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  • International Union of Crystallography (IUCr)  (1.175)
  • 2005-2009
  • 1980-1984
  • 1975-1979  (1.175)
  • 1975  (1.175)
Sammlung
Verlag/Herausgeber
Erscheinungszeitraum
  • 2005-2009
  • 1980-1984
  • 1975-1979  (1.175)
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    On the dielectric behaviour of cadmium iodide polytypes (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 645-648 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The dielectric constants (εr) of cadmium iodide polytypes have been measured and found to be higher than that of the parent 4H structure. For example, whereas the εr for polytypic structures 32H and 34H is between 120 and 150, for the 4H structure it is between 20 and 25. A possible explanation for this decrease is suggested in terms of the occurrence of the stacking faults and their effect on the orientation polarizability of the cadmium iodide crystals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011533
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  • 2
    Digitale Medien
    Digitale Medien
    Analyse des bandes de diffraction affectées par une fonction défaut instrumentale (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 653-656 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A turbostratic layer lattice is characterized by asymmetric X-ray diffraction bands the shape of which is a function of the average diameter L of the two-dimensional scattering domains. The mathematical relationship between the band shape and L is known. The larger the domains, the narrower and more asymmetric is the band. The band width is also influenced by the instrumental broadening. Consequently the apparent diameter L, is smaller than L. The proposed graphical method allows L to be obtained from L, and from the characteristic parameters of the apparatus. The experimental results can be fitted from the convolution of the theoretical function corresponding to L with the experimentally measured instrumental broadening function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011557
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  • 3
    Digitale Medien
    Digitale Medien
    Ein neues Verfahren zur gleichzeitigen Photographie zweier Netzebenen des reziproken Gitters (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 670-673 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new experimental technique in which direct photographs of two reciprocal planes are taken simultaneously is described. The method combines the advantages of the precession method (a series of reciprocal planes is accessible with the adjustment of a single reciprocal direction) and the de Jong Bouman method (high diffraction angles are possible). Consequently many crystals (e.g. organic ones) may be measured with copper radiation without loss of information. The advantages of the new method and the final construction for practical X-ray diffractometry are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011570
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  • 4
    Digitale Medien
    Digitale Medien
    The termination effect for amorphous patterns (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 674-677 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Termination of the experimental intensity curve and the use of a convergence factor leads to an uncorrected radial distribution function which is equal to the true distribution function convoluted with a termination factor of the form sin x/x, and with a convergence factor of exponential form. Although the convolution factors are known, a deconvolution of the uncorrected curve to obtain the true radial distribution function is not possible by the usual methods. However, for the case of moderately sharp peaks on a slowly varying background, an approximate method can be developed. For each peak of the uncorrected curve, we introduce a Gaussian A exp [−a2r2] whose convolution with the termination and convergence factors has the same width and height as the peak. These Gaussians are then used for the first step in a deconvolution of the uncorrected curve. Although it is approximate, the resulting curve is closer to the true distribution function than the original uncorrected curve, and the termination ripples have been eliminated. The method is completely objective, and free from all arbitrary adjustments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011582
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  • 5
    Digitale Medien
    Digitale Medien
    Crystal data for the tetraphenylarsonium salt of the monoanion of theophylline, [(C6H5)4As] [C7N4O2H7].5H2O (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 686-686 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The title compound crystallizes in the triclinic system with a = 13.13 (1), b= 19.80 (2), c = 12.916 (3) Å, α = 90.01 (5), β = 102.96 (6), γ = 96.45 (7)°, V= 3251.6 Å3.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011636
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  • 6
    Digitale Medien
    Digitale Medien
    An X-ray study of silver amalgam and its stoichiometry (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 693-694 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The powder diffraction data and the cell constants of silver amalgam crystal (grown from N/50 AgNO3 solution and a globule of mercury) are given. The formula AgHg for the compound is suggested on the basis of X-ray data and chemical analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011661
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  • 7
    Digitale Medien
    Digitale Medien
    Acta Crystallographica and Journals of Applied Crystallography (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 696-697 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011703
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  • 8
    Digitale Medien
    Digitale Medien
    Metallphysik by G. E. R. Schulze (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 698-698 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011739
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  • 9
    Digitale Medien
    Digitale Medien
    Sur une nouvelle forme cristalline de GeSe2 (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 325-327 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Single crystals belonging to a new modification of GeSe2 have been prepared by several methods. This new form appears orthorhombic with parameters a = 7.037±0.30, b = 11.826±0.010, c = 16.821± 0.040 Å and z = 16. The measured density is 4.35±0.040 g cm−3. The space group has not yet been determined because cutting thin X-ray samples from large as-grown crystals induces considerable cleavage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010527
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  • 10
    Digitale Medien
    Digitale Medien
    Etude des défauts dans des monocristaux naturels de topaze. II. Etude de genèse (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 315-324 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Two samples of monocrystal topaz from Nigeria and Brazil are studied by X-ray topography. The plates are obtained by cleavage and in both growth bands are observed. These bands are parallel to the different faces of the morphology and are grouped in sectors. The limits between two adjacent growth sectors induce more or less misorientation. Observations of topographs allow the reconstruction of different stages of crystal growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010515
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  • 11
    Digitale Medien
    Digitale Medien
    Al2SiO5, Al2GeO5 and Cr2GeO5 kyanites: X-ray powder data and infrared absorption spectra (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 329-332 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Kyanite phases Al2SiO5 (I), Al2GeO5 (II) and Cr2GeO5 (III) were synthesized at 20 kb/1000°C (I, II) and at 1 atm/1150°C (III). Powder X-ray patterns for II and III are presented in comparison with that of I. Triclinic lattice constants are a0 = 7.127 (7.253, 7.422), b0 = 7.858 (8.011, 8.244), c0 = 5.570 (5.649, 5.815) Å, α = 89.99 (89.97, 90.58), β = 101.22 (101.23, 101.10), γ = 106.04 (106.05, 106.01)°, and V0 = 293.6 (308.9, 339.9) Å3 for the kyanite phases I (II, III, respectively). Infrared absorption spectra of I (II, III) were measured between 1400 and 200 cm−1. Band shifts produced by the isomorphous substitutions allow tentative band assignments of the Al2SiO5-kyanite spectrum: 1032, 1009, 940 cm−1 ν3 (SiO4); 898 cm−1 ν1 (SiO4); 720, 438 cm−1 ν4, ν2 (SiO4) ?; banes between 674 and 505 cm−1 and at 467 cm−1 are mainly due to octahedral Al–O vibrations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010540
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  • 12
    Digitale Medien
    Digitale Medien
    Crystal data for a new molecular addition compound, triphenyllead(IV) chloride–hexamethylphosphoramide (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 495-496 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Colourless crystals of (C6H5)3PbCl.[(CH3)2N]3PO have been grown by mixing the two components in acetone solution, in which the complex is monomeric. They were recrystallized from acetone or benzene. Precession and Weissenberg photographs yield space group P21/n and cell data, at 20°C: a = 18.35 (6), b = 15.62 (5), c = 9.43 (5) Å, β = 93°30′ (10′), Z = 4. Dm = 1.50 (2), 20°C.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011065
