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  • 1
    Electronic Resource
    Electronic Resource
    Calcul du Profil des bandes de diffraction produites par des empilements de feuillets de nature différente (1980)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 13 (1980), S. 148-153 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Until now, the calculation of intensities diffracted by layer structures has only been treated in the two extreme cases, namely (i) the layers interfere completely and (ii) the layers do not interfere (turbostratic structures). The present paper develops the mathematical treatment which allows the calculation in the intermediate case, namely when layers are only partially interfering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889880011764
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  • 2
    Electronic Resource
    Electronic Resource
    Diffraction by layer structures containing different kinds of layers and stacking faults (1981)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 14 (1981), S. 300-304 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A description is given of a mathematical formalism which allows the study of diffraction by stacks which contain, simultaneously or not, (i) layers of different kinds, (ii) different translations or rotations between layers and (iii) different thicknesses. The formalism allows the calculation of intensities for all the hkl reflections or (h,k) reciprocal rods, and not just the 00l reflections. It accounts for an Sth-neighbour interaction (S≥1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889881009424
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  • 3
    Electronic Resource
    Electronic Resource
    Calculation of intensity distribution in the case of oblique texture electron diffraction (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 191-196 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A new method is described to determine accurately the intensities of reflexions in the case of oblique texture electron diffraction. The method is based on a comparison between experimental values of intensities and those calculated with a formalism that takes into account the orientation function of the particles. It allows the problems that arise from frequent overlapping of reflexions to be surmounted. A concrete example of the application of this method is given the structure refinement of a mica with muscovite–phengite composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889885010147
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  • 4
    Electronic Resource
    Electronic Resource
    Evolution structurale de la nacrite en fonction de la nature des molécules organiques intercalees (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 1351-1359 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Nacrite has been intercalated with two polar organic molecules: dimethyl sulfoxide (DMSO) and N-methylacetamide (NMA). The homogeneous nacrite complexes have been studied by X-ray diffraction (XRD) and infrared (IR) spectroscopy. The XRD study is based on a comparison between experimental and calculated patterns. The structures of the intercalated compounds have been determined, including the mutual positions of the layers after intercalation and the positions of the intercalated molecules in the interlayer space. It has been shown that the intercalation process causes not only a swelling of the interlayer space but also a shift in the mutual in-plane positions of the layers. This shift depends on the nature of the intercalated molecules and is related to their shape and the hydrogen bonds which are established with the surrounding surfaces. For a given molecule, the intercalation process is the same for the different polytypes of the kaolinite family. These XRD results are consistent with those of IR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889800011730
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  • 5
    Electronic Resource
    Electronic Resource
    Etude des fautes d'empilement dans les kaolinites partiellement désordonnées. I. Modèle d'empilement ne comportant que des fautes de translation (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 582-588 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: By the use of a model with two kinds of stacking faults it is possible to explain quantitatively X-ray powder diffraction patterns of disordered kaolinites. The first kind of defect consists of random translations which limit coherent scattering regions in all hk directions except h = k = 0. The second kind consists of shifts between layers of ± nb/3 (n integer) which limit coherent scattering only in hk directions with k ≠ 3n. The comparison of calculated patterns with experimental (02,11) and (20,13) bands gives the proportions of different kinds of layer displacements in two disordered kaolinites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889875011429
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  • 6
    Electronic Resource
    Electronic Resource
