First-Principles Study of Enhanced Oxygen incorporation Near the Grain Boundary on Yttria-Stabilized Zirconia

The recently reported oxygen incorporation enhancement near the grain boundary (GB) of yttria-stabilized zirconia (YSZ) provided a potential to enable the low temperature solid oxide fuel cell. However, these empirical observations have not yet explained the detailed reaction mechanism. Here, we performed first-principles calculations to quantitatively access the mechanism that may govern the fast oxygen incorporation at the GB. We investigated the key elementary steps of oxygen incorporation onto both Sigma 5 (310)/[001] GB and (001) surfaces of YSZ at the atomic scale; yttrium dopant segregation, vacancy formation, and oxygen adsorption. Our results showed that the doped yttrium preferentially segregates toward the GB, inducing the easier formation of oxygen vacancy between the yttrium pair at the GB. After these steps, oxygen is favorably adsorbed near the oxygen vacancy accumulated at the GB, eventually incorporating into the vacancy site. On the basis of our results, we suggest the fast oxygen incorporation mechanism near the GB of YSZ, providing fundamental insight of oxygen surface kinetics at the interfaces of defected oxide materials.