If it is assumed that the temperature dependence of the spin-lattice (T 1 ) relaxation of the O Bi site(s) is driven by transient, motion-induced changes in the apparent O quadrupolar coupling, activation energies for oxide ion and/or vacancy mobility can be extracted. In this analysis, inverse correlation times τ -1 c are first calculated, which can be derived from fits to the T 1 data using the following equation: 1