Materials Data on KGd2CuSe4 by Materials Project
KGd2CuSe4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to eight Se2- atoms. There are a spread of K–Se bond distances ranging from 3.26–3.96 Å. Gd3+ is bonded to six Se2- atoms to form GdSe6 octahedra that share corners with three equivalent GdSe6 octahedra, a cornercorner with one CuSe4 tetrahedra, edges with five equivalent GdSe6 octahedra, and edges with two equivalent CuSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 0–41°. There are a spread of Gd–Se bond distances ranging from 2.87–2.98 Å. Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with two equivalent GdSe6 octahedra, corners with two equivalent CuSe4 tetrahedra, and edges with four equivalent GdSe6 octahedra. The corner-sharing octahedral tilt angles are 8°. All Cu–Se bond lengths are 2.49 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted square co-planar geometry to two equivalent K1+ and four equivalent Gd3+ atoms. In the second Se2- site, Se2- is bonded to two equivalent K1+, three equivalent Gd3+, and one Cu1+ atom to form a mixture of distorted corner, edge, and face-sharing SeK2Gd3Cu octahedra. The corner-sharing octahedral tilt angles are 63°. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent K1+, two equivalent Gd3+, and two equivalent Cu1+ atoms.