Synthesis and Structure of New Layered Oxides, MIILa2Ti3O10 (M = Co, Cu, and Zn)

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• 作者：Ki-An Hyeon and Song-Ho Byeon
• 刊名：Chemistry of Materials
• 出版年：1999
• 出版时间：February 1999
• 年：1999
• 卷：11
• 期：2
• 页码：352 - 357
• 全文大小：129K
• 年卷期：v.11,no.2(February 1999)
• ISSN：1520-5002

文摘

New layered perovskite compounds, M^II[La₂Ti₃O₁₀] (M = Co, Cu, and Zn) were synthesizedby the ion-exchange reaction of the parent Na₂La₂Ti₃O₁₀ in molten salts. The crystal structureof the as-synthesized phases was determined by the Rietveld refinement for the powderX-ray diffraction patterns. The unit cells are tetragonal with a = 3.8128(1), 3.8248(2), and3.8127(1) Å and c = 27.568(1), 26.329(1), and 27.5129(9) Å with an I4/mmm (Z = 2) spacegroup for the Co, Cu, and Zn phases, respectively. The transition-metal atoms occupy stronglyflattened tetrahedral sites with 50% probability between the perovskite slabs. These oxidesrepresent the first example of layered perovskite whose interlayer spaces are occupied bysmall transition-metal cations. Particularly for the Cu oxide, remarkable shortening of thec-axis was observed upon heating up to 700 C under an Ar atmosphere. Such a contractionis likely to result from the flattening of the CuO₄ unit toward a quasi-square planarcoordination.