DOE OSTI2020
Ag7TaS6 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. Ta5+ is bonded to four S2- atoms to form TaS4 tetrahedra that share corners with two equivalent AgS4 tetrahedra. All Ta–S bond lengths are 2.32 Å. There are seven inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.55–2.92 Å. In the second Ag1+ site, Ag1+ is bonded to four S2- atoms to form distorted AgS4 tetrahedra that share corners with two equivalent TaS4 tetrahedra. There are a spread of Ag–S bond distances ranging from 2.62–2.76 Å. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.52–2.57 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.52–2.69 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are two shorter (2.55 Å) and one longer (2.65 Å) Ag–S bond lengths. In the sixth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.52–2.66 Å. In the seventh Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.53–3.21 Å. There are six inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to six Ag1+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to one Ta5+ and three Ag1+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to one Ta5+ and four Ag1+ atoms. In the fifth S2- site, S2- is bonded in a 4-coordinate geometry to one Ta5+ and three Ag1+ atoms. In the sixth S2- site, S2- is bonded in a 1-coordinate geometry to one Ta5+ and three Ag1+ atoms.