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  • International Union of Crystallography (IUCr)  (6.930)
  • American Association for the Advancement of Science (AAAS)
  • American Association of Petroleum Geologists (AAPG)
  • 1975-1979  (10.755)
  • 1945-1949  (204)
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  • 1
    Digitale Medien
    Digitale Medien
    Curve analysis of small-angle scattering by triaxial body models using a graphic display device (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 628-628 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An interactive program using a graphic display device for the analysis of small-angle scattering has been developed. It includes the curve fitting of experimental data to theoretical results calculated through a triaxial body approximation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013510
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  • 2
    Digitale Medien
    Digitale Medien
    X-ray television area detectors for macromolecular structural studies with synchrotron radiation sources (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 1-9 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Two-dimensional X-ray diffraction patterns may be recorded quantitatively by means of X-ray-to-electron converters which are scanned in a television-type raster scan. Detectors of this type are capable of operating over the whole range of counting rates from very low to higher than those with which other types of converters can deal. The component parts of an X-ray television detector are examined and the limits to the precision of the measurements are analysed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011663
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  • 3
    Digitale Medien
    Digitale Medien
    On the possibility of utilizing holographic schemes in X-ray microscopy (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 19-24 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: X-ray holography schemes are analyzed. It is shown that they have a very low aperture ratio, and this limits the size of objects from which a hologram can be recorded. It is indicated that holography schemes can be constructed on the basis of the methods of X-ray diffraction optics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011699
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  • 4
    Digitale Medien
    Digitale Medien
    Small-angle X-ray data processing for planar multilayered structures. I. Theory (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 42-48 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The Fourier transform values are obtained by multiplying the integrated intensities by the correction factor C(h). The problem of calculating the correction factor for biological specimens which have a multilayered structure is treated. Allowance is made for the transverse size of the specimen, the disorientation in the specimen (ω), the divergence of the X-ray beam (ε), the size of the repeating unit and the curvature of the sphere of reflection. The correction factor C(h) is given by C(h) = Ω[1 + 2γh2]1/2 exp (πδ2)exp (−Ω2[1 + 2γh2]), where γ = (ω2 + ε2)/2(Ω2d2) and where Ω is the diameter of the hth order disc when ω = ε = 0. The formula for C(h) applies to specimens which remain stationary during the X-ray experiment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011742
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  • 5
    Digitale Medien
    Digitale Medien
    Pyroelectric temperature analysis as a method for study of ferroelectric transitions in polycrystalline materials (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 54-56 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The transition temperature of ferro- and antiferroelectric crystals can be simply determined by continuous pyroelectric temperature analysis (PTA) of unsintered pressed powder. In order to avoid excessive stored charge the samples were not previously treated by a polarizing electric field. Experiments performed with (NH4)2SO4, KH2PO4 and NH4H2PO4 showed the transition points with a precision of 1°C.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011766
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  • 6
    Digitale Medien
    Digitale Medien
    Five new polytypes and polytypic change in PbI2 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 57-59 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Five new PbI2 polytypes, 8H(1232), 10H(11112112), 10H(112222), 22H[11(22)5] and 30R[111313]3, were solved by the X-ray diffraction method. It was found on polytypic change that (a) the 2H polytype is changed into various polytypes on heating at 130°C and most of these further change to 12R[13]3 on heating at 260°C; (b) the polytypes 4H, faulted 4H, 14H, 22H, 26H and 30R with layer structures similar to the 12R[13]3 are fairly stable at high temperatures; (c) the 2H-30R [111313]3 transformation occurs reversibly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011778
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  • 7
    Digitale Medien
    Digitale Medien
    Orientations mutuelles observées sur des cristaux d'hématite (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 66-69 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The reactivity of hematite depends among other factors on the morphology of the crystal. The choice of the orientation of the reference axes has been made with the help of stereographic projection combined with the morphology of the etch figures on the different faces of the crystal. That the most stable face of a crystal corresponds to the composition plane is shown for crystals of hematite from Elba.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011791
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  • 8
    Digitale Medien
    Digitale Medien
    Etude des défauts dans des monocristaux naturels de béryl. I. Observations des dislocations (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 70-77 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The lattice defects of beryl single crystals from Brazil and Madagascar have been studied by X-ray topography. Two types of linear defects are observed: channels and grown-in dislocations. Slip systems and Burgers-vector moduli are determined. Some calculations of directions of minimum dislocation energy are given and they are in quite good agreement with the observations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011808
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  • 9
    Digitale Medien
    Digitale Medien
    FN: A criterion for rating powder diffraction patterns and evaluating the reliability of powder-pattern indexing (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 60-65 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: At present, over 30 000 powder diffraction patterns are available as references. It is proposed that the patterns on file as well as new patterns submitted for publication be assigned quantitative quality factors. A simple-to-use figure of merit, FN, covering both accuracy in the measurement of the positions of the diffraction lines and completeness of the pattern, has been derived: FN = (1/|{\bar \Delta 2 \theta}|) (N/Nposs), where Nposs is the number of independent diffraction lines possible up to the Nth observed line and |{\bar \Delta 2 \theta}| is the average absolute discrepancy between observed and calculated 2θ values. This figure of merit provides a rapid evaluation of powder patterns, in much the same way as the R factor provides a rating for single-crystal structure determinations. This figure of merit also provides a means to assess the reliability of a unit derived solely from powder data. At present FN ranking scheme is shown to be superior to de Wolff's M20 for ranking patterns. It is recommended that use of the latter be discontinued for that purpose. Guidelines are given on the use and implementation of the FN rating of powder diffraction patterns.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901178X
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  • 10
    Digitale Medien
    Digitale Medien
    Gandolfi attachment for a Debye–Scherrer camera (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 126-126 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A standard Debye–Scherrer camera can be readily converted to operate in the Gandolfi mode by the addition of a simple attachment. The attachment replaces the usual camera cover; no changes to the original powder camera are required and its inherent accuracy is preserved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011912
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  • 11
    Digitale Medien
    Digitale Medien
    New crystal data for silver sulphide sulphate, Ag8S3SO4 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 129-130 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The title compound was recognized from the new and unexpected powder pattern of aged precipitates obtained by mixing solutions of excess silver nitrate and sodium thiosulphate under specified conditions. The possible crystalline impurities were identified and conditions were established to yield a pure product. The brown microcrystalline material is tetragonal with a = b = 7.201; c = 10.220 Å. It is a solid electrolyte, has an irreversible transition point at 246°C and melts at 405°C. Method of preparation and powder data are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011948
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  • 12
    Digitale Medien
    Digitale Medien
    Computer-generated standard stereographic projections (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 133-134 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Two Fortran programs have been written. The first determines the coordinates of points on a standard stereographic projection, and the second plots these points. The programs may also be used to draw pole figures of so-called `ideal' sheet textures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011961
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  • 13
    Digitale Medien
    Digitale Medien
