron diffraction (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 191-196 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new method is described to determine accurately the intensities of reflexions in the case of oblique texture electron diffraction. The method is based on a comparison between experimental values of intensities and those calculated with a formalism that takes into account the orientation function of the particles. It allows the problems that arise from frequent overlapping of reflexions to be surmounted. A concrete example of the application of this method is given the structure refinement of a mica with muscovite–phengite composition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010147
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  • 37
    Digitale Medien
    Digitale Medien
    Electron optical study of rutile (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 197-204 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Convergent-beam electron diffraction has been used to confirm the accepted space group of rutile (TiO2) and to study in detail the dependence of the intensity of the space-group-forbidden reflections on crystal thickness and orientation. The observations are shown to be in detailed agreement with computer-simulated patterns calculated using the standard structural parameters. The diffraction results provide a basis for understanding the high-resolution electron-microscope images of rutile crystals oriented close to the [001] zone in which the effects of the space-group-forbidden reflections are important. It is concluded that satisfactory agreement exists between experimental and calculated images provided that allowance is made for uncertainty in the orientation of the crystal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010159
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  • 38
    Digitale Medien
    Digitale Medien
    LASIP: a liquid and amorphous structure investigation package (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 214-218 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new integrated device for the structural study of liquid or amorphous compounds is described. The X-ray scattering pattern produced by the sample is quickly recorded by a micro-computer-controlled goniometer with position-sensitive detection. Interactive software allows both experimental data processing and simulation from structural models.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010172
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  • 39
    Digitale Medien
    Digitale Medien
    Particle size distribution from small-angle X-ray scattering data (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 205-213 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An improved transform technique has been developed [Gerber (1983). Thesis, Wilhelm-Pieck-University Rostock, German Democratic Republic] for calculating the particle size distribution N(R) for spherical particles with radii R from small-angle X-ray scattering data. This method permits N(R) to be calculated from analytical expressions that were derived for point collimation and for infinitely long slit collimation. A special procedure has been introduced in order to reduce termination errors. The technique described and those developed by Schmidt [Brill, Weil & Schmidt (1968). J. Colloid Interface Sci. 27, 479–492], Vonk [J. Appl. Cryst. (1976), 9, 433–440] and Glatter [J. Appl. Cryst. (1980), 13, 7–11] were used for calculating particle size distributions from theoretical scattering curves and from an experimental scattering curve of suspended SiO2 particles (Ludox). The results obtained by the different techniques were compared, and reasonable results are given by all methods employed. The accuracy of the size distributions calculated by the improved method is somewhat higher than that obtained by Schmidt's transform technique. With Glatter's procedure, the deviations from the exact distributions are comparable to those from this improved transform technique, but the use of Glatter's program requires a large computer, whereas the new method has the advantage of being suitable for a small computer. Vonk's program also requires a large computer, and the deviations obtained are larger than those produced by other methods. The experimental scattering curve of the Ludox sample was also evaluated by assuming a log-normal distribution for the particles. The parameters μ and σ of this function were determined from a set of small-angle X-ray scattering structural parameters. The resulting log-normal distribution is significantly different from the size distribution calculated by our method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010160
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  • 40
    Digitale Medien
    Digitale Medien
    The structural chirality and optical activity of α-LiIO3 (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 237-240 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: It is shown by anomalous X-ray scattering that the absolute configuration of LiIO3, originally determined by Li Yin-yuan, Fan Hai-fu & Chia Shou-chuan [Sci. Sin. (1973), 16, 130–135], is incorrect, in accordance with the prediction of Glazer & Stadnicka [(1985). Submitted to J. Appl. Cryst.]. Measurements of the optical rotatory dispersion are also reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010202
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  • 41
    Digitale Medien
    Digitale Medien
    Parameterizations of scattering intensities and values of the angularities and of the interphase surfaces for three-component amorphous samples (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 219-229 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Different functional parameterizations of the radiation intensity scattered by an N-component amorphous sample are considered. Each parameterization is such that (i) it depends only on the areas and on the angularities of the samples' interphase surfaces, (ii) it fulfils all the known physical constraints and (iii) it yields a rather simple algebraic expression both for the correlation function and for the scattered intensity. The parameterizations have been used for analysing the scattering data relevant to some three-component catalysts. Provided the volume fraction of the metal is not very small, the best fit yields satisfactory results only for some of the considered parameterizations. In this way, the determination of both the areas and the angularities of catalysts appears possible.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010184
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  • 42
    Digitale Medien
    Digitale Medien
    A comparison of the merits of isotopic substitution in neutron small-angle scattering and anomalous X-ray scattering for the evaluation of partial structure functions in a ternary alloy (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 230-236 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Solute partitioning during decomposition of a ternary alloy may be evaluated through the inversion of a system of linear equations, obtained by performing at least three independent small-angle scattering experiments. The merits of neutron scattering (with isotopic contrast) and of anomalous X-ray scattering (near the absorption edges) are compared. It appears that neutron scattering, although having good contrast, is not suited to these studies since slight structural differences between the three samples may lead to erroneous results. On the other hand, the use of the same sample in anomalous scattering avoids this problem, but with the drawback of a more ill-conditioned system. Nevertheless, the possibility of performing more than three anomalous experiments may improve the results and a new analysis of data is proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010196
