ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • National Academy of Sciences  (3,454)
  • International Union of Crystallography (IUCr)
  • 1980-1984  (5,960)
  • 1984  (2,940)
  • 1982  (3,020)
Collection
Years
  • 1980-1984  (5,960)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 5-14 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A method of measuring accurate cubic lattice parameters is developed which is suited to the type of conditions encountered in high- and low-temperature powder diffractometry. This is based on the fact that the absolute Bragg angle of each line in an indexed cubic diffraction pattern can be determined from a knowledge of the differences in angles between lines. Accurate zero-angle alignment, therefore, is unnecessary. Furthermore, it is shown that the peak or centroid shift of the line profiles arising from the instrumental and physical aberrations can be determined directly from the measured angular data without assuming a specific angular dependence. In practice the accuracy of the method is of the order of 0.0002 Å for a lattice parameter of approximately 8 Å.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 20-26 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Calculations of diffraction line profiles and Scherrer constants for crystallites whose external shape has cubic symmetry are extended to crystallites of cylindrical shape. The analysis includes the limiting cases of acicular crystals and disks and, to a reasonable degree of approximation in many cases, to hexagonal prisms. These shapes have applications in size determination for materials which form prismatic crystallites, particularly those which belong to the hexagonal system or have been derived from substances with this symmetry.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 35-38 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The Warren–Averbach profile analysis was modified to study the deformed state of Al. The X-ray diffraction effect of dislocations locating on cell boundaries may be treated as `size broadening', while that of dislocations inside cells is `strain broadening', which may be treated with Wilkens's theory. X-ray Debye profile measurement was performed on deformed, recovered and annealed samples of commercial pure Al. Some information concerning the dislocation glide systems and distribution as well as the differences between the deformed and recovered state were given by the Debye profile analysis. The results are in good agreement with those obtained by other authors, which prove the reliability and correctness of the method.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 39-47 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The extended structure of the Pt L3 X-ray absorption edge for some platinum compounds was measured and Fourier inverted. It is shown that the way in which the contribution of the isolated atom is subtracted from the absorption spectrum may influence the shape of the first peak in the Fourier transform and possibly lead to erroneous structural interpretations concerning the first-neighbour shell of the absorbing atom. These errors are the more important the smaller the separation between the absorbing atom and its nearest neighbours. An improved method of subtraction of the isolated-atom absorption is proposed and checked.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 251-254 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Changes in the microporosity of several types of Brazilian high-ash coals have been analyzed by small-angle X-ray scattering as a function of thermal treatment. Pore size, determined using Guinier plots, decreased following thermal treatment of the samples. The modification of porosity induced by thermal treatment was similar for high-ash and low-ash coals, from which it may be inferred that mineral content is not a determining factor in the process of pore formation. Internal surface area for the samples was calculated with SAXS data. A correlation is established between the internal surface area values obtained and the carbon content and heat-treatment temperatures of the samples.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 279-281 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Crystal data for the series of piperazinium bis(n-alkanoates) of the type 2[CxH2x − 1O2−] [C4H12N22+] for x = 1 to 16 are presented. Most of these compounds have triclinic unit cells whose dimensions, obtained from single-crystal work, have been used to index their powder diagrams. The a ({\bar a} = 5.718 Å) and b ({\bar b} = 7.481 Å) cell dimensions remain nearly constant while the c dimension and the volume of the unit cell increase linearly with x, the number of carbon atoms in the alkanoate anion. Presumably the aliphatic sequence in the alkanoate anion adopts the fully extended conformation and lies in the bc plane and nearly along the c direction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 461-462 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Lattice-constant thermal expansions, Δa/a and Δc/c, have been measured on α-HgI2 single crystals from 293 K up to the red-to-yellow transition temperature. The curves Δa/a(T) and Δc/c(T) are linear. The thermal expansion coefficients are determined: α[100] = (1.0 ± 0.1) × 10−5 K−1 and α[001] = (4.6 ± 0.1) × 10−5 K−1. No evidence of a red-to-orange phase transition could be found.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 452-460 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Total neutron scattering data were collected on sputtered YFe2 at 298 K and TbFe2 at 423 K with a wavelength of 0.7 Å. The TbFe2 data were collected above the magnetic ordering temperature of 383 K. In addition, the elastic neutron scattering of TbFe2 was measured with the use of a pyrolytic graphite analyzer at a wavelength of 1.5 Å, and its total X-ray scattering was measured with Mo radiation and a silicon-lithium drifted detector. Experimental radial distribution functions, with statistical error limits, were calculated. Errors due to an incorrect background, scaling of the data and termination effects were minimized. The scale and shape of the experimental background and the coordination numbers, internuclear distances and disorder parameters, for the first six coordination spheres, have been determined. The contribution of paramagnetic inelastic scattering from TbFe2 to the total neutron scattering is quite appreciable. The shape of the background scattering, which goes through a maximum, is indicative of residual coherence and suggests short-range magnetic ordering where neighboring atom spins are aligned. These effects are not observed in YFe2, nor in the elastic TbFe2 data. The metallic glasses have a structural topology which is quite different from that found in their crystalline analogues. The transition-metal substructure, consisting of corner-sharing tetrahedra, is the only aspect of the crystalline topology preserved in the amorphous phase. The structural parameters suggest a tendency of the rare-earth atoms to cluster, thereby decreasing the number of Fe nearest neighbors relative to the crystalline structure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 55-59 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: By using data from the Wallace & Ward [J. Appl. Cryst. (1975), 8, 255–260] cylindrical texture camera integrated with other traditional X-ray powder film techniques for very low and very high diffraction angles, a new high-temperature modification of CeO2 was identified and indexed resulting in a trigonal or hexagonal unit cell with a = 8.36(2) and c = 10.42(2) Å, (axial ratio 1.264) and Z = 16. The new phase is an oxidation product of CeO2-doped hot-pressed silicon nitride. It can be quenched to room temperature under appropriate conditions. Its stability on reheating is strictly related to its interaction with the silicate phase.