Ion diffusion across/along symmetric tilt grain boundaries in yttria-stabilized zirconia investigated by molecular dynamics simulations

Atomic arrangements around symmetric tilt grain boundaries (GBs) sigma 3[110]/{111}, sigma 9[110]/{221} and sigma 11 [110]/{113} in yttria-stabilized zirconia (YSZ) and influence of these GBs on oxygen ion diffusion were inves-tigated by molecular dynamics (MD) simulations. The models including those GBs along which yttrium ions are segregated were used for simulations. The atomic arrangements obtained by MD simulations were consistent with the structure obtained by using advanced electron microscopy techniques. MD simulations predict that sigma 11 [110]/{113} GB reduce oxygen ion diffusion both across and along GB, while sigma 9[110]/{221} GB does not give large influence on the diffusion. The origin of such difference can be explained systematically based on the variation of nearest neighbor O-O distance which may change the probability of oxygen ion hopping from one site to another. The simulated results also predict the emergence of two-dimensional honeycomb-shaped path networks of oxygen ion diffusion along the cores of sigma 3[110]/{111} symmetric tilt GB in YSZ. The unique honeycomb networks have the potential for enhancing the ion diffusion along GBs.

Automated summary

Atomic arrangements and their influence on oxygen ion diffusion were investigated in yttria-stabilized zirconia (YSZ) using molecular dynamics (MD) simulations. The results showed that the sigma 11 [110]/{113} grain boundary (GB) reduces oxygen ion diffusion across and along the GB, while the sigma 9 [110]/{221} GB has little influence on the diffusion. The difference can be explained by the variation in nearest neighbor O-O distance. MD simulations also predicted the formation of two-dimensional honeycomb-shaped path networks of oxygen ion diffusion along the cores of the sigma 3[110]/{111} GB in YSZ, which has the potential to enhance ion diffusion along GBs.