First-principles-based simulation of interlayer water and alkali metal ions in weathered biotite

Takashi Ikeda

doi:10.1063/1.4963017

First-principles-based simulation of interlayer water and alkali metal ions in weathered biotite

J Chem Phys. 2016 Sep 28;145(12):124703. doi: 10.1063/1.4963017.

Author

Takashi Ikeda¹

Affiliation

¹ Synchrotron Radiation Research Center, Quantum Beam Science Research Directorate (QuBS), National Institutes for Quantum and Radiological Science and Technology (QST), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.

PMID: 27782619
DOI: 10.1063/1.4963017

Abstract

We performed first-principles-based simulations of weathered biotites (WBs) including alkali metal ions to investigate the adsorption states of interlayer cations and the cation/water distribution in their interlayer. Our simulations suggest that the inclusion of Fe³⁺ ions in octahedral sheets of WBs alters significantly the vibrational states, the adsorption states of alkali ions, and the cation/water distribution in our WBs. The Al-O bond cleavage suggested to occur in Fe³⁺-rich regions of WBs upon the H₂O adsorption on Al³⁺ in tetrahedral sheets enhances greatly the dipole moment of adsorbed H₂O molecules, thus enhancing the preference for aggregating inner-sphere complexes of heavy alkali ions particularly Cs⁺.