Multinuclear NMR study of phosphosilicate gels derived from POCl3 and Si(OC2H5)(4)

Clayden, N. J., Pernice, P. and Aronne, A. (2005) Multinuclear NMR study of phosphosilicate gels derived from POCl3 and Si(OC2H5)(4). Journal of Non-Crystalline Solids, 351 (3). pp. 195-202. ISSN 0022-3093

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Solid state H-1, Si-29 and (31)p MAS NMR have been used to investigate the microstructure of phosphosilicate gels prepared by a modified sol-gel method involving hydrolysis of silicon precursors in a solely aqueous environment at 50degreesC. Gels with molar compositions 5, 10, 20 and 30 mol% P2O5 in P2O5-SiO2 were studied. After drying to 400degreesC the gels have very similar structure, formed by a siloxane framework containing silanol groups and trapped molecules of orthophosphoric acid together with a very small amount, of pyrophosphoric acid. Unlike the gel samples previously synthesized by the hydrolysis of the silicon precursor in alcoholic solution at room temperature, the co-polymerization of phosphorus and silicon is much reduced. Although co-polymerization increases with phosphorus content, it still represents less than 50% of the phosphorus in the 30 mol% P2O5 gel. Furthermore there is no evidence for six-coordinated silicon in the glassy matrix. (C) 2004 Published by Elsevier B.V.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
UEA Research Groups: Faculty of Science > Research Groups > Physical and Analytical Chemistry (former - to 2017)
Depositing User: Rachel Smith
Date Deposited: 14 Jun 2011 14:50
Last Modified: 24 Oct 2022 02:16
DOI: 10.1016/j.jnoncrysol.2004.11.009

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