Journal of Materials Science

, Volume 34, Issue 8, pp 1767–1774

Trimethylsilylation analysis of the silicate structure of fluoro-alumino-silicate glasses and the structural role of fluorine

Authors

  • R. Hill
    • Department of Material Science and Technology,University of Limerick,
  • D. Wood
    • Department of Dental Biomaterials, Leeds Dental Institute,University of Leeds, Clarendon Way,
  • M. Thomas
    • School of Chemical and Biological Sciences,University of Greenwich,
Article

DOI: 10.1023/A:1004550907134

Cite this article as:
Hill, R., Wood, D. & Thomas, M. Journal of Materials Science (1999) 34: 1767. doi:10.1023/A:1004550907134

Abstract

Trimethylsilylation (TMS) reactions have been carried out on acid degradable fluoro-alumino-silicate glasses containing a basic oxide. The siloxanes produced by the TMS reactions were analysed in order to gain information about the silicate structure of the glass. The results indicate a non-random arrangement of SiO4 and AlO4 tetrahedra in the glasses studied. No fluorinated derivatives of siloxanes were found, indicating that fluorine atoms are not bonded to the silicon atoms of the glass network. It is thought that fluorine atoms are instead bonded to the aluminium atoms present. The bonding of fluorine to aluminium and not to silicon atoms explains the prevention of fluorine loss as silicon tetrafluoride (SiF4) from melts containing both aluminium and a basic oxide, and in addition explains the reduction in the glass transition temperature behaviour found on incorporating fluorine into alumino-silicate glasses.

The results suggest that the environmental problem of silicon tetrafluoride loss from fluoro-silicate glass melts and its subsequent hydrolysis to hydrofluoric acid and silica can be avoided by including a basic oxide in the composition.

Copyright information

© Kluwer Academic Publishers 1999