Materials Data on Na6Ge2S7 by Materials Project
Na6Ge2S7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six S2- atoms to form distorted NaS6 octahedra that share corners with two NaS6 octahedra, a cornercorner with one GeS4 tetrahedra, edges with four NaS6 octahedra, and edges with three equivalent GeS4 tetrahedra. The corner-sharing octahedra tilt angles range from 6–40°. There are a spread of Na–S bond distances ranging from 2.89–3.33 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six S2- atoms. There are a spread of Na–S bond distances ranging from 2.87–3.45 Å. In the third Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are two shorter (2.75 Å) and two longer (2.81 Å) Na–S bond lengths. In the fourth Na1+ site, Na1+ is bonded to six S2- atoms to form NaS6 octahedra that share corners with two equivalent NaS6 octahedra, corners with two equivalent GeS4 tetrahedra, edges with four equivalent NaS6 octahedra, and edges with two equivalent GeS4 tetrahedra. The corner-sharing octahedral tilt angles are 6°. There are a spread of Na–S bond distances ranging from 2.78–3.13 Å. Ge4+ is bonded to four S2- atoms to form GeS4 tetrahedra that share corners with two NaS6 octahedra, a cornercorner with one GeS4 tetrahedra, and edges with four NaS6 octahedra. The corner-sharing octahedra tilt angles range from 20–59°. There are a spread of Ge–S bond distances ranging from 2.21–2.29 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to five Na1+ and one Ge4+ atom to form a mixture of distorted corner and edge-sharing SNa5Ge octahedra. The corner-sharing octahedra tilt angles range from 0–78°. In the second S2- site, S2- is bonded to five Na1+ and one Ge4+ atom to form a mixture of corner and edge-sharing SNa5Ge octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the third S2- site, S2- is bonded in a 6-coordinate geometry to five Na1+ and one Ge4+ atom. In the fourth S2- site, S2- is bonded in a 2-coordinate geometry to four Na1+ and two equivalent Ge4+ atoms.