Effect of the Si/Al ordering on structural parameters and the energetic stabilization of vermiculites - A theoretical study

D. Tunega, H. Lischka

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The effect of the Si/Al distribution in the tetrahedral sheets of the vermiculite mineral has been investigated employing density functional theory. The structures of six models for vermiculite with the structural formula (Mg4)(Mg12 (Si8Al8)O40(OH 8·24(H2O) per unit cell were fully optimized. The models differ by the T⋯Mg2+⋯T' coordination of the interlayer Mg2+ cations by two central cations from the adjacent tetrahedral sheets of the 2:1 vermiculite layers (T,T' = Si,Al). We observed the formation of very strong hydrogen bonds between water molecules solvating the interlayer Mg2+ cations and the surface basal oxygen atoms of the 2:1 layers. The directionality of hydrogen bonds is the major factor determining the layer stacking in the vermiculite structure. Results showed that the most stable model is that where only silicon atoms in the tetrahedral sheets coordinate all interlayer Mg2+ cations.

Original languageEnglish
Pages (from-to)517-522
Number of pages6
JournalPhysics and Chemistry of Minerals
Volume30
Issue number9
DOIs
StatePublished - Oct 2003

Keywords

  • Calculation
  • Density functional theory
  • Vermiculite

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