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Variability in sepiolite: Diffraction studies

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Sánchez del Río, Manuel y García Romero, Emilia y Súarez Barrios, Mercedes y Silva, Iván da y Fuentes Montero, Luis y Martínez Críado, Gema (2011) Variability in sepiolite: Diffraction studies. The American mineralogist, 96 . pp. 1443-1454. ISSN 0003-004X

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Resumen

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 °C (for zeolitically dehydrated sepiolite) and 25 °C (for hydrated ambient sepiolite). The
latter permitted to locate ca. six molecules of the zeolitic H2O 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 wellstructured
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.


Tipo de documento:Artículo
Palabras clave:Sepiolite, X-ray diffraction, Rietveld, 2D diffraction pattern, SEM, TEM, SAED, Ab initio simulations
Materias:Ciencias > Geología > Mineralogía
Código ID:21637
Depositado:03 Jun 2013 10:26
Última Modificación:11 Dic 2018 08:46

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