Materials Data on K3Nb3Ge2O13 by Materials Project
K3Nb3Ge2O13 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of K–O bond distances ranging from 3.00–3.27 Å. In the second K1+ site, K1+ is bonded in a 2-coordinate geometry to four O2- atoms. There are two shorter (2.70 Å) and two longer (2.93 Å) K–O bond lengths. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with four equivalent NbO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–33°. There are a spread of Nb–O bond distances ranging from 1.98–2.07 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent NbO6 octahedra and a cornercorner with one GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 26°. There is three shorter (1.74 Å) and one longer (1.77 Å) Ge–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent K1+ and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to three equivalent K1+ and two equivalent Ge4+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two equivalent Nb5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+, one Nb5+, and one Ge4+ atom.