タイトル | Quantum-chemical modeling of smectite clays |
著者(英) | Lawless, J.; Coyne, L.; Rishpon, J.; Aronowitz, S. |
著者所属(英) | NASA Ames Research Center |
発行日 | 1982-01-01 |
言語 | eng |
内容記述 | A self-consistent charge extended Hueckel program is used in modeling isomorphic substitution of Al(3+) by Na(+), K(+), Mg(2+), Fe(2+), and Fe(3+) in the octahedral layer of a dioctahedral smectite clay, such as montmorillonite. Upon comparison of the energies involved in the isomorphic substitution, it is found that the order for successful substitution is as follows: Al(3+), Fe(3+), Mg(2+), Fe(2+), Na(+), which is equivalent to Ca(2+), and then K(+). This ordering is found to be consistent with experimental observation. The calculations also make it possible to determine the possible penetration of metal ions into the clay's 2:1 crystalline layer. For the cases studied, this type of penetration can occur at elevated temperatures into regions where isomorphic substitution has occurred with metal ions that bear a formal charge of less than 3+. The computed behavior of the electronic structure in the presence of isomorphic substitution is found to be similar to behavior associated with semiconductors. |
NASA分類 | CHEMISTRY AND MATERIALS (GENERAL) |
レポートNO | 83A21044 |
権利 | Copyright |
URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/405655 |
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