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 60-64 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Multiple electron scattering between weak beams has been used as the basis for a simple method to determine the absolute polarity of some non-centrosymmetric crystals. For crystals with the sphalerite structure many orientations have been found in which small departures from centrosymmetry produce large effects on the convergent-beam diffraction patterns (microdiffraction). The effects are reasonably independent of thickness and so can be analyzed qualitatively without the use of computers.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 570-571 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A method is proposed for unambiguously indexing X-ray multiple diffraction patterns obtained with irregularly shaped crystals on a four-circle diffractometer. The method is derived from the orientation matrix together with the operation of crystal rotation. It is shown that this method facilitates the procedures in the experimental method for phase determination.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 574-576 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Unit-cell constants for synthetic fluoroalleghanyite compounds have been determined by the refinement of X-ray powder diffraction data. Manganese norbergite: Pbnm, a = 4.862(2), b = 10.797(3), c = 9.188(2) Å, U = 482.4(4) Å3, Z = 4; alleghanyite: P21/b, a = 4.871(2), b = 10.818(6), c = 8.206(5) Å, α = 108.58(5)°, U = 414.1(7) Å3, Z = 2; manganhumite: Pbnm, a = 4.888 (2), b = 10.712(2), c = 21.749(6), U = 1138.8(5) Å3, Z = 4; sonolite: P21/b, a = 4.889(1), b = 10.668(3), c = 14.239(5), α = 100.83(5)°, U = 731.9(5) Å3, Z = 2. The JCPDS Powder Diffraction File numbers are: for manganese norbergerite 33–1500; for alleghanyite 33–1499; for manganhumite 33–1498; for sonolite 33–1497.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 577-577 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 577-578 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 579-579 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 579-580 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 116-119 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Three members of a new family of phases, Li3Mg2XO6: X = Nb, Ta, Sb, have been prepared by solid-state reaction of MgO and Li3XO4. Unit-cell parameters of Li3Mg2TaO6 determined by electron diffraction and refined by X-ray powder diffraction are a = 8.883(2), b = 5.802(2), c = 17.437(6) Å, with space group Fddd; z = 8. Powder diffraction data of Li3Mg2NbO6 and Li3Mg2SbO6 were indexed by analogy with those of Li3Mg2TaO6 and unit-cell dimensions obtained by least-squares refinement: Li3Mg2NbO6 a = 8.552(2), b = 5.897(1), c = 17.721(5) Å; Li3Mg2SbO6 a = 8.614 (1), b = 5.908(1), c = 17.759(5) Å.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 590-593 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The structure of the transition phase M′ in AlZnMg alloys has been studied by Buerger X-ray precession photographs and transmission electron microscopy. The M′ phase, also called η′ or R, has a hexagonal or pseudo-hexagonal cell with a = 4.96, c = 14.03 Å. It is confirmed that M′ precipitates are hexagonal platelets with the following epitaxy: (00.1)M′//(111)Al and |10.0|M′//1{\bar 1}0|Al. It is shown that none of the known models of the unit cell accounts for the observed scattered intensities.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 602-604 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: An improved `substitution method' for the separation of X-ray diffraction α1−α2 doublets is based on the possibility of refining both the proportionality constant between the α1 and α2 contributions to the line intensity and the doublet separation expressed in terms of the diffraction angle or of a related variable in the reciprocal space. Optimization of these two parameters, with a proper evaluation of the error, clearly shows the statistical nature of the oscillations appearing on the high-angle side of the pure α1 component after correction; their elimination by polynomial smoothing can therefore be performed and a procedure is suggested for achieving this result. A computer program, based on these principles, has been written and tested in many practical cases.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 611-614 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The precipitation behavior in the Ti–27at.%Nb–6at.%Ta–6at.%Zr alloy aged at 643 K was examined by means of time-of-flight neutron small-angle scattering. When the alloy was aged, fine-scale α precipitates appeared. During the precipitation process, each precipitate grew in size, but the total number of precipitates remained nearly constant up to 1 Ms of ageing. The increase of critical superconducting current density could be connected with increasing size of α precipitates. The specimen for the measurements consisted of a composite containing 3721 filaments in a copper matrix. The use of neutrons was shown to give great advantages for the investigation of precipitation phenomena.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 632-632 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The wrong original was used for Fig. 6(b) of Gastaldi, Jourdan, Marzo, Allasia & Jullien [J. Appl. Cryst. (1982), 15, 391–395]. The correct version of Fig. 6(b) is given. In Fig. 6(c) the growth time increases from right to left.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 635-636 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The high-temperature paraelectric phase of dicalcium lead propionate, DCLP, at 363 ± 5 K is tetragonal, with a = 12.574 (6), c = 17.403 (9) Å, V = 2751.4 Å3, Z = 4 and corresponds to the space group P41212 (or P43212). The thermal expansion curve shows the transition somewhere between 328 and 343 K.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 638-638 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 638-639 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 639-639 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 640-676 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 182-189 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The method of determining the thickness of a diffuse phase boundary with density profile governed by equilibrium conditions is proposed. It follows the well known procedure of analyzing the deviations from Porod's law. Errors in the obtained boundary thickness, owing to the statistical scatter in the intensity data and to the difficulty of separating the effect of density fluctuations within the phases, are examined. For this purpose, scattering curves are synthesized on the basis of a well defined model structure with known boundary thicknesses. These synthesized curves, when analyzed according to the proposed method, yield the correct boundary thickness under favorable conditions, but are also shown to lead to very erroneous results in some cases.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 211-215 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Monoclinic Gd2SiO5 has been investigated by high-resolution electron microscopy (HREM) at 100 kV. Structure images are observed in the [100] and [001] projections and calculations of the image contrast using the multislice approximation are carried out to interpret the observations. For thin samples the image fit is improved by Fourier filtering of the observed images. For thicker samples the fit is found to be very sensitive to small tilt deviations of the zone axis to the electron beam. For defects observed in a fast-cooled specimen, a model in which Gd atoms replace Si atoms in segments along the (100) plane is proposed and tested by contrast calculations. These defects may be one of the reasons for deviations from stoichiometry as frequently observed in rare-earth silicates.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 241-244 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A low-temperature camera for single-crystal X-ray investigation between 28 and 350 K has been developed for a modified Weissenberg goniometer. Cooling is provided by a double-stage cryorefrigerator which is firmly attached to the low-temperature camera. Stranded copper cables ensure a flexible heat transfer between crystal and cold finger allowing a crystal rotation of 180°. Compared to the usual Weissenberg technique almost no further limitation is given on the accessible angular range of the scattered radiation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 248-248 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The X-ray powder data have been obtained for a new phase MoGa5(CuS2)0.0556. The powder patterns were indexed on the basis of a tetragonal body-centred unit cell with the lattice constants a = 12.872, c = 5.284 Å, c/a = 0.410, dm = 6.825(8), dx = 6.869 Mg m−3, Z = 8.