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ID 34000
フルテキストURL
著者
Nanba, Tokuro Okayama University
Nishimura, Mitsunori Okayama University
Miura, Yoshinari Okayama University
抄録
In Si-29-NMR, it has so far been accepted that the chemical shifts of Q(n) Species (SiO4 units containing n bridging oxygens) were equivalent between alkali borosilicate, and boron-free alkali silicate classes. In the sodium borosilicate glasses with low sodium content. however. a contradiction was confirmed in the estimation of alkali distributions B-11 NMR suggested that Na ions were entirely distributed to berate groups to form BO4 units, whereas a -90 ppm component Was also observed in Si-29-NMR spectra, which has been attributed to Q(3) species associated with a nonbridging oxygen (NBO). Then. cluster molecular orbital calculations were performed to interpret the -90 ppm component in the borosilicate, glasses. It Was found that a silicon atom which had two tetrahedral borons (B4) as its second nearest neighbors was similar in atomic charge and Si2p energy to the Q(3) species in boron-free alkali silicates. Unequal distribution of electrons in Si-O-B4 bridging bonds was also found. where much electrons Were localized oil the Si-O bonds. It was finally concluded that the Si-O-B4 bridges with narrow bond angle were responsible for the -90 ppm Si-29 component in the borosilicate glasses. There still remained another interpretation: the Q(3) species were actually present in the glasses. and NBOs in the Q(3) species were derived from the tricluster groups. such as (O3Si)O(BO3)(2). In the classes With low sodium content. however. it was concluded that the tricluster groups were not so abundant to contribute to the -90 ppm component.
キーワード
short-range order
nuclear-magnetic-resonance
mas-nmr
structural
groups
oxygen sites
ab-initio
o-17 nmr
b-11
na20-b2-3-s1-2
spectroscopy
備考
Digital Object Identifer:doi:10.1016/j.gca.2004.05.042
Published with permission from the copyright holder. This is the author's copy, as published in Geochimica et Cosmochimica Acta, December 2004, Volume 68, Issue 24, Pages 5103-5111.
Publisher URL:http://dx.doi.org/doi:10.1016/j.gca.2004.05.042
Direct access to Thomson Web of Science record
Copyright © 2004 Elsevier Ltd All rights reserved. All rights reserved.
発行日
2004-12-15
出版物タイトル
Geochimica et Cosmochimica Acta
68巻
24号
出版者
Pergamon-Elsevier Science Ltd.
開始ページ
5103
終了ページ
5111
ISSN
0016-7037
NCID
AA00655038
資料タイプ
学術雑誌論文
言語
English
著作権者
Elsevier Ltd.
論文のバージョン
author
査読
有り
DOI
Web of Sience KeyUT
Submission Path
geology_general/1