Materials Data on K3Ge7O20 by Materials Project
K3Ge7O20 crystallizes in the cubic P-43m space group. The structure is three-dimensional. K is bonded in a 12-coordinate geometry to twelve O atoms. There are eight shorter (3.15 Å) and four longer (3.17 Å) K–O bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded to six O atoms to form GeO6 octahedra that share corners with three equivalent GeO4 tetrahedra and edges with three equivalent GeO6 octahedra. There is three shorter (1.85 Å) and three longer (2.00 Å) Ge–O bond length. In the second Ge site, Ge is bonded to four equivalent O atoms to form corner-sharing GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. All Ge–O bond lengths are 1.76 Å. There are three inequivalent O sites. In the first O site, O is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ge atoms. In the second O site, O is bonded in a bent 120 degrees geometry to two equivalent K and two Ge atoms. In the third O site, O is bonded in a trigonal planar geometry to three equivalent K atoms.