The incommensurate structure of (Sr14−xCax)Cu24O41 (0 < x ∼ 8) a superconductor byproduct
The incommensurate structure of (Sr14−xCax)Cu24O41 (0 < x ∼ 8) a superconductor byproduct
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DOI：
10.1016/0025-5408(88)90124-9
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发表时间：
1988-09
影响因子：
5.4
通讯作者：
E. Mccarron;M. A. Subramanian;J. Calabrese;R. Harlow
中科院分区：
文献类型：
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作者：
E. Mccarron;M. A. Subramanian;J. Calabrese;R. Harlow
用X-射线单晶衍射法测定了标题化合物的两个组分：Sr8Ca6Cu24O41和Sr14Cu24O41的结构。第一种结构可以很好地描述为两种互穿结构：一种是在a=11.375(2)，b=12.9027(2)，c=3.910(1)Å的正交晶胞中具有(Sr，Ca)(Cu2 O3Sheet)(SR，Ca)层的结构；另一种是在a和b值相同但c=2.753 Å的晶胞中具有(CuO2链)层的结构。标题公式的产生是因为这两个亚晶胞在7×c(单)=27.372(2)和10×c(链)=27.534时几乎相称。纯锶的结构非常相似，但在给定的层中相邻的CuO2链转变为较少约束的构象：a=11.459(2)，b=13.368(5)，c(Sheet)=3.931(1)，c(Chain)=2.749(1)Å。X-射线粉末衍射研究表明，x的变化范围从0到∼8，层轴b对成分最敏感。这些相的单晶被发现是半导体。
The structures of two compositions of the title compound, Sr 8 Ca 6 Cu 24 O 41 and Sr 14 Cu 24 O 41, have been determined by x-ray, single-crystal diffraction techniques. The structure of the first is best described as two interpenetrating structures: one with (Sr, Ca)(Cu 2 O 3 sheets)(Sr, Ca) layers in an orthorhombic cell with dimensions of a= 11.375 (2), b= 12.9027 (2), c= 3.910 (1) A ̊ and a second structure with layers of (CuO 2 chains) in a cell having identical a and b values but with c= 2.753 A ̊. The title formulation arises because these two subcells are nearly commensurate at 7× c (sheet)= 27.372 (2) and 10× c (chain)= 27.534. The structure of the pure strontium phase is very similar but the adjacent CuO 2 chains in a given layer shift to a less constrained conformation: a= 11.459 (2), b= 13.368 (5), c (sheet)= 3.931 (1), c (chain)= 2.749 (1) A ̊. X-ray powder diffraction studies have shown that x may vary from 0 to∼ 8, with the layer axis, b, showing the most sensitivity to composition. Single crystals of these phases were found to be semiconductors.