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  • 43
    Digitale Medien
    Digitale Medien
    Some geometrical problems related to the rotation camera. I. X-ray diffraction pattern generation (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 253-257 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An algorithm for a safe generation of the table of expected reflections in the Arndt–Wonnacott rotation camera is given. It relies upon classic quadratic matrix algebra. Some mathematical theorems are recalled. This algorithm is part of a series of programs developed at Orsay for the treatment of rotation-camera photographs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010238
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  • 44
    Digitale Medien
    Digitale Medien
    Lissage d'un profil de raie de diffraction pour analyse de Fourier (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 248-252 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The fast Fourier transform algorithm commonly used for line profile analysis requires a list of values of the diffracted intensity with constant sinθ step; raw data are usually obtained at constant 2θ step; to interpolate between the measured values an analytic expression of the profile function is very useful. Statistical estimation is used to fit an analytic function to data; the only assumption made is the continuity of this function and no critical initialization is needed. Three different expressions are used: a Fourier sum for the peak and two polynomials of a suitable variable for the tails; the algorithm provides continuity for the function and its first derivative. Simulated examples using a Lorentzian and a Gaussian function are given and several criteria of goodness of fit are examined. The program runs on a PDP 11/03 Digital computer with only 45 kbytes available memory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010226
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  • 45
    Digitale Medien
    Digitale Medien
    The model resolution function – a technique for estimating the quality of approximation of particles by models in small-angle X-ray or neutron scattering (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 241-247 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Although the quality of a structure model obtained from small-angle X-ray or neutron scattering curves for polymers can be determined qualitatively by comparing the isotropic scattering curve calculated for the model with the experimental scattering data for a solution of polymer molecules, other methods are needed for a more precise evaluation. A model resolution function has been defined to permit quantitative comparisons. With this function, the quality of the approximation can be assessed, and the structure resolution can be determined. An overinterpretation of scattering curves by use of complex but uniform-density models can thus be avoided. Furthermore, the value of the Porod volume calculated from the scattering data has been found to depend strongly on the interval in which the scattering data are recorded or selected for evaluation. The calculations with the atomic model curves showed that it is impossible to compute physically meaningful values of the hydration of the molecules from the Porod volume and the dry volume by use of extrapolated scattering curves with an insufficient resolution. The theory of the model resolution function and the interpretation of the Porod volume have been verified and tested with experimental scattering curves from solutions of RNA molecules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010214
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  • 46
    Digitale Medien
    Digitale Medien
    XTAL: a program system for crystallographic calculations (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 263-263 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010251
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  • 47
    Digitale Medien
    Digitale Medien
    STRUPLO84, a Fortran plot program for crystal structure illustrations in polyhedral representation (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 258-262 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: STRUPL084 is a Fortran plot program for drawing crystal structures in polyhedral or skeletal representation. All data are read in free format by standard Fortran routines. Atomic positions are also accepted in formats compatible with the input for the programs SHELX and ORFLS. The structure can be rotated by three rotation angles applied to the orthogonal axes. Instead of giving the rotation angles a view direction can be specified. The output includes a list of direct and orthogonal coordinates and tables with interatomic distances and angles. Atoms that were found to form coordination polyhedra are listed separately. The program is `user friendly' inasmuch as an acceptable plot can be achieved with minimum input by making use of the default options. Atoms not belonging to any polyhedra can be drawn as circles with specified radii.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501024X
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  • 48
    Digitale Medien
    Digitale Medien
    Crystallographers (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 264-264 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010275
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  • 49
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    Digitale Medien
    GENEV, GENSIN, GENTAN: phase determination within the XTAL system (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 263-264 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010263
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  • 50
    Digitale Medien
    Digitale Medien
    Industrial crystallization edited by Grootscholten Jancic P. A. M. (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 264-265 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010287
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  • 51
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    Digitale Medien
    Industrial crystallization 84 edited by S. J. Jancic and E. J. de Jong (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 265-265 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010299
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  • 52
    Digitale Medien
    Digitale Medien
    Current topics in materials sceince. Vol. 10 edited by E. Kaldis (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 265-266 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010305
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  • 53
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    Digitale Medien
