DOE OSTI2020
Pr6Ti2S7O6 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are six inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded in a 9-coordinate geometry to five S2- and four O2- atoms. There are three shorter (2.95 Å) and two longer (3.06 Å) Pr–S bond lengths. There are three shorter (2.49 Å) and one longer (2.74 Å) Pr–O bond lengths. In the second Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to seven S2- and one O2- atom. There are a spread of Pr–S bond distances ranging from 2.85–3.02 Å. The Pr–O bond length is 2.66 Å. In the third Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to five S2- and three O2- atoms. There are a spread of Pr–S bond distances ranging from 2.90–3.22 Å. There are one shorter (2.39 Å) and two longer (2.58 Å) Pr–O bond lengths. In the fourth Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to seven S2- and one O2- atom. There are a spread of Pr–S bond distances ranging from 2.86–3.05 Å. The Pr–O bond length is 2.70 Å. In the fifth Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to two equivalent S2- and five O2- atoms. Both Pr–S bond lengths are 2.98 Å. There are a spread of Pr–O bond distances ranging from 2.34–2.55 Å. In the sixth Pr3+ site, Pr3+ is bonded in a 2-coordinate geometry to six S2- and three O2- atoms. There are a spread of Pr–S bond distances ranging from 2.94–3.17 Å. There are two shorter (2.46 Å) and one longer (2.76 Å) Pr–O bond lengths. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to three S2- and three O2- atoms. There are a spread of Ti–S bond distances ranging from 2.29–2.73 Å. There is one shorter (1.81 Å) and two longer (2.00 Å) Ti–O bond length. In the second Ti4+ site, Ti4+ is bonded in a 4-coordinate geometry to two S2- and four O2- atoms. There are one shorter (2.61 Å) and one longer (2.85 Å) Ti–S bond lengths. There are a spread of Ti–O bond distances ranging from 1.82–2.01 Å. There are seven inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to three Pr3+ and one Ti4+ atom. In the second S2- site, S2- is bonded in a 5-coordinate geometry to five Pr3+ atoms. In the third S2- site, S2- is bonded in a 6-coordinate geometry to five Pr3+ and one Ti4+ atom. In the fourth S2- site, S2- is bonded in a 6-coordinate geometry to four Pr3+ and two Ti4+ atoms. In the fifth S2- site, S2- is bonded in a 6-coordinate geometry to five Pr3+ and one O2- atom. The S–O bond length is 3.12 Å. In the sixth S2- site, S2- is bonded in a 5-coordinate geometry to five Pr3+ atoms. In the seventh S2- site, S2- is bonded in a 6-coordinate geometry to five Pr3+ and one Ti4+ atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Pr3+ and two equivalent Ti4+ atoms. In the second O2- site, O2- is bonded to three Pr3+ and one Ti4+ atom to form distorted OPr3Ti tetrahedra that share corners with three OPr3Ti tetrahedra and edges with two equivalent OPr4 tetrahedra. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Pr3+ and two equivalent Ti4+ atoms. In the fourth O2- site, O2- is bonded to four Pr3+ atoms to form OPr4 tetrahedra that share corners with four OPr4 tetrahedra and edges with two equivalent OPr3Ti tetrahedra. In the fifth O2- site, O2- is bonded to three Pr3+ and one Ti4+ atom to form distorted corner-sharing OPr3Ti tetrahedra. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to three Pr3+, one Ti4+, and one S2- atom.