    Crystal data for calcium fluoride silicon oxide (CaF2.SiO2), a dehydration product of fluorapophyllite (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 131-132 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Powder data for a previously unreported dehydration product of fluorapophyllite (KCa4Si8O20F.8H2O) are presented. The reflexions are indexed on the basis of a tetragonal cell with a = 6.937 ± 0.003 and c = 8.488 ± 0.004 Å, (c/a = 1.2235 ± 0.0008). The d spacings and intensities correspond to the unindexed data for CaF2.SiO2 in the JCPDS file (Card No. 20-1050) and the refined cell dimensions are identical, to within the experimental error. Single-crystal data have not yet been obtained for this phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901195X
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  • 14
    Digitale Medien
    Digitale Medien
    Profile analysis of diffractometer data (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 134-134 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A computer program has been written for the evaluation of integrated intensities from X-ray diffractometer data. It has been compiled for IBM 360/65 and HP 2100A. The Lehmann–Larsen profile-analysis method [Lehmann & Larsen (1974). Acta Cryst. A30, 580–584] has been used. For weak reflections, profiles obtained from well defined, neighbouring reflections are employed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879011973
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  • 15
    Digitale Medien
    Digitale Medien
    A semiautomatic coordinate measuring device for molecular models (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 135-135 
    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/S0021889879011997
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  • 16
    Digitale Medien
    Digitale Medien
    A status monitor for the Elliott rotating-anode X-ray source (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 136-136 
    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/S0021889879012000
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  • 17
    Digitale Medien
    Digitale Medien
    Model drawing programs: manufacture of masks to produce optical transforms (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 135-136 
    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/S0021889879011985
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  • 18
    Digitale Medien
    Digitale Medien
    A low-cost Richards box for superimposing molecular models on three-dimensional electron density maps (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 137-137 
    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/S0021889879012012
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  • 19
    Digitale Medien
    Digitale Medien
    Synchrotron Radiation Symposium, European Physical Society Fourth General Conference, York, England, 25–29 September 1978 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 137-138 
    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/S0021889879012024
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  • 20
    Digitale Medien
    Digitale Medien
    Union Office, Change of Address (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 138-138 
    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/S002188987901205X
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  • 21
    Digitale Medien
    Digitale Medien
    Crystallographers (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 138-138 
    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/S0021889879012048
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  • 22
    Digitale Medien
    Digitale Medien
    Teaching Crystallography for Today's Sciences, Summer School, Erice, Sicily, Italy, 6–16 September 1977 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 138-138 
    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/S0021889879012036
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  • 23
    Digitale Medien
    Digitale Medien
    Copying Fees and Copyright Law (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 138-139 
    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/S0021889879012061
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  • 24
    Digitale Medien
    Digitale Medien
    Determination of intersubunit distances and subunit shape parameters in DNA-dependent RNA polymerase by neutron small-angle scattering (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 176-185 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: In all organisms the multi-subunit enzyme DNA-dependent RNA polymerase catalyses the first basic step in gene expression, the transcription of DNA into RNA. The neutron small-angle scattering effects were studied in the Guinier region by applying the contrast-matching technique. Isotopic labelling was realised by culturing fully deuterated E. coli cells in a heavy-water medium containing deuterated substrates. One or two completely deuterated components (subunits) of polymerase holoenzyme (composition formula α2ββ′σ, molecular weight 497000) were recombined with the remaining natural (`hydrogenated') subunits for these neutron measurements. Measurements are presented of radii of gyration R, overall shapes, and pair distances d, of three components (subunits α2β,β′) in RNA polymerase of E. coli. The subunits β′, β and α2 are obviously rather elongated in situ and exhibit (as scattering-equivalent prolate ellipsoids) axial ratios of about 7:1 up to 9:1. The intersubunit centre of gravity distances were analysed to be 7.3 ± 0.8 nm for β−β′, 8.2 ± 1.2 nm for α2−β′ and 7.0 ± 1.7 nm for α2−β.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012140
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  • 25
    Digitale Medien
    Digitale Medien
    A perfect-crystal neutron polarizer as an application of magnetic prism refraction (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 186-191 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: It is demonstrated experimentally that the well known spin-selective deflection of neutrons transmitted through a static magnetic field region with triangular geometric boundaries combined with the high angular resolution of a non-dispersive double-crystal arrangement can be used to polarize a thermal neutron beam to a degree close to unity at reasonably low laboratory fields of 1.0 to 1.5 T.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012152
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  • 26
    Digitale Medien
    Digitale Medien
    The small-angle neutron scattering facility at the SAFARI-1 reactor (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 192-200 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A long-wavelength neutron scattering facility at the SAFARI-1 reactor is described. Neutrons of wavelength between 5 and 15 Å can be selected. Features of the facility are the use of microwave guides as neutron conductors, flexible guide-pipe configuration and automatic sequential sample changing. Examples are given of measurements on radiation-induced voids in copper, aluminium, Al-0.4%Si and Al-0.1%In after neutron irradiation and magnetic scattering in US and in 80US-10UC-10UC2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012164
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  • 27
    Digitale Medien
    Digitale Medien
    The use of nuclear emulsions in X-ray topography: improvement of the development methods (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 201-204 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The development is critical in recording X-ray topographs since it takes a long time and determines the final quality of the pictures. It is shown that, in most cases, it is possible to decrease both exposure time and development time and still obtain pictures of good quality. Standard conditions of development should be used to achieve higher resolution only. This new standard may be of great use with the modern high-power sources.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012176
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  • 28
    Digitale Medien
    Digitale Medien
    The doping method in quantitative X-ray diffraction phase analysis (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 205-208 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The doping method in quantitative X-ray diffraction phase analysis is described. The method involves the addition to the investigated system of known amounts of the components, the weight fractions of which are to be simultaneously determined. The weight fraction of a component is related to the intensities diffracted by that component and by any non-added component, before and after doping. The method can also be applied to systems containing unidentified components by analysing for only those components of interest, as well as for amorphous-content determination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012188
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  • 29
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    Digitale Medien
    Determination of strain distribution in elastically bent materials by X-ray intensity measurement (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 209-220 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A method for quantitative determination of local curvature in elastically bent perfect crystals is described. The method is based on X-ray intensity measurements, and a comparison of experimentally determined values with those derived from diffraction theory gives satisfactory agreement. The method was applied to determine the strain gradient and strain concentration in the vicinity of the notch of an elastically bent crystal. The experimental results were compared with those derived from a similar model based on continuum mechanics. Possible applications of the X-ray method are discussed to obtain experimental solutions to strain analyses which, when approached by continuum mechanics, pose formidable mathematical obstacles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901219X
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  • 30
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    Digitale Medien
    A solid-state transformation in 1,5-dichloroanthraquinone (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 239-239 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: 1,5-Dichloroanthraquinone undergoes a solid-state transformation at 470 K. The two modifications are very similar, except that a is greater than b above the transition temperature and the inverse is true at room temperature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901222X
