Acceptor Doping and Oxygen Vacancy Migration in Layered Perovskite NdBaInO4-Based Mixed Conductors

Abstract

The Ca2+ and Ba2+ solubility on Nd3+ sites in new layered perovskite NdBaInO4 mixed oxide ionic and hole conductor and their effect on the oxide ion conductivity of NdBaInO4 were investigated. Among the alkaline earth metal cations Ca2+, Sr2+, and Ba2+, Ca2+ was shown to be the optimum acceptor–dopant for Nd3+ in NdBaInO4 showing the largest substitution for Nd3+ up to 20% and leading to oxide ion conductivities ∼3 × 10–4–1.3 × 10–3 s/cm within 600–800 °C on Nd0.8Ca0.2BaInO3.9 composition, exceeding the most-conducting Nd0.9Sr0.1BaInO3.95 in the Sr-doped NdBaInO4. Energetics of defect formation and oxygen vacancy migration in NdBaInO4 were computed through the atomistic static-lattice simulation. The solution energies of Ca2+/Sr2+/Ba2+ on the Nd3+ site in NdBaInO4 for creating the oxygen vacancies confirm the predominance of Ca2+ on the substitution for Nd3+ and enhancement of the oxygen vacancy conductivity over the larger Sr2+ and Ba2+. The electronic defect formation energies indicate that the p-type c...