    X-ray diffraction by cathodically charged austenitic stainless steel (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 267-271 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The diffraction pattern of cathodically charged austenite consists of broad diffraction bands, often composed of more than one maximum and located close to the position of the regular diffraction peak of the f.c.c. austenitic lattice. The source of these bands was attributed to a nonuniform spatial distribution of hydrogen within the thin surface layer of the material. Calculated diffraction profiles are in good qualitative agreement with the observed profiles. Measurements of the shift of the centroid of the diffraction band were used to estimate the effective diffusion coefficient of hydrogen in austenite.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010317
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  • 54
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    Digitale Medien
    Parallel-beam geometry for single-crystal diffraction (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 272-274 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Reflection from a perfect crystal is used to produce a parallel beam of Kα1 radiation. The losses due to large distances, which are needed for elimination of the Kα2 component, are compensated by a totally reflecting guide tube. The measured flux of Kα1 from a Cu-target X-ray tube at 40 kV and 40 mA was 5 × 105 counts s−1 on an area of 0.5 mm2, when an Si(220) monochromator and a glass guide tube were used. It is estimated that 1 × 107 counts s−1 are available with a Ge(111) monochromator and a gold-plated guide tube. The angular resolution is about 0.1 mrad.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010329
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  • 55
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    Digitale Medien
    Growth defects in quartz druses, 〈a〉 pseudo-basal dislocations (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 275-278 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Growth defects were studied by X-ray topography in a succession of plates cut parallel to the basal planes of two quartz crystals from an Italian druse (Rocca dei Cristalli, Val Malenco, Italy). Growth bands, dislocations and precipitates are the dominant defects. Defect configurations, Burgers vectors and orientations of line defects were found to be similar in both crystals. Distinctive growth marks characterize the growth history of the druse: in particular, characterization was made of unreported dislocations with 〈a〉 Burgers vectors, whose line orientations deviate from the basal plane by an angle of about 10°. These dislocations, referred to here as pseudo-basal dislocations (p.b.d.), were found to be perpendicular to the x {51{\bar 6}1} faces.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010330
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  • 56
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    Digitale Medien
    Synchrotron X-radiation protein crystallography: CEA film absorption factor as a function of wavelength 0.3≤λ≤2Å (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 296-300 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The film absorption factors for CEA Reflex 25 X-ray film have been estimated by three different methods as a function of wavelength in the range 0.3 ≤ λ ≤ 2 Å. This wavelength range encompasses many absorption edges of interest in X-ray crystallography to optimize anomalous dispersion, those wavelengths used to reduce protein crystal absorption (λ ≤ 1 Å), and the spectral range utilized for protein crystal Laue diffraction at synchrotron radiation sources. The value of the film factor at a given λ is important to many protein structural projects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010354
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  • 57
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    Digitale Medien
    Odd-order O.D.F. expansion coefficient determination. Case of diffraction strain measurements on cubic materials under macrostress loading (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 279-295 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Diffraction intensity pole figures are often used for the determination of orientation distribution function (o.d.f.) expansion coefficients. The intensity can be seen as a convolution of the o.d.f. times unity with respect to one rotation angle (about the direction of measurement). The `normal' polycrystalline diffraction experiment only yields the even-order o.d.f. coefficients. The experiment itself imposes a centre of inversion even upon non-centrosymmetric crystals. Crystals may exhibit a centre of inversion themselves. The hkl and {\bar h}{\bar k}{\bar l}contributions to the intensity are indistinguishable then owing to the centre of inversion. As a consequence, the odd-order coefficients cannot be determined. The mean value of a general physical property determined by means of diffraction can be taken as a convolution of the o.d.f. times the single-crystal value of the physical property with respect to the rotation angle mentioned before. The dependency of the physical property on the rotation angle leads to more information being extracted from the o.d.f. in the property's mean-value pole figure. Then, all o.d.f. coefficients may be present in the mean value, i.e. the measurement. Consequently, diffraction-line-shift strain pole figures exhibit even- and odd-order o.d.f. coefficients, present or induced centres of inversion notwithstanding. If the dependency of the single-crystal strain on the rotation angle is known no model of elastic polycrystal coupling is needed. However, this does not occur in practice. The present state of the art does not allow the Kröner model to be used for textured materials. In this paper the Reuss model is used. If the (applied) macrostresses are known, the o.d.f. coefficients can be obtained from the formulae presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010342
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  • 58
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    Digitale Medien
    Calculation of diffraction line profiles in the case of a major size effect: application to boehmite AlOOH (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 301-307 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A method allowing the calculation of the diffraction line profiles of a powder, whose crystallites are convex polyhedrons, is described. The decomposition of the crystallite volume into elementary prisms distinguishes three cases. The analytical expression of the results allows their derivation in the case of a linear size distribution. With instrumental broadening causes taken into account, an application of this method is given in restoring the whole X-ray diffraction pattern of samples of finely divided powders of boehmite, AlOOH.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010366
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  • 59
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    Digitale Medien
    Error analysis of a smeared SAXS curve of polystyrene in benzene (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 308-315 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An error analysis is performed for a slit-length-smeared SAXS curve of polystyrene in benzene. The desmearing and further calculations are done by indirect Fourier transformation. Four different functions are considered. The results are compared and the different error propagation properties of the chosen functions are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010378
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  • 60
    Digitale Medien
    Digitale Medien
