Influence of In3+ doped on the oxygen ion conductivity and relaxation behavior of BaBiNb5O15 compound

BaBiNb5O15 (BBN) compound exhibits exceptional chemical and structural stability at the intermediate temperatures, which is crucial for the long-term operation of solid oxide fuel cells. The electrical performance of BBN compound can be improved by the In3+ ion acceptor doping. The oxygen ion conductivity of the BaBiNb5−xInxO15−δ compound exhibits an initial increase followed by a decrease with rising In3+ ion doping concentration. The optimal oxygen ion conductivity is achieved at x = 0.075, reaching 1.5 × 10−4 S/cm at 773 K, which is 1.5 times higher than that of the parent BBN material. The oxygen relaxation activation energy of the BaBiNb5−xInxO15−δ sample follows a similar trend. By the dielectric relaxation spectroscopy, the BaBiNb4.925In0.075O15−δ (x = 0.075) sample shows a higher concentration and better mobility of oxygen vacancies, likely contributing to its enhanced oxygen ion conductivity. These findings contribute to the understanding of oxygen diffusion mechanisms and enhance the electrical performance of BBN-based oxide ion conductors.