Modulated Structure of Misfit-Layered Cobalt Oxide [Ca2(Co0.65Cu0.35)2O4]0.63CoO2
Modulated Structure of Misfit-Layered Cobalt Oxide [Ca2(Co0.65Cu0.35)2O4]0.63CoO2
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DOI：
10.1143/jjap.42.7467
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发表时间：
2003-12
影响因子：
1.5
通讯作者：
Y. Miyazaki;T. Miura;M. Onoda;M. Uchida;Y. Ishii;Y. Ono;Y. Morii;T. Kajitani
中科院分区：
文献类型：
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作者：
Y. Miyazaki;T. Miura;M. Onoda;M. Uchida;Y. Ishii;Y. Ono;Y. Morii;T. Kajitani
用超空间群方法确定了新型热电化合物[Ca_2（Co_（0.65）Cu_（0.35））_2 O_4]_（0.63）CoO_2的晶体结构。利用293 K下的粉末中子衍射数据，在C2/m（1 p0）s 0超空间群下，对结构参数进行了修正。该化合物由相互贯穿的三角形CoO 2层和扭曲的四层岩盐型Ca 2（Co0.65Cu0.35）2 O 4片，这是无公度平行于b轴。CoO 2层由CdI 2型共边CoO 6八面体组成。两个子系统具有共同的a轴和c轴，以及β角，其中a=4.8212（4）°，c=12.7671（8）°，β=93.93（1）°。[CoO 2]子系统的b轴长度为b1=2.8103（3）μ m，[Ca 2（Co0.65Cu0.35）2 O 4]子系统的b轴长度为b2=4.4915（3）μ m。在[Ca_2（Co_（0.65）Cu_（0.35））_2 O_4]子系统中观察到（Co，Cu）和O位的位移调制，（Co，Cu）-O距离在1.8 ~ 2.7 μ m范围内有较大的波动. Cu 2+离子似乎在稳定这种化合物中的四个原子厚的子系统中发挥了重要作用。
We have determined the crystal structure of novel thermoelectric compound [Ca2(Co0.65Cu0.35)2O4]0.63CoO2 by a superspace group approach. Structural parameters have been refined with a superspace group of C2/m(1 p 0)s0 using powder neutron diffraction data collected at 293 K. The compound consists of mutually interpenetrating triangular CoO2 layers and distorted four-layered rock salt-type Ca2(Co0.65Cu0.35)2O4 slabs, which are incommensurate parallel to the b-axis. The CoO2 layer is composed of the CdI2-type edge-shared CoO6 octahedra. Both the subsystems have common a- and c-axes, and β-angle with a=4.8212(4) Å, c=12.7671(8) Å and β=93.93(1)°. The b-axis lengths are b1=2.8103(3) Å for the [CoO2] subsystem and b2=4.4915(3) Å for the [Ca2(Co0.65Cu0.35)2O4] subsystem. A marked displacive modulation of the (Co,Cu) and O sites in the [Ca2(Co0.65Cu0.35)2O4] subsystem has been observed, yielding a large fluctuation of the (Co,Cu)–O distances in the range from 1.8 Å to 2.7 Å. Cu2+ ions appear to play an important role in stabilizing such a four-atom thick subsystem in this compound.