Molecular dynamics simulation of yttria-stabilized zirconia (YSZ) crystalline and amorphous solids.

An empirically fitted atomic potential allows a classical molecular dynamics study of the static and dynamic properties of both crystalline and amorphous yttria-stabilized zirconia (YSZ) with typical dilute Y(2)O(3) concentrations (i.e. 3.0-12.0 mol% Y(2)O(3)) in the temperature range 300-1400 K. Based on the rigid ion model approximation, we find, regardless of the distinctly different geometries, that the oxygen ionic conductivity shows a maximum at ∼ 8.0 mol% Y(2)O(3), close to the experimental maximum. A lower absolute ionic conductivity is found for the high density YSZ amorphous solid, relative to crystalline YSZ, consistent with the trends observed in crystalline and stabilized amorphous thin films of YSZ reported in experiments. Different from YSZ crystals, intriguing features of mutual diffusion among the heavy cations and mobile anions are found in the amorphous phase.