We have determined the crystal structure of the quasi one-dimensional cuprate Ca0.83CuO2, known as Ca4Cu5O10, etc., by a superspace group approach. The compound consists of two interpenetrating subsystems of CuO2 chains and Ca atoms. Structural parameters were refined with a superspace group of F2/m(1+α 0 γ)0s using powder X-ray and neutron diffraction data. Lattice parameters were refined to be a1 = 2.8043(2) Å, b = 6.3179(2) Å, c1 = 10.5744(5) Å, and β1 = 90.10(1)° for the [CuO2] subsystem and a2 = 3.3652(2) Å, b = 6.3179(2) Å, c2 = 10.5893(5) Å, and β2 = 93.04(1)° for the [Ca] subsystem. Remarkable displacive modulation of the O and Ca atom sites is observed parallel to the b-axis and the c-axis, respectively. On the other hand, the Cu atom sites deviate mainly in the a direction to yield a periodic fluctuation between the nearest Cu-Cu distances. The Ca atoms suitably sit in the center of the modulated O6 octahedra.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry