Browsing by Author "Fuentes-Montero, L"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    The software package ANAELU for X-ray diffraction analysis using two-dimensional patterns
    (International Union of Crystallography, 2011-02-01) Fuentes-Montero, L; Montero-Cabrera, ME; Fuentes-Cobas, L
    A new software package for interpreting two-dimensional diffraction diagrams is presented. The application capabilities include representation of single- and polycrystal structures with an inverse pole figure treatment of texture phenomena, measurement and analysis of diffraction signals, and different approaches to the modelling of two-dimensional diffraction patterns obtained from both single-crystal and polycrystalline samples. Particular consideration is given to the effect of axially symmetric textures on two-dimensional diffraction patterns. An example showing the capabilities of the software is presented. Copyright © International Union of Crystallography
  • No Thumbnail Available
    Item
    Variability in sepiolite: diffraction studies
    (GeoScienceWorld, 2011-10-01) del Río, MS; García-Romero, E; Suárez, M; da Silva, I; Fuentes-Montero, L; Martinez-Criado, G
    Twenty sepiolites of known composition from different origins were analyzed to quantify the variability in structural parameters and its possible relationships with composition and morphology. Morphology SEM analyses led to classify the sepiolites into several groups, beyond the two simple macroscopic or clay groups. X-ray powder diffraction with synchrotron light was used to discuss the variability of the a and b cell parameters with the nature of the cations and occupancy of the octahedral shell. Rietveld refinement using the ideal sepiolite model is performed on sepiolites at two temperatures: 225 degrees C (for zeolitically dehydrated sepiolite) and 25 degrees C (for hydrated ambient sepiolite). The latter permitted to locate ca. six molecules of the zeolitic H(2)O within the tunnels. A few samples were selected to evaluate the feasibility and potential of single-crystal diffraction methods: X-ray microdiffraction and electron diffraction. The macroscopic sepiolites gave well-structured and rich X-ray fiber diffraction patterns, in excellent agreement with ab initio simulations. High-quality single-crystal electron diffraction patterns for three axis zones are indexed and compared with simulations. The experimental and modeling results for X-ray microdiffraction and electron diffraction open a new path for quantitative crystallography on sepiolite and other fibrous clays from the sepiolite-palygorskite group. © 2011, Mineralogical Society of America