DOE OSTI2020
Pb7F12Br2 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 9-coordinate geometry to two equivalent Br1- and seven F1- atoms. Both Pb–Br bond lengths are 3.28 Å. There are a spread of Pb–F bond distances ranging from 2.44–3.08 Å. In the second Pb2+ site, Pb2+ is bonded in a 7-coordinate geometry to two equivalent Br1- and seven F1- atoms. Both Pb–Br bond lengths are 3.35 Å. There are a spread of Pb–F bond distances ranging from 2.46–2.78 Å. In the third Pb2+ site, Pb2+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are three shorter (2.51 Å) and six longer (2.78 Å) Pb–F bond lengths. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 12-coordinate geometry to six equivalent Pb2+ and twelve F1- atoms. There are a spread of Br–F bond distances ranging from 3.50–3.61 Å. In the second Br1- site, Br1- is bonded in a 12-coordinate geometry to six equivalent Pb2+ and nine F1- atoms. There are six shorter (3.43 Å) and three longer (3.53 Å) Br–F bond lengths. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded to four Pb2+ and three Br1- atoms to form a mixture of distorted corner, edge, and face-sharing FPb4Br3 tetrahedra. In the second F1- site, F1- is bonded in a 3-coordinate geometry to five Pb2+ atoms. In the third F1- site, F1- is bonded to four Pb2+ and three Br1- atoms to form a mixture of distorted corner, edge, and face-sharing FPb4Br3 tetrahedra. In the fourth F1- site, F1- is bonded to four Pb2+ and one Br1- atom to form a mixture of corner, edge, and face-sharing FPb4Br tetrahedra.