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  • 13
    Digitale Medien
    Digitale Medien
    Technische Mineralogie. Band 7. Materialverhalten anisotropher Festkörper by W. Dreyer (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 497-497 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011107
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  • 14
    Digitale Medien
    Digitale Medien
    CAMEL JOCKEY, an absorption correction program (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 520-521 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A greatly improved version of the program CAMEL JOCKEY for the absorption correction method of Flack [Acta Cryst. (1974). A30, 569–573] is described. The program is written in FORTRAN for a minicomputer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011168
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  • 15
    Digitale Medien
    Digitale Medien
    Cu Kα2 elimination algorithm (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 499-506 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The existence of the Kα2 lines in powder diffractograms has always obscured the interpretation of the diffraction patterns. Studies involving integrated intensity measurements, peak intensities and line broadening have been hampered owing to these extraneous lines. Crystal monochromators are ineffective for eliminating the Kα2 profile. This paper presents an algorithm which practically removes the Cu Kα2 profile. Previous procedures to remove the Kα2 line or resolve the Kα doublet assumed the shape of the α2 component to be identical to that of the a, component. The algorithm presented here uses the actual shape relationship between observed α1 and α2 components as a basis for elimination of the α2 profile. This algorithm has been applied to an on-line computer-controlled diffractometer to produce `real time' Cu Kα2-free diffraction patterns. The method is quite general and can be extended to remove the Kα2 lines of other radiations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011132
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  • 16
    Digitale Medien
    Digitale Medien
    A probabilistic theory in P\overline{1} of the invariant EhEkElEh+k+1 (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 252-259 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Some joint probability distributions are studied in order to derive an estimate of the probability that the sign of the invariant EhEkElEh + k + 1 is positive. It is shown that this probability depends chiefly on the seven magnitudes |Eh|, |Ek|, |El|, |Eh + k + 1|, |Eh + k|, Eh + l|, Ek + l|, and may be larger as well as smaller than ½.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000514
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  • 17
    Digitale Medien
    Digitale Medien
    The calculation of peak heights on Fourier maps (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 265-266 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The paper describes a method for the rapid calculation of expected peak heights on Fourier maps for each atom type over a range of temperature factors, given the crystal data and the number of independent reflexions collected. An algorism is presented for assigning unidentified peaks to specific atom types.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947500054X
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  • 18
    Digitale Medien
    Digitale Medien
    Surface and defect properties of solids edited by M. W. Roberts and J. M. Thomas (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 271-271 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000575
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  • 19
    Digitale Medien
    Digitale Medien
    Discrepancy indices for use in crystal structure analysis. IV. Theoretical expressions for the indices BR1(I) and BR(I) for any incomplete model of a complex structure (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 375-380 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: General expressions for the discrepancy indices BR1(IN) and BR(IN), which are needed to test the correctness of any type of incomplete model of a complex structure containing any number and species of atoms in the unit cell, are derived for the related and unrelated cases. Explicit expressions for these indices for crystals containing all atoms in general positions are also tabulated for the seven categories of space group in the triclinic, monoclinic and orthorhombic systems. Expressions needed for handling crystals containing atoms in both general and special positions and those needed for taking into account random errors of observation in the intensities are also derived.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000794
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  • 20
    Digitale Medien
    Digitale Medien
    Barrie Dawson, 1925-1974 (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 269-270 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000563
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  • 21
    Digitale Medien
    Digitale Medien
    Introduction à la cristallographie et à la chimie structurale by M. Van Meerssche and J. Feneau-Dupont (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 271-271 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000587
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  • 22
    Digitale Medien
    Digitale Medien
    Removal of the white-radiation background from data collected with, β-filtered Mo Kα, and Ag Kα X-rays (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 273-279 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The usual methods of collecting diffraction data using β-filtered X-rays lead to significant systematic errors in the low-angle data, especially when the shorter-wavelength radiations (e.g. Mo Kα and Ag Kα) are employed. These errors arise because of the structure introduced into the white-radiation background by the filter absorption edge. A technique is proposed for the correct removal of the structured white-radiation profile from low-angle data. Some experimental measures are recommended which will reduce the number of reflexions affected. The proposed procedures are simple and can be carried out 'by hand' or, preferably, incorporated in the data-reduction program. Given an accurate and easily applied technique for removing the white-radiation background, it is argued that in the majority of cases data collection with β-filtered radiation is to be preferred over other methods such as the use of monochromated radiation or balanced filters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000617
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  • 23
    Digitale Medien
    Digitale Medien
    n-Beam lattice images. V. The use of the charge-density approximation in the interpretation of lattice images (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 300-307 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The simple infinite-aperture charge-density approximation to lattice imaging is extended to include the effects of finite aperture and objective-lens spherical aberration. Images computed using these approximations are compared with images computed by the accurate N-beam technique and with experiment in order to establish the bounds of applicability of the extended-charge-density approximations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000642
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  • 24
    Digitale Medien
    Digitale Medien
    X-ray and neutron diffraction by nematic liquid crystals (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 323-327 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: An expression for the neutron (or X-ray) diffraction cross section for a nematic liquid crystal is derived. From this expression it is deduced that such diffraction experiments may be used to measure the nematic order parameter. It is further shown that scattering recorded at temperature close to the nematic-isotropic transition may show weak pretransitional effects even at finite values of the scattering wave vector.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947500068X
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  • 25
    Digitale Medien
    Digitale Medien
    Energy-dispersive spectroscopic methods applied to X-ray diffraction in single crystals (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 327-333 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Two single-crystal energy-dispersive crystallographic methods (the fixed-crystal method and the rotating-crystal method) are described and investigated. Formulae for integrated intensities are derived for mosaic and perfect single crystals. Experimental results and a comparison between measured and calculated integrated intensities for a perfect germanium crystal are given. Special features and possible applications of the methods are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000691
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  • 26
