Spontaneous Superlattice Formation in the Doubly Ordered Perovskite KLaMnWO6

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• 作者：Susana Garcia-Martin ; Graham King ; Esteban Urones-Garrote ; Gwilherm N茅nert ; Patrick M. Woodward
• 刊名：Chemistry of Materials
• 出版年：2011
• 出版时间：January 25, 2011
• 年：2011
• 卷：23
• 期：2
• 页码：163-170
• 全文大小：1082K
• 年卷期：v.23,no.2(January 25, 2011)
• ISSN：1520-5002

文摘

Electron, neutron, and synchrotron X-ray diffraction together with transmission electron microscopy studies reveal the spontaneous formation of a complex superlattice in bulk samples of the perovskite KLaMnWO₆. The superlattice structure, which possesses P4̅2m space group symmetry with a = 40.0637(7) 脜 and c = 8.1306(3) 脜, results from a two-dimensional compositional modulation of the A-site cations (K⁺ and La³⁺), combined with a complex pattern of tilts involving the corner connected octahedra. The basic pattern of octahedral tilting involves out-of-phase tilts of neighboring octahedra about the pseudocubic a and b axes (a^{鈭?/sup>a鈭?/sup>c0 tilting). Unexpectedly, the out-of-phase tilting is disrupted in both directions by an in-phase tilt once every five octahedra. The occurrence of regularly repeating, well-separated in-phase tilts helps to alleviate strains that arise from formation of the compositionally modulated chessboard superlattice.}