Materials Data on Ca2Ge7O16 by Materials Project
Ca2Ge7O16 crystallizes in the orthorhombic Pba2 space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.97 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 GeO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–62°. There are a spread of Ge–O bond distances ranging from 1.78–1.81 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent GeO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–61°. There are a spread of Ge–O bond distances ranging from 1.78–1.81 Å. In the third Ge4+ site, Ge4+ is bonded to six O2- atoms to form corner-sharing GeO6 octahedra. There are a spread of Ge–O bond distances ranging from 1.89–1.95 Å. In the fourth Ge4+ site, Ge4+ is bonded to four O2- atoms to form corner-sharing GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 62°. All Ge–O bond lengths are 1.78 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Ge4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Ge4+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Ge4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and two Ge4+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and two Ge4+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Ge4+ atoms. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Ge4+ atoms.