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 249-249 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 250-250 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 255-259 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The identification of twofold axes is straightforward if the cell is based on three of the shortest lattice translations. The distribution of twofold axes in space fixes the lattice symmetry and most conventional cell edges. A program based on this approach has been written. It works for the seven cases with minimum branching of the algorithm.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 266-274 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The commonest natural diamonds (classification type Ia) contain platelet defects on {100}, usually with mean diameters in the 20 to 100 nm range, which generate disorder diffuse X-ray reflections in the form of (100) spikes through reciprocal-lattice points. Corresponding spikes in electron diffraction patterns of diamonds, recorded with 100 and 120 kV electrons, have been investigated. It has been established that (100) spikes appear most strongly in electron diffraction patterns of diamonds very rich in platelets, and are absent in the case of platelet-free diamonds (types IIa and IIb). Spikes from diamonds containing relatively large platelets are sharper than those from diamonds containing very small platelets. Multiple scattering of electrons prevents measurement of the dependence of spike intensity upon diffraction order as can be done in the X-ray case. Some experiments with spike electron reflections have been performed that are impossible in the X-ray case. It has been shown that when the crystal volume sampled by the electron beam contains only one platelet, then the spike distribution reduces to a pattern containing only spikes normal to the platelet concerned. Also, dark-field weak-beam microscopy has been applied, by selecting one spike only in the diffraction pattern, to identify orientations of small platelets through the imaging of only those platelets normal to the spike selected.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 301-307 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The amplitude and phase of a wave scattered by an adsorbed layer can be deduced from the modifications of the Bragg peak of the powder by adsorption. The treatment of experimental data involves the interpretation of a function of the extra intensity detected and has the advantages of an integrated intensity method. Powders containing crystallites limited by several types of faces can be studied. The Co3O4 sample studied is limited only by (110) and (111) faces of respective areas 11 and 27 m2 g−1. The (111) planes terminating crystallites contain oxygen covering a layer of cobalt in octahedral sites. Other possible terminating layers are ruled out for (111) planes. The structures of the bidimensional layers of argon on (110) and (111) planes are determined.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 315-322 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A correction for the unavoidable truncation of line profiles and an improved correction for the inherent curvature of the variance–range function are discussed. An analytical procedure for making the corrections is proposed and applied to theoretical and practical small-crystallite line profiles. An alternative procedure for obtaining the integrated intensity, and hence the integral breadth, and the variance (Fourier) apparent size is also presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 289-300 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: As a consequence of several technological developments, the speed and sensitivity of solution X-ray (and neutron) scattering studies have recently risen by factors which may be as large as 105; formal problems – like assessing the information content of the data and retrieving that information in structural terms – have thus become of immediate practical interest. The general problem of the information content of scattering experiments is discussed; its mathematical expression is derived, which depends on both the experimental data (observed values and estimated accuracy) and the a priori stochastic assumptions on the structure of the sample. The practical application of these notions to solution scattering studies involves several steps, three of which – choice of the degrees of freedom, data reduction and error analysis – are dealt with in this work. The first step is to specify the minimal number of independent parameters necessary and sufficient to describe the whole of the scattering properties of the system. Whenever the solute particles are of finite dimensions the entire scattering curve is defined by its values at a one-dimensional lattice; if, moreover, the asymptotic trend of the scattering curves is known, then the degrees of freedom are the ideal intensities at a finite number of points plus a small number of parameters describing the asymptotic trend. It is also possible to include among the degrees of freedom a few subsidiary parameters like the normalization factors. The next step is, starting from a composite set of data, to determine the most probable numerical value of each degree of freedom and to evaluate its range of uncertainty. This is discussed within the framework of variable-contrast studies, assuming that the invariant-volume hypothesis is fulfilled. An algorithm is formulated which treats all the experimental observations and determines simultaneously all the degrees of freedom and the error matrix. The algorithm also allows one to introduce additional linear constraints on the degrees of freedom. As an example, the algorithm is applied to solution X-ray scattering data recorded with a low-density serum lipoprotein. The determination of the maximal chord of the particle – an important parameter in the informational analysis – turns out to be rather tricky.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 330-337 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The design and operation of a focusing camera for high-resolution macromolecular crystallography with synchrotron radiation (SR) are described. The performance of this service-oriented instrument is evaluated on the basis of five years of use. Standard procedures for data collection, data processing and data reduction have been modified to take unusual features of the SR source into account; the effect of polarization is thoroughly discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 338-351 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Expressions are developed for reflecting range from various models, and the practical application of these in terms of reflection prediction and calculation of partiality is discussed here for conventional sources. Synchrotron sources utilizing focusing monochromator systems, where the wavelength of the radiation incident at the sample is correlated with the angular direction of that radiation, are dealt with elsewhere. Even for conventional sources spectral dispersion is shown to be an important factor, particularly in the case of high-resolution data. The various published methods are discussed and expressions are derived from first principles showing that all are inherently equivalent, differing only when approximations are used, and revealing a missing factor of two in the treatments of Rossmann [J. Appl. Cryst. (1979), 12, 225–238] and Rossmann, Leslie, Abdel-Meguid & Tsukihara [J. Appl. Cryst. (1979), 12, 570–581]. Particular emphasis is placed on the method which uses a spherical reciprocal-lattice volume element whose dimensions are designed to reproduce the expected or observed reflecting ranges, showing that for all practical purposes the effects of beam cross-fire, mosaic spread and spectral dispersion can be adequately simulated by such a volume. The equations for reflecting range are of particular interest in the electronic stationary-picture method and in the use of electronic area detectors.