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  • 31
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    Digitale Medien
    A high-temperature focusing X-ray powder camera with new features (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 221-224 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A film-type X-ray high-temperature (up to about 2250 K) powder camera using the Guinier focusing principle in transmission is described. Use is made of a germanium monochromator. The powder specimen is spread without adhesive on a horizontal supporting film of refractory material, and rotates about a vertical axis. The support is surrounded by a cylindrical furnace of thin tantalum sheet enclosed in a chamber which can be evacuated or filled with an inert gas. The X-radiation enters and leaves the chamber through beryllium windows. The film holder is situated outside the chamber. The sample temperature is measured by thermocouples and optical pyrometry. Problems due to the coating by evaporated material of the silica glass window used to observe the specimen are obviated by the use of a transparent shield which can be rotated to give fresh surfaces when needed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012206
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  • 32
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    Digitale Medien
    Crystal data for isotypic Cs2[M(CN)4].H2O compounds, M=Pt, Pd and Ni (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 241-242 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Cs2[Pd(CN)4].H2O and Cs2[Ni(CN)4].H2O were found to be isotypic with the known hexagonal Pt compound which shows an unusual helical chain of six [Pt(CN)4]2− groups in the unit cell, space group P61 or P65. The crystal data are a = 9.559 (2) and c = 19.308 (4) Å, Dm = 2.87 (4), Dx = 2.912 Mg m−3 for the Ni compound, and a = 9.704 (2), c = 19.388 (4) Å, Dm = 3.12 (4), Dx = 3.115 Mg m−3 for the Pd compound. X-ray powder data are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012243
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  • 33
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    Digitale Medien
    Crystal data for Na3Mg2P5O16 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 244-244 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Na3Mg2P5O16 is monoclinic, P21/c, Z = 2, with unit-cell parameters a = 5.177 (1), b = 6.853 (1), c = 18.628 (5) Å, β = 90.00 (4)°.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012267
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  • 34
    Digitale Medien
    Digitale Medien
    Semi-metals & narrow-bandgap semiconductors by D. R. Lovett (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 262-262 
    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/S0021889879012437
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  • 35
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    Digitale Medien
    Comparison and optimization of smoothing procedures for small-angle X-ray scattering curves. Polynomial fitting and modified frequency filtering (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 267-274 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The filter theory allows one to compare the efficiencies of smoothing procedures widely used in the field of small-angle X-ray scattering. This method is demonstrated for polynomial fitting and modified frequency filtering. Optimized and objective smoothing parameters are determined for both procedures through the knowledge of variance reduction factors, transfer functions of the filters, the largest value of the spatial frequencies of the scattering curve and the distortions caused by the smoothing procedures. The comparison of the efficiency of polynomial fitting and frequency filtering clearly shows the superiority of the latter; therefore, this method has to be preferred.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012450
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  • 36
    Digitale Medien
    Digitale Medien
    Détermination expérimentale de la fonction d'orientation – son application dans le calcul des bandes de diffraction (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 332-338 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The influence of orientation on the powder diagrams produced by lamellar structure systems is studied in the case where the bidimensional lattice is very limited and where the layer structure is complex. The orientation distribution must be included in the numerical integration which leads to the line diffraction profile. The technical measurement of the real experimental orientation is discussed. An example is given showing the influence of the orientation on the interference function in the absolute scale.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012644
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  • 37
    Digitale Medien
    Digitale Medien
    Geometrical problems with a position-sensitive detector employed on a diffractometer, including its use in the measurement of stress (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 339-345 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Defocusing errors associated with the use of a one-dimensional position-sensitive proportional counter on a powder diffractometer are considered. These errors are small in the measurement of residual stress and it is not necessary to apply mathematical corrections, especially if the X-ray tube is aligned properly. Correspondingly, these errors are small for high-angle peaks in any reflection experiment compared with the present detector resolution. The equations presented allow for an evaluation of this error in most equipment configurations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012656
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  • 38
    Digitale Medien
    Digitale Medien
    Determination of local atomic configurations for binary substitutional alloys (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 351-356 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A method is described whereby the complete distribution of first-nearest-neighbor atomic configurations can be determined from experimental short-range order coefficients for binary substitutional f.c.c. alloys. The process involves the computer simulation of the structure represented by the experimental αi by a Gehlen–Cohen-type procedure, followed by the classification of each atom of a given species in the model as one of the 144 crystallographically distinct nearest-neighbor types. These simulation and searching procedures are then used to demonstrate the consistency of the information one can expect to obtain from a given set of αi by `close fitting' to different numbers of coordination shells. It is shown, for example, that a six-shell close fit to a selected set of αi can yield a solution with a mean relative deviation of about five per cent for the nearest-neighbor configuration concentrations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901267X
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  • 39
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    Digitale Medien
    Simple methods of aligning four-circle diffractometers with crystal reflections (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 357-359 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Simple methods of aligning four-circle diffractometers with crystal reflections are devised. They provide the methods to check (1) perpendicularity of χ plane to the incident beam, (2) zero point of 2θ and linearity of focus-χ center-receiving aperture and (3) zero point of χ.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012681
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  • 40
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    Digitale Medien
    Total thermal neutron cross sections of Al, Si, Cu, Zn, Ge, Pb and Bi single crystals (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 399-400 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Experimental values of the cross sections of Al, Si, Cu, Zn, Ge, Pb and Bi at room temperature for several neutron energies between 2 × 10−3 and 10−1 eV, are reported. The measurements were repeated for a Bi single crystal at T = 80 K.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012784
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  • 41
    Digitale Medien
    Digitale Medien
    Absorption correction and normalization of X-ray small-angle scattering data for materials producing intense scattering at extremely low angles (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 401-402 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Some materials of low absorption that contain particles in the several thousand Å range can produce an intensity of small-angle scattering that is a significant fraction of that of the transmitted beam. This is quite apparent in the range of a few s scattering angle when a Bonse–Hart small-angle scattering diffractometer is used. A method was developed that allows an accurate absorption correction to be calculated when the scattering by the sample can be approximated by an exponential function in the range of 0 to 5 s double Bragg angle 2θ. Variation of sample thickness allows the correction method to be checked.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012796
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  • 42
    Digitale Medien
    Digitale Medien
    Crystal data for Na4Mg2Si3O10 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 405-406 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An indexed powder pattern is reported for Mg2Na4O10Si3. The unit cell is orthorhombic, a = 10.584 (7), b = 14.328 (7), c = 10.457 (7) Å. Transition to a cubic phase, a = 7.440 Å, occurs at 918 K. A Na-deficient tetragonal phase was also observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012814
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  • 43
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    Digitale Medien
