First-principles study on oxygen ion conduction of La₂GeO ₅ based on the density functional theory

We performed first-principles simulations based on the density functional theory for investigations on the atomic geometry of La₂GeO ₅, which is a fast oxygen ion conductor applicable to solid oxide fuel cells. While two experimental studies have reported contradicting results about the configuration of GeO₄ tetrahedral substructures, i.e., sp²- or sp³-like, we found that only the sp ³-like form is stable. We confirmed that the favorability of oxygen sites for vacancy formation is fundamentally affected by this configuration. The bonding mechanisms between atoms are discussed based on analyses of atomic distances and electronic density of states.