Activation enthalpies for oxygen ion motion in cubic yttria-stabilized zirconia
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The high oxygen ion conductivity of the yttria-stabilized zirconia (YSZ) system is well known. The conductivity at 1000 °C increases with YO1.5 addition to around 15–18 mol.% YO1.5, when the dopant content is just sufficient to fully stabilize the cubic fluorite phase. Further yttria additions result in a decrease in the conductivity [1, 2]. There are several contributory factors suggested to explain the conductivity decrease: formation of defect clusters reducing oxygen vacancy mobility [3, 4, 5], hindrance of oxygen ion motion due to the increasing presence of ‘large’ yttrium ions [6, 7, 8], and the increasing presence of a grain boundary phase . Support for the influence of defect clusters is the observation that the activation enthalpy for oxygen ion conduction decreases at high temperatures (decreasing by ~0.2 eV above ~650 °C for 15 mol.% YO1.5) [4, 10, 11]. This has been correlated with the breaking-up of short-range order .
Although there is a wide...
KeywordsEnthalpy Oxygen Vacancy Activation Enthalpy Defect Cluster Yttria Content
R.J.D. and R.V·K. would like to thank Ian Farnan for helpful discussions. R.J.D. acknowledges funding from UK Engineering and Physical Sciences Research Council.
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