Materials Data on K4Sn(TeSe)2 by Materials Project

Abstract

K4Sn(TeSe)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to four Te2- and two equivalent Se2- atoms to form KTe4Se2 octahedra that share corners with two equivalent SnTe2Se2 tetrahedra, edges with two equivalent KTe4Se2 octahedra, and edges with two equivalent SnTe2Se2 tetrahedra. There are two shorter (3.75 Å) and two longer (3.85 Å) K–Te bond lengths. Both K–Se bond lengths are 3.36 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to four Te2- and two equivalent Se2- atoms. There are a spread of K–Te bond distances ranging from 3.53–3.93 Å. There are one shorter (3.32 Å) and one longer (3.52 Å) K–Se bond lengths. In the third K1+ site, K1+ is bonded in a 6-coordinate geometry to two Te2- and four equivalent Se2- atoms. There are one shorter (3.68 Å) and one longer (4.12 Å) K–Te bond lengths. There are two shorter (3.40 Å) and two longer (3.49 Å) K–Se bond lengths. Sn4+ is bonded to two Te2- and two equivalent Se2- atoms to form SnTe2Se2 tetrahedra that share corners with two equivalent KTe4Se2 octahedra and edges with two equivalent KTe4Se2 octahedra. The corner-sharing octahedral tilt angles are 45°. There are one shorter (2.80 Å) and one longer (2.81 Å) Sn–Te bond lengths. Both Sn–Se bond lengths are 2.55 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 8-coordinate geometry to seven K1+ and one Sn4+ atom. In the second Te2- site, Te2- is bonded in a 8-coordinate geometry to seven K1+ and one Sn4+ atom. Se2- is bonded in a 6-coordinate geometry to five K1+ and one Sn4+ atom.