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Updated: Sep 25, 2025
Quantitative Atomic-Site Analysis of Functional Dopants/Point Defects in Crystalline Materials by Electron-Channeling-Enhanced Microanalysis
Published on: May 10, 2021
Site-selective doping effect, phase separation, and structure evolution in 1:1:1 triple-cation B-site ordered
He Huang1, Pengfei Jiang1,2, Wenliang Gao1
1College of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P. R. China pengfeijiang@cqu.edu.cn taoyang@cqu.edu.cn.
Abstract:
Oxygen-deficient perovskites are a family of important materials that may exhibit oxide ionic conductivities. We attempted to introduce oxygen-vacancy disordering in perovskite Ca4GaNbO8 (Ca4-type) by substituting Ca2+ with larger Sr2+. Sr2+-to-Ca2+ substitution did not lead to oxygen-vacancy ordering-disordering transition but an interesting Ca4-to-Sr4 type structure transition. Rietveld refinements revealed that the two-type structures exhibit similar oxygen-vacancy ordering and identical 1:1:1 triple-cation B-site ordering. Close inspection of the two-type structures revealed the subtle structure difference lies in the orientations of GaO4 tetrahedra, which is the origin of the formation of the narrow two-phase region (0.3 ≤ x < 0.65) in Ca4- Sr GaNbO8. More importantly, the A- and B-site cavities with large differences in size for both structures resulted in a site-selective doping behaviour for Sr2+ in Ca4- Sr GaNbO8. These structural changes found in Ca4- Sr GaNbO8 will provide a broad route approaching new oxygen-deficient phases with oxide ionic conductivities.
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