Materials Data on KTb2CuS4 by Materials Project
KTb2CuS4 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 3.13–3.75 Å. Tb3+ is bonded to six S2- atoms to form TbS6 octahedra that share corners with three equivalent TbS6 octahedra, a cornercorner with one CuS4 tetrahedra, edges with five equivalent TbS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 0–38°. There are a spread of Tb–S bond distances ranging from 2.72–2.83 Å. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with two equivalent TbS6 octahedra, corners with two equivalent CuS4 tetrahedra, and edges with four equivalent TbS6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are two shorter (2.34 Å) and two longer (2.36 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 Tb3+ atoms. In the second S2- site, S2- is bonded to two equivalent K1+, three equivalent Tb3+, and one Cu1+ atom to form a mixture of distorted face, edge, and corner-sharing SK2Tb3Cu 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 Tb3+, and two equivalent Cu1+ atoms.