    Digitale Medien
    Digitale Medien
    Physical properties and phase transitions in WO3 (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 356-359 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A study of the phase transitions in WO3 crystals by Raman and absorption spectroscopy reveals that WO3 possesses two stable (or metastable) modifications at room temperature, differing slightly but definitely in their physical properties. Measurements of electrical conductivity show that both are insulators at low temperatures and semiconductors at higher temperatures. One is monoclinic and the other triclinic. Both exhibit at lower temperatures discontinuities in their physical properties without accompanying changes in cell parameters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000745
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  • 27
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    Digitale Medien
    Real-space methods for interpreting electron micrographs in cross-grating orientations. I. Exact wave-mechanical formulation (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 435-442 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Alternative procedures are presented to the usual dynamical matrix method of calculating the dispersion surface, which suffers from very slow convergence in orientations where the diffraction pattern exhibits a full plane of the reciprocal lattice. A preliminary discussion is given of the cylindrical 'muffin-tin' approximation to the real-space projected crystal potential, the basis of the adaptation for use in high- energy electron-diffraction theory of both the APW and KKR methods. Full formulae for the diffracted amplitudes are arrived at, and an evaluation is made of the respective merits of the KKR and APW methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475000988
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  • 28
    Digitale Medien
    Digitale Medien
    Applications of the King and Lipscomb expression for the X-ray scattering of a hindered rotor (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 488-494 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The King and Lipscomb expression for the scattering of groups undergoing hindered rotation against a cosine potential function about an axis has been modified and incorporated into a routine full-matrix structure-factor and least-squares program. The model has been evaluated in several cases and has been found to be an excellent representation for π-bonded CnHn groups in organometallic compounds in that the hindered rotor representation, with only nine variables, is frequently competitive with individual atom models. The parameters of the model concerned with thermal motion have been related to the more conventional parameters to enable the deduction of good starting values for the hindered-rotor refinement. The parameter that in the formal model is associated with the height of the barrier potential function is shown to be a shape parameter that is related more properly with the root-mean-square libration about the axis. Bond lengths derived from the model are corrected for this dominant libration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001052
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  • 29
    Digitale Medien
    Digitale Medien
    Seminvariants for space groups I\overline{4}2m and I\overline{4}2d (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 521-521 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Errors in the tables of seminvariants given by Karle & Hauptman [Acta Cryst. (1961). 14, 217-223] are corrected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001106
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  • 30
    Digitale Medien
    Digitale Medien
    Anomalous reflexion in a neutron triple-axis crystal spectrometer (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 523-525 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The origin of the anomalous peaks occurring in a neutron crystal spectrometer is explained by the use of reciprocal-space geometry. The anomalous peaks are due to Bragg reflexion in the sample of the incident neutrons with wavelengths different from the central value of the nominally monochromatic beam.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947500112X
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  • 31
    Digitale Medien
    Digitale Medien
    A joint probability distribution of seven structure factors (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 671-679 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: It is assumed that a crystal structure in P1 is fixed and that the random variables (vectors) h, k, l, m, subject to h + k + I + m = 0, are uniformly and independently distributed in reciprocal space. Then the seven structure factors Eh, Ek, El, Em, Eh + k, Ek + l, El + h, as functions of the primitive random variables h, k, 1, m, are themselves random variables, and their joint probability distribution is found. This distribution plays the central role in the theory and estimation of the cosine invariants cos (φh + φk + φ + l̃ + φm).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001416
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  • 32
    Digitale Medien
    Digitale Medien
    A reply to Agrawal's comments on the papers (a) The streaking of X-ray diffraction spots in the platelet-shaped polytypic crystals and (b) Arcing of X-ray difraction spots in the X-ray photographs of cadmium iodide crystals (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 697-698 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The c-axis oscillation photographs of platelet-shaped crystals exhibit curious disorder features on X-ray diffraction photographs. These disorders are shown to be shape-dependent and are not caused by any real disorder in the stacking of layers. Another type of disorder which appears on X-ray diffraction photographs of cadmium iodide polytypic crystals is the 'arcing' disorder. It is shown that in view of the paucity of experimental evidence, the 'arcing' cannot be understood on the basis of the occurrence of manifold tilt boundaries.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001453
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  • 33
    Digitale Medien
    Digitale Medien
    Single-crystal diffractometer data: economizing in background counting times (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 700-701 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A method is described for economizing the time spent in background counting during a single-crystal data collection with a computer-controlled diffractometer. The percentage time saved for a reflexion depends on the peak-to-background ratio whereas the fraction of peak counting time spent on the background depends, in addition, on the background level and on the precision required for the reflexion intensity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001489
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  • 34
    Digitale Medien
    Digitale Medien
    Self-crystallizing molecular models. IV. Revision and conclusion (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 718-721 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Molecular models with magnetic multipoles, which were invented by the author for the purpose of simulating crystal structures, are revised. The models of the new type are made of Ba ferrite magnets and plastic pieces only, no Mn-Zn ferrite being used. The crystal structures of SiF4 and α-CF4, as well as those of UCI6 and WCI6 are represented by use of different species of molecular models.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001556
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  • 35
    Digitale Medien
    Digitale Medien
    The location of light-atom positions in crystal structures (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 743-746 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A procedure is described for the location of light atoms, particularly hydrogen, by means of a weighted difference synthesis, in which the weight is taken to be the scattering factor of the light atom which is sought. This convolution technique is illustrated in applications to the structures of an amine hydrochloride, C20H27N. HCI, and a complex borohydride, Mg(B6H9)2.2C4H8O.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947500160X
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  • 36
    Digitale Medien
    Digitale Medien
    Simple ways of determining perovskite structures (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 756-762 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A simple technique is described for ascertaining trial models for the structures of perovskites. The method relies on an understanding of the fundamental components of the structure. Rules are given for determining trial models rapidly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001635
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  • 37
    Digitale Medien
    Digitale Medien