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 361-374 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In the Rietveld method of analysing powder diffraction data, the crystal structure is refined by fitting the entire profile of the diffraction pattern to a calculated profile. There is no intermediate step of extracting structure factors. The method was applied first to diffraction patterns recorded with neutrons at a fixed wavelength. It has now been used successfully for the treatment of results from the four categories of experimental technique, with neutrons or X-rays as the primary radiation and with the scattered intensity measured at a fixed wavelength or at a fixed scattering angle. In this article we discuss the application of the Rietveld method to each of these techniques.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 540-541 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Second-harmonic generator tests for non-centrosymmetry have been applied to five monoclinic potassium feldspars. Four samples yielded null results; one specimen displayed a positive test for non-centrosymmetry.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 564-566 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Clays prepared by sedimentation from aqueous suspension were shown to contain aggregates much larger than individual clay particles. Small-angle X-ray scattering data were obtained with an automated Bonse–Hart instrument. The distance distribution functions for the clay aggregates were obtained using the Glatter indirect Fourier transform method. The distance distribution function extended to over 200000 Å, and the average radius of gyration was over 50000 Å in the most extreme cases.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 567-569 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The intensity of the small-angle X-ray and neutron scattering from a polydisperse system of randomly oriented independently scattering particles is shown to be proportional to h−α for all values of the scattering vector h when the distribution of particle dimensions is proportional to r−(2d + 1 − α), where h = 4πλ−1 sin(θ/2);θ is the scattering angle; λ is the wavelength; r is the maximum dimension of a particle; and d is the number of dimensions of the particles. The value of α lies in the interval 0 〈 α 〈 ω, where ω = 4, 2, and 1 for d = 3, 2, and 1 respectively. This relationship between the scattered intensity and the particle-dimension distribution does not depend on the shape of the particles in the polydisperse system, provided that the particle-shape distribution is independent of the distribution of particle dimensions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 571-573 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A simple method is described for increasing the lifetimes for several crystals of proteins and viruses during collection of high-resolution X-ray diffraction data on film. Crystals are mounted in a capillary filled with mother liquor, with cotton lint fibers nested against them to prevent movement. Some results and limitations of the method are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 578-578 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 579-579 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 580-580 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 594-601 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Dislocation-free silicon crystals of ({\bar 2 \bar 1 \bar 1}) orientation with a hyperbolic notch, subjected to tensile deformation at 1073 K, were used as model material for the analysis of the induced plastic zone. The results obtained by X-ray topography and X-ray rocking-curve measurements were compared to theoretical calculations and predictions based on continuum mechanics. Good agreement between experiment and theory was obtained regarding the shape of the plastic zone, the contribution of the active slip systems to the size of the plastic zone and the direction of the maximum plastic strain trajectory in the zone. Discrepancies between experiment and theory regarding the symmetry relation of the plastic zone lobes and the dislocation density near the notch tip were attributed to the interactions and resulting work-hardening. These aspects were not taken into account in calculations of continuum mechanics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 605-610 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In two previous papers, algorithms designed for searching, matching and identifying phases in qualitative X-ray powder analysis were reported [Schreiner, Surdukowski & Jenkins (1982). J. Appl. Cryst. 15, 513–523, 524–530]. This paper extends the searching technique to unknowns containing isotypical phases and solid solutions. Methods are described for distinguishing among isotypical compounds in qualitative analyses, and for permitting the retrieval of phases in a data base that differ from measured patterns by a uniform Δd/d scale factor.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 615-620 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Neutron powder diffractometers operating with large vertical counter acceptance angles produce diffraction patterns in which the peaks are shifted and broadened, and may become distinctly asymmetric. It is shown that a sum of Gaussians generally provides a good approximation to these peaks. The sum of Gaussians has been included as an optional description of the profile within an existing profile refinement program. In this application, the sum incorporates a single asymmetry parameter which can be estimated from the diffractometer geometry or determined in the refinement. It is recommended that, in describing asymmetric peaks, the sum of Gaussians be used in place of the simple Gaussian multiplied by Rietveld's semi-empirical asymmetry factor.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 621-625 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Two distinct X-ray diffraction studies of 2̃ mol dm−3 ZnSO4 solutions were carried out in order to assess the possibility of studying the state of the sulfate ion in water and to verify whether and how structural information depends on possible differences in experimental data. It is shown that the X-ray diffraction method is unable to provide results capable of unambiguous modelling of the SO2−4 coordination; even the complete omission of sulfate-water interactions does not lead to unsatisfactory synthetic structure functions. This conclusion does not seem to be affected by differences in the experimental data; however, some characteristics of the `best' models can be affected by differences in experimental data that are within the limits of experimental uncertainties.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A coordinate X-ray diffractometer based on a flat two-coordinate multiwire proportional chamber 350 × 350 × 10 mm and information readout from cathode printed-circuit delay lines is described. The diffractometer is used to study macromolecular single crystals. The chamber is placed on a two-circle goniometer at distances of 300, 500 and 750 mm from the crystal. The diffractometer operates on-line with an SM-2 computer. A diffraction picture is collected in a 64 K 16-bit word computer core memory with the maximum count rate of 250000 events s−1. The detection quantum efficiency of Cu Kα radiation is about 70%. The number of spatial resolution elements of a diffraction picture is ̃50000, the resolution time ̃0.5 μs. The general case of inclined geometry is used. The diffraction picture is collected during quasi-continuous scanning. Control of the diffractometer, data collection and pre-computing X,Z are performed at the same time. The diffractometer makes it possible to study single crystals having unit cells up to 250 Å at a resolution of 3.5 Å and to 84 Å at a resolution of 1.5 Å.