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  • 1
    Electronic Resource
    Electronic Resource
    THE VARIABILITY OF MICACEOUS MINERALS IN SEDIMENTARY ROCKS (1970)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 15 (1970), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Relationships between crystal chemistry and genetic conditions are presented for a series of dioctahedral micaceous minerals. Using a ferruginicity index, three groups of micaceous minerals are distinguished: Al-micas, Fe-illites, and glauconites. The degree of Al-for-Si substitution in the tetrahedral sheets of micaceous minerals depends on their thermodynamic genetic conditions. If pressure and temperature increase, the Al-IV content increases and the octahedral sheet is “cleaned” from divalent cations. This process is accompanied by structural alteration with a polytype sequence 1Md-1M-2M1. Tetrahedral and octahedral charges are the same for micaceous minerals formed at the surface (sedimentogenesis/diagenesis) and are independent of the iron content. For most illites of sedimentary rocks an authigenic origin is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1970.tb00207.x
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  • 2
    Electronic Resource
    Electronic Resource
    NEW ASPECTS OF THE OPTICAL STUDY OF LAYER SILICATES (1970)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 15 (1970), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The structure of multilayer polytype modifications of layer silicates may be regarded as the result of a combination of regularly oriented single layers. Accordingly, the optical constants of a single layer (of a monolayer polytype modification) may be used for the calculation of optical constants of any other multilayer polytype modification of a given type of layers.The formulas connecting the constants of a polytype modification of layer silicates have enabled the establishment of the main parameters (Ng, Nm, Np, 2V) of the muscovites 1M and 2M2 according to the known optical constants of the muscovite 2M1, and the computation of the new constants of kaolinite and nacrite based on the known parameters of dickite. The optical constants established theoretically were confirmed by direct measurements for muscovite 1M, muscovite 2M2 (gämbelite) and kaolinite. The optically positive character of kaolinite with +2V = 25° has been established.The assumption of the optical mixibility of finely dispersed polyminerallic media, in which the dimensions of monotype crystals are smaller than the visible light waves, made it possible to determine the quantitative relations of clay minerals in the mixtures based on optical constants of oriented aggregates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1970.tb00214.x
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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
    Polytypes of the two-packet chlorites (1969)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 25 (1969), S. 632-639 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567740869002743
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  • 5
    Electronic Resource
    Electronic Resource
    An introduction to rock forming minerals. Vols. I-V by W. A. Deer, R. A. Howie and J. Zussman (1970)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 3 (1970), S. 426-428 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889870006702
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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Use of diffraction and Mössbauer methods for the structural and crystallochemical characterization of nontronites (1983)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 16 (1983), S. 374-383 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The aim of this work is the study of the order-disorder distribution of the Fe3+ cations in a dioctahedral smectite: the Garfield nontronite. The structural characteristics have been determined by selected-area electron diffraction, oblique texture electron diffraction and X-ray diffraction. These methods lead to the conclusion that the octahedral vacancies are in trans positions and that part of the Fe3 + ions is occupying the tetrahedral sites. The Mössbauer spectra of the nontronite were decomposed into four doublets. According to the determined structural characteristics, these doublets are interpreted in terms of trans vacant octahedral positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889883010651
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  • 9
    Electronic Resource
    Electronic Resource
    Distribution of isomorphous cations within octahedral sheets in montmorillonite from Camp-Bertaux (1997)
    Springer
    Physics and chemistry of minerals 24 (1997), S. 159-166 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Ni-saturated montmorillonite from Camp-Bertaux heated at different temperatures has been studied by X-ray powder diffraction, X-ray absorption (EXAFS) and vibration IR spectroscopy. Analysis of the experimental data has shown that heating of samples at temperatures higher than 150° C was accompanied by migration of Ni cations into vacant cis-octahedra of 2:1 layers. In the octahedral sheet the Ni cation has two “heavy” (Fe) and four “light” (Al and Mg) nearest octahedral cations. A model for the octahedral cation distribution in Camp-Bertaux montmorillonite was proposed in which Fe and Mg octahedral cations are segregated in small clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690050029
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  • 10
    Electronic Resource
    Electronic Resource
    Study of structural heterogeneity of HTSC Bi-ceramics (1994)
    Springer
    Journal of structural chemistry 34 (1994), S. 771-783 
    Details
    ISSN: 1573-8779
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Using Bi-ceramics as an example, we estimate here the possibility of detemination of the structural heterogeneity of HTSC materials from X-ray powder diJjZaction data. me heterogeneity is due to the presence of alternating layers of different types within individual microcrystals. Explicit information on alternating fragments of diferent height is provided by the intensity distribution data of basal reflections, therefore we studied X-ray diffraction patterns of oriented specimens. The dipaction patterns from unidimensionally disordered structures were simulated based on a previously devised procedure for the calculation of dipaction profiles of mixed-layer minerals. The comparison of calculated and experimental dipaction patterns testifies that defects in the samples are really caused by the presence of layers of different heights corresponding to the 2212 phase built into the matrix of the basic 2223 phase. The concentration of such defects reaches 20% with a high segregation degree of both layer types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753579
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