    Ordering of the point defects in nonstoichiometric crystals of Nb12O29 (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 784-790 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The reduction of crystals of Nb12O29, having an excess of oxygen, has been studied by high-resolution electron microscopy and electron diffraction. A superstructure and faulted slabs are formed, by aggregation of the point defects forming chains with a limited length in the matrix structure, induced by electron-beam irradiation. Ordering of the chains of point defects in the crystals is directly observed by electron microscopy with resolution of the atomic level. A mechanism for the dissipation of the point defects is discussed in terms of the reduction and oxidation of the nonstoichiometric crystals of Nb12O29.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001696
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  • 38
    Digitale Medien
    Digitale Medien
    The influence of piezoelectric coupling on material constants determining Brillouin scattering (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 801-803 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The piezoelectric modifications of the tensors of elastic, optical and photoelastic constants and their consequences on spontaneous and stimulated Brillouin scattering are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001726
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  • 39
    Digitale Medien
    Digitale Medien
    The application of direct methods to centrosymmetric structures containing heavy atoms. II (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 813-817 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Direct methods are applied to the difference structure factors for a structure containing one or more heavy atoms in known positions. For those reflexions whose sign is determined by the heavy atoms, the known heavy-atom contribution is subtracted from the observed structure factor to obtain the magnitude and the sign of the light-atom contribution. The signs of the reflexions that do not have an appreciable heavy-atom contribution are found using the Σ2 sign relationship. For reflexions with an intermediate heavy-atom contribution the sign and magnitude ambiguity is also solved by the Σ2 formula. Thus it is possible to maximize the number of correct signs, and correct some of the amplitudes, before a difference Fourier map is calculated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001751
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  • 40
    Digitale Medien
    Digitale Medien
    A vibrating perfect crystal assumed to be a real one (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 688-693 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A generalized formula for the integrated intensity of neutrons diffracted by a vibrating perfect crystal is derived on the basis of the lamella structure with the symbols of Zachariasen's general theory. The formula is introduced together with new experimental data for diffraction from a longitudinally vibrating quartz single crystal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947500143X
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  • 41
    Digitale Medien
    Digitale Medien
    A xenon-filled multiwire arc detector for X-ray diffraction (1975)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 702-703 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A xenon-filled multiwire proportional chamber with high and uniform photon-detection efficiency has been built and incorporated into a high-speed data-collection system for protein crystallography. This system has been used to collect more than 200 000 reflection intensities from one parent and four heavy-atom derivative crystals of a complex of dihydrofolate reductase and methotrexate (a cancer drug). Its data collection rate is about 30 times faster than the rate of a standard diffractometer (1400 reflection intensities per hour versus 50 reflection intensities per hour). The precision of the chamber data is also better with an intensity reliability R of 5% as compared with 6.7% from the diffractometer data. The difference Patterson maps between parent and heavy-atom derivative data show very clearly the positions of the heavy atoms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739475001490
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  • 42
    Digitale Medien
    Digitale Medien
    The avoidance of multiple diffraction errors in single-crystal intensity measurements at low temperatures (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 37-41 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A modified geometry for a three-circle (χ = 90°) X-ray or neutron single-crystal, low-temperature diffractometer is described in which the detector is mounted on a partial vertical circle. It is shown that this extra facility permits sufficient rotation about the scattering vector to enable the effects of multiple diffraction to be detected and thus avoided.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987500948X
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  • 43
    Digitale Medien
    Digitale Medien
    Dislocations and plastic deformation by I. Kovács and L. Zsoldos (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 78-78 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009673
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  • 44
    Digitale Medien
    Digitale Medien
    International Discussion Meeting on Studies of Lattice Distortions and Local Atomic Arrangements by X-Ray, Neutron and Electron Diffraction (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 79-80 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009697
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  • 45
    Digitale Medien
    Digitale Medien
    Experimental considerations in measurements of diffuse scattering (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 87-95 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A brief review is given of the Borie–Sparks method of measuring and separating the diffuse scattering in alloys due to local displacements of atoms from lattice sites. Experimental techniques are reviewed with particular emphasis on simple computer controls, dead time, monochromators and specimens. After this, sources of error in the measurements are discussed and simple methods for assessing these errors presented. Equations for estimating higher-order terms than those included by Borie and Sparks are presented. It now appears that a thorough analysis of the errors needs to be made for each measurement prior to its publication. As this kind of experiment is readily automated and easily analyzed for errors with modern computers, this should now become standard procedure. It is also suggested that intensities in electron units be kept on file and made available when requested, as is done with structure factors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009715
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  • 46
    Digitale Medien
    Digitale Medien
    Screening singularities and Fermi surface effects in the diffuse scattering from alloys (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 96-107 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The formalism for the modification of the pair interaction energy between the atoms of a binary alloy due to the electron-ion interaction as modified by the electron–electron interaction, is developed to lowest order. In a manner analogous to the treatment of Krivoglaz it is shown how the fluctuation-dependent part of the alloy pair energy contains a contribution from ε(q), the dielectric function for the alloy, which in turn reflects singularities at ε(2kF), where kF is the Fermi wavevector. The strength of these singularities and their contribution to the diffuse scattering of radiation is discussed and recent experimental observations of several groups on `imaging' the Fermi surface in this manner are presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009727
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  • 47
    Digitale Medien
    Digitale Medien
    The separation of displacement and substitutional disorder scattering: a correction for structure-factor ratio variation (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 111-114 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The assumptions in the Borie & Sparks [Acta Cryst. (1971). A27, 198–201] procedure for the separation of order- and displacement-dependent components of diffuse X-ray scattering from a binary system AB are examined with the use of the concentration deviation (spin-like) notation. The more limiting assumption, that the structure-factor ratio η = (mAfA + mBfB)/(fA−fB) is constant in reciprocal space, is shown to produce an incomplete separation for normal variations in η. A matrix-inversion method for completing the separation is suggested for those cases in which the approximate equality of the Debye–Waller factors (DWF) of the individual atomic species indicates that some terms of the scattering equation may be neglected. The extension suggested by Ramesh & Ramaseshan [Acta Cryst. (1971). A27, 569–572] that anomalous dispersion induced changes in η could be used to separate the atomic static displacement properties of the various atomic pairs is shown to require a change in η greater than the variation of η across the reciprocal-space volume. Some difficulties of obtaining such a change are pointed out.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009740
