FitzGerald, V. and Pickup, D.M. and Drake, K.O. and Smith, M.E. and Newport, R.J. (2007) A high energy X-ray diffraction study of sol-gel derived (Ta2O5)(x)(SiO2)(1-x) glasses (x=0.05, 0.11 and 0.25) - elucidating the role of tantalum in silica. Journal of Sol-gel Science and Technology, 44 (2). pp. 153-159. ISSN 0928-0707 .
High energy X-ray diffraction (HEXRD) has been used to study the atomic structure of (Ta2O5) (x) (SiO2)(1-x) (x = 0.05, 0.11 and 0.25) xerogels; the direct interpretation of the resultant data has been augmented using reverse Monte Carlo (RMC) modelling. For the first time in this type of material, two Ta-O correlations have been identified (at similar to 1.8 angstrom and 2.0 angstrom). The RMC modelling approach explicitly used MAS-NMR data to define its constraints; when combined with HEXRD data, it helps to confirm the more directly determined total coordination of five for the two Ta-O correlation distances and suggests Ta center dot center dot center dot Si and Ta center dot center dot center dot Ta coordination distances of similar to 3.3 angstrom and similar to 3.8 angstrom, respectively. The O center dot center dot center dot O and Si center dot center dot center dot Si distances and coordination numbers associated with the host silica network suggest that the Ta (V) is acting as a network modifier. The way in which the Ta-O correlations are affected by composition and calcination temperature suggest some phase separation in the (Ta2O5)(0.25)(SiO2)(0.75) sample. However, in general, the results indicate good mixing of the component oxides.
|Uncontrolled keywords:||high energy x-ray diffraction; reverse monte carlo modelling; tantalum; xerogels|
|Subjects:||Q Science > QC Physics|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Physical Sciences > Functional Materials Group|
|Depositing User:||Louise Dorman|
|Date Deposited:||24 Apr 2008 08:57|
|Last Modified:||05 Sep 2011 23:29|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/2786 (The current URI for this page, for reference purposes)|
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