中国物理B ›› 2012, Vol. 21 ›› Issue (4): 47201-047201.doi: 10.1088/1674-1056/21/4/047201

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张洁,梁二军,孙强,贾瑜   

  • 收稿日期:2011-09-28 修回日期:2011-10-17 出版日期:2012-02-29 发布日期:2012-02-29
  • 通讯作者: 梁二军,ejliang@zzu.edu.cn E-mail:ejliang@zzu.edu.cn

Oxygen vacancy formation and migration in Sr- and Mg-doped LaGaO3: a density functional theory study

Zhang Jie(张洁), Liang Er-Jun(梁二军), Sun Qiang(孙强), and Jia Yu(贾瑜)   

  1. School of Physics and Engineering, Zhengzhou University, Zhengzhou 450052, China
  • Received:2011-09-28 Revised:2011-10-17 Online:2012-02-29 Published:2012-02-29
  • Contact: Liang Er-Jun,ejliang@zzu.edu.cn E-mail:ejliang@zzu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 10974183).

Abstract: Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O0.3-$\delta$ (LSGM) with various crystal symmetries (cubic, rhombohedral, orthorhombic, and monoclinic) are studied by employing first-principles calculations based on density functional theory (DFT). It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In our calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and O2 oxygen sites. The migration energies along the migration pathway linking the two O2 sites are obviously lower than those along the pathway linking the O1 and O2 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.

Key words: density functional theory, oxygen vacancy formation energy, oxygen vacancy migration energy, migration pathway

中图分类号:  (Mixed conductivity and conductivity transitions)

  • 72.60.+g
71.20.Ps (Other inorganic compounds) 72.10.Fk (Scattering by point defects, dislocations, surfaces, and other imperfections (including Kondo effect))