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Surface Chemical Structure of Sío2-TiO2 Sol-Gel Powders

Published online by Cambridge University Press:  21 February 2011

G.M. Ingo ,
G. Padeletti ,
S. Dire'  and
F. Babonneau
G.M. Ingo
Affiliation:
C.N.R., Istituto di Chimica dei Materiali, CP 10, 00016 Monterotondo Stazione Rome, Italy
G. Padeletti
Affiliation:
C.N.R., Istituto di Chimica dei Materiali, CP 10, 00016 Monterotondo Stazione Rome, Italy
S. Dire'
Affiliation:
Dipartimento di Ingegneria dei Materiali, Università di Trento, 38050 Mesiano, Italy
F. Babonneau
Affiliation:
L.C.M.C, URA CNRS, Université Pierre et Marie Curie, 4 Jussieu, 75252 Paris, France
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Abstract

Amorphous SiO2, TiO2 and x SiO2-(1-x) TiO2 powders, with nominal values of x=0.9, 0.7 and 0.5, have been prepared via sol-gel, using silicon tetrahoxysilane (TEOS) and titanium tetraisopropoxide Ti(OPri)4. X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) are used for studying the surface chemical structure of the powders as a function of the air thermal treatment temperature up to 1273 K. For the whole range of temperature, XPS and XAES signals indicate that silicon and titanium are present as Si4+ and Ti4+ oxides. From the line shape of the O 1s peak, it is possible to distinguish between the single O-Ti and O-Si bonds and to disclose also the presence of Si-O-Ti cross linking bonds that are supposed to act as bridges between SiO2 and TiO2 moieties. Starting from 873 K, the Si-O-Ti bonds are broken and formation of a low amount of new Ti-O and a higher amount of Si-O bonds takes place. Si/Ti atomic ratios obtained by curve fitting the O Is peaks and from Ti 2p3/2 and Si 2p peaks, confirm the silicon oxide surface enrichment. Furthermore, with increasing temperature, XAES data indicate the formation of crystalline phases.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 346: Symposium N – Better Ceramics Through Chemistry VI , 1994 , 421
Copyright
Copyright © Materials Research Society 1998

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References

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