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 632-635 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: X-ray powder data have been recorded for the 32 complexes: CuL2X2 [L = 2-(2-pyridyl)acetamide (aapH), N-(2-pyridyl)benzamide (bapH), N,N′-diacetyl-2,6-diaminopyridine (daapH), N,N′-dibenzoyl-2,6-diaminopyridine (dbapH); X = Cl, Br]; ML2X2(M = Ni, Co; L = aapH, bapH, daapH, dbapH; X = Cl, Br, I). These data indicate that, in all cases: (a) complexes ML2X2(M = Ni, Co; X = Cl, Br, I) are isomorphous; (b) complexes CuL2X2(X = Cl, Br) are isomorphous; (c) the Cu complexes are not isomorphous with the Ni and Co analogues (a difference ascribed to the Jahn–Teller effect); and (d) the three points (a)–(c) above are consistent with the available spectral and magnetic data.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 636-637 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: To allow a convenient three-dimensional visualization of protein features and particularly of binding sites van der Waals contour levels are produced on large-scale stereopairs (about 0.3 to 1.0 cm Å-1). A chain of Fortran programs has been written and give screen or paper graphic outputs. The large-scale stereopairs can be easily viewed with only two ordinary mirrors.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 639-639 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 238-243 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Selective application of only parameter shifts with large eigenvalues permits singular or near-singular least-squares problems to be solved. This `eigenvalue filtering' process has been applied to the refinement of the unit-cell, crystal-orientation and reflecting-range parameters needed to process oscillation films. Eigenvalue filtering permits automatic identification and determination of just those combinations of parameters that are most relevant for processing films from a particular crystal in a particular setting. The procedure may be carried out with alignment information from an individual data film or from multiple alignment films taken at different spindle angles. Eigenvalue filtering has been incorporated in a refinement program that minimizes discrepancies between observed and calculated fractions recorded for partially recorded reflections. This permits the reflecting range (combined mosaic spread, beam cross-fire, and wavelength spread) to be refined along with the unit-cell and orientation parameters. Observed fractions recorded may be obtained by visual estimation prior to film scanning, or the program may be used in a `post-refinement' mode with data obtained from actual intensity measurements. The relatively unreliable information represented by the positions of spots on the film is not used except for indexing. The program handles crystals of any symmetry in any setting and the oscillation spindle may be inclined from normal beam geometry. The mis-setting angles are defined in a crystal-fixed coordinate system, making it easy to compare refinement results for data taken at different spindle angles.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 249-256 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The instrumental optimization conditions for most small-angle scattering experiments in which the data are azimuthally symmetric require that the scattered flight path be equal to the incident flight path. This is in contrast to a recent analysis which shows that under some conditions the incident and scattered flight paths are in a ratio of two to one. The equal flight-path condition is also valid for experiments measuring sharp (Bragg-like) peaks, or where the intensity is required at specific scattering vectors, as in low-angle diffraction of ordered or semiordered systems. The implications of the optimization conditions on the resolution and count rates at the detector are discussed for both types of experiment, and the dependence of the resolution on the spectrometer geometry is considered.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 257-264 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: With a compact arrangement using single-crystal collimator and analyzer (silicon 220 reflection) of channel-cut type, angle-resolved scattering (ARS) curves of X-rays (Cu Kα1) for optically flat mirrors have been measured at various glancing angles, ω, of X-rays to the mirror surface with an angular resolution of 4′′. Weak scattered intensity (10−3–10−5 of the specularly reflected beam) is observed over an angular range of a few hundred arc s below and above the direction of specular reflection. When ω is close to the critical angle for total reflection, the scattered intensity at the low-angle tail of ARS curves is higher than that at the high-angle tail. This asymmetric tail profile of ARS curves is explained by simply superposing intensities of specularly reflected beams from surface elements inclined to each other.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 293-294 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A recent comparison of data for a specific experiment taken on a time-of-flight small-angle scattering spectrometer on a pulsed neutron source and data for the same kind of experiment taken at a steady-state reactor suggests that the instruments have similar performances, and in particular comparable count rates at the detector. This similarity disappears when resolution is taken into account. The criterion for a valid comparison should be the detector count rate for instruments measuring over similar ranges of scattering vector and with similar resolutions, as required by the particular experiment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 273-285 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The purpose of this paper is to establish an explicit correlation between the values and probable deviations of the observed intensities and the potential accuracy of the structure eventually determined using those intensities. This problem involves several steps: the choice in real space of a reference stochastic model defining the ideal state of ignorance; the determination in reciprocal space of the probability density corresponding to that model and of the probability law corresponding to the experiment; the determination of the information; the transfer of the information from reciprocal to real space; the interpretation of the information in terms of structural resolution. A rigorous treatment of this problem is hindered by the inadequate knowledge of the statistical correlations between different reflections; more realistically, it is convenient to address a simpler problem, corresponding to an ideal experiment in which the intensities relevant to each reflection are measured independently of all the other reflections. In this case the mathematical problems can easily be solved and a parameter introduced – called projection information – whose value can be determined. This information is the sum of two terms, one associated with the modulus, the other with the phase of each reflection. By resorting to a mathematical model it is possible to make use of the projection information to determine the value of a parameter akin to structure resolution. The final result of this work is an operational definition of resolution, based upon the stochastic properties of the experimental observations. This resolution can be used to assess and compare the intrinsic quality of different structure analyses and of different stages of one structure determination, before the structure is solved.