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Inhomogeneities in acid-catalyzed titania–silica and zirconia–silica xerogels as revealed by small-angle x-ray scattering

Published online by Cambridge University Press:  31 January 2011

G. Mountjoy ,
J. S. Rigden ,
R. Anderson ,
G. W. Wallidge ,
R. J. Newport  and
M. E. Smith
G. Mountjoy
Affiliation:
School of Physical Sciences, University of Kent at Canterbury, Canterbury CT2 7NR, United Kingdom
J. S. Rigden
Affiliation:
School of Physical Sciences, University of Kent at Canterbury, Canterbury CT2 7NR, United Kingdom
R. Anderson
Affiliation:
School of Physical Sciences, University of Kent at Canterbury, Canterbury CT2 7NR, United Kingdom
G. W. Wallidge
Affiliation:
Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
R. J. Newport
Affiliation:
School of Physical Sciences, University of Kent at Canterbury, Canterbury CT2 7NR, United Kingdom
M. E. Smith
Affiliation:
Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
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Abstract

The small-angle x-ray scattering (SAXS) technique was used to investigate inhomogeneities on the scale of 10 to 600 Å in acid-catalyzed titania–silica and zirconia–silica xerogels. SAXS of (TiO2)x(SiO2)1−x and (ZrO2)x(SiO2)1−x xerogels with x < 0.1, in which there was no phase separation, showed the presence of two types of inhomogeneity. For Q < 0.05 Å−1 there was a clear departure from Porod scattering which showed that xerogel powder particle surfaces were rough. For 0.1 < Q < 0.4 Å−1 there was a plateau feature corresponding to micropores within the silica-based network, and this feature changes with heat treatment. SAXS of xerogels with x > 0.3 showed the presence of phase-separated regions of metal oxide, which were initially amorphous and crystallized at higher temperatures. A (TiO2)0.18(SiO2)0.82 xerogel that was not initially phase separated became phase separated after heat treatment at 750 °C due to reduced solubility of Ti in the silica network.

Type
Articles
Information
Journal of Materials Research , Volume 15 , Issue 9 , September 2000 , pp. 1998 - 2005
Copyright
Copyright © Materials Research Society 2000

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