Materials Data on KGe2(PO4)3 by Materials Project
KGe2(PO4)3 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to twelve O2- atoms to form distorted KO12 cuboctahedra that share corners with six equivalent GeO6 octahedra, edges with six equivalent PO4 tetrahedra, and faces with two equivalent GeO6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are six shorter (2.63 Å) and six longer (3.23 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form distorted KO12 cuboctahedra that share corners with six equivalent GeO6 octahedra, edges with six equivalent PO4 tetrahedra, and faces with two equivalent GeO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are six shorter (2.77 Å) and six longer (3.32 Å) K–O bond lengths. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to six O2- atoms to form GeO6 octahedra that share corners with three equivalent KO12 cuboctahedra, corners with six equivalent PO4 tetrahedra, and a faceface with one KO12 cuboctahedra. There is three shorter (1.88 Å) and three longer (1.91 Å) Ge–O bond length. In the second Ge4+ site, Ge4+ is bonded to six O2- atoms to form GeO6 octahedra that share corners with three equivalent KO12 cuboctahedra, corners with six equivalent PO4 tetrahedra, and a faceface with one KO12 cuboctahedra. There is three shorter (1.90 Å) and three longer (1.91 Å) Ge–O bond length. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four GeO6 octahedra and edges with two KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 32–45°. There is two shorter (1.54 Å) and two longer (1.55 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Ge4+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ge4+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one K1+, one Ge4+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ge4+, and one P5+ atom.