    Programmed crystal growth on a diffractometer with focused heat radiation (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 316-319 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: To improve the growing of single crystals for structural analysis, especially those of low-melting-point materials, a new technique and the appropriate apparatus have been developed. The heat radiation of a halogen lamp of adjustable intensity is focused by a parabolic mirror on the sample capillary, which is mounted on a diffractometer and cooled by a gas stream at a controlled temperature. The focus can be moved along the length of the capillary in any direction, for horizontal or vertical miniature zone melting or Bridgman techniques. The heat source and the movable mirror are controlled by a microprocessor, which allows systematic and software-supported search and reproduction of suitable experimental growing conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501038X
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  • 61
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    Digitale Medien
    Analysis of diffuse scattering in neutron powder diagrams. Application to glassy carbon (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 320-325 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: From the quantitative analysis of the diffuse scattered intensity in powder diagrams valuable information about the disorder in crystals may be obtained. According to the dimensionality of this disorder (0D, 1D, 2D or 3D corresponding to diffuse peaks, streaks, planes or volume in reciprocal space) a characteristic modulation of the background is observed, which is described by specific functions. These are derived by averaging the appropriate cross sections over all crystallite orientations in the powder and folding with the resolution function of the instrument. If proper account is taken of all proportionality factors different components of the background can be put on one relative scale. The results are applied to two samples of glassy carbon differing in their degree of disorder. The neutron powder patterns contain contributions from 0D (00l peaks due to the stacking of graphitic layers), 1D (hkζ(streaks caused by the random orientation of these layers) and 3D (incoherent scattering, averaged thermal diffuse scattering, multiple scattering). From the fit to the observed data various parameters of the disorder like domain sizes, strains, interlayer distances, amount of incorporated hydrogen, pore sizes etc. are determined. It is shown that the omission of resolution corrections leads to false parameters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010391
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  • 62
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    Digitale Medien
    Neutron interferometry: antiphasing effects caused by geometrical aberrations (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 326-333 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Intensity profiles of exit beams of a triple-Laue-case neutron interferometer have been measured photographically and compared with profiles calculated from the dynamical theory of perfect-crystal neutron diffraction. In order to avoid smear by an extended source a narrow incident beam only 0.2 mm wide was used. The spreading in the Borrmann triangles of the component crystals S, M, A of the interferometer was taken into account by a spherical wave calculation. The particular aim was to trace the influence of geometrical aberrations of the wafer thicknesses and deviations from so-called ideal geometries on the profile shapes and the phase homogeneity of the interferometer. It could be shown that previously observed `plait'- or `chessboard'-like patterns occurring in exit beams of neutron interferometers can be fully explained by the action of spherical wave interference disturbed by imperfections of the geometry. The agreement found between theory and experiment is very good. From the results, experimentally confirmed geometrical tolerances for the manufacture of neutron interferometers can be deduced.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010408
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  • 63
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    Digitale Medien
    Alignment of double-crystal diffractometers (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 334-338 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A rapid method is described for aligning a double-crystal diffractometer based on the design of Hart (Characterization of Crystal Growth Defects by X-ray Methods, edited by Tanner & Bowen, pp. 483–485. Plenum Press, London, 1980). The theoretical intensity profiles are derived for variations in crystal tilt and rotation, and a method is described that uses these profiles to align any double-crystal diffractometer in a systematic way, suitable for computer automation. The alignment requirements for simple mismatch measurements are also given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501041X
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  • 64
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    Digitale Medien
    The crystal structure and the equation of state of thorium nitride for pressures up to 47 GPa (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 339-341 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Experimental high-pressure X-ray diffraction studies have been performed on ThN powder for pressures up to 47 GPa using synchrotron radiation and a diamond anvil cell. The bulk modulus B0 and its pressure derivative B′0 have been determined: B0 = 175(15) GPa and B'0 = 4.0(4). No structural phase transition has been found in contrast to UN studied previously.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010421
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  • 65
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    Digitale Medien
    The observation of resonant neutron diffraction (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 359-361 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The phenomenon of resonant neutron diffraction as proposed by Brugger [(1983). Unpublished] has been observed at a neutron energy of 6.67 eV using a single-crystal of uranium dioxide on the Harwell linac pulsed neutron source. It is believed to be the first positive experimental observation of such an effect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010457
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  • 66
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    Digitale Medien
    Strategy for data collection from protein crystals using a multiwire counter area detector diffractometer (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 342-350 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A strategy for data collection using a diffractometer equipped with a multiwire proportional counter is described. Data are collected using an electronic rotation method similar to an earlier developed `still' method. Data are collected as a set of three to 12 or more `runs'. A data collection `run' consists of a consecutive series of hundreds of electronic rotation pictures with ω advanced by a specific amount (from 0.07 to 0.20°, depending on the mosaicity of the crystal) during each picture. Every picture in a run is taken at the same: χ and φ setting angles and exposure time. Information on how to extract the intensity data from these electronic rotation pictures is given elsewhere. Here, the only concern is how to choose a set of ω, χ and φ angles for defining a set of runs in order to get a complete set of data in a minimum time. First the diffraction geometry is discussed, then the strategy is outlined; finally, some examples are given to illustrate how the strategy is used in some typical protein data collection problems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010433
