Materials Data on K3(FeS2)2 by Materials Project
K3Fe2S4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to six S2- atoms. There are a spread of K–S bond distances ranging from 3.13–3.59 Å. In the second K1+ site, K1+ is bonded to six S2- atoms to form distorted KS6 octahedra that share corners with eight equivalent FeS4 tetrahedra, edges with two equivalent FeS4 tetrahedra, and faces with two equivalent KS6 octahedra. There are a spread of K–S bond distances ranging from 3.12–3.32 Å. Fe+2.50+ is bonded to four S2- atoms to form FeS4 tetrahedra that share corners with four equivalent KS6 octahedra, an edgeedge with one KS6 octahedra, and edges with two equivalent FeS4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–64°. There are a spread of Fe–S bond distances ranging from 2.26–2.31 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to four equivalent K1+ and two equivalent Fe+2.50+ atoms. In the second S2- site, S2- is bonded in a 7-coordinate geometry to five K1+ and two equivalent Fe+2.50+ atoms. In the third S2- site, S2- is bonded in a 6-coordinate geometry to four K1+ and two equivalent Fe+2.50+ atoms.