Materials Data on K4GeSe4 by Materials Project
K4GeSe4 crystallizes in the cubic P-43n space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 octahedra that share corners with six KSe6 octahedra, corners with three GeSe4 tetrahedra, edges with twelve KSe6 octahedra, and a faceface with one GeSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–23°. There are a spread of K–Se bond distances ranging from 3.34–3.54 Å. In the second K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 octahedra that share corners with six equivalent KSe6 octahedra, corners with three equivalent GeSe4 tetrahedra, edges with twelve KSe6 octahedra, and a faceface with one GeSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–20°. There are three shorter (3.44 Å) and three longer (3.52 Å) K–Se bond lengths. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four equivalent Se2- atoms to form GeSe4 tetrahedra that share corners with twelve equivalent KSe6 octahedra and faces with four equivalent KSe6 octahedra. The corner-sharing octahedral tilt angles are 52°. All Ge–Se bond lengths are 2.39 Å. In the second Ge4+ site, Ge4+ is bonded to four equivalent Se2- atoms to form GeSe4 tetrahedra that share corners with twelve KSe6 octahedra and faces with four equivalent KSe6 octahedra. The corner-sharing octahedra tilt angles range from 46–51°. All Ge–Se bond lengths are 2.40 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to six K1+ and one Ge4+ atom. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to six K1+ and one Ge4+ atom.