MOLECULAR-DYNAMICS SIMULATIONS OF YTTRIA-STABILIZED ZIRCONIA

Oxygen diffusion in the oxygen ionic conductor yttria-stabilized zirco nia is investigated by means of the molecular dynamics simulation tech nique. Oxygen ions migrate by means of a discrete hopping process, mai nly between neighbouring tetrahedral sites. Diffusion appears to occur in a short time and a long time regime. Only when the oxygen ions hav e moved over distances much larger than the characteristic distances o f the underlying crystal structure, a linear relation is found between the mean square displacement and time. The oxygen tracer diffusion co efficient, obtained from this long time regime, is 1.85 x 10(-6) and 3 .23 x 10(-6) cm(2)/s at 1759 and 2057 K, respectively. The ionic condu ctivity, calculated from the tracer diffusion coefficient, agrees well with experimental values.