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 297-306 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Crystal structure parameters have been obtained for α-Al2O3, β-PbO2 and (Mg, Fe)2SiO4 by Rietveld analysis of Cu Kα X-ray powder diffraction data collected on a conventional diffractometer using counting times ranging from 0.01 to 5 s per step. For all but the 0.01 s data collected on (Mg, Fe)2SiO4 the structural parameters obtained at different counting times are statistically identical at the 3 σ level, and the spread in the values is essentially the same as that obtained by sample repacking at a fixed counting time of 1 s per step. The parameter e.s.d.'s and conventional agreement indices Rwp and RB decrease to values limited by residual model errors as the counting time increases, but the goodness-of-fit parameter becomes unacceptably larger than its ideal value of unity. When more than a few thousand counts are accumulated for the maximum step intensity in the diffraction profile a weighting scheme based solely on counting variance is inappropriate and the parameter e.s.d.'s are no longer a reflection of their accuracy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 307-314 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The many-beam dynamical theory of moiré fringes of Gevers [Phys. Status Solidi (1963). 3, 2289–2297] has been applied to the parallel moiré case and the results have been verified on epitaxically grown Sn/SnTe specimens showing the sensitivity of moiré patterns to the presence of systematic reflections. The Fourier analysis of the calculated intensity profiles showed that each additional diffracted beam gives rise to a new term in the Fourier series so that the profile can be sinusoidal only in the two-beam approximation. The same result has been obtained recently by Pardo, Pariset & Renard [Phys. Status Solidi A. (1981). 64, 283–295], who applied a slightly different theoretical approach to Sb/Bi specimens. It is shown that the corrections to scattering factors for temperature effects are not important since they do not affect the general character of the moiré profiles. Some experiments were performed showing the dependence of the moiré pattern on the number of beams that are transmitted through the objective aperture. The effect of the gradual thinning of one layer on the moiré pattern could be reproduced by computer simulation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 331-333 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A combination of X-ray powder diffraction and single-crystal Laue photography was used to determine the unit-cell parameters for letovicite. μr = 247.25. The unit cell is triclinic, P1 or P{\bar 1}, and has dimensions a0 = 5.87(1), b0 = 10.17(3), c0 = 8.27(1) Å, α = 101.1(4), β = 111.1(1), γ = 89.9(2)°, V = 450.7 Å3, Z = 2, Dx = 1.82 Mg m−3. The M(20) cell reliability is 23.8. Many weak powder spectra were observed, which preclude the possibility of monoclinic cell symmetry previously reported. Projection of the letovicite Laue data along [001] reveals the striking pseudo-hexagonal symmetry observed optically. The JCPDS Diffraction File No. for ammonium hydrogen sulfate is 35-1500.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 364-366 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A program is presented that solves crystal structures completely using advanced Fourier methods starting from a small known fraction (about 8%) of the structure. The program uses a statistical test based on the R2 factor to check the correctness of the model obtained so far. The results obtained with four test structures are given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 369-370 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 370-370 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 372-372 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 373-373 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 22-26 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Several procedures for Fourier analysis of single diffraction peaks for microstrains and mosaic sizes are compared. A simple new method works well, especially when the size distribution is broad, and/or when the strains vary in an unusual manner.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 39-42 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A computer program for unambiguous and consistent indexing of a series of single-crystal diffraction patterns is discussed which allows determination of the unit triangle and therefore tilting of the specimen into any special orientation even if no Kikuchi patterns can be observed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 47-54 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: For the application of Rietveld profile analysis to neutron powder diffraction data a precise knowledge of the peak profile, in both shape and position, is required. The method now in use employs a Gaussian-shaped profile with a semi-empirical asymmetry correction for low-angle peaks. The integrated intensity is taken to be proportional to the classical Lorentz factor calculated for the X-ray case. In this paper an exact expression is given for the peak profile based upon the geometrical dimensions of the diffractometer. It is shown that the asymmetry of observed peaks is well reproduced by this expression. The angular displacement of the experimental profile with respect to the nominal Bragg angle value is larger than expected. Values for the correction to the classical Lorentz factor for the integrated intensity are given. The exact peak profile expression has been incorporated into a Rietveld profile analysis refinement program.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 77-84 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In the solvent contrast variation technique, the structure factor is a linear function of contrast, and the intensity is therefore a parabolic function of contrast. A method has been developed which scales together data measured at different contrasts on different samples. Once the data are scaled, structure-factor amplitudes or intensities for any other contrast can be obtained by inter- (or extra-)polation. The magnitude of the relative phase change between contrast, an important piece of phasing information in single-crystal studies, can be determined.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 100-102 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: These studies on phase transition and crystal structure in a single-crystal of CTFP by X-ray diffraction in the temperature range 88 to 293 K show that CTFP undergoes successive phase transitions at about 123, 143 and 178 K and that the existence of another phase transition at about 168 K is possible. In the lowest-temperature phase, various commensurate and incommensurate structures were found. The appearance of the structure depends on storage duration at 293 K after undergoing the successive phase transitions. The original crystal, just crystallized from acetone solution, showed commensurate structure of which the modulation wave number, δ, is 0.20. The samples stored for a week and a month were both incommensurate. However, the crystals stored for two months were commensurate (δ = 0.20). Therefore, the storage duration of two months is a relaxation time long enough to recover the genuine structure. In the other temperature phases below 178 K, the crystals were all incommensurate. Consequently, the complicated structural change of CTFP crystals during storage is now well understood as a thermal relaxation phenomenon.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 120-121 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 122-122 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 131-133 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A procedure based on successive convolution operations is developed and associated with the Warren–Averbach method. Applications to cold-worked lithium fluoride samples are presented. The microstrain results are compared with those obtained in the classical way including the use of the direct deconvolution method. It is shown experimentally that the difficulties involved in the deconvolution operation have no significant effect on the evaluation of microstrains by the classical X-ray line-profile analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 134-139 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Equations are derived for the intensity ratio R of secondary to primary scattering in the fixed-sample transmission case with an incident-beam monochromator crystal that results in a polarization ratio Km for unpolarized incident radiation. A table allows R to be calculated for Km = 0. This table, along with the one for Km = 1 published previously for the case without a monochromator, allows R to be estimated before an experiment is done and thus an optimum experiment can be designed. A simple computer program allows direct calculation of R once experimental data are obtained if it is desired to avoid interpolation. Determination of R involves some approximation, but the values obtained are sufficiently accurate for most purposes. However, R can be improved using exact equations, if desired. If synchrotron radiation polarized normal to the plane of scattering of the monochromator is used, R does not depend on Km, and the value of R for Km = 0 applies despite the true value of Km. As is expected from symmetry considerations, R is independent of Km in the small-angle scattering limit.