New insights into the molecular structures, compositions, and cation distributions in synthetic and natural montmorillonite clays

Sylvian Cadars, Régis Guégan, Mounesha N. Garaga, Xavier Bourrat, Lydie Le Forestier, Franck Fayon, Tan Vu Huynh, Teddy Allier, Zalfa Nour, Dominique Massiot

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

We present a detailed investigation of the molecular structure of montmorillonite, an aluminosilicate clay with important applications in materials sciences, such as for catalysis, drug delivery, or as a waste barrier. Solid-state 29Si, 27Al, 25Mg, and 1H nuclear magnetic resonance (NMR) measurements combined with density functional theory (DFT) calculations provide a comprehensive picture of the local structure and composition of a synthetic clay and its naturally occurring analogue. A revised composition is proposed based on NMR results that allow the identification and quantification of the signatures of otherwise undetectable noncrystalline impurities, thus largely complementing the traditional elemental analyses. Solid-state 1H NMR at fast magic-angle spinning (MAS) and high magnetic field provide quantitative information on intra- and interlayer local environments that are crucial for the determination of the amount of Mg/Al substitution within the octahedral layer. In combination with DFT calculations of energies, it suggests that pairs of adjacent Mg atoms are unfavorable, leading to a nonrandom cationic distribution within the layers.

Original languageEnglish
Pages (from-to)4376-4389
Number of pages14
JournalChemistry of Materials
Volume24
Issue number22
DOIs
Publication statusPublished - 2012 Nov 27

Keywords

  • 2:1 clays
  • NMR
  • ab initio calculations
  • first-principles calculations
  • layered alumino-silicates
  • smectite

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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  • Cite this

    Cadars, S., Guégan, R., Garaga, M. N., Bourrat, X., Le Forestier, L., Fayon, F., Huynh, T. V., Allier, T., Nour, Z., & Massiot, D. (2012). New insights into the molecular structures, compositions, and cation distributions in synthetic and natural montmorillonite clays. Chemistry of Materials, 24(22), 4376-4389. https://doi.org/10.1021/cm302549k