Materials Data on KSm2CuS4 by Materials Project
KSm2CuS4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of K–S bond distances ranging from 3.17–3.79 Å. Sm3+ is bonded to six S2- atoms to form SmS6 octahedra that share corners with three equivalent SmS6 octahedra, a cornercorner with one CuS4 tetrahedra, edges with five equivalent SmS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 0–38°. There are a spread of Sm–S bond distances ranging from 2.76–2.87 Å. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with two equivalent SmS6 octahedra, corners with two equivalent CuS4 tetrahedra, and edges with four equivalent SmS6 octahedra. The corner-sharing octahedral tilt angles are 6°. There are two shorter (2.35 Å) and two longer (2.39 Å) Cu–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted square co-planar geometry to two equivalent K1+ and four equivalent Sm3+ atoms. In the second S2- site, S2- is bonded to two equivalent K1+, three equivalent Sm3+, and one Cu1+ atom to form a mixture of distorted corner, edge, and face-sharing SK2Sm3Cu octahedra. The corner-sharing octahedral tilt angles are 65°. In the third S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent K1+, two equivalent Sm3+, and two equivalent Cu1+ atoms.