DOE OSTI2020
Cs2Ti2S9 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are four inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 3-coordinate geometry to fifteen S+1.11- atoms. There are a spread of Cs–S bond distances ranging from 3.45–4.08 Å. In the second Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine S+1.11- atoms. There are a spread of Cs–S bond distances ranging from 3.60–4.19 Å. In the third Cs1+ site, Cs1+ is bonded in a 6-coordinate geometry to nine S+1.11- atoms. There are a spread of Cs–S bond distances ranging from 3.61–4.02 Å. In the fourth Cs1+ site, Cs1+ is bonded in a 6-coordinate geometry to six S+1.11- atoms. There are three shorter (3.43 Å) and three longer (3.62 Å) Cs–S bond lengths. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to seven S+1.11- atoms to form a mixture of distorted edge and face-sharing TiS7 pentagonal bipyramids. There are a spread of Ti–S bond distances ranging from 2.38–2.72 Å. In the second Ti4+ site, Ti4+ is bonded to seven S+1.11- atoms to form a mixture of distorted edge and face-sharing TiS7 pentagonal bipyramids. There are a spread of Ti–S bond distances ranging from 2.40–2.65 Å. There are nine inequivalent S+1.11- sites. In the first S+1.11- site, S+1.11- is bonded in a distorted L-shaped geometry to three Cs1+ and two Ti4+ atoms. In the second S+1.11- site, S+1.11- is bonded in a 2-coordinate geometry to two Cs1+ and two Ti4+ atoms. In the third S+1.11- site, S+1.11- is bonded in a 4-coordinate geometry to two Cs1+, two Ti4+, and one S+1.11- atom. The S–S bond length is 2.07 Å. In the fourth S+1.11- site, S+1.11- is bonded in a 1-coordinate geometry to three Cs1+ and one Ti4+ atom. In the fifth S+1.11- site, S+1.11- is bonded in a 1-coordinate geometry to two Cs1+, one Ti4+, and one S+1.11- atom. In the sixth S+1.11- site, S+1.11- is bonded in a 1-coordinate geometry to two Cs1+ and one Ti4+ atom. In the seventh S+1.11- site, S+1.11- is bonded in a 2-coordinate geometry to one Cs1+ and two Ti4+ atoms. In the eighth S+1.11- site, S+1.11- is bonded in a 2-coordinate geometry to two Cs1+ and two Ti4+ atoms. In the ninth S+1.11- site, S+1.11- is bonded in a 1-coordinate geometry to two Cs1+ and one Ti4+ atom.