DOE OSTI2020
Cs4Au6S5 crystallizes in the trigonal P31m space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 6-coordinate geometry to six equivalent S2- atoms. There are three shorter (3.56 Å) and three longer (4.17 Å) Cs–S bond lengths. In the second Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to four equivalent Au1+ and five S2- atoms. There are two shorter (3.84 Å) and two longer (3.85 Å) Cs–Au bond lengths. There are a spread of Cs–S bond distances ranging from 3.68–4.06 Å. Au1+ is bonded in a 2-coordinate geometry to two equivalent Cs1+ and two S2- atoms. There are one shorter (2.32 Å) and one longer (2.34 Å) Au–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to three equivalent Cs1+ and three equivalent Au1+ atoms to form SCs3Au3 octahedra that share corners with three equivalent SCs3Au3 octahedra, corners with six equivalent SCs5Au2 pentagonal bipyramids, and edges with three equivalent SCs5Au2 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 67°. In the second S2- site, S2- is bonded to five Cs1+ and two equivalent Au1+ atoms to form distorted SCs5Au2 pentagonal bipyramids that share corners with four equivalent SCs3Au3 octahedra, corners with ten equivalent SCs5Au2 pentagonal bipyramids, edges with two equivalent SCs3Au3 octahedra, and faces with two equivalent SCs5Au2 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 3–33°.