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 159-166 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A new linear position-sensitive scintillation detector has been developed and installed on a neutron powder diffractometer. The physical properties of this detector are described; test powder diffractograms are presented. The special advantages of this detector for neutron powder diffractometry are discussed: high detection efficiency also in the region of short wavelengths (75% for λ = 1.3 Å), good spatial resolution (FWHM = 2.5 mm), and high data-point density (Δ2θ = 0.02°). Special emphasis is placed on peak-profile analysis for the powder diffraction patterns. Examples for position and intensity separation of overlapping reflections are presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 167-171 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A 3 mm long double-polytype region was found in a ZnS needle. The region consists of a fine mixture of 47% of each of the polytypes 20L(5753) and 60R(5537)3 and about 6% of the polytype 60R(511553)3. The latter polytype is assumed to be the parent polytype transforming into the two others. It is the first time that traces of the parent polytype have been found in a double-polytype region. The formation mechanism of double-polytype regions is explained as a two-stage transformation process: expansion of grown-in stacking faults taking place at temperatures just below the hexagonal-to-cubic transition temperature, followed by a sudden formation and expansion of stacking faults at a lower temperature. It is suggested that a similar mechanism operates in the formation of single polytype regions and disordered ones.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 189-195 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The optimum parameters and properties of a new type of neutron monochromator based on elastically bent silicon single crystals are theoretically evaluated. The use of a fully asymmetrical geometry permits the achievement of rocking-curve widths exceeding 20' in the incident beam. The associated effect of the reflected-beam widening is compensated for by the second crystal in the parallel (1,−1) setting in opposite geometry. Reflectivity calculations indicate that this double-crystal system might be compared with the best single-crystal mosaic monochromators. Besides the easy control of the effective mosaicity and the corresponding integrated reflectivity by variation of the bending radius, a further advantage of this system is its simultaneous action as a neutron filter improving the ratio of the thermal neutron signal to the background.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 209-210 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A simple technique has been developed to lessen radiation damage of protein crystals grown from low-ionic strength solution. The technique consists of replacing the mother liquor with solutions containing 10–20% of polyethylene glycol 4000 or 20000.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 210-211 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The powder data at 293 K of p-dichlorobenzene (pDCB), C6H4Cl2, p-dibromobenzene (pDBB), C6H4Br2, and of their mixed crystals [pDCB]x [pDBB](1−x) are reported. Their thermal stability at 293 K is given. They are all isomorphous, monoclinic, P21/a with Z = 2. a = 14.792 (6), b = 5.839 (2), c = 4.036 (2) Å, β = 112.52 (4)°, V = 322.0 (5) Å3, Dx = 1.516 Mg m−3 for pDCB; a = 15.487 (2), b = 5.836 (2), c = 4.108 (1) Å, β = 112.74 (1), V = 342.5 (3) Å3, Dx = 2.289 Mg m−3 for pDBB; a = 14.893 (10), b = 5.837 (7), c = 4.046 (3) Å, β = 112.48 (5)°, V = 325.1 (9) Å3, Dx = 1.592 Mg m−3 for [pDCB]0.90[pDBB]0.10; a = 14.942 (5), b = 5.840 (2), c = 4.048 (1) Å, β = 112.53 (3)°, V = 326.3 (4) Å3, Dx = 1.677 Mg m−3 for [pDCB]0.80 [pDBB]0.20; a = 15.018 (4), b = 5.846 (1), c = 4.061 (1) Å, β = 112.50 (2)°, V = 329.4 (3) Å3, Dx = 1.751 Mg m−3 for [pDCB]0.70 [pDBB]0.30; a = 15.138 (11), b = 5.843 (3), c = 4.067 (3) Å3, β = 112.57 (8)°, V = 332.2 (8) Å3, Dx = 1.825 Mg m−3 for [pDCB]0.60 [pDBB]0.40; a = 15.247 (6), b = 5.842 (2), c = 4.081 (2) Å, β = 112.66 (5)°, V = 335.4 (5) Å3, Dx = 1.896 Mg m−3 for [pDCB]0.50 [pDBB]0.50; a = 15.300 (5), b = 5.838 (1), c = 4.081 (1) Å, β = 112.54 (4)°, V = 336.7 (3) Å3, Dx = 1.976 Mg m−3 for [pDCB]0.40 [pDBB]0.60; a = 15.373 (4), b = 5.842 (1), c = 4.094 (1) Å, β = 112.64 (3), V = 339.3 (3) Å3, Dx = 2.048 Mg m−3 for [pDCB]0.30 [pDBB]0.70; a = 15.410 (7), b = 5.838 (4), c = 4.098 (2) Å, β = 112.65 (3)°, V = 340.2 (6) Å3, Dx = 2.129 Mg m−3 for [pDCB]0.20 [pDBB]0.80; and a = 15.450 (3), b = 5.838 (1), c = 4.103 (1) Å, β = 112.69 (1)°, V = 341.4 (2) Å3, Dx = 2.208 Mg m−3 for [pDCB]0.10 [pDBB]0.90. The JCPDS Diffraction File Nos. are: 34-1987 for pDCB; 34-1985 for pDBB; 34-1986 for [pDCB]0.50 [pDBB]0.50.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 212-214 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A microcomputer-based method has been developed for rapid search/match analysis of X-ray diffraction patterns from compound mixtures with user-assembled data bases for specific sample types, e.g. air pollutants, asbestiform minerals, mineral sands and coal ash. Accidental coincidences between stored and measured patterns are largely eliminated using status parameters which are assigned to each data base and measured line. Scaling factors determined for each of the identified compounds afford calculation of relative concentration values. The list of unassigned lines is presented for subsequent analysis with other compact data bases or using more complex search/match methods.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 217-218 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 231-237 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The potential of synchrotron radiation sources (SRS) for the topography of polytypic structures has been assessed. Thus it has been found that the white radiation and low divergence characteristics of the SRS are uniquely suitable for accommodating the complications of mixed polytypes, heavily distorted crystals and edge-reflection topography. Computer aids are particularly important for separating contributions from mixed polytype crystals. All these techniques are illustrated in this paper using silicon carbide as a prototype polytypic crystal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 244-248 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A single-stage computer procedure to calculate an electron density map suitable to detect errors in a tentative macromolecular model has been developed. In this procedure, an atom of the tentative model does not contribute to the phases used to calculate electron density values at or near its current position, that is within the region containing it and a neighborhood surrounding that region. In this way, the phases used to calculate electron density values within a region are not biased by the model atoms contained within that region or its neighborhood. The number of atoms which are omitted for a given region is maintained at a small fraction of the total structure so that the phases used to calculate electron density values may still be a good approximation to the phases of the complete structure. The procedure was used to improve the model of the Fab portion of the mouse galactan-binding immunoglobulin J539 (IgA2, κ), which contains 431 residues.