Hostname: page-component-7b7567c8c-wxvwp Total loading time: 0 Render date: 2026-11-15T21:08:40.202Z Has data issue: false hasContentIssue false

Stability of Montmorillonite Edge Faces Studied Using First-Principles Calculations

Published online by Cambridge University Press:  01 January 2024

Hiroshi Sakuma*
Affiliation:
National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 3050044, Japan
Yukio Tachi
Affiliation:
Japan Atomic Energy Agency, 4-33, Muramatsu, Tokai-mura, Ibaraki, 3191194, Japan
Kenji Yotsuji
Affiliation:
Japan Atomic Energy Agency, 4-33, Muramatsu, Tokai-mura, Ibaraki, 3191194, Japan
Shigeru Suehara
Affiliation:
National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 3050044, Japan
Tatsumi Arima
Affiliation:
Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 8190395, Japan
Naoki Fujii
Affiliation:
Radioactive Waste Management Funding and Research Center, 6-4 Akashicho, Chuo-ku, Tokyo 1040044, Japan
Katsuyuki Kawamura
Affiliation:
Okayama University, 3-1-1, Tsushimanaka, Kita-ku, Okayama 7008530, Japan
Akira Honda
Affiliation:
Japan Atomic Energy Agency, 4-33, Muramatsu, Tokai-mura, Ibaraki, 3191194, Japan
*
*E-mail address of corresponding author: sakuma.hiroshi@nims.go.jp
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the 'Save PDF' action button.

The reactivity and stability of the edge faces of swelling clay minerals can be altered by layer charge and the stacking structure; however, these effects are poorly understood due to experimental limitations. The structure and stability of the montmorillonite {110}, {010}, {100}, and {130} edge faces with a layer charge of either y = 0.50 or y = 0.33 (e−/Si4O10) were investigated using first-principles calculations based on density functional theory. Stacked- and single-layer models were tested and compared to understand the effect of stacking on the stability of montmorillonite edge faces. Most stacked layers stabilize the edge faces by creating hydrogen bonds between the layers; therefore, the surface energy of the layers in the stacked-layer model is lower than in the single-layer model. This indicates that the estimates of edge face surface energy should consider the swelling conditions. Negative surface energies were calculated for these edge faces in the presence of chemisorbed water molecules. A high layer charge of 0.50 reduced the surface energy relative to that of the low layer charge of 0.33. The isomorphic substitution of Mg for Al increased the stability of interlayer Na ion positions, which were stable in the trigonal ring next to the Mg ions. The lowest surface energies of the {010} and {130} edge faces were characterized by the presence of Mg ions on edge faces, which had a strong cation adsorption site due to the local negative charge of the edges. The coordination numbers of O atoms around cations adsorbed to these edge faces were small in comparison to interlayers without water.

Information

Type
Article
Copyright
Copyright © Clay Minerals Society 2017