Enhanced Oxygen Ion Conductivity and Ionic Conduction Mechanistic Visualization in Tetragonal Zircon-Type PrSrVO.

Oxide-ion conductors based on tetrahedral anion-related oxides have attracted considerable attention due to their high oxygen-ion conductivity and potential applications in clean energy devices, such as solid-state fuel cells. In this study, we report the improvement of oxide-ion conductivity by Sr doping in isolated tetrahedral zircon-type PrVO. It is found that PrSrVO features the highest oxide-ion conductivity of 2.62 × 10 S·cm at 800 °C under air, with an oxygen transport number of 0.93. The formation and stabilization of oxygen vacancy defects, as well as the oxide-ion migration mechanism in PrVO, were investigated through combining experimental characterizations and computing simulations. The results indicate that the concentration of oxygen vacancy defects increases with Sr substitution, and the vacancies are accommodated by the formation of corner-sharing VO dimers. Oxygen-ion migration proceeds via a cooperative mechanism involving VO-dimer breaking and reforming assisted by synergistic rotation and deformation of neighboring VO tetrahedra. The results provide valuable insights for further investigation and optimization of zircon-type oxides as potential oxide-ion conductors for electrochemical devices.