The ionic diffusion of 8 mol% yttria-stabilized zirconia (8YSZ) was investigated using atomistic simulation. The well-known inverse relation between oxygen conductivity and temperature is reproduced for a wide range of temperatures (623-1500 K). A strong defect clustering between oxygen vacancies and trivalent yttrium ions was statistically treated and explained by the simulated results, including the effect of temperature. Oxygen migration was less effective at lower temperatures, suggesting that the diffusion of oxygen was localized by jumping back-and-forth through specific lower-energy-barrier paths. Static lattice calculations further confirmed the favorable diffusion routes, of which two adjacent oxygen sites had two or more common second-nearest-neighbor yttrium atoms.

Keywords: molecular dynamics; clustering; enthalpy; oxygen jumping; diffusion; ZrO2