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  • 67
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    Digitale Medien
    Rietveld analysis of powder patterns obtained by TOF neutron diffraction using cold neutron sources (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 411-418 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A computer program has been developed for the Rietveld analysis of time-of-flight neutron diffraction data taken on a high-resolution powder diffractometer, HRP, at the pulsed spallation neutron source, KENS. A new profile shape function is implemented which is optimized for a solid-methane moderator at 20 K. The program has several convenient features such as single-pass operation, multiphase capability, automatic successive refinements and constrained minimization. The results of Rietveld refinements of Si and α-Al2O3 show that the profile shape function fits neutron diffraction patterns taken on the HRP very well, and that very precise crystal-structure parameters can be obtained with this program.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887086382
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  • 68
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    Digitale Medien
    Determination of the crystal symmetry of two Al–Fe–Si phases by convergent-beam electron diffraction (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 425-427 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The crystal symmetries of two precipitate phases, q1-AlFeSi (C-centred orthorhombic) and q2-AlFeSi (monoclinic), which were discovered in a dilute Al–Fe–Si alloy, have been determined with the use of convergent-beam electron diffraction (CBED). The space group of q1-AlFeSi is Cmmm and that of q2-AlFeSi is Pm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887086369
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  • 69
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    Digitale Medien
    Data averaging with normal down-weighting of outliers (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 427-428 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A simple scheme is described for calculating weighted averages of multiple equivalent measurements using weights based on estimated normal probabilities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887086357
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  • 70
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    Digitale Medien
    An experimental test of an elastically bent silicon crystal as a thermal-neutron monochromator (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 428-430 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The effectiveness of employing an elastically bent perfect Si (111) crystal as a monochromator for neutron-diffraction experiments is demonstrated on rocking curves presented for a flat perfect Si (220) crystal and a mosaic Fe (110) crystal, for two different collimations of the incident beam. For the sake of comparison equivalent rocking curves with a conventional mosaic Zn monochromator are also introduced. The experimental results obtained indicate that curved perfect-crystal monochromators may become a useful alternative to mosaic-crystal ones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887086345
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  • 71
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    Digitale Medien
    Recent advances in X-ray characterisation of materials edited by P. Krishna (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 450-450 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887086230
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  • 72
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    Digitale Medien
    A lathe-like crystal grinder for grinding pre-aligned crystals into cylindrical cross section (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 371-372 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010548
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  • 73
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    Digitale Medien
    NEWMAN, program for calculating and plotting Newman projections from atomic coordinates and cell constants (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 370-370 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010524
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  • 74
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    Digitale Medien
    Crystallographers (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 373-374 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010561
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  • 75
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    Digitale Medien
    Precise orientation of semiconductor surfaces by the back-reflection Laue technique (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 373-373 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501055X
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  • 76
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    Digitale Medien
    New Commercial Products (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 374-376 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010573
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  • 77
    Digitale Medien
    Digitale Medien
    Diffuse scattering measurements with synchrotron radiation: instrumentation and techniques (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 377-383 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The analysis of diffuse scattering from single crystalline specimens in the reflection mode has generally been acknowledged as a very powerful means of obtaining structural information on local atomic arrangements in disordered alloys, intermetallics and ceramics. However, owing to the low intensities encountered and the large number of measurements required for such an analysis, experiments have been extremely time consuming and few have been attempted. Synchrotron radiation makes it possible to conduct such experiments in a matter of hours and much higher quality data can be obtained than in the laboratory. This paper describes the experimental procedures and methods applied to a study of Al–Cu age hardening alloys conducted at the Cornell Synchrotron Source (CHESS).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010585
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  • 78
    Digitale Medien
    Digitale Medien
    Optical properties of synthetic and mineral chlorapatites (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 384-387 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The birefringence and orientation of the indicatrix for acicular and prismatic habits of monoclinic flux-grown chlorapatite (ClAp), Ca5(PO4)3Cl, have been measured. There are slight differences in birefringence between the habits due to compositional changes, which, because the indicatrix is very nearly spherical, cause the optic axial plane (OAP) to change its orientation by 90°, although the direction of the axes of the indicatrix do not change. The acicular crystals are the purer and are biaxial (−), γ − β = 2.9 × 10−5, β − α = 8.2 × 10−5, mean refractive index (n) = 1.6672 and have the unique c axis normal to the OAP. ClAp is uniaxial (+) above its monoclinic-to-hexagonal transition. Hydrothermally grown monoclinic ClAp has optical properties that can be understood from the results for the flux-grown crystals. Synthetic monoclinic F,ClAp and monoclinic ClAp from Bob's Lake, Ontario, is biaxial (+) with the unique axis lying in the OAP and n = 1.6635.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010597
