Glasses Tech

March 8, 2010

Titanium coordination in silicate glasses investigated using O K-edge X-ray absorption spectroscopy

Filed under: Glasses 2003 — admin @ 5:38 am

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A series of titanium silicate glasses along the composition joins TiO2–SiO2, TiO2–Na2SiO3, TiO2–K2SiO3 and TiO2–CaSiO3, has been examined using oxygen K-edge X-ray absorption near edge structure spectroscopy (XANES) confined to the near-surface region. Sharp pre-edge features in the spectra can be used to determine the Ti coordination in the glasses. The presence of [4]Ti is indicated by a pre-edge peak at ~534 eV while [5]Ti is indicated by a peak at ~533 eV. Titanium exists in all these glasses as [4]Ti and [5]Ti with no [6]Ti being present. For alkali-containing glasses the [5]Ti site becomes more prevalent with increasing TiO2. TiO2-K2SiO3 compositions contain a greater proportion of [4]Ti than comparable Na2O compositions. This is consistent with earlier Ti L-edge findings. The TEY spectra for the TiO2-CaSiO3 compositions indicate the presence of significant amounts of [5]Ti at high TiO2 contents; however, comparison of TEY (near surface) and FY (bulk sample) XANES shows that the [5]Ti is confined to the surface of the glass sample with the bulk of the glass containing [4]Ti.

KEYWORDS: Ti, XANES, silicate glasses

G. S. Henderson1,*, Xiaoyang Liu2 and M. E. Fleet2
1 Department of Geology, University of Toronto, 22 Russell Street, Toronto, Ontario M5S 3B1, Canada
2 Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada

* E-mail: henders@geology.utoronto.ca

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