DOI: 10.17188/1318077
title: Materials Data on CaCu2(GeO3)4 by Materials Project

description: CaCu2(GeO3)4 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.56 Å. There are two inequivalent Cu3+ sites. In the first Cu3+ site, Cu3+ is bonded to six O2- atoms to form distorted CuO6 octahedra that share corners with three GeO4 tetrahedra, corners with two equivalent GeO5 trigonal bipyramids, and an edgeedge with one GeO5 trigonal bipyramid. There are a spread of Cu–O bond distances ranging from 1.88–2.32 Å. In the second Cu3+ site, Cu3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 1.85–2.52 Å. There are four inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent CuO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–65°. There is three shorter (1.77 Å) and one longer (1.80 Å) Ge–O bond length. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one CuO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. There are a spread of Ge–O bond distances ranging from 1.75–1.81 Å. In the third Ge4+ site, Ge4+ is bonded to five O2- atoms to form GeO5 trigonal bipyramids that share corners with two equivalent CuO6 octahedra, corners with two equivalent GeO5 trigonal bipyramids, and an edgeedge with one GeO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 42°. There are a spread of Ge–O bond distances ranging from 1.80–1.97 Å. In the fourth Ge4+ site, Ge4+ is bonded to five O2- atoms to form GeO5 trigonal bipyramids that share corners with two equivalent GeO5 trigonal bipyramids, an edgeedge with one CuO6 octahedra, and an edgeedge with one GeO5 trigonal bipyramid. There are a spread of Ge–O bond distances ranging from 1.77–2.08 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Cu3+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Cu3+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted tetrahedral geometry to one Ca2+, two Cu3+, and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Ge4+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Ge4+ atoms. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two Ge4+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Cu3+ and two Ge4+ atoms. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+, one Cu3+, and two Ge4+ atoms. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu3+ and one Ge4+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Cu3+, and one Ge4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Cu3+ and one Ge4+ atom.