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  • 79
    Digitale Medien
    Digitale Medien
    Generalization of the parallel position in diffraction using elastically curved crystals (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 388-395 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A theoretical and experimental study of double-crystal rocking curves with elastically deformed silicon wafers yields the result that rotating one of the crystals through 180° can change the peak intensity by a large factor, limited only by the sharpness of the intrinsic mosaic spread. The conventional double-crystal rocking curve with equivalent scattering vectors in what is called the parallel position has its counterpart for two crystals with different scattering vectors if each crystal is bent to its proper radius of curvature. Like the parallel-position case, the collimation does not enter into the width of the rocking curve. The rocking curve can be sharper than the usual parallel-position convolution of the two mosaic spreads. The often observed lack of agreement between rocking curves in what seem to be identical geometries is explained as a rotation of the mean of the mosaic spread across a crystal, which is equivalent to a bent crystal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010603
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  • 80
    Digitale Medien
    Digitale Medien
    Commission on Powder Diffraction (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 537-537 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887085960
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  • 81
    Digitale Medien
    Digitale Medien
    A fixture for X-ray crystallographic studies of biomolecules under high gas pressure (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 4-10 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A fixture is described for collecting X-ray diffraction data from biomolecule crystals under gas pressures up to 300 atm (30 MPa). The fixture is completely portable and can be used on conventional diffractometers. Normal procedures for crystal mounting, alignment and data collection require only slight modification. A test data set of the protein sperm whale metmyoglobin under a gas pressure of 145 atm of N2 gas has been collected to a nominal resolution of 2.0 Å using Cu Kα radiation and refined to an R-factor of 16.2%. Data collection beyond 2.0 Å resolution is hampered by the presence of strong powder diffraction from the beryllium shroud.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887008173
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  • 82
    Digitale Medien
    Digitale Medien
    X-ray absorption spectroscopy in the dispersive mode with synchrotron radiation: optical considerations (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 15-22 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Aspects of the optics of the energy-dispersive scheme for X-ray absorption spectroscopy are discussed. The idea of a set of monochromatic focus points related to a set of local Rowland circles is introduced to account for the source-size effect on the energy resolution. It is shown that there exists an optimized location of the position-sensitive detector where the energy resolution is no longer source-size dependent. In addition, the stability of the dispersive optical system has been estimated and a 10 meV energy-scale reliability is currently achieved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887008239
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  • 83
    Digitale Medien
    Digitale Medien
    The effect of sample position on the determination of triaxial stress by X-ray diffraction (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 38-41 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The determination of the full three-dimensional stress tensor in a specimen by X-ray diffraction requires that the strain be measured with the sample tilted in both a positive and a negative sense for different rotations of the sample in its own plane. The error introduced in the measured strain as a function of the position of the specimen relative to the X-ray diffractometer axis is investigated and it is shown that the negative tilt values are more sensitive to sample position than the positive tilt values. The determination of the shear stress components uses the difference between the measured strain at equivalent positive and negative tilts and hence it is shown that displacement of the sample could lead to incorrect deductions concerning the presence and magnitude of the shear stress components.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887008860
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  • 84
    Digitale Medien
    Digitale Medien
    Standard Crystallographic File Structure-87 (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 537-538 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887086047
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  • 85
    Digitale Medien
    Digitale Medien
    The tensor of compositional deformation. A new crystallographic way to analyse syncrystallization (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 10-15 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Syncrystallization can be analysed through a new approach: the determination of the `tensor of compositional deformation'. It is a convenient way to take structural anisotropy into account and to point out the directions of strongest and weakest modifications of the intermolecular interactions due to the substitution process. The example of 2-chloronaphthalene-2-methylnaphthalene alloys is given in order to illustrate the interest of this new tool.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887008185
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  • 86
    Digitale Medien
    Digitale Medien
    A position-sensitive detector for neutron diffraction topography (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 28-33 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The first test of a position-sensitive photomultiplier in a thermal neutron diffraction topography experiment is reported: a spatial resolution was obtained of ∼200 μm in FWHM over a sensitive area of size ∼8 × 8 mm (∼1600 pixels) and a detection efficiency of the order of 15% when using a 0.25 mm thick ZnS–LiF (NE 426) scintillator. The advantages of this detector, its foreseeable improvements, and the scientific problems it could help to solve are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887008343
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  • 87
    Digitale Medien
    Digitale Medien
    Publish your Crystallographic Computer Programs (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 76-76 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889888099777
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  • 88
    Digitale Medien
    Digitale Medien