    Etude des fautes d'empilement dans les kaolinites partiellement désordonnées. II. Modèles d'empilement comportant des fautes par rotation (1976)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 9 (1976), S. 279-285 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: This work describes a method of calculating the profile of the X-ray diffraction bands (for a powder) for partially disordered kaolinites containing rotational stacking faults. The profiles of the bands have been calculated for stackings containing ±2π/3 rotational faults. These faults are such that two first neighbouring layers (i) are translated as in a perfect kaolinite but additionally rotated by +2π/3 or −2π/3; (ii) are disposed strictly as in dickite, or (iii) start with the enantiomorphic kaolinite structure. Among the different models envisaged, only the model with faults of the first type mentioned above seems to agree with the experimental profiles of the different natural kaolinites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889876011369
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  • 7
    Electronic Resource
    Electronic Resource
    Powder diffraction by layered minerals containing different layers and/or stacking defects. Comparison between Markovian and non-Markovian models (1983)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 16 (1983), S. 62-69 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The models used up to now for the calculation of powder patterns of layer minerals containing defects have adopted a Markovian hypothesis for the law of defect occurrence. One consequence of this hypothesis is that in a powder obeying this law the particles differ in their contents (chemical composition and/or abundance of stacking defects). Another model can be considered in which the particles have identical contents of each type of layers or stacking defects. This is denoted here by the `identical contents crystal model' (ICC model). In this article are described: (i) the calculation of diffracted intensities for the ICC model and its comparison with that of the Markovian one, and (ii) the application of this calculation to a two-component mixed-layer system. It is shown which kind of modification of intensities or peak positions occur with the ICC model for thin crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889883009954
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  • 8
    Electronic Resource
    Electronic Resource
    Etude structurale d'un hydrate 10 Å instable de kaolinite (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 1075-1081 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The treatment of KGa-1 kaolinite with dimethyl sulfoxide and ammonium fluoride heated at 383 K provides an unstable hydrated phase characterized by a 10 Å basal distance. When air-dried, this hydrate gives a dehydrated phase at 7.15 Å. The aim of this work is to determine the structural characteristics of this hydrate. The method used to characterize this hydrate is based on the comparison between experimental and calculated X-ray diffraction profiles. This study is achieved in two steps: the study of 00l reflections enabled the determination of the number of intercalated water molecules, their positions and the stacking mode along the normal to the (a, b) plane; and the study of the hkl reflections with h and/or k ≠ 0 enabled the determination of the stacking mode and the positions of water molecules in the (a, b) plane. The unstable hydrate is characterized by two water molecules per Al2Si2O5(OH)4 unit situated at z1 = z2 = 7.57 Å. Two adjacent layers are translated with respect to each other with TI = −0.155a + 0.13b + 10n.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889800004878
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  • 9
    Electronic Resource
    Electronic Resource
    Recording and calculation of hk rod intensities in case of diffraction by highly oriented powders of lamellar samples (1982)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 509-512 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The aim of this paper is to describe a technique for recording the intensity distribution along definite crystallographic directions by using a classical θ,2θ powder goniometer. This method was developed for application to highly oriented powders. In the calculation of simulated spectra, the partial misorientation of the particles is considered. The reflection intensities and profiles are compared for different shapes of the misorientation function N(α).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889882012497
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  • 10
    Electronic Resource
    Electronic Resource
    Étude par Diffraction X des Modes d'Empilement de la Nacrite Hydratée et Deshydratée (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 31 (1998), S. 654-662 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: X-ray diffraction based on the comparison of experimental and calculated powder profiles enabled the determination of the structural characteristics of hydrated and dehydrated Tunisian nacrite. Using the concept describing the structure of natural nacrite, the stacking mode of the layers in the hydrated and dehydrated nacrite has been determined. The hydrate is characterized by an 8.42 Å basal distance; one water molecule per Si2Al2O5(OH)4 is intercalated in the interlamellar space, located above the vacant octahedral site of the layer at z = 6.5 Å and inserted inside the ditrigonal cavity of the tetrahedral sheet of the upper layer. The dehydrated nacrite obtained by heating of the hydrate at 423 K has the same interlayer shift t = −0.35a as the natural nacrite. Coherence domain sizes along c^{\ast} and in the ab plane are the same as those in the hydrate but different from those of the natural mineral. After dehydration, 5% of the layers had an interlayer shift similar to that obtained from the hydrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889898000363
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