Oxygen vacancy migration and its lattice structural origin in A-site non-stoichiometric bismuth sodium titanate perovskites

Journal of Materiomics

Xiao Liu¹  Wenchao Tian¹  Tao Zhang²  Rongrong Rao³  Tangyuan Li⁴  Jing Shi⁴  Laijun Liu⁵  Fangyuan Zhu⁵  Yuanhua Xia⁶ 

[1]Corresponding author.

[2]Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, China

[3]Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, China

[4]Key Laboratory of Electronic Equipment Structure Design (MOE), School of Mechano-Electronic Engineering, Xidian University, Xi'an, 710071, China

[5]School of Materials Science and Engineering, Xi'an University of Science and Technology, Xi'an, 710054, China

[6]Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China

关键词: Ferroelectrics;    Bismuth sodium titanate;    Oxide ion conductors;    Neutron powder diffraction;    Oxygen vacancy;   

DOI  :  

来源: DOAJ

【 摘 要 】

Off-stoichiometry of perovskite structural Bi0.5Na0.5TiO3 (BNT) ferroelectrics can give rise to considerable oxide-ion conductivity. The inherent structural characteristics are urgent to be resolved due to its particular sensitivity of the conduction mechanism to the nominal composition and synthesis process. Herein, a thorough study of the temperature-dependent neutron, X-ray diffraction and Raman spectrum is carried out on a series of equivalently substituted A-site deficient non-stoichiometric and pristine BNT. Phase transition and defect association are systemically investigated in these dominated rhombohedral phases at room temperature, associated with well saturated ferroelectric states. Significant structural evolution identified by Rietveld refinements and the origin of the electrical performance are clarified at elevated temperatures, focusing on the subtle distortions of ionic displacements, oxygen octahedral tilts and local chemical environments for oxygen vacancies. The ion migration ability mediated by oxygen vacancies that are not energetically favorable in BNT mainly depends on the external substitutional disorder, and is strongly affected by the dopant concentration. Together with the lone pair substitution concept, superior oxide ionic conductivity is achieved, and an alternative strategy is provided in designing BNT based oxide ion conductors.

【 授权许可】

Unknown