    A simple furnace for neutron diffraction studies (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 403-404 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A simple yet effective high temperature furnace for heating crystals or powder specimens for neutron diffraction studies on a θ/2θ diffractometer is described. The furnace can maintain samples at temperatures up to 1573 K, in air, with a stability of ± 4 K for periods of many hours. Specimen temperature is uniform within 12 K, or much less with the use of a silica sleeve.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012802
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  • 44
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    Digitale Medien
    Powder diffraction data for compounds in the series Nax(Ca3±xNax)Al2O6 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 407-410 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Indexed powder diffraction data are presented for Ca3Al2O6 and its sodium-containing solid solutions. Powder patterns of the cubic and orthorhombic phases calculated from the crystal structure data are compared with the observed patterns. Indexed data are presented for the monoclinic phase, which is stabilized by sodium and silicon. The so-called tetragonal phase is shown by electron diffraction to be orthorhombic, pseudo-tetragonal. It probably has the symmetry Pcaa with a = b = 10.8599 (9), c = 15.1234 (20) Å.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012826
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  • 45
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    Digitale Medien
    Crystal data and molecular packing of drug charge-transfer complexes. I. Promethazine picrate (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 413-413 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Crystal data for promethazine picrate (C23H23N5O7S) complex are: triclinic P1 or P{\bar 1}, Z = 2, a = 18.49 (1), b = 7.77 (1), c = 7.79 (1) Å, α = 70.9 (2), β = 90.0 (2), γ=83.0 (2)°.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901284X
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  • 46
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    Digitale Medien
    Crystal data of tris(2-cyanoethyl)phosphine oxide, tris(2-cyanoethyl)phosphine sulphide and tris(2-cyanoethyl)phosphine selenide (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 414-415 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Tris(2-cyanoethyl)phosphine oxide, OP(C2H4CN)3, C9H12N3OP, is hexagonal (rhombohedral), space group R3c, with a = 13.484 (1) and c = 10.162 (1) Å. The sulphide and selenide are triclinic, space group P{\bar 1}. Cell dimensions for SP(C2H4CN)3, C9H12N3PS, are a = 8.363 (8), b = 9.026 (4), c = 9.777 (6) Å; α = 98.75 (4), β = 107.31 (5), γ = 115.85 (5), and for SeP(C2H4CN)3, C9H12N3PSe, a = 8.497 (5), b = 9.148 (2), c = 9.972 (8) Å; α = 98.85 (2), β = 107.20 (6), γ = 116.96 (3)°. X-ray powder diffraction data are quoted.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879012851
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  • 47
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    Digitale Medien
    Radiation Leakage around X-ray Tube Shields (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 488-488 
    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/S0021889879013145
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  • 48
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    Digitale Medien
    Advances in X-ray analysis. Vol. 21. Proceedings of 26th Annual Conference on Application of X-ray Analysis, Aug. 3-5, 1977 edited by C. S. Barrett, D. E. Leyden, J. B. Newkirk and C. O. Ruud (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 488-488 
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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/S0021889879013157
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  • 49
    Digitale Medien
    Digitale Medien
    Etude d'un systeme micellaire de type inverse par diffusion centrale des neutrons (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 502-510 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The study by neutron small-angle scattering of reverse-type micellar solutions of the ternary system water–OT aerosol–n-heptane is reported. The contrast variation method used both on the water inside the micelle and on the solvent makes it possible to determine some structural parameters of the micelle and to propose two micellar models.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013170
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  • 50
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    Digitale Medien
    The influence of multiaxial stress states, stress gradients and elastic anisotropy on the evaluation of (Residual) stresses by X-rays (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 489-501 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: In recent years, nonlinear d versus sin2 ψ distributions have been observed in stressed materials which cannot be explained by the classical fundamentals of X-ray stress measurement, d is the interplanar spacing measured and ψ is the angle between the surface normal of the sample and the measuring direction. This paper reviews treatments for these nonlinear distributions, including stress gradients, shear stresses and anisotropic X-ray elastic constants. Methods for the evaluation of stresses are reported, and recommendations are given for the practical application of X-ray stress measurement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013169
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  • 51
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    Digitale Medien
    Pressure-induced tetrahedral tilting and deformation in Ge2N2O (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 511-516 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: High-pressure time-of-flight neutron diffraction studies have been carried out on orthorhombic Ge2N2O to 25.4 × 108 Pa and by X-ray diffraction to 49 × 108 Pa. The zero-pressure axial compressibility coefficients are Ka = 33 (2), Kb = 41 (2), Kc = 28 (2), and volume Kv = 99 (5) × 10 −13 Pa−1. The changes in bond angles and bond lengths at pressures from 105 to 25.4 × 108 Pa have been measured. The structure of Ge2N2O consists of GeN3O tetrahedra linked along the a direction by Ge–O–Ge bonds and along the b and c directions by three coordinated Ge–N bonds. This structural framework adjusts to applied pressure by tetrahedra tilting in a cooperative fashion, the biggest change being observed in the Ge–O–Ge angle which decreases by 12.4°. The behavior of Ge2N2O is very similar to its isomorph Si2N2O, though the tetrahedra deform somewhat more for Ge2N2O. The pressure changes in the lattice parameters of Ge2N2O up to 8̃ × 108 Pa are very similar to those of Si2N2O up to 2̃4 × 108 Pa, supporting the contention that germanates behave as high-pressure models for silicates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013182
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  • 52
    Digitale Medien
    Digitale Medien
    Determination of inter-element effects through Monte Carlo simulation of X-ray fluorescence (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 517-524 
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    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A Monte Carlo model is developed to simulate the X-ray fluorescence process within a homogeneous multi-element mixture. Validation of the model is obtained through comparison of the model's predictions with experimental data for the iron–nickel–chromium system, for which the inter-element effects are severe. The results indicate that the Monte Carlo model is an excellent simulator and may be used in place of a set of standards to determine the influence coefficients for analysis of fluorescence data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013194
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  • 53
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    Digitale Medien
    Quantitative structural studies by means of the energy-dispersive method with X-rays from a storage ring (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 531-536 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Test experiments were made using the X-ray energy-dispersive method at the storage ring DORIS (Hamburg) working in the single-bunch mode. It is shown that the spectral distribution of the incident beam calculated from the storage-ring parameters is in very good agreement with that derived from measured diffraction patterns of known substances, and thus it can be used for structural studies. This is illustrated with results of profile-fitting refinement applied to urea (CH4N2O) and naphthalene (C10H8). It is also shown that because of an improved detector system and the time structure of the radiation emitted from the storage ring one is able to record 7 × 104 photons per second and obtain reliable patterns in times of the order of 1 s.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013212
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  • 54
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    Digitale Medien
    The determination of crystallite dimensions using synchrotron-radiation X-ray diffraction photographs (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 525-530 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Synchrotron-radiation Laue patterns give valuable information on the sizes and shapes of grains in a polycrystalline material even if these are too small for synchrotron topography. A calculation, based on kinematic theory, is presented for the radial and lateral broadening of the diffraction spots obtained with white radiation. The most conspicuous broadening is to be expected when the dimensions of the reflecting planes are small and not their number; this is at variance with the conditions leading to broadening with conventional monochromatic methods. Quantitative assessment of the crystal dimensions is possible if auxiliary spectral information is obtained by using selectively absorbing filters. The theory was applied to the analysis of Laue photographs of xenon and krypton crystallites condensed on a cooled beryllium substrate. Crystal dimension down to a few nanometers could be determined. The method is, in principle, applicable to the determination of the grain size and shape distribution of fine-grained polycrystalline samples of any material. Changes during crystallization and recrystallization can be easily followed by virtue of the simple experimental set-up and short exposure times involved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013200
