Activation enthalpies for oxygen ion motion in cubic yttria-stabilized zirconia

摘要

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 [3–5], hindrance of oxygen ion motion due to the increasing presence of ‘large’ yttrium ions [6–8], and the increasing presence of a grain boundary phase [9]. 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 *650C for 15 mol.% YO1.5) [4, 10, 11]. This has been correlated with the breaking-up of short-range order [11].