Abstract
The crystal structure of Ca2CuO2Cl2, dicalcium oxidocuprate(II) dichloride, was redetermined on the basis of single-crystal X-ray diffraction data using a laboratory Mo anode. Previous structure determinations based on single-crystal X-ray data [Grande & Müller-Buschbaum (1977). Z. Anorg. Allg. Chem. 429, 88–90], powder X-ray diffraction data [Yamada et al. (2005). Phys. Rev. B, 72, 224503–1–5] or neutron diffraction data [Argyriou et al. (1995). Phys. Rev. B, 51, 8434–8437] were confirmed. The present study allowed the refinement of anisotropic displacement parameters for all crystallographic sites, accompanied with higher accuracy and precision for bond lengths and angles. The layered title compound comprises of [CuO4] square-planar and [CaO4Cl4] square-antiprismatic coordination polyhedra, and is the undoped parent compound of a high-temperature superconducting cuprate.
Highlights
The crystal structure of Ca2CuO2Cl2, dicalcium oxidocuprate(II) dichloride, was redetermined on the basis of single-crystal X-ray diffraction data using a laboratory Mo anode
Previous structure determinations based on single-crystal X-ray data [Grande & Muller-Buschbaum (1977)
The present study allowed the refinement of anisotropic displacement parameters for all crystallographic sites, accompanied with higher accuracy and precision for bond lengths and angles
Summary
The layered crystal structure of Ca2CuO2Cl2 (Fig. 1) has tetragonal symmetry (space group I4/mmm), and is the undoped parent compound of a high-temperature superconducting cuprate (Hiroi et al, 1994; Kohsaka et al, 2002; Yamada et al, 2005). Previous structure determinations of Ca2CuO2Cl2 based on single-crystal X-ray data (Grande & Muller-Buschbaum, 1977), powder X-ray diffraction data (Yamada et al, 2005) or neutron diffraction data (Argyriou et al, 1995) are confirmed by the current study. The first determination of the crystal structure of Ca2CuO2Cl2 converged with rather high residuals (R1 = 0.105; Grande & Muller-Buschbaum, 1977). Another previous attempt to determine anisotropic displacement parameters for all crystallographic sites has been made on basis of neutron powder diffraction data (Argyriou et al, 1995). We estimate that our model shows a lower correlation between fitted parameters
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