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  • 55
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    Digitale Medien
    A liquid-helium cryostat for collection of three-dimensional X-ray intensity data down to 20 K. The crystal structure of D(+)-tartaric acid at 35, 105, 160 and 295 K (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 537-544 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A Be-walled conduction cooling He(l) cryostat intended for the interval 20–80 K and the κ geometry of the CAD4 X-ray diffractometer is described. Three-dimensional X-ray intensity data can be collected in the interval − 45 〈 χ 〈 45° with the temperature stability maintained within ± 1 K. The experimental problems caused by centering an unseen crystal and by the absorption and scattering in the Be walls are discussed. D(+)-tartaric acid, C4H6O6, was chosen as a test compound. Only minor differences occur in its crystal and molecular geometry between 295 and 35 K.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013224
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  • 56
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    Digitale Medien
    X-ray diffraction profiles from single crystals of Cu–Ge alloy containing heavily faulted regions (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 545-550 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Intensity profiles of diffuse streaks along [111] were accurately measured for heavily faulted regions in deformed specimens. They often showed two or three broad peaks and differ remarkably from Paterson's [J. Appl. Phys. (1952). 23, 805–811] profiles (Reichweite s = 1), but are in fairly good agreement with Kakinoki's [Acta Cryst. (1967). 23, 875–885] profile of s = 2 with the sequence probabilities α1 = 0.45–0.85 and α2 = 0–0.1. This means that the deformation (intrinsic) faults are produced more easily on every other (111) plane than on successive planes. A model which shows the distribution of the deformation faults is constructed by a computer simulation. A detailed study using Kakinoki's theory with s = 3 shows a better fit with the experimental profile.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013236
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  • 57
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    Digitale Medien
    Analysis of two-dimensional reflections from a fine-particle carbon (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 551-553 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The intensities of two-dimensional reflections from a non-graphitic carbon were correctly calculated by using the general Debye scattering equation and the hypothesis of small (about 12 Å in diameter) domains diffracting incoherently with respect to one another.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013248
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  • 58
    Digitale Medien
    Digitale Medien
    A texture goniometer with variable radius and collimation for analysis of textures in rocks (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 564-569 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A texture goniometer has been built specifically for geologic applications. Features include (1) a large and variable radius, (2) a variable collimation system that is simple to use and which permits excellent resolution, (3) a wide main circle that allows large specimens to be analysed, (4) partial vacuum paths for the incident and diffracted beams, (5) a θ:2θ drive that allows 2θ scans. The performance of the goniometer is assessed by determining resolution and count rate for various collimations and radii.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013261
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  • 59
    Digitale Medien
    Digitale Medien
    An analysis of the Rietveld refinement method (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 554-563 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An analysis of the Rietveld profile refinement method used in the interpretation of neutron or X-ray powder diffraction patterns has been carried out. It is shown that the values obtained for the structural parameters are not exactly the same as those obtained from an integrated intensity refinement of the same data and that the standard deviations of the parameters are determined incorrectly. Whilst the differences in the values of the parameters may not be statistically significant, the fact that their standard deviations are estimated incorrectly severely limits their usefulness. These conclusions are confirmed by refinement of a number of data sets using both methods and in most of these cases the standard deviations are found to be underestimated by the profile refinement method by a factor of at least two. Discussions based on the results of profile refinement must therefore be reconsidered and the relative value of powder diffraction techniques must be reviewed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901325X
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  • 60
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    Digitale Medien
    Etude cristallographique des monophosphates acides du type MII(H2PO4)2.2H2O pour MII=MnII, FeII, CoII (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 609-610 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Acid monophosphates MII(H2PO4).2H2O with MII = Mn, Fe and Co are isotypic with the corresponding Cd and Zn salts. Crystal data and powder diffraction data for these three salts are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901339X
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  • 61
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    Digitale Medien
    Crystal data for ammonium magnesium carbonate tetrahydrate [(NH4)2Mg(CO3)2.4H2O] (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 611-611 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Ammonium magnesium carbonate tetrahydrate crystallizes with an orthorhombic unit cell, a = 7.697, b = 10.287, c = 6.639 Å, Z = 2; Dx = 1.595, DM = 1.61 ± 0.01 Mg m−3. An indexed powder pattern is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013406
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  • 62
    Digitale Medien
    Digitale Medien
    Crystal data for pipemidic acid trihydrate C14H17N5O3.3H2O (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 612-612 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The powder data for pipemidic acid trihydrate are reported. This compound is triclinic with a = 8.570 (3), b = 8.514 (3), c = 15.208 (6) Å, α = 105.14 (4), β = 110.84 (5), γ = 113.96 (5)°. Z = 2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013418
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  • 63
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    Digitale Medien
    Crystal data for sodium propanoate: C2H5COONa (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 613-614 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Indexed powder patterns of three monoclinic phases of sodium propanoate, Na+.C3H5O2−, are given. The cell dimensions are a = 3.624 (3), b = 5.338 (4), c = 11.414 (8) Å, β = 90.84 (3)° at 507.7 K; a = 3.622 (3), b = 5.359 (5), c = 11.400 (10) Å, β = 90.58 (2)° at 489.8 K and a = 3.569 (3), b = 5.306 (4), c = 11.188 (9) Å, β = 92.86 (2)° at 298.1 K. For the room temperature phase III, smoothing equations are given to describe the thermal expansion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S002188987901342X
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  • 64
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    Digitale Medien
    Données crystallographiques sur la forme basse température de (NH4)3In(SO4)3 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 615-615 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The low-temperature modification of (NH4)3In(SO4)3 is monoclinic, space group P21/c. The lattice constants are a = 8.963 (7), b = 15.644 (15), c = 9.131 (6) Å, β = 108.28 (5)° (Z = 4). The indexed powder diagram is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013431
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  • 65
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    Digitale Medien
    New crystal data for Ca, Cu, UO2 hydrated carbonate: voglite (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 616-616 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Voglite, Ca2Cu(UO2)(CO3)4.6H2O (?) is monoclinic with a = 25.97, b = 24.50, c = 10.70 Å, β = 104.0°, Z = 16. Probable space group P21 or P21/m. Powder diffraction data are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013443
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  • 66
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    Digitale Medien
    Crystal data for N(CH3)4GeCl3 (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 617-618 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The ionic conductor N(CH3)4GeCl3 shows a phase transition at 424 K. The high-temperature modification is cubic with a = 6.552 (2)Å, space group Pm3m. At 293 K the compound is orthorhombic with unit-cell parameters a = 13.096 (2), b = 8.911 (1), c = 9.128 (2) Å, space group Pna21.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013455
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  • 67
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    Digitale Medien
    Crystal data for a second polymorph (β) of C.I. Pigment Red 1,1-[(4-nitrophenyl)azo]-2-naphthol (1979)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 12 (1979), S. 626-627 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The preliminary single-crystal data and powder pattern are given for a second polymorph of C.I. Pigment Red 1, C16H11N3O3. The powder pattern has been indexed using the single-crystal dimensions; the problems of multiple indexing have been reduced by comparison with single-crystal intensities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889879013509
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  • 68
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    Digitale Medien
    A review of my papers on crystal optics 1912 to 1968 (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 1-9 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The theory of the diffraction of X-rays by crystals was developed by Ewald as part of a unified study of the interaction of light of all wavelengths with crystals, beginning with the work for his 1912 thesis and extending to his papers in 1968. The formulation of the problem in terms of the interaction of electromagnetic radiation with a periodic array of dipoles is placed in its historical perspective and is compared with Laue's version based on the assumption of a continuous electron density distribution. The Borrmann effect, hinted at in 1917, is derived readily from consideration of the dispersion surface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000024
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  • 69
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    Digitale Medien
    A solution of the X-ray `phase problem' (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 17-21 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The phases of X-ray reflections are lost in the diffraction process in conventional two-beam diffraction. It is shown that the phases are not lost when three beams diffract simultaneously, and that phase information can be extracted from knowledge of the spatial distribution of the diffracted intensities about the three-beam point. In centrosymmetric crystals, the distribution is a sensitive function of the invariant phase of the product of the structure factors involved in simultaneous diffraction. High-resolution divergent-beam photographs illustrating the intensity differences associated with positive and negative triplet-phase products are shown.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000048
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  • 70
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    Digitale Medien
    Tensorial covariants for the 32 crystal point groups (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 83-95 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The recently published tables of Clebsch-Gordan products are applied to derive the tensorial covariants (bases of irreducible or physically irreducible representations) for the 32 crystal point groups. Tensors of the following intrinsic symmetries in Jahn notation are considered: &egr; (pseudoscalar), V (polar vector), [V2], V[V2], [[V2]2], [V2]2, &egr;[V2], and &egr;V[V2]. With this choice the most important tensors of optical and other properties are covered. Explicit lists of covariants in components of these tensors are given for the non- centrosymmetric groups; with the use of parity arguments the lists also apply to centrosymmetric groups. Applications, especially for phase transitions with reduction of the point symmetry, are briefly discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000152
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  • 71
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    Digitale Medien
    Ferroelastic transformations in lead orthophosphate and its structure as a function of temperature (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 108-114 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: In Pb3(PO4)2 there are in general triplets of crystallographically independent atoms of the same kind that are pseudosymmetrically related by a pseudo-threefold rotation and interchange identity in ferroelastic transformations. By means of a rotation of axes that takes into account the distortion of the real monoclinic lattice, the atomic coordinates in the ferroelastic transformations of Pb3(PO4)2 are calculated. The results of the refinement of the structure by means of the Rietveld technique, at several temperatures below and above the phase transition, are reported, as well as the atomic displacements involved in the ferroelastic switching as a function of temperature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947900019X
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  • 72
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    Digitale Medien
    Conditional phase probability distributions of structure factors in a Karle–Hauptman matrix (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 105-107 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: From the joint probability distribution of all structure factors in a Karle-Hauptman matrix new phase probability distributions are obtained. These calculations lead to a reformulation of the maximum-determinant rule for phase determination. In addition a new function is derived whose maximum corresponds to the most probable values for the phases of an arbitrary subset of the structure factors in a Karle-Hauptman matrix. This function accounts for the interaction among phases in a Karle-Hauptman matrix through triple products and quartets simultaneously.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000188
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  • 73
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    Digitale Medien
    Use of the neutron time-of-flight technique for structure investigations (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 131-136 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The application of a time-of-flight neutron diffractometer for crystallographic investigations, designed on the basis of a pulsed neutron source, is discussed. The procedure for obtaining integrated intensities and introducing corrections is described. The results of a test experiment with perdeuteronaphthalene are given. The deuterium atom positions in the structure of La2Mg3(NO3)12.24D2O are also refined and compared with those obtained using X-ray diffraction techniques. The observed systematic differences in bond lengths and valence angles are explained by the differences between the 'X-ray' and 'neutron' coordinates of the light atoms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947900022X
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  • 74
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    Digitale Medien
    Experimental electronic valence charge density of NaCl and SrCl2 along the nearest-neighbour axis (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 140-142 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Valence-electron charge distributions have been calculated by difference Fourier inversion of experimental structure factors. The contribution of core electrons has been subtracted by using a one-term Gaussian representation. The results are in agreement with theoretical charge distributions obtained by the local-orbitals Hartree-Fock method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000243
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  • 75
    Digitale Medien
    Digitale Medien
    Transformations to optimize the superposition of similar structures (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 158-163 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A simple, efficient and general method is described for finding the linear orthogonal transformation to superpose two similar structures given by sets of equivalent points, usually atomic position vectors. Formulae are also given for extracting the independent variables of rotation from the resulting transformation matrix. In addition, general transformations are derived, both in the case of proper rotation and in the case of rotatory inversion, to convert to a molecular frame of reference based on the superposition axis of symmetry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000279
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  • 76
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    Digitale Medien
    Diffraction profiles from small crystallites (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 171-176 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The diffraction profile for a small crystallite has been obtained as the orientational average of the diffraction intensity given by Ino & Minami [Acta Cryst. (1979), A35, 163-170]. The formula obtained is a type of Debye interference function modified by a function {cal V}(r) (the self-convolution of a crystal shape function) and is expressed as a sum over all the atomic distance vectors in the crystal structure. Since the set of the vectors has Laue symmetry (the order of the group: L), the summation can be simplified to a sum over a reduced range corresponding to 1/L of the original range, while the {cal V}(r) is changed to {\bar v}(r) = ΣLp = 1= {cal V}(Rpr)/(LVt) (Vt: volume of the crystal; R1, . . . , RL: element of Laue symmetry group). Once the {\bar v} function is determined, the profile for a complicated crystal of any size and any crystal system can be systematically and efficiently calculated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000292
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  • 77
    Digitale Medien
    Digitale Medien
    The structure of ordered Ag3Mg: an ordinary long-period alloy as opposed to periodically antiphased alloys (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 181-188 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A necessary distinction is established between two kinds of long-period ordered structures: (1) periodic antiphases (PAP), whose principal characteristic feature is a continuous variation of antiphase half-period M as the composition changes; (2) 'ordinary' long-period structures, which show, as the composition changes, a series of phases stable in small composition ranges, every phase displaying a different, but well-defined, crystallographic structure. It is shown, through electron diffraction studies, that the ordered Ag3Mg alloy belongs to the second kind, unlike standard PAP alloys such as AuCu, AuCu3, Au3Cu, Cu3Pt and Cu3Pd. It is stressed that standard PAP structures can always be obtained by heating, above some transition temperature, a L 12 (or L 10) phase which always exists at lower temperature. This is not the case for ordered Ag3Mg. In this connection, the theory about stabilization of long-period structures is discussed [Sato & Toth (1965). Alloying Behaviour and Effects in Concentrated Solid Solutions, pp. 295-419. New York: Gordon & Breach].
