Materials Data on CaCr2(CuO4)2 by Materials Project
CaCr2(CuO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six CrO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with two equivalent CuO5 trigonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.29–2.42 Å. There are two inequivalent Cr6+ sites. In the first Cr6+ site, Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with two equivalent CuO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 36–60°. There are a spread of Cr–O bond distances ranging from 1.68–1.71 Å. In the second Cr6+ site, Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with three equivalent CuO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 49–64°. There are a spread of Cr–O bond distances ranging from 1.67–1.72 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to five O2- atoms to form distorted CuO5 trigonal bipyramids that share corners with five CrO4 tetrahedra and edges with two equivalent CaO6 octahedra. There are a spread of Cu–O bond distances ranging from 1.94–2.44 Å. In the second Cu1+ site, Cu1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.98–2.06 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cr6+, and one Cu1+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cr6+, and one Cu1+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Cr6+, and one Cu1+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr6+ and one Cu1+ atom. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca2+, one Cr6+, and one Cu1+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cr6+, and one Cu1+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr6+ and one Cu1+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cr6+ and two Cu1+ atoms.