NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Quantum-chemical modeling of smectite claysA 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.
Document ID
19830039826
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Aronowitz, S.
(NASA Ames Research Center Moffett Field, CA, United States)
Coyne, L.
(NASA Ames Research Center Moffett Field, CA, United States)
Lawless, J.
(NASA Ames Research Center Moffett Field, CA, United States)
Rishpon, J.
(NASA Ames Research Center Extraterrestrial Research Div., Moffett Field, CA, United States)
Date Acquired
August 11, 2013
Publication Date
January 1, 1982
Publication Information
Publication: Inorganic Chemistry
Volume: 21
Issue: 10, 1
Subject Category
Chemistry And Materials (General)
Accession Number
83A21044
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available