Modeling of La³⁺ doping segregation in nanocrystalline yttria-stabilized zirconia using a combintaion of atomistic MD, Monte Carlo and Nudged Elatic Band calculations

The effect of La3+ doping on the structure and ionic conductivity change in nanocrystalline yttriastabilized zirconia (YSZ) was studied using a combination of Monte Carlo and molecular dynamics and Nudge Elastic Band simulations. Simulations of specific grain boundary configurations are developed. Systems with and withoout La doping are studied and equilibrated using a combintaion of techniques and eventually anaylzed using Voronoi tesselation analysis for the density of the dopants.

The simulation revealed the segregation of La3+ at eight tilt grain boundary (GB) structures and predicted an average grain boundary (GB) energy decrease of 0.25 J m-2, which is close to the experimental values reported in the literature. Cation stabilization was found to be the main reason for the GB energy decrease, and energy fluctuations near the grain boundary are smoothed out with La3+ segregation. Both dynamic and energetic analysis on the S13(510)/[001] GB structure revealed La3+ doping hinders O2- diffusion in the GB region, where the diffusion coefficient monotonically decreases with increasing La3+ doping concentration. T