Materials Data on K2NbCuS4 by Materials Project
K2NbCuS4 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. K1+ is bonded to eight equivalent S2- atoms to form distorted KS8 hexagonal bipyramids that share corners with four equivalent KS8 hexagonal bipyramids, corners with two equivalent NbS4 tetrahedra, corners with four equivalent CuS4 tetrahedra, edges with six equivalent KS8 hexagonal bipyramids, edges with two equivalent CuS4 tetrahedra, edges with three equivalent NbS4 tetrahedra, and faces with two equivalent KS8 hexagonal bipyramids. There are a spread of K–S bond distances ranging from 3.43–3.59 Å. Nb5+ is bonded to four equivalent S2- atoms to form NbS4 tetrahedra that share corners with four equivalent KS8 hexagonal bipyramids, edges with six equivalent KS8 hexagonal bipyramids, and edges with two equivalent CuS4 tetrahedra. All Nb–S bond lengths are 2.30 Å. Cu1+ is bonded to four equivalent S2- atoms to form CuS4 tetrahedra that share corners with eight equivalent KS8 hexagonal bipyramids, edges with four equivalent KS8 hexagonal bipyramids, and edges with two equivalent NbS4 tetrahedra. All Cu–S bond lengths are 2.35 Å. S2- is bonded in a 6-coordinate geometry to four equivalent K1+, one Nb5+, and one Cu1+ atom.