    Laboratory EXAFS in a dispersive mode (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 79-85 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A laboratory dispersive mode spectrometer, capable of operating in either the analysing crystal transmission mode or a reflection mode, is described. Extended X-ray absorption fine structure (EXAFS) spectra of Re and ReO2, obtained in the transmission mode, compare favourably with those from a scanning spectrometer at a synchrotron source. Factors affecting resolution, intensity and background in this transmission mode are discussed. Experiments with asymmetric reflection geometries, which have shown both improved resolution for X-ray absorption near edge structure (XANES) and reduced collection times, are reported. Methods of reducing backgrounds due to multiple Bragg reflections and Compton scattering are proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887008641
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  • 89
    Digitale Medien
    Digitale Medien
    Interpretation of the pair function for laminar amorphous materials in the case of coals. II. Structure of coals (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 102-105 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: From studies on six petrographic components of Polish coals by the radial distribution function method and the interatomic distances calculated from them the proportions of atoms with sp2 and sp3 hybridization and the extent of units with sp3-type structure were determined. From these data and the results of the pair-function analysis performed in paper I [Grigoriew (1988). J. Appl. Cryst. 21, 97–101], the model interpretation of the structure of these materials was carried out by matching experimental and model pair functions P(r). The model was defined as an average structural unit which scatters X-rays coherently. It appears that such units in these materials are larger than previously expected and for vitrinites and fuzinites they are in the form of turbostratic layers. The process of formation of stacks of layers was observed in components with the lowest degree of ordering.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887009907
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  • 90
    Digitale Medien
    Digitale Medien
    Simulation of X-ray double-crystal rocking curves at multiple and inhomogeneous heteroepitaxial layers (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 446-451 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Synchrotron radiation has been used to obtain double-crystal X-ray rocking curves from inhomogeneous layers of GaInAs on InP at a range of wavelengths. The consistency of the lattice-parameter profiles deduced by simulating the rocking curves using the Takagi–Taupin equations is shown to be good. The computational method has been extended to calculate the rocking curves from relatively thick multilayer structures of GaAlAs on GaAs grown by molecular beam epitaxy. This dynamical-theory approach permits the prediction of positions, heights and widths of major and satellite peaks. Results are in excellent agreement with experimental measurements, and by comparing experimental and calculated profiles the structural parameters of the layer can be deduced. The dynamical theory is particularly suitable for calculating the complete rocking curve especially where thick confining layers are present and the computational model is directly applicable to multi-layers with varying layer thicknesses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501069X
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  • 91
    Digitale Medien
    Digitale Medien
    Characterization of alumina powder using multiple small-angle neutron scattering. I. Theory (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 467-472 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Microstructural parameters of high-purity alumina powder are determined quantitatively throughout the bulk of the material using small-angle neutron scattering techniques. A unified theoretical and experimental approach for analyzing multiple scattering data is developed to obtain values for particle size, volume fraction and surface area. It is shown how particle size and volume fraction can be measured in a practical way from SANS data totally dominated by incoherent multiple scattering (`beam broadening'). The general phase-shift dependence of single-particle scattering is incorporated into the multiple scattering formalism, and it is also shown that the diffractive limit (small phase shift) applies even for phase shifts as large as unity (particle radii of order 1 μm). The stability of the Porod law against multiple scattering and the phase-shift scale are described, a useful empirical formula for analysis of beam broadening data is exhibited, and the applicability of the formulations to polydispersed systems is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188988501072X
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  • 92
    Digitale Medien
    Digitale Medien
    Profile refinement of powder diffraction patterns using the Voigt function (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 461-466 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The Voigt function has been incorporated as a peak-shape description into a program for the refinement of constant-wavelength X-ray and neutron diffraction patterns. The results obtained for neutron diffraction are encouraging and indicate that the Voigt function describes the symmetrical component of the profile peak shape to high accuracy even in the presence of substantial line broadening from particle-size effects. In contrast with approximations to the Voigt function, such as the pseudo-Voigt and Pearson VII functions, the present treatment allows the angular dependences of line-broadening effects resulting from particle-size and instrumental contributions to be coded independently from each other in the Rietveld technique. The present treatment, which details improvements to the symmetrical component of the peak shape, does not offer a fully rigorous description of the peak shape as asymmetry corrections such as those given by Howard [J. Appl. Cryst. (1982), 15, 615–620] are not included.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010718
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  • 93
    Digitale Medien
    Digitale Medien
    The small-angle approximation of X-ray and neutron scatter from rigid rods of non-uniform cross section of finite length (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 452-460 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The theory of small-angle neutron or X-ray scattering from a solution consisting of rods that are uncorrelated in position and orientation and its use in determining the mass per unit length and cross-sectional radius of gyration is extended to rods of finite length and non-uniform cross-sectional structure. The case of a rod made up of identical motifs spaced in a regularly repeating axial structure is considered first. Analysis of the small-angle scatter by a modified Guinier plot gives the mean mass per unit length of the motifs. The apparent squared cross-sectional radius of gyration is the weight average. These results are then generalized to the case where variable randomly distributed structural elements are present including variable spacing between the motifs making up the rod. In this way expressions are obtained that describe the scatter from rods with structural contributions from random thermal fluctuations, bound ligands and intrinsic structural heterogeneity. It is shown that, in general, systematic errors are introduced in the analysis of rods of finite length having variable structural components. However, if all the motifs have the same mass, and if the variance in their spacing is small, such errors are not important provided that the rods are of sufficient length.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010706
