Effect of Lone-Electron-Pair Cations on the Orientation of Crystallographic Shear Planes in Anion-Deficient Perovskites

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• 作者：Dmitry Batuk ; Maria Batuk ; Artem M. Abakumov ; Alexander A. Tsirlin ; Catherine McCammon ; Leonid Dubrovinsky ; Joke Hadermann
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：September 3, 2013
• 年：2013
• 卷：52
• 期：17
• 页码：10009-10020
• 全文大小：670K
• 年卷期：v.52,no.17(September 3, 2013)
• ISSN：1520-510X

文摘

Factors affecting the structure and orientation of the crystallographic shear (CS) planes in anion-deficient perovskites were investigated using the (Pb_1鈥?i>zSr_z)_1鈥?i>xFe_1+xO_3鈥?i>y perovskites as a model system. The isovalent substitution of Sr²⁺ for Pb²⁺ highlights the influence of the A cation electronic structure because these cations exhibit very close ionic radii. Two compositional ranges have been identified in the system: 0.05 鈮?z 鈮?0.2, where the CS plane orientation gradually varies but stays close to (203)_p, and 0.3 鈮?z 鈮?0.45 with (101)_p CS planes. The incommensurately modulated structure of Pb_0.792Sr_0.168Fe_1.040O_2.529 was refined from neutron powder diffraction data using the (3 + 1)D approach (space group X2/m(伪0纬), X = (¹/₂, ¹/₂, ¹/₂, ¹/₂), a = 3.9512(1) 脜, b = 3.9483(1) 脜, c = 3.9165(1) 脜, 尾 = 93.268(2)掳, q = 0.0879(1)a* + 0.1276(1)c*, R_F = 0.023, R_P = 0.029, and T = 900 K). A comparison of the compounds with different CS planes indicates that the orientation of the CS planes is governed mainly by the stereochemical activity of the lone-electron-pair cations inside the perovskite blocks.