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  • 48
    Digitale Medien
    Digitale Medien
    Positional information in solid-solution models (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 121-126 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The role of positional information in determining the thermodynamics of crystalline solid solutions is considered. It is noted that, with certain exceptions (e.g.b.c.c. Fe–B), such solutions can be classified as being exclusively either substitutional or interstitial with respect to each solute. Calculation of thermodynamic properties of intersitital solutions requires knowledge of the types of sites preferentially occupied by the solute. The problem of determining that occupancy is considered for several binary systems. A cumulant expansion technique, which meets with good success in describing dilute, high-temperature, interstitial solutions, is applied to the case of high-temperature binary substitutional systems of similar metals. The technique is shown to be of limited utility in this application.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009776
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  • 49
    Digitale Medien
    Digitale Medien
    On the evolution of states from a non-equilibrium solid solution (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 126-126 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Despite the enormous variety of structural states that evolve from non-equilibrium solid solutions and despite the even larger number of models that have been proposed for them, it is becoming apparent that only a limited number of basic types of evolutionary paths exist.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987500979X
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  • 50
    Digitale Medien
    Digitale Medien
    Scattering of X-rays by correlated defect distributions (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 127-127 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: It may be essential in certain cases (e.g. non-dilute alloys and dislocations) to take into account the (pair and higher-order) correlations in the defect distribution. To this end the kinematic expression for the total scattered intensity is rewritten.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009818
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  • 51
    Digitale Medien
    Digitale Medien
    Linear local order (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 132-132 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: If the occurrence of one or two-dimensional local order in alloys or in neutron-irradiated materials has been known for many years, the observation by X-ray and neutron scattering of quasi-one-dimensional order due to displacements or correlated motions of atoms along independent chains is more recent. Examples to be discussed are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009843
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  • 52
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    Digitale Medien
    On the problem of fluctuations near first-order phase transformations in solids (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 132-140 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The recent experimental results on the phonon structure of b.c.c. Zr–Nb alloys are reviewed. The central (elastic) phonon peak is discussed in terms of quasi-static heterophase fluctuations which are postulated to form by thermal excitation to a coherent-metastable state and to decay by boundary collapse. This concept is extended qualitatively to the problem of fluctuations associated with first-order compositional transformations – clustering and ordering. It is suggested that quasi-static fluctuations should also occur near the coherent phase boundary for first-order compositional transformations. These fluctuations can be properly interpreted as small particles of the low-temperature phase. The model is used to discuss qualitatively the disorder to long-period and long-period to ideally ordered phase transitions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009855
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  • 53
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    Digitale Medien
    A study on the fine structure in metastable β1 crystal of Cu–40 wt.% Zn alloy (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 141-141 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Detailed analysis of the various diffraction patterns has been made in order to determine the crystal structure of the fine product in the matrix.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009880
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  • 54
    Digitale Medien
    Digitale Medien
    Local arrangement of the conducting ions in the super-ionic conductor βAg-alumina (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 142-142 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The organization of the conducting ions in β-alumina is studied by means of X-ray diffuse scattering as a function of temperature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009892
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  • 55
    Digitale Medien
    Digitale Medien
    Huang scattering from Frenkel defects in electron-irradiated f.c.c metals (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 150-150 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Diffuse scattering of X-rays (Cu Kα1) has been investigated close to different Bragg reflections of Al and Cu after low-temperature electron irradiation (defect concentrations between 2 and 6 × 10−4) and results discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009934
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  • 56
    Digitale Medien
    Digitale Medien
    X-ray studies of defect clusters in copper (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 150-160 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: X-ray diffraction techniques provide powerful tools for the study of lattice defects in crystals. For the case of clustered defects, many of these techniques are based on the scattering properties of the strained regions surrounding the defects rather than on the scattering from the defects themselves. This is particularly true of Huang diffuse scattering, anomalous transmission, and lattice-parameter measurements; the interpretation of these measurements, therefore, relies on a detailed knowledge of the strains around the defects. The Fourier-transformed, long-range strain fields entering into the Huang diffuse scattering can be expressed in terms of the dipole force model, and in this work comparisons of calculations based on this model with measured scattering from spherical precipitates and dislocation loops in copper are reviewed. The use of integral diffuse scattering measurements, made with a two-axis diffractometer, are discussed in terms of a direct analysis of the defect systems in the form of defect concentrations and size distributions and this procedure is applied to the study of the effects of irradiation conditions and post-irradiation annealing on the defect distributions in neutron-irradiated copper. The relation of these diffuse scattering measurements to lattice parameter, anomalous transmission, electron microscopy and electrical resistivity measurement is also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009946
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  • 57
    Digitale Medien
    Digitale Medien
    Mechanische anisotropie edited by H. P. Stüwe (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 78-78 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009685
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  • 58
    Digitale Medien
    Digitale Medien
    Clustering and ordering in solid solutions (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 81-86 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Theoretical models of order–disorder and clustering reactions in solid solutions are briefly reviewed. The simplest model is that based on the point-cluster expansion, or single-site average, which yields a generalized multicomponent Bragg–Williams, model. The contribution to the free energy which is quadratic in the configuration variables (harmonic portion) governs the behavior of high-temperature concentration fluctuations and of incipient Brillouin zone-center (clustering) and zone-boundary (ordering) instabilities. Anharmonic contributions determine the equilibrium structures. The description of states of partial order from knowledge of short-range-order intensity is briefly discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875009703
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  • 59
    Digitale Medien
    Digitale Medien
    An investigation of the nature of the -X,Z growth sector boundary in synthetic quartz (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 203-203 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The boundary between the −X and Z growth regions in synthetic quartz has been studied using X-ray topography and other techniques and it has been found that the crystal lattice remains coherent at the boundary.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010151
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  • 60
