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

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• 作者：Xiaoyan Yang ; Shuaibo Liu ; Fengqi Lu ; Jungu Xu ; Xiaojun Kuang
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：March 31, 2016
• 年：2016
• 卷：120
• 期：12
• 页码：6416-6426
• 全文大小：735K
• ISSN：1932-7455

文摘

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 Nd_0.8Ca_0.2BaInO_3.9 composition, exceeding the most-conducting Nd_0.9Sr_0.1BaInO_3.95 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 conduction in a high partial oxygen pressure range of the NdBaInO₄-based materials is from the oxidation reaction forming the holes centered on O atoms. Both the static lattice and molecular dynamic simulations indicate two-dimensional oxygen vacancy migration within the perovskite slab boundaries for the acceptor-doped NdBaInO₄. Molecular dynamic simulations on the Ca-doped NdBaInO₄ specify two major vacancy migration events, respectively, via one intraslab path along the b axis and one interslab path along the c axis. These paths are composed by two terminal oxygen sites within the perovskite slab boundaries.