Mountjoy, G. and Pickup, D.M. and Anderson, R. and Wallidge, G.W. and Holland, M.A. and Newport, R.J. and Smith, M.E. (2000) Changes in the Zr environment in zirconia-silica xerogels with composition and heat treatment as revealed by ZrK-edge XANES and EXAFS. Physical Chemistry Chemical Physics, 2 (10). pp. 2455-2460. ISSN 1463-9076.
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| Official URL 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 |
|---|---|
| Subjects: | Q Science > QD Chemistry Q Science > QC Physics |
| Divisions: | Faculties > Science Technology and Medical Studies > School of Physical Sciences |
| Depositing User: | A. Xie |
| Date Deposited: | 24 Aug 2009 15:09 |
| Last Modified: | 24 Aug 2009 15:09 |
| Resource URI: | http://kar.kent.ac.uk/id/eprint/16432 (The current URI for this page, for reference purposes) |
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