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Ab initio studies of possible fluorine-bearing four- and fivefold coordinated Al species in aluminosilicate glasses

Yun Liu and Hanna Nekvasil
Ab initio studies of possible fluorine-bearing four- and fivefold coordinated Al species in aluminosilicate glasses
American Mineralogist (April 2001) 86 (4): 491-497

Abstract

Ab initio NMR gauge-including atomic orbital (GIAO) calculations were used to constrain assignments of resonances in (super 27) Al NMR spectra of F-bearing alkali aluminosilicate glasses. The effect of bond angles within the range 126-150 degrees on the chemical shift was investigated using cluster models of next-nearest atoms that are charge balanced by hydrogen atoms. GIAO calculations used geometries obtained through optimization at fixed Al-O-Si bond angles. The calculated peak positions for all of the 4-fold coordinated Al species yielded calculated (super 27) Al NMR peak positions in good agreement with the experimental data, suggesting that any or all of the species AlF (super -) (sub 4) , AlF (sub 3) O(SiH (sub 3) ) (super -) , AlF (sub 2) O (sub 2) (SiH (sub 3) ) (super -) (sub 2) , and AlFO (sub 3) (SiH (sub 3) ) (super -) (sub 3) may be present. Three of the investigated 5-fold coordinated species AlF (super 2-) (sub 5) , AlF (sub 3) O (sub 2) (SiH (sub 3) ) (super 2-) (sub 2) , and AlF (sub 2) O (sub 3) (SiH (sub 3) ) (super 2-) (sub 3) fit the experimental requirements well, whereas the remaining 5-fold coordinated species that were tested [AlF (sub 4) O(SiH (sub 3) ) (super 2-) , and AlFO (sub 4) (SiH (sub 3) ) (super 2-) (sub 4) ] did not.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 86
Serial Issue: 4
Title: Ab initio studies of possible fluorine-bearing four- and fivefold coordinated Al species in aluminosilicate glasses
Affiliation: State University of New York, Department of Geosciences, Stony Brook, NY, United States
Pages: 491-497
Published: 200104
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 28
Accession Number: 2001-049392
Categories: General mineralogy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200115
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