Materials Data on K3(FeSe2)2 by Materials Project

Abstract

K3(FeSe2)2 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 to six Se2- atoms to form KSe6 octahedra that share corners with eight equivalent FeSe4 tetrahedra, edges with two equivalent FeSe4 tetrahedra, and faces with two equivalent KSe6 octahedra. There are a spread of K–Se bond distances ranging from 3.26–3.41 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of K–Se bond distances ranging from 3.26–3.95 Å. Fe+2.50+ is bonded to four Se2- atoms to form FeSe4 tetrahedra that share corners with four equivalent KSe6 octahedra, an edgeedge with one KSe6 octahedra, and edges with two equivalent FeSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–62°. There are a spread of Fe–Se bond distances ranging from 2.40–2.46 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to four equivalent K1+ and two equivalent Fe+2.50+ atoms. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to five K1+ and two equivalent Fe+2.50+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to six K1+ and two equivalent Fe+2.50+ atoms.