DOI: 10.17188/1677818
title: Materials Data on KMg3AlGe3(O5F)2 by Materials Project

description: KMg3AlGe3(O5F)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. K1+ is bonded to six O2- atoms to form KO6 octahedra that share corners with three equivalent AlO4 tetrahedra and corners with nine GeO4 tetrahedra. There are a spread of K–O bond distances ranging from 2.71–3.04 Å. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- and two F1- atoms to form MgO4F2 octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three GeO4 tetrahedra, and edges with six MgO4F2 octahedra. There are a spread of Mg–O bond distances ranging from 2.04–2.19 Å. There are one shorter (2.04 Å) and one longer (2.10 Å) Mg–F bond lengths. In the second Mg2+ site, Mg2+ is bonded to four O2- and two F1- atoms to form MgO4F2 octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three GeO4 tetrahedra, and edges with six MgO4F2 octahedra. There are a spread of Mg–O bond distances ranging from 2.05–2.19 Å. There are one shorter (2.04 Å) and one longer (2.11 Å) Mg–F bond lengths. In the third Mg2+ site, Mg2+ is bonded to four O2- and two F1- atoms to form MgO4F2 octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three GeO4 tetrahedra, and edges with six MgO4F2 octahedra. There are a spread of Mg–O bond distances ranging from 2.05–2.19 Å. There are one shorter (2.03 Å) and one longer (2.07 Å) Mg–F bond lengths. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent KO6 octahedra, corners with three MgO4F2 octahedra, and corners with three equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 61–65°. There is three shorter (1.77 Å) and one longer (1.78 Å) Al–O bond length. There are three inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent KO6 octahedra, corners with three MgO4F2 octahedra, and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 61–66°. There is three shorter (1.75 Å) and one longer (1.81 Å) Ge–O bond length. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent KO6 octahedra, corners with three MgO4F2 octahedra, and corners with three equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–64°. There is one shorter (1.74 Å) and three longer (1.78 Å) Ge–O bond length. In the third Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent KO6 octahedra, corners with three MgO4F2 octahedra, and corners with three equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–64°. There is one shorter (1.74 Å) and three longer (1.78 Å) Ge–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one K1+, one Al3+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one K1+, one Al3+, and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and two Ge4+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded to three Mg2+ and one Al3+ atom to form distorted corner-sharing OMg3Al tetrahedra. In the sixth O2- site, O2- is bonded to three Mg2+ and one Ge4+ atom to form distorted corner-sharing OMg3Ge tetrahedra. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mg2+ and one Ge4+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mg2+ and one Ge4+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one K1+, one Al3+, and one Ge4+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and two Ge4+ atoms. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a trigonal non-coplanar geometry to three Mg2+ atoms. In the second F1- site, F1- is bonded in a distorted T-shaped geometry to three Mg2+ atoms.