From Carbonate-Cuprates to Cuprate-Carbonates: The Structural Equivalence of CO3and CuOxGroups in the Ba–Cu–C–O System☆
From Carbonate-Cuprates to Cuprate-Carbonates: The Structural Equivalence of CO3and CuOxGroups in the Ba–Cu–C–O System☆
复制标题
从碳酸盐-铜酸盐到铜酸盐-碳酸盐：Ba-Cu-C-O体系中CO3和CuOx基团的结构等价☆
DOI：
10.1006/jssc.1996.7167
复制
发表时间：
1997
影响因子：
5.4
通讯作者：
K. A. Thomas
中科院分区：
文献类型：
--
作者：
F. C. Matacotta;G. Calestani;A. Migliori;P. Nozar;P. Scardi;O. Greco;P. Ricci;A. Tomasi;K. A. Thomas
亚稳双钙钛矿Ba{sub2}Cu{sub1+x}(CO{sub3}){sub1-x}O{sub2+{Delta}}或BaCO{sub3}、BaO{sub2}和CuO分解形成的物相的X射线衍射分析没有明显显示或仅显示出微量的含铜化合物。得到的衍射图非常接近于类文石的{伽马}-BaCO{sub3}。然而，红外和拉曼光谱数据、电子衍射、对单晶微晶进行的能量色散X射线分析和高分辨电子显微镜表明，存在一种与式BA(CuO{subx}){sub1-y}(CO{sub3}){suby}，{Gamma}{Le}0.5相对应的模拟化合物，其晶格常数几乎与{Gamma}-BaCo{sub3}的晶格常数相同。新结构的特点是Ba原子的六方紧密堆积，但八面体空穴被碳酸盐基团或CuO{subx}平面单元无关紧要地占据，连接成单轴链状。BaO(CuO{subx}){sub1-y}(CO{sub3}){suby}相的长度级数极短，反映了一排空穴被碳酸盐柱或CuO{subx}链占据的几率相等。在合适的条件下，双钙钛矿和类文石结构在热循环中转化为另一种结构。
X-ray diffraction analysis of the phases forming from the decomposition of metastable double perovskites Ba{sub 2}Cu{sub 1+x}(CO{sub 3}){sub 1-x}O{sub 2+{delta}} or by reacting BaCO{sub 3}, BaO{sub 2}, and CuO does not apparently reveal, or shows only traces of, copper containing compounds. The resulting diffraction patterns are very close to aragonite-like {gamma}-BaCO{sub 3}. However, infrared and Raman spectroscopy data, electron diffraction, energy dispersion X-ray analysis performed on single crystal micrograins, and high-resolution electron microscopy reveal the existence of a mimetic compound corresponding to the formula Ba(CuO{sub x}){sub 1-y}(CO{sub 3}){sub y}, {gamma}{le}0.5, with lattice constants practically identical to those of {gamma}-BaCO{sub 3}. The new structure is characterized by the same hexagonal close packing of the Ba atoms, but the octahedral cavities are indifferently occupied by carbonate groups or CuO{sub x} planar units, linked to form uniaxial chains. The length order in the Ba(CuO{sub x}){sub 1-y}(CO{sub 3}){sub y} phase is extremely short reflecting the equal probability that a row of cavities is occupied by carbonate columns or CuO{sub x} chains. Under suitable conditions, not completely identified as yet, the double perovskite and the aragonite-like structures transform one into the other on thermal cycling.