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000310
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  • 78
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    Digitale Medien
    A hard-disc system: structures of a close-packed thin layer (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 194-196 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The possible structural transitions between n and (n - 1) thin layers of hard discs are considered. The apparently obvious homogeneous transition postulated on the basis of n = 2 is shown by an analogue experiment not to be the general solution. It is argued that the maximum density is retained by a 'Δ-form' transition which minimizes the density deficit at the boundary walls, and can be referred to different sections of a two-dimensional close packing.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000334
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  • 79
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    Digitale Medien
    Structural changes in β-FeOOH caused by radiation damage (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 197-200 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A high-resolution electron-microscope study of β-FeOOH (akaganéite) has been carried out. Examination of intact crystals and ultrathin sections provided no evidence for the hollow-rod structure proposed by earlier workers. It was found also that features, such as mottling and striations, previously thought to be indicative of a porous structure, were due to radiation damage. It is concluded that the β-FeOOH crystals are not porous, but are, in fact, crystallographically homogeneous.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000346
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  • 80
    Digitale Medien
    Digitale Medien
    A new Monte Carlo method for phase determination (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 220-224 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: An extended version of the multi-solution method has been devised by introducing a Monte Carlo technique. This Monte Carlo direct method differs from the ordinary multi-solution procedure in two respects: (1) The starting set usually consists of as many as 10-50 phases; (2) Tentative phase values assigned to the members of the starting set are derived from successively generated random numbers. The application of the new method to several unknown structures has shown that it can be used as an effective means of phase determination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000371
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  • 81
    Digitale Medien
    Digitale Medien
    Electrogyration and piezogyration in NaClO3 (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 225-232 
    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 developed for measuring electrogyration and piezogyration effects in polar crystals. The influence of linear electro-optic and piezo-optic effects is discussed in detail. By the use of different directions of measurement, the tensorial behaviour of the induced gyration is proved unequivocally. The magnitudes of the electrogyration and piezogyration coefficients are 10-16 m V-1 and 10-15 m2 N-1 respectively. The relations between constants measured under different thermodynamic conditions are considered. An analysis of results on the basis of a coupled oscillator model reveals a strong sensitivity of induced gyration to changes in the arrangement of the oscillators.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000383
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  • 82
    Digitale Medien
    Digitale Medien
    On the treatment of protein data measured on the oscillation camera (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 146-157 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The method used in Oxford for the collection and reduction of protein data from the Arndt-Wonacott oscillation camera [Arndt, Champness, Phizackerley & Wonacott (1973). J. Appl. Cryst. 6, 457-463] is described. The photographs are digitized with an Optronics Photoscan P-1000 drum scanner operated in an off-line mode, and the magnetic tapes are subsequently processed on an ICL 1906A computer. Results are presented for the protein phosphorylase b. The estimation of standard deviations for both fully and partially recorded observations is discussed, and the intensities for these two categories of term are compared.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000267
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  • 83
    Digitale Medien
    Digitale Medien
    Extinction in sodium fluoride (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 176-180 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: X-ray intensity measurements for a single crystal of sodium fluoride obtained at four wavelengths by Howard & Jones [Acta Cryst. (1977). A33, 776-783] have been reanalysed using both the Cooper-Rouse and Becker-Coppens extinction formalisms in order to study the wavelength dependence of the extinction in this crystal, since the original analysis was unable to account for the wavelength dependence of the intensities of the strong reflections. The results indicate that the crystal is intermediate between type I and type II in nature and are consistent with the wavelength dependence predicted by the theories, although the extinction is not large enough at the shorter wavelengths to provide a useful test of the validity of the theoretical wavelength dependence. The analysis also demonstrates some of the possible consequences of the use of unbalanced weighting schemes and of inappropriate models for the scattering factors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000309
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  • 84
    Digitale Medien
    Digitale Medien
    X-ray diffraction by small crystals (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 163-170 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A general method of calculating the intensity of X-ray diffraction from small crystalline particles whose boundary is defined by a shape function is discussed. The intensity formula which is generally given by a double sum over the reciprocal-lattice points is simplified into the form of a single sum, using 'the random-shift treatment' which assumes that the position of the boundary relative to the crystal lattice varies at random from crystal to crystal. By the use of Fourier theorems, the intensity formulas are also converted into a single sum over the direct lattice. Although the electron distribution in the particle has been defined in various ways by the shape function, a more reasonable expression of the electron density appropriate to small crystals is introduced. The intensity formulas derived on the basis of the new form of the electron density are compared with other intensity formulas which have so far been proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000280
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  • 85
    Digitale Medien
    Digitale Medien
    Defect structure of the ionic conductor lithium nitride (Li3N) (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 309-314 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The defect structure of Li3N (space group P6/mmm, a ∼ 3.65, c ∼ 3.88 Å) has been investigated with data sets measured at seven temperatures in the range 153 to 678 K. The data have been used for normal and high-order refinements and for the calculation of the corresponding difference electron densities. The final Rw ranged between 0.7 and 1.3%. The N atom position at z = 0 and the Li(1) positions at z = ½ are completely occupied and remain ordered within the whole temperature range. The Li(2) sites at z = 0 already show a vacancy concentration of 1-2% at low temperatures, which does not change significantly with increasing temperature. The Li(2) ions exhibit strong anharmonic thermal vibrations within the Li2N layers at z = 0 along the Li(2)-Li(2) connection lines. The high Li ionic conduction is caused by jumps of Li(2) ions from an occupied Li(2) site into an unoccupied one. The anharmonic thermal vibrations are the precursors of these jumps. Interstitial sites are not involved in this mechanism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000632
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  • 86
    Digitale Medien
    Digitale Medien
    Derivation of three-phase invariants from the Patterson function (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 213-220 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The idea of Anzenhofer & Hoppe [Phys. Verh. (1962), 13, 119] that all the Fourier coefficients of the function ρ(r).ρ(r + u) are zero if the Patterson function is zero at vector point u is first developed; it is shown that the three-phase cosine and sine invariants may be derived jointly by solving two sets of linear equations. A least-squares method exploiting the entire Patterson function is then presented; this may allow the three-phase cosine and sine invariants to be determined and/or refined. As expected, the low-valued Patterson regions contribute most to the least-squares procedure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947900036X
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  • 87
    Digitale Medien
    Digitale Medien
    X-ray interferometry with divergent polychromatic beams (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 201-213 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The theory of a strongly absorbing Laue interferometer for an arbitrary composition of the X-radiation has been developed on the basis of the Takagi equations. The coherent properties of interfering beams of polychromatic radiation are discussed. Formulas have been derived showing the dependence on the moiré pattern and the contrast of interference fringes of the type of deviation of the interferometer geometry from the perfectly aligned case. The results of an experiment for obtaining the moiré pattern of a symmetric Laue case (LLL) interferometer with Bremsstrahlung radiation are presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000358
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  • 88
    Digitale Medien
    Digitale Medien
    The crystal structure of hexabromobenzene: constrained refinement of neutron powder diffraction data (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 233-235 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The structure of hexabromobenzene, C6Br6, has been determined at 300 K by neutron powder diffraction. The crystal is monoclinic, a = 15.357 (4), b = 4.007 (1), c = 8.364 (2) Å, β = 92.65 (2)°, space group P21/n, Z = 2. The problem is well suited for a constrained refinement with the program EDINP. Within the accuracy of the analysis the orientation of a planar molecule is found and all intramolecular separations correspond to normal van der Waals interactions. No explanation of the multiple-crystal formation can be proposed and, in fact, packing considerations would support twinning on (101) which has not been observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000395
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  • 89
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    Digitale Medien
    Lindemann's rule and the X-ray Debye temperature of anisotropic Zn and Cd single crystals (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 243-245 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Lindemann's rule was applied to Zn and Cd single crystals and found to be valid for these solids, xz being in the range 0.2 to 0.25.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000425
