Internal friction experiments were performed on the systems, ZrO2-(8 to 12)mol%Y2O3 and ZrO2-(9 to 12)mol%Sc2O3. An internal friction peak, around 500K in both systems, was attributed to the hopping of trapped O vacancies (1.2 to 1.3eV). In polycrystalline materials, a high-temperature damping background was related to cation diffusion. There was an order/disorder phase transition at 1450K in ZrO2–12mol%Y2O3. In ZrO2–Sc2O3, there was a ferroelastic ↔ ferroelectric phase transition (750K) from the rhombohedral to the cubic phase. Cation diffusion experiments in ZrO2–Sc2O3 revealed an activation enthalpy, for Zr diffusion, of 5.3eV; indicating that short- and long-range cation transport was governed by one type of cation diffusion process.

Defects and Phase Transitions in Yttria- and Scandia-Doped Zirconia. M.Weller, F.Khelfaoui, M.Kilo, M.A.Taylor, C.Argirusis, G.Borchardt: Solid State Ionics, 2004, 175[1-4], 329-33