Characteristics (grain boundary energies, radial distribution functions for pairs of ions, O diffusion along grain boundaries) of Σ3, Σ5, Σ11 and Σ13 grain boundaries in model yttria-stabilised zirconia bicrystals were systematically studied as functions of the yttria concentration and temperature. The concentration of dopants affected the local structure at the grain boundaries, and a preferential location of oxygen vacancies around yttrium cations was detected. The grain boundary energies generally decreased with temperature, although no clear dependence upon the amount of yttria was apparent. Diffusion of oxygen was found to proceed more slowly along the grain boundaries than within the bulk, with the difference becoming less important with increasing temperature. The grain boundary diffusion coefficients for oxygen did not depend greatly upon the yttria concentration, but the activation energies exhibited a maximum at around 15mol% yttria for all of the geometries.

A Molecular Dynamics Study of Grain Boundaries in YSZ: Structure, Energetics and Diffusion of Oxygen. González-Romero, R.L., Meléndez, J.J., Gómez-García, D., Cumbrera, F.L., Domínguez-Rodríguez, A.: Solid State Ionics, 2012, 219, 1-10

Table 25

Self-diffusion coefficients for O ion diffusion

in bulk YSZ and YSZ/CeO2 superlattices