DOE OSTI2020
Rb2Gd4Cu4S9 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Rb–S bond distances ranging from 3.25–3.86 Å. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Rb–S bond distances ranging from 3.25–3.90 Å. There are four inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded to six S2- atoms to form GdS6 octahedra that share corners with three GdS6 octahedra, a cornercorner with one CuS4 tetrahedra, edges with five GdS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 1–31°. There are a spread of Gd–S bond distances ranging from 2.72–2.86 Å. In the second Gd3+ site, Gd3+ is bonded to six S2- atoms to form GdS6 octahedra that share a cornercorner with one GdS6 octahedra, corners with four equivalent CuS4 tetrahedra, edges with four GdS6 octahedra, and edges with five CuS4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. There are a spread of Gd–S bond distances ranging from 2.72–2.86 Å. In the third Gd3+ site, Gd3+ is bonded to six S2- atoms to form GdS6 octahedra that share a cornercorner with one GdS6 octahedra, corners with four equivalent CuS4 tetrahedra, edges with four GdS6 octahedra, and edges with five CuS4 tetrahedra. The corner-sharing octahedral tilt angles are 30°. There are a spread of Gd–S bond distances ranging from 2.72–2.85 Å. In the fourth Gd3+ site, Gd3+ is bonded to six S2- atoms to form GdS6 octahedra that share corners with three GdS6 octahedra, a cornercorner with one CuS4 tetrahedra, edges with five GdS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 1–30°. There are a spread of Gd–S bond distances ranging from 2.72–2.86 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 four equivalent GdS6 octahedra, corners with four CuS4 tetrahedra, edges with three GdS6 octahedra, and an edgeedge with one CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 14–60°. There are a spread of Cu–S bond distances ranging from 2.37–2.53 Å. In the second Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share a cornercorner with one GdS6 octahedra, corners with four CuS4 tetrahedra, and edges with four GdS6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are a spread of Cu–S bond distances ranging from 2.33–2.59 Å. In the third Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share a cornercorner with one GdS6 octahedra, corners with four CuS4 tetrahedra, and edges with four GdS6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are a spread of Cu–S bond distances ranging from 2.34–2.59 Å. In the fourth Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with four equivalent GdS6 octahedra, corners with four CuS4 tetrahedra, edges with three GdS6 octahedra, and an edgeedge with one CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–59°. There are a spread of Cu–S bond distances ranging from 2.35–2.59 Å. There are nine inequivalent S2- sites. In the first S2- site, S2- is bonded in a 7-coordinate geometry to two equivalent Rb1+, two equivalent Gd3+, and three Cu1+ atoms. In the second S2- site, S2- is bonded in a 7-coordinate geometry to two equivalent Rb1+, two equivalent Gd3+, and three Cu1+ atoms. In the third S2- site, S2- is bonded to two equivalent Rb1+, three Gd3+, and one Cu1+ atom to form distorted SRb2Gd3Cu octahedra that share corners with two equivalent SRbGd3Cu2 octahedra and edges with four SRb2Gd3Cu octahedra. The corner-sharing octahedra tilt angles range from 40–41°. In the fourth S2- site, S2- is bonded to two equivalent Rb1+, three Gd3+, and one Cu1+ atom to form distorted SRb2Gd3Cu octahedra that share corners with two equivalent SRbGd3Cu2 octahedra and edges with four SRb2Gd3Cu octahedra. The corner-sharing octahedra tilt angles range from 40–42°. In the fifth S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent Rb1+, two Gd3+, and two equivalent Cu1+ atoms. In the sixth S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent Rb1+, two Gd3+, and two equivalent Cu1+ atoms. In the seventh S2- site, S2- is bonded in a distorted square co-planar geometry to two Rb1+ and four Gd3+ atoms. In the eighth S2- site, S2- is bonded to one Rb1+, three Gd3+, and two equivalent Cu1+ atoms to form distorted SRbGd3Cu2 octahedra that share corners with two equivalent SRb2Gd3Cu octahedra and edges with four SRbGd3Cu2 octahedra. The corner-sharing octahedra tilt angles range from 40–41°. In the ninth S2- site, S2- is bonded to one Rb1+, three Gd3+, and two equivalent Cu1+ atoms to form distorted SRbGd3Cu2 octahedra that share corners with two equivalent SRb2Gd3Cu octahedra and edges with four SRbGd3Cu2 octahedra. The corner-sharing octahedra tilt angles range from 40–42°.