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  • 94
    Digitale Medien
    Digitale Medien
    Characterization of alumina powder using multiple small-angle neutron scattering. II. Experiment (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 473-479 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Small-angle neutron scattering techniques developed in the preceding paper [Berk & Hardman-Rhyne (1985). J. Appl. Cryst. 18, 467–472] are used to obtain microstructural parameters of high-purity alumina powder. The values of the particle size, volume fraction and surface area have been obtained and are compared to data from techniques such as laser light scattering, X-ray sedigraph and scanning electron microscopy. The particles exhibit a log–normal distribution and are spherical in shape with a mean particle size of 342 nm determined from SANS analyses of both beam broadening and Porod regions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010731
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  • 95
    Digitale Medien
    Digitale Medien
    Absorption corrections and digital filtering of X-ray diffraction profiles recorded with a position-sensitive detector (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 487-492 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Expressions for the absorption correction function are obtained in the form of integral equations for the case of a flat-plate sample and a position-sensitive detector. It is shown that the absorption correction used for both transmission and reflection geometries with a conventional diffractometer may be applied to a diffractometer equipped with a linear position-sensitive detector. The application of a Savitzky–Golay-type digital filter considerably facilitates the analysis of the data without losing pertinent information.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010755
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  • 96
    Digitale Medien
    Digitale Medien
    Analysis of single- and double-crystal spectrometers using three-dimensional DuMond diagrams and the high-precision measurement of the Cu Kα1 line profile (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 218-223 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The general principles of single- and double-crystal spectrometers are described using the three-dimensional DuMond diagram and new formulae for the resolution of the spectrometers are deduced. A method for measuring the fine structure of spectral lines with high precision is suggested and a generalized method of refraction correction is discussed. The Cu Kα line profile is measured carefully by double-crystal spectrometers using (nS, nS) and (nV, nR) arrangements, and a hump is found unambiguously on the long-wavelength side of the Cu Kα1 line.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889887011841
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  • 97
    Digitale Medien
    Digitale Medien
    SHAMGAR's OXGOAD: A new approach to the problem of resolution corrections for triple-axis neutron inelastic scattering data using parallel processors (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 493-498 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: One problem in the analysis of triple-axis neutron inelastic scattering data is the large numerical computations involved in applying full resolution corrections, which in one extreme involves an often-repeated four-dimensional numerical integral. A program called SHAMGAR has been written for an ICL Distributed Array Processor that will both calculate the full convolution of a model scattering function with the resolution function and allow refinement of the model simultaneously to many sets of experimental data by a non-linear least-squares fit. Sample results and performance figures are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010767
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  • 98
    Digitale Medien
    Digitale Medien
    Molecular surface Triangulation (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 499-505 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A method is presented for triangulating the surface of a molecule. A triangulated surface is a polyhedron, all of whose faces are triangles. The triangles are created by subdividing the curved faces of an analytical molecular surface that has been precalculated by an earlier algorithm. The triangulated surface has many applications. Molecular areas and volumes may be calculated from it. Packing defects in proteins may be identified. It may be used to determine whether a particular water molecule lies in the interior of the protein or on the surface. The triangulated surface may be drawn on pen plotters, vector graphics systems and raster graphics terminals. Mathematical functions defined on the surface may be contoured. Local maxima and minima of functions may be located. While the triangulated surface is less accurate than the analytical molecular surface it is derived from, it has the advantage of being much simpler and easier to deal with. It combines the simplicity of a dot surface with the continuity of an analytical surface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010779
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  • 99
    Digitale Medien
    Digitale Medien
    Use of kinematical diffraction in X-ray topography (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 509-512 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new X-ray topographic method is proposed that makes use of the kinematical diffraction component, which is significantly more sensitive to the crystal-surface imperfections than dynamical Laue–Bragg diffraction. The sensitivity of the method has been studied using a triple crystal diffractometer to separate kinematical and dynamical components of the diffraction intensity curve when the Bragg condition is nearly satisfied.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889885010792
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  • 100
    Digitale Medien
    Digitale Medien
    Statistical treatment of measured orientation relationships in orientation space (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 311-316 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Measured orientation relationships between neighbouring grains in single-phase α- and β- and dual-phase α + β-brasses are analysed by means of the χ2-test. The orientation relationships are characterized by the three Euler angles and hence can be represented as points in orientation space. A description of the symmetry relations of equivalent points in this space is given and then the distribution function for random orientation relationships is derived. This distribution is compared with the distribution of the measured orientation relationships using only a single χ2-test for each boundary type. The results of the tests are the same as obtained from the analysis of axis-angle pairs, in which case twoχ2-tests are necessary. None of the measured distributions is random.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889888002316
    Standort Signatur Erwartet Verfügbarkeit
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