Events Calendar
Oct 31
14:00 - 15:00
Isaac Abrahams, School of Biological and Chemical Sciences, Queen Mary University of London: Watch this space: vacancy association and ordering in oxide ion conducting solid electrolytes
Physical Sciences colloquia

Oxide ion conducting solid electrolytes are the key components of solid oxide fuel cells. Bismuth oxide has the highest known oxide ion conductivity of any solid but exhibits this only in its delta-phase which is only stable above 730 °C and exhibits a defect fluorite structure. 

Substitution of Bi3+ by a range of other cations can lead to preservation of the delta phase to room temperature and despite concern over their stability under reducing atmospheres it has been demonstrated that they can be successfully incorporated into intermediate temperature fuel cells.  

These systems show high concentrations of vacancies on the oxide ion sublattice with respect to the ideal fluorite structure. Ordering of vacancies at intermediate temperature and related changes in the oxide ion distribution can lead to conductivity decay and in some cases a change in gross structure. 

In this work we show how this vacancy ordering can be probed directly using reverse Monte Carlo modelling of total neutron scattering data.  Thermally induced changes in the oxide ion-vacancy distribution are shown to be correlated with changes in the conductivity behaviour.


Ingram Lecture Theatre
United Kingdom
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Contact: Helena Shepherd
School of Physical Sciences


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Last Updated: 10/01/2012