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 352-357 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A modification of the Rietveld refinement program is introduced by replacing the Gaussian profile function with a Voigtian. The performance of the program is tested by an application to simulated and measured diffraction patterns of NaTaO3, and excellent results are obtained when the tails of the reflections are included at distances 10 to 20 times the half-width of the reflections. Comparison between Gaussian and Voigtian refinements show large differences in the thermal parameters. This is due to the high level of background that is assumed in the Gaussian refinement to compensate for the lack of tail overlap. Application of the Voigtian refinement to the measured pattern of Ni yields a thermal parameter that is close to the literature values, while the Gaussian analysis gives a value which is 35% too large. The isotropic temperature factors of the room-temperature structure of NaTaO3, respectively, drop down to the values B(Ta) = 0.09(2), B(Na) = 1.21(3), B(O1) = 0.59(3) and B(O2) = 0.61(3) Å2, when the Voigtian analysis with a proper background is carried out. The role of background in powder pattern refinement is discussed, and it is suggested that a calculation of the average TDS should be included in the refinement.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 361-362 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The segment description of the unique set of reflections of Gabe [In Crystallographic Computing, edited by F.R. Ahmed. Copenhagen: Munksgaard (1969)] and Le Page & Gabe [J. Appl. Cryst. (1979). 12, 464–466] has been extended to the non-centrosymmetric crystal classes. To the reflections generated by the unique set of the Laue group are added the anti-reflections generated by a set of anti-segments. These anti-segments are defined by the same lattice rows as those of the corresponding Laue group but their origins are shifted to avoid generating anti-reflections in any centrosymmetric section of reciprocal space.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 362-362 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In the paper by Kervarec, Baudet, Caulet, Auvrey, Emery & Regreny [J. Appl. Cryst. (1984). 17, 196–205], an error has been introduced. On page 202, right-hand column, the second paragraph should read: The uneven surfaces of the interfaces can be taken into account by assuming that the SL is made of a juxtaposition of perfect crystallites of the same composition x whose period varies between the extreme values of 2n1d1 + 2n2d2. In this hypothesis, the experimental diagram is the sum of the X-ray diagrams given by each crystallite; the value of n1 + n2 deduced from such a diagram is an average value in the sample zone analyzed, therefore most of the time not integer.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 366-368 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The well known molecular drawing program, PLUTO78, has been made more widely available in the UK by mounting it on the minicomputers of the Joint Academic Network (JANET) wide-area network. Enhancements include interaction, faster plotting, use of colour and simulated half tone, easy access to centrally maintained high-quality-output devices, and the provision of comprehensive documentation in the form of on-line help and a user manual.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 369-369 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 371-371 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 372-373 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 373-374 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 17 (1984), S. 375-384 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The calculated intensities of the X-ray beam behind the exit surface of the Ge [440, {\bar 2}20] dispersive monolithic monochromator for Co Kα1 radiation are presented. The reflections 440 and {\bar 2}20 resulting from Ge {000, 440, 260, {\bar 2}20} coplanar four-beam diffraction were taken into account and the influence of the π/2 reflection 260 is discussed. The four-surface arrangement of Ge [440, {\bar 2}20] providing the resultant beam parallel to the incident beam is considered. For comparison Ge [440, {\bar 2}20] in the two-beam approximation is solved. The obtained results demonstrate that the four-beam basis of diffraction affects the resultant beam. The quality of the X-ray beam evaluated behind the examined monochromators also provided the conditions for the use of such monochromators as wavelength standards.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 27-34 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A high-resolution time-of-flight powder diffractometer has been operated at Argonne's ZING-P′ pulsed neutron source for over 2½ years. The diffractometer achieves Δd/d≤ 3 × 10−3 over a broad range of plane spacings. Even though the flux at the sample position is comparatively low due to the 18.37 m incident flight path, count rates competitive with typical two-axis diffractometers are achieved because of large detector areas. A Rietveld refinement of data for a standard Al2O3 sample gives results as good as or better than those obtained with the best two-axis diffractometers.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 48-54 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The concept of X-ray diffraction topography, which has been ordinarily applied to single crystals, has been extended to the observation of polycrystals and amorphous materials. This new method utilizes X-rays scattered elastically or inelastically from a specimen to observe polycrystals, and is called polycrystal scattering topography (PST). The principle and some PST techniques are described. The discussion is further extended to the potentiality of PST and an experimental method with synchrotron radiation. In order to demonstrate the capability of this method, several techniques of PST have been applied to metallurgical problems. It has been found that the PST provides a helpful tool in studying polycrystals in which neither X-ray radiography nor X-ray diffraction topography would be helpful.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 65-71 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A new structure model of Au4Mg is proposed for the long-period superstructure which exists in the Au–Mg alloys with 16–22 at.% Mg at 570–470 K and gives electron diffraction patterns of the two-dimensional antiphase structure of Cu3Pd-type (2d–Cu3Pd), with the aid of high-resolution structure images taken with the 1000 kV electron microscope. The superlattice has monoclinic symmetry with the space group P21/m (No. 11), and the lattice parameters are A = 5a, B = b, C = 4c and β = 90°, where a(= b) and c(∼a) are those of the fundamental face-centred cell. The structure can be described as the two-dimensional antiphase structure having the first- and second-kind boundaries parallel to (001) and (100), respectively, and the domain size of 2.5a × b × 2c. Nearest-neighbour Mg atom pairs are not formed across the second-kind boundaries in this structure, in contrast with the ideal 2d-Cu3Pd-type structure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 89-93 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A five-channel solid-state detector of Si(Li) type has been made together with the necessary data-collecting system. Its characteristics and a preliminary application on the intensity measurements and on the anomalous scattering near the Ga K edge of GaP as a function of X-ray energy are described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 94-97 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A diffractometer specifically built for X-ray diffuse intensity measurements is described. The design for a low-temperature cryostat allowing measurements between 80 and 300 K with the sample under vacuum, the use of an Si(Li) solid-state detector, the design of the alignment procedure and the automation are presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...