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Changes in the Zr environment in zirconia-silica xerogels with composition and heat treatment as revealed by Zr K-edge XANES and EXAFS

Mountjoy, Gavin, Pickup, David M., Anderson, Ruth, Wallidge, Graham, Holland, Mark A., Newport, Robert J., Smith, Mark E. (2000) Changes in the Zr environment in zirconia-silica xerogels with composition and heat treatment as revealed by Zr K-edge XANES and EXAFS. Physical Chemistry Chemical Physics, 2 (10). pp. 2455-2460. ISSN 1463-9076. (doi:10.1039/a910300g) (KAR id:15927)

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http://dx.doi.org/10.1039/a910300g

Abstract

X-ray absorption spectroscopy at the Zr K-edge is an important technique for probing the environment of Zr. Here it is applied to zirconia-silica xerogels with composition 0.07 less than or equal to x less than or equal to 0.40, where x is the molar ratio Zr : (Zr + Si). Reference samples of crystalline ZrO2, ZrSiO4, BaZrO3 and liquid Zr n-propoxide were also examined. New XANES (X-ray adsorption near edge structure) results are presented for zirconia-silica xerogels, and compared with previous EXAFS (extended X-ray absorption fine structure) results. For high Zr contents (x = 0.4) there is a separate, amorphous ZrO2 phase, which before heat treatment is similar to Zr hydroxide, and after heat treatment at 750 degrees C is similar to an amorphous precursor of tetragonal ZrO2. For low Zr contents (x = 0.1) there is atomic mixing of Zr in the SiO2 network, and the environment of Zr is more similar to that in Zr n-propoxide compared to other reference samples. New in situ XANES and EXAFS results are presented for x = 0.1 xerogels heated at 250 degrees C. These clearly show that the Zr environment depends on ambient moisture in addition to heat treatment.

Item Type: Article
DOI/Identification number: 10.1039/a910300g
Subjects: Q Science
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
Depositing User: J.M. Smith
Date Deposited: 08 May 2009 15:43 UTC
Last Modified: 16 Nov 2021 09:53 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/15927 (The current URI for this page, for reference purposes)
Mountjoy, Gavin: https://orcid.org/0000-0002-6495-2006
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