    Digitale Medien
    Digitale Medien
    Decomposition and ordering in Fe1−xO (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 206-206 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Wüstite which exists above 570°C, has a defect NaCl-type structure. The considerations of iron vacancies and interstitials depends on the deviation from stoichiometry and are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010199
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  • 61
    Digitale Medien
    Digitale Medien
    Lattice relaxation at antiphase boundaries in ordered Ni–Mo alloys (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 211-211 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Different types of antiphase boundaries have been studied by electron microscopy in the Ni–Mo alloys and from observations it could be deduced that some relaxation of the lattice has occurred.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010229
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  • 62
    Digitale Medien
    Digitale Medien
    The diffuse scattering in electron diffraction from the high-temperature phase of silver selenide (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 211-211 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The diffuse scattering as observed in electron diffraction patterns of α-Ag2Se is associated with a disordered silver–vacancy system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010217
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  • 63
    Digitale Medien
    Digitale Medien
    Theoretical basis of diffraction contrast of lattice imperfections in transmission electron microscopy (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 212-213 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The dynamical theory of diffraction, both for X-rays and electrons, was formulated many years ago but for several decades found only limited application in the analysis of diffraction patterns because of the difficulty in obtaining specimens whose defect content was known with sufficient precision. This situation was transformed with the advent of real-space techniques, such as transmission electron microscopy and X-ray topography, which allowed the dynamical theory to be applied to local regions in the vicinity of individual defects instead of to the diffraction pattern coming from the specimen as a whole.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010242
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  • 64
    Digitale Medien
    Digitale Medien
    Kinematical theory of images from polycrystalline and random-network structures (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 213-219 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Kinematical electron microscope images to be expected from the Polk continuous random-network model and from a polycrystalline cluster have been computed. Dark-field images of both models show qualitatively similar speckle patterns. Fringes are observed in bright-field images of thin polycrystals (t≲ 40Å), but they disappear in thicker samples and are not observed in any of the Polk-model images. The experimental observation of fringes therefore cannot be explained by the current theory, possibly because it does not take account of the angular spread of illumination. Except perhaps in very thin specimens, it seems impossible at present to draw any reliable conclusions about the local atomic arrangement in amorphous materials by simple examination of electron micrographs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010254
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  • 65
    Digitale Medien
    Digitale Medien
    Crystal data for some guanidinium salts (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 392-395 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Several guanidinium salts have been studied since, because they contain six hydrogen atoms per unit charge, they are likely to contain multiple hydrogen bonding systems [see e.g. Adams & Small (1974). Acta Cryst. B30, 2191–2193], which are of interest in themselves and are also likely to cause stabilization of the structure. The crystal data of a range of salts were collected and are given. Space group and approximate cell dimensions were obtained from oscillation and Weissenberg photographs. Powder diffraction data [0° to 60° (2&thgr; using Cu Kα)] were indexed and the cell parameters refined using the programs PIRUM of Werner [Program No. 1, World List of Crystallographic Computer Programs (3rd. ed.): J. Appl. Cryst. (1973). 6, 309–346] and CELFIT of Bracher [UKAEA Research Report, AERE-R5412 (1967)].
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010783
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  • 66
    Digitale Medien
    Digitale Medien
    Crystal data on ortho-substituted benzaldehydes (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 397-397 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Unlike the position with negatively charged substituents, little has been done on benzaldehydes ortho-substituted with positively charged groups. This is more especially true in the field of crystallography where only the X-ray and neutron diffraction study of o-nitrobenzaldehyde has been reported [Coppens & Schmidt, Acta Cryst. (1964). 17, 222–228; Coppens, Acta Cryst. (1964). 17, 573–578]. Preliminary results of a structural investigation on Se- and Te-containing benzaldehydes are presented. The main purpose is to corroborate and to complete the conclusion of recent n.m.r. work on the conformation of these molecules [Baiwir, Llabres, Denoel & Piette, Mol. Phys. (1973). 25, 1–7]. The following compounds have been studied: C6H4.COH.TeCl, C6H4.COH.TeBr, C6H4.COH.TeI, C6H4 COH.SeCl, C6H4.COH.SeBr. The crystal structure of the second (TeBr) has been recently reported [Baiwir Llabres, Dideberg, Dupont & Piette, Acta Cryst. (1974). B30, 139–143] and the structure of the last (SeBr) is presently in the final stage of refinement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010801
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  • 67
    Digitale Medien
    Digitale Medien
    Crystallographers (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 402-402 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010837
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  • 68
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    Digitale Medien
    Electronic absorption and internal and external vibrational data of atomic and molecular ions doped in alkali halide crystals by S. C. Jain, A. V. R. Warrier and S. K. Agarwal (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 403-403 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010862
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  • 69
    Digitale Medien
    Digitale Medien
    Liquid-structure analysis by energy-scanning X-ray diffraction: mercury (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 405-414 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Quantitative liquid-structure analysis using energy-scanning diffraction rather than the traditional angle-scanning diffraction is introduced. In the experimental method, white radiation and a solid-state detector are employed. This new method is inherently faster and less beset with problems of experimental instability than are angular-scanning methods. However, many differences in analysis are introduced. In particular, measurement of the primary beam spectrum, the nature of the absorption and dispersion corrections, details of the polarization correction, the ranges of the atomic scattering factor and of the incoherent scattering term, and the mating of different scattering regimes all require special consideration. Application of the new instrumental method and the reconstructed analytical procedure to liquid mercury at room temperature has produced a result in agreement with other recent studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010898
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  • 70
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    Digitale Medien
    A new small-angle X-ray scattering facility utilizing a rotating anode, pin-hole collimation and a position-sensitive proportional counter (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 421-429 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new small-angle X-ray scattering facility which utilizes a 6 kW rotating anode, pin-hole collimation, and a position-sensitive proportional counter has been developed. As presently constructed, the minimum scattering vector κ (= 4π sin &thgr;/2) which can be reached with Cu Kα radiation is 5 × 10−3 Å−1. Under these conditions the flux incident on the specimen has been found to be 6 × 105 photons s−1. The system has several advantages compared with traditional long-slit geometries; namely, (i) it can quantitatively measure anisotropic scattering distributions, (ii) it avoids large mathematical corrections of the data for slit-smearing effects, and (iii) it minimizes double Bragg scattering in crystalline materials and multiple diffuse scattering in amorphous or liquid materials. To illustrate the performance of this instrument, the scattering curves obtained from four widely different samples are shown. These are: polyethylene, a neutron-irradiated aluminium single-crystal containing voids, a dilute suspension of Ludox spheres, and duck tendon collagen. Quantitative comparisons of the performance with a Kratky camera and with the neutron small-angle scattering facility in Jülich are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010916
