Materials Data on K3TaNbCu3S8 by Materials Project

Abstract

K3TaNbCu3S8 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are a spread of K–S bond distances ranging from 3.32–3.55 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of K–S bond distances ranging from 3.23–3.68 Å. In the third K1+ site, K1+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of K–S bond distances ranging from 3.23–3.67 Å. Ta5+ is bonded to four S2- atoms to form TaS4 tetrahedra that share edges with three CuS4 tetrahedra. There are a spread of Ta–S bond distances ranging from 2.29–2.31 Å. Nb5+ is bonded to four S2- atoms to form NbS4 tetrahedra that share edges with three CuS4 tetrahedra. There are a spread of Nb–S bond distances ranging from 2.29–2.32 Å. There are four inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with two equivalent CuS4 tetrahedra and edges with two equivalent TaS4 tetrahedra. There are a spread of Cu–S bond distances ranging from 2.33–2.38 Å. In the second Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with two equivalent CuS4 tetrahedra and edges with two equivalent NbS4 tetrahedra. There are a spread of Cu–S bond distances ranging from 2.33–2.38 Å. In the third Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with four equivalent CuS4 tetrahedra and edges with two equivalent TaS4 tetrahedra. There are two shorter (2.36 Å) and two longer (2.37 Å) Cu–S bond lengths. In the fourth Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with four equivalent CuS4 tetrahedra and edges with two equivalent NbS4 tetrahedra. There are two shorter (2.35 Å) and two longer (2.37 Å) Cu–S bond lengths. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to three K1+, one Ta5+, and one Cu1+ atom. In the second S2- site, S2- is bonded in a 5-coordinate geometry to three K1+, one Nb5+, and one Cu1+ atom. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two K1+, one Ta5+, and two Cu1+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two K1+, one Nb5+, and two Cu1+ atoms. In the fifth S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent K1+, one Ta5+, and two Cu1+ atoms. In the sixth S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent K1+, one Nb5+, and two Cu1+ atoms. In the seventh S2- site, S2- is bonded in a 6-coordinate geometry to four K1+, one Ta5+, and one Cu1+ atom. In the eighth S2- site, S2- is bonded to four K1+, one Nb5+, and one Cu1+ atom to form a mixture of distorted corner and edge-sharing SK4NbCu octahedra. The corner-sharing octahedral tilt angles are 69°.