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  • 90
    Digitale Medien
    Digitale Medien
    Absorption corrections for neutron diffraction (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 248-248 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The transmission factors tabulated by Rouse, Cooper, York & Chakera [Acta Cryst. (1970). A26, 682-691] for μr 〈 1 can be expressed as the product of two factors: a scale factor and a Debye-Waller factor. In the case of a sphere or a cylinder, the absorption corrections then reduce to simple adjustments of these parameters at the end of the refinement, instead of tedious corrections to the data itself. The results are of particular use for powder data. A printing error in the original paper is also corrected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479000449
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  • 91
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    Digitale Medien
    Refinement of metal d-orbital occupancies from X-ray diffraction data (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 536-539 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Expressions are derived relating the occupancies of transition-metal d orbitals in a trigonal distortion of an octahedral field to the populations of multipole density functions refined from X-ray diffraction data. The expressions are used to obtain the iron d-orbital configuration in cubic FeS2 by least-squares refinement of very high resolution single-crystal X-ray intensity measurements. The refined populations correspond to a large distortion of the iron electron density from spherical symmetry towards a low-spin configuration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001285
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  • 92
    Digitale Medien
    Digitale Medien
    Structure, morphologie et macles des polymères (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 422-428 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Polymer crystal structures are tentatively grouped according to the relations between the symmetries of the macromolecular chain and the space group. Three possibilities occur: helical molecular symmetry (a) compatible with a crystalline lattice, or (b) incompatible, but with the chain axis parallel to the lattice principal axis; and low symmetry of the chain and lattice with random orientation of the chain. In the first two cases, the affinity between molecular and lattice symmetry allows us to describe the morphology and twinning of dilute-solution-grown crystals according to the classical laws. In the last case, these laws should be adjusted to the two-dimensional lattice which characterizes the chains packing orthogonally to their axis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001029
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  • 93
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    Digitale Medien
    Intersecting defect structures in gallia-and magnesia-doped rutiles (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 449-458 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The possible { 210 } (0½0) defect intersection structures of rutile are analysed. There are 41 distinct intersection classes, 26 of which may exist as enantiomorphic forms. A classification scheme is introduced and used to analyse 386 observed intersections. Examples of 25 classes occur; eight of these account for 87% of the observations. The occurrence frequency may be understood by analysis of the stair-rod dislocation Burger's vector, required for continuity of the rutile structure around the intersection. Structural models for the commonly observed intersections and the nature of the 'dislocation-core' structures are presented. Exceptionally large tunnels are generated at orthogonal intersections and some high-resolution images are discussed. Statistical analysis shows that the distribution over the possible classes is not random, suggesting that an equilibrium network of intersecting defects may arise after long reaction times. The stability and mobility of intersections is expected to determine the kinetics of the reaction between rutile and dopants. Intersection structures may act as nuclei for low- to high-temperature phase transformations and they may aggregate and order to form new ordered structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001066
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  • 94
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    Digitale Medien
    A statistical method for selecting reflections for Bijvoet difference measurement in crystals with heavy atoms (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 463-467 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The conditional probability distribution of the Bijvoet ratio δ for given |F'N| and |F'P| is worked out for a noncentrosymmetric crystal with one species of anomalous scatterers (besides a large number of normal scatterers) in the unit cell. The expression for the conditional probability for |δ| to be greater than any given value δo is then deduced. The use of this expression for testing the suitability of a given Bijvoet pair of a crystal for Bijvoet difference measurement is pointed out. Numerical tables which aid easy implementation of the results to actual crystals are provided. Application of the result in a few actual crystal structures is also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S056773947900108X
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  • 95
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    Digitale Medien
    X–N and X–X (1s2 core) maps for cyanuric acid (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 458-462 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: X–N maps and X–X (1s2 core) maps for cyanuric acid, C3H3N3O3, at 100 K are presented. The differences in scale and in the atomic parameters have large effects (≤ 0.4 e Å-3) on the difference density at the nuclei but smaller effects (≤ 0.15 e Å-3) on the bond density distributions. In particular, the density distribution around the O atoms, where polarization is likely to occur, is different in the two types of maps. It is concluded that, in these regions, the X-N maps yield the more reliable results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001078
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  • 96
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    Digitale Medien
    Le groupe P1 et ses sous-groupes. I. Outillage mathématique: automorphisme et factorisation matricielle (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 485-496 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Nowadays there is a good knowledge of space subgroups but, curiously, the subgroups of the simplest space group P1 are poorly known. This is due to the fact that P1 is the sole space group possessing only isosymbolic subgroups while more complicated space groups possess extra translationengleich, klassengleich and other subgroups whose derivation is easier than that of isosymbolic subgroups. Thus the examination of the subgroups of P1 has been undertaken. This problem is connected to a large extent with matrix transformations and automorphisms which constitute the mathematical tools developed in this first paper. The subgroups of P1 are connected with changes of the unit cell, i.e. with matrices having integer coefficients. Such matrices can be decomposed into the products of simpler matrices and reduced to diagonal matrices having integer coefficients. The results of these theoretical considerations will be applied, in a following paper, to subgroups of P1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001121
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  • 97
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    Digitale Medien
    The chemical and magnetic transformation of the series NixFe2O4 (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 501-503 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The gradual degradation of the cubic spinel phase in ferrimagnetic compounds of composition NixFe2O4 (x = 1.0 to 0.1) has been doubly confirmed by the X-ray diffraction and microwave initial magnetic-susceptibility measurements on the samples. The sharp ferrimagnetic-antiferromagnetic transition occurring at a composition corresponding to (x = 0.1) indicates a change in crystal symmetry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001157
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  • 98
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    Digitale Medien
    On the application of phase relationships to complex structures. XVII. When MULTAN fails (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 622-626 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Two new multisolution direct-methods procedures are described: MAGIC, which employs the magic-integer concept and YZARC which refines initially random sets of phases by a least-squares approach. Each procedure produces several sets of phases for a number of reflexions, usually in the range 35-100. These are then extended by the tangent formula but with the constraint that the basis phases are not allowed to change until the final cycle. It is shown that for difficult structures these methods, which deal simultaneously with many phase relationships, may have intrinsic advantages over the MUL TAN procedure. Examples of their use are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001455
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  • 99
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    Digitale Medien
    On the contributions of the internal modes of molecules to the Debye–Waller factors. III. Urea (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 613-616 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: The contributions of the internal modes of urea molecules, CH4N2O, to the vibration tensors of their atoms are calculated at 0, 100 and 300 K. The calculations are based on IR and Raman date from the literature, and the force constants determined are of the Urey-Bradley type. The temperature dependence of the vibration tensors of the internal modes (diagonal components) is represented graphically in the 0-300 K region (interpolation over nine calculated points); in this region it is weak. Since, for urea, there are vibration tensors available which were determined by neutron diffraction, the contributions of the internal modes could be estimated. On average over the C, N, O atoms it is 1.8% at 300 K, 4.4% at 98 K and 5.8% at 60 K; on average over the H atoms it is 22.6% at 300 K, 39.9% at 98 K and 46.3% at 60 K.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001431
    Standort Signatur Erwartet Verfügbarkeit
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    Digitale Medien
    Digitale Medien
    On the derivation of integrated reflected energy formulae (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 634-641 
    Details
    ISSN: 1600-5724
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A systematic procedure for deriving the equations of the integrated reflected X-ray energy is presented and conditions for the validity of the equations are formulated. Existing formulae are critically examined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0567739479001480
    Standort Signatur Erwartet Verfügbarkeit
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