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  • 71
    Digitale Medien
    Digitale Medien
    Crystallographers (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 496-497 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011089
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  • 72
    Digitale Medien
    Digitale Medien
    Handbook of Geochemistry. Vol. 2, Part 4 edited by K. H. Wedepohl (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 498-498 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011120
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  • 73
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    Digitale Medien
    Unusual crystallization behaviour (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 342-342 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987501062X
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  • 74
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    Digitale Medien
    Ein gekrümmter Neutronenmonochromator hoher Reflektivität (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 361-364 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A neutron monochromator built by stacking elastically curved ideal germanium crystals is examined. The radius of curvature of the crystals was 566 + 5 cm. The measured reflectivity, for a 220 reflexion, was in the region of 60 % for neutrons with wavelengths of 1 to 2 Å. It is shown that the momentum resolution depends in a simple way on the thickness of the monochromator, which was up to 7.2 mm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010692
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  • 75
    Digitale Medien
    Digitale Medien
    Absolute intensity measurement in neutron powder diffraction (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 522-524 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Advantages and possibilities of absolute intensity measurements in neutron powder diffraction are discussed. To study experimental techniques, the scale factors of Ni and NH4Cl have been determined. The present techniques are found to be accurate enough to encourage further studies in this field.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987501117X
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  • 76
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    Digitale Medien
    The determination of the scattering density distribution of polydisperse solutions by contrast variation: a neutron scattering study of ferritin (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 538-542 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: From the dependence of zero-angle scattering of polydisperse solutions on the scattering density of the solvent, information about the mean scattering density and the width of the scattering density distribution of different dissolved molecules can be obtained. This method has been tried with a commercial solution of native ferritin. The root-mean-square deviation of the scattering density was 0.35 × 1010 cm−2 with respect to the mean value of 3.15 × 1010 cm−2. From these data the mean saturation of native ferritin with iron is estimated to about 0.6 and the root-mean-square fluctuation of the iron contents of different ferritin molecules to about 0.4. The neutron scattering curves agree with the results from X-ray small-angle scattering.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011211
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  • 77
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    Digitale Medien
    The use of a projector–digitizer–calculator combination for the interpretation of diffraction photographs (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 557-558 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An arrangement is described in which a 6 cm square area of film is projected onto a digitizer platen. Features of interest are scanned manually and the output fed to a Hewlett-Packard desk calculator, which is programmed to process the data, but can be used interactively. Applications to Guinier-type X-ray photographs and electron diffraction photographs are described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011247
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  • 78
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    Digitale Medien
    Données cristallographiques sur l'orthophosphate de cuivre-potassium hydraté CuKPO4.H2O (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 395-396 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The chemical preparation of CuKPO4.H2O is described and crystal data given. CuKPO4.H2O is monoclinic with a = 10.538, b = 6.783, c = 6.721 Å, β=93.01 °. The space group is P21/c.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010795
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  • 79
    Digitale Medien
    Digitale Medien
    Crystal data for two dihydrated compounds of methanesulphonic acid with Mn(II) and Cd(II): Mn(CH3SO3)2.2H2O and Cd(CH3SO3)2.2H2O (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 400-401 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The unit-cell parameters and indexed powder patterns are reported for the title compounds. Both these compounds are new; they crystallize in the triclinic system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010825
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  • 80
    Digitale Medien
    Digitale Medien
    Notes and News (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 402-402 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010850
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  • 81
    Digitale Medien
    Digitale Medien
    Low energy electron diffraction. The theory and its application to determination of surface structure by J. B. Pendry (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 403-404 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010886
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  • 82
    Digitale Medien
    Digitale Medien
    International tables for X-ray crystallography. Vol. IV edited by J. A. Ibers and W. C. Hamilton (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 572-572 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011363
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  • 83
    Digitale Medien
    Digitale Medien
    Systematic materials analysis. Vol. 1 edited by J. H. Richardson and R. V. Peterson (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 573-573 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011387
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  • 84
    Digitale Medien
    Digitale Medien
    Etude des fautes d'empilement dans les kaolinites partiellement désordonnées. I. Modèle d'empilement ne comportant que des fautes de translation (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 582-588 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: By the use of a model with two kinds of stacking faults it is possible to explain quantitatively X-ray powder diffraction patterns of disordered kaolinites. The first kind of defect consists of random translations which limit coherent scattering regions in all hk directions except h = k = 0. The second kind consists of shifts between layers of ± nb/3 (n integer) which limit coherent scattering only in hk directions with k ≠ 3n. The comparison of calculated patterns with experimental (02,11) and (20,13) bands gives the proportions of different kinds of layer displacements in two disordered kaolinites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011429
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  • 85
    Digitale Medien
    Digitale Medien
    Formation des polytypes rhomboédriques de sulfure de titane (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 603-608 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Relations between the structure and the morphology of titanium sulphide polytypic crystals are pointed out. A formation mechanism able to explain such relations in the case of rhombohedral polytypes is described. Experimental data supporting this mechanism are: the structures determined, the measure of crystal deformation and the frequent coexistence of some kinds of polytypes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011454
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  • 86
    Digitale Medien
    Digitale Medien
    The asymmetry of neutron powder diffraction peaks (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 615-618 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Profile analysis methods used with neutron diffraction data from powder samples require a knowledge of the shape and position of individual peaks. Because of the finite aperture of the detector these peaks become increasingly asymmetric at smaller Bragg angles, becoming broadened and shifted from the true Bragg angle. These effects are considered in detail by deriving the intensity distribution resulting from the resolution function of the diffractometer and evaluating it for a number of sets of instrumental parameters. The results are compared to those calculated ignoring the asymmetry, and empirical functions are derived for the required correction factors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987501148X
