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The x-ray identification and crystal structures of clay minerals
01 Jan 1961-
About: The article was published on 1961-01-01 and is currently open access. It has received 966 citations till now. The article focuses on the topics: Clay minerals.
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TL;DR: In this paper, diffusion mechanisms with moving reaction interfaces involved in the reduction process of oolitic iron oxide, containing small goethite particles in a kaolinite matrix, are presented.
Abstract: Diffusion mechanisms with moving reaction interfaces involved in the reduction process of oolitic iron oxide, containing small goethite particles in a kaolinite matrix, are presented. Reduction was effected by means of CO gas at 950° C, with the oolite already transformed by dehydroxylation into haematite particles and a metakaolinite matrix. The haematite particle under the CO + O → CO2 reaction taking place at its external surface develops concentric layers with unreacted haematite at the core enclosed by magnetite wustite and metallic iron, in that order. In the matrix between particles, “bridges” of a two-phase mixture of hercynite and fayalite develop by diffusion of iron ions and “reactive transport” of oxygen (by means of CO2 molecules), thereby permitting coarsening of the metallic particles. Detailed models are presented for the diffusion mechanisms and reactions involved, and the thermodynamical picture is brought out.
10 citations
TL;DR: The Feldbegriff „Glaukonitkorner“ is fast in den Oberflachensedimenten des Persischen Golfs eine Vielzahl von grunen Grobfraktionskomponenten, voran Schlammkrusten as mentioned in this paper.
Abstract: Der Feldbegriff „Glaukonitkorner“ umfast in den Oberflachensedimenten des Persischen Golfs eine Vielzahl von grunen Grobfraktionskomponenten, voran Schlammkrusten. Beschrankt auf Gebiete mit niederer Sedimentationsgeschwindigkeit finden sich diese Korner in allen Wassertiefen bis etwa 110 m, der Schelfkante im Golf von Oman (Abb. 1).
9 citations
TL;DR: Palygorskite was the dominant clay mineral in some Ground-water rendzinas developed on Pleistocene interdunal flats in the south-east of South Australia as mentioned in this paper.
Abstract: Palygorskite was the dominant clay mineral in some Ground-water rendzinas developed on Pleistocene interdunal flats in the south-east of South Australia. The clay fraction from one soil contained 9.2% MgO and palygorskite was identified by a prominent 10.5 A X-ray diffraction spacing for the c-axis and by fine rod-like morphology. The clay had a high charge and surface area and was strongly associated with organic matter. It is concluded that the palygorskite developed in situ along with smectite in an environment subject to prolonged seasonal inundation by surface waters and groundwaters containing substantial quantities of salts including Ca and Mg.
9 citations
TL;DR: The traditional concept of the two-phase or the crystal-defect model is an oversimplification of the complex reality and the exploitation of anomalous diffractometry has illustrated that polyethylene has an intermediate ordered structure.
Abstract: Background
The Fourier space (reciprocal space) image of bulk polyethylene consists of lines superimposed on the coherent diffuse background. The mixed character of the image indicates the complex nature of these compounds. The inability in detecting full images of reciprocal space of polymeric substances without Compton radiation and the other undesirable diffuse scatterings has misled the structural analysis (structural characterisation) of these materials.
Principal Findings
We propose the use of anomalous diffractometry where, it is possible to obtain a real image of reciprocal space without Compton radiation and other undesirable scatterings. By using classical diffractometry techniques this procedure is not possible. This methodology permitted us to obtain the “Direct Delta function”, in the case of polycrystalline substances that was not previously detected. A new procedure was proposed to interpret the image of reciprocal space of bulk polyethylene. The results show the predominance of the geometry of local order determination compared to the crystal unit cell. The analysis of x-ray diffraction images illustrates that the elementary structural unit is a tetrahedron. This structural unit illustrates the atoms in the network scatter in a coherent diffuse manner. Moreover, the interference function derived from the coherent diffuse scattering dampens out quickly and the degree of randomness is superior to a liquid state. The radial distribution function derived from this interference function shows bond shortening in the tetrahedron configuration. It is this particular effect, which stabilises polyethylene.
Conclusion
Here we show by anomalous diffractometry that the traditional concept of the two-phase or the crystal-defect model is an oversimplification of the complex reality. The exploitation of anomalous diffractometry has illustrated that polyethylene has an intermediate ordered structure.
9 citations
01 Jan 1975
TL;DR: In this article, the authors show that all rock-forming minerals can occur in soils, in addition to minerals formed as a result of pedogenic processes, irrespective of which of these is involved, all soils may be traced back to parent rocks.
Abstract: Soils may be developed on either sedentary or transported materials, but irrespective of which of these is involved, all soils may be traced back to parent rocks. Hence all rock-forming minerals can occur in soils, in addition to minerals formed as a result of pedogenic processes.
9 citations