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Materials Data on Ca2CuO3 by Materials Project

Ca2CuO3 crystallizes in the orthorhombic Immm space group. The structure is two-dimensional and consists of two CuO ribbons oriented in the (0, 1, 0) direction and two CaO sheets oriented in the (0, 0, 1) direction. In each CuO ribbon, Cu2+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.69 Å. O2- is bonded in a linear geometry to two equivalent Cu2+ atoms. In each CaO sheet, Ca2+ is bonded to five equivalent O2- atoms to form a mixture of corner and edge-sharing CaO5 square pyramids. There are one shorter (2.35 Å) and four longer (2.37 Å) Ca–O bond lengths. O2- is bonded to five equivalent Ca2+ atoms to form a mixture of corner and edge-sharing OCa5 square pyramids.

36 MATERIALS SCIENCE↗

Materials Data on Ca2CuO3 by Materials Project

Ca2CuO3 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Ca2+ is bonded to seven O2- atoms to form a mixture of distorted corner, edge, and face-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.32–2.53 Å. Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.92 Å) and two longer (1.96 Å) Cu–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Ca2+ and two equivalent Cu2+ atoms to form OCa4Cu2 octahedra that share corners with fourteen OCa4Cu2 octahedra, edges with two equivalent OCa4Cu2 octahedra, and faces with four equivalent OCa5Cu octahedra. The corner-sharing octahedra tilt angles range from 0–61°. In the second O2- site, O2- is bonded to five equivalent Ca2+ and one Cu2+ atom to form OCa5Cu octahedra that share corners with eleven OCa4Cu2 octahedra, edges with eight equivalent OCa5Cu octahedra, and faces with two equivalent OCa4Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–61°.

36 MATERIALS SCIENCE↗

The series Bi2Sr2Ca(n-1) Cu(n)O(2n+4) (1 less than or equal to n less than or equal to 5): Phase stability and superconducting properties

Phase relations at 850 and 870 C, melting transitions in air, oxygen, and helium were studied for Bi(2.1)Sr(1.9) CuO6 and for the Bi2Sr2Ca(n-1) Cu(n)O(2n+4) for n = 1, 2, 3, 4, 5, and infinity (CaCuO2). Up to 870 C, the n = 2 composition resides in the compatibility tetrahedron bounded by Bi(2+x)(Sr,Ca)(3-y) Cu2O8, (Sr,Ca)14 Cu24O41, Ca2CuO3, and a Bi-Sr-Ca-O phase. The n is greater than or equal to 3 compositions reside in the compatibility tetrahedron Bi(2+x)(Sr,Ca)(3-y) Cu2O8 - (Sr,Ca)14 Cu24O41 - Ca2CuO3 - CuO up to 850 C. However, Bi(2+x)Sr(4-y) Cu3O10 forms for n is greater than or equal to 3 after extended heating at 870 C. Bi(2+x)Sr(2-y) CuO6 and Bi(2+x)(Sr,Ca)(3-y) Cu2O8 melt in air at 914 C and 895 C respectively. During melting, all of the compositions studied lose 1 to 2 percent by weight of oxygen from the reduction of copper. Bi(2+x)Sr(2-y) CuO6, Bi(2+n)(Sr,Ca)(3-y) Cu2O8, and Bi(2+x)(Sr,Ca)(4-y) Cu3O10 exhibit crystallographic alignment in a magnetic field, with the c-axes orienting parallel to the field.

Deguire, Mark R.↗