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  • 87
    Digitale Medien
    Digitale Medien
    Crystal data for two tetrahydrated compounds of methanesulphonic acid with Cu(II) and Zn(II): Cu(CH3SO3)2.4H2O and Zn(CH3SO3)2.4H2O (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 493-494 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The copper(II) methanesulphonate tetrahydrate and zinc(II) methanesulphonate tetrahydrate are both new compounds which crystallize in monoclinic space group P21/c. Their unit-cell parameters and indexed powder patterns are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011053
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  • 88
    Digitale Medien
    Digitale Medien
    Notes and News (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 497-497 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011090
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  • 89
    Digitale Medien
    Digitale Medien
    Crystallographers (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 696-696 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011697
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  • 90
    Digitale Medien
    Digitale Medien
    Notes and News (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 697-697 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011715
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  • 91
    Digitale Medien
    Digitale Medien
    An analysis of errors in the Fourier coefficients of the α1 line profile (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 612-614 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The errors in the Fourier coefficients of the α1 component obtained by α2 elimination are investigated analytically. The effects of counting statistics, of an incorrect intensity ratio of the α1 and α2 components and of an incorrect doublet separation are calculated. The mean-square error in the Fourier coefficient caused by counting statistics is a periodic function of the harmonic number, while errors in the intensity ratio and in the doublet separation primarily affect the first Fourier coefficients. The results are confirmed by computer simulations and by computations with experimental line profiles. The α2 elimination methods assume a perfect shape identity of the α1 and α2 components, but this assumption is not completely justified. Deviations might be interpreted as local errors in the doublet separation and the intensity ratio.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875011478
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  • 92
    Digitale Medien
    Digitale Medien
    Textures of cold-rolled pure aluminum measured by neutron and X-ray diffraction (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 628-635 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The textures of undirectionally and reversed rolled aluminium sheets were measured using thermal neutrons and Cu and Mo Kα radiation. The samples for the X-ray measurements were prepared in three different ways so that the degree of correspondence between textures as measured with neutrons and X-rays could be investigated. It is shown that agreement can be achieved if the X-rays used penetrate sufficiently into the sample and if a composite type sample is used.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987501151X
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  • 93
    Digitale Medien
    Digitale Medien
    Crystal data on 2AlCl3.3POCl3 (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 337-338 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Crystal data has been established for the compound 2AlCl3.3POCl3. It is tetragonal, space group P42 or P42/m with cell dimensions a = b = 19.39 (3) and c = 13.05 (3) Å.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987501059X
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  • 94
    Digitale Medien
    Digitale Medien
    A general computer program for the processing of small-angle X-ray scattering data (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 340-341 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The program comprises a main program for inspection and correction of the intensity data, and a number of subroutines covering specific operations. These subroutines can be called upon in any desired sequence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010618
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  • 95
    Digitale Medien
    Digitale Medien
    Die Mineralfunde der Schweiz by R. L. Parker (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 343-344 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010655
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  • 96
    Digitale Medien
    Digitale Medien
    Méthode du faisceau convergent: application à la sélection et à l'étude de cristaux polytypiques (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 352-355 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An attractive use of a convergent-beam camera is described. Its advantages, with respect to classical methods, are pointed out. The short exposure time provided by this device is very useful in the selection and detailed study of polytypic crystals. Some X-ray photographs obtained from a titanium sulphide polytypic crystal are displayed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010679
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  • 97
    Digitale Medien
    Digitale Medien
    Méthode d'analyse du profil de bande produite par des feuillets diffractants ayant une forme anisométrique (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 365-371 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Solids characterized by lamellar structure are often made from ribbon or lath-shaped sheets. Such a morphology has been observed in phyllosilicates (hectorite or nontronite, for example) and in carbon fibres. This contribution aims to show that elongated planar sheets can be detected from the profile of the X-ray diffraction bands yielded by the powdered solid. The numerical technique originally developed by Brindley & Méring [Acta Cryst. (1951). 4, 441–447] for isometric layers, has been extended to ribbon or lath-shaped elementary layers. An example of application is given when the sheet is a carbon layer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010709
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  • 98
    Digitale Medien
    Digitale Medien
    Etude par diffraction des rayons X sur poudre de la transition ordre–désordre du ferrocène Fe(C5H5)2 (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 380-385 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: About fifty X-ray powder diagrams were recorded in the range 15 to 295 K, by means of a prototype diffractometer and a high-efficiency cryostat, so that a very precise study of the anisotropic structural evolution of ferrocene could be made. The cell parameters and volume have been computed. These parameters present a discontinuity at 164 K; the cell is triclinic below and monoclinic above this temperature. The transition is first order. The principal thermal expansion coefficients have been computed and their evolution, in terms of temperature, has been related to the anisotropic change of the intermolecular contacts in the crystal. Assumptions about the mechanism of transition and about the ferrocene configuration in the ordered phase are expressed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010734
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  • 99
    Digitale Medien
    Digitale Medien
    Precession photography: orienting crystals by means of the stereographic projection (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 388-389 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A graphical construction on the Wulff net permits corrections on both arcs and the dial to be determined even if neither of the arcs is parallel to the film and/or the outer arc reading is large. The procedure requires that the orientation errors be multiplied by an arbitrary common factor smaller than ten, while the biggest multiplied error should be less than ten degrees: the corrections are obtained graphically and divided by the factor. Corrections thus obtained are within 10% of their true values.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010758
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  • 100
    Digitale Medien
    Digitale Medien
    Synthesè et données cristallographiques de trois polymolybdates de thallium I (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 398-400 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Tl2Mo7O22 is monoclinic with space groupe C2/c or Cc and with a = 20,512 (6); b = 5,526 (2); c = 19,460 (6) Å; β = 125,20 (3)°: Z = 4. Tl2Mo4O13 is orthorhombic with space group Pbca and with a = 7,583 (3); b = 15,409 (3); c = 18,798 (3) Å; Z = 8. Tl7Mo2O7 is monoclinic with a = 8,427 (2); b = 5,690 (2); c = 7,935 (2) Å; β = 108,90 (2)°; Z = 2. The indexed powder diagrams are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889875010813
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