DOE OSTI2020
Sr3LaBr9 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are six inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to seven Br1- atoms to form distorted SrBr7 pentagonal bipyramids that share corners with two equivalent SrBr7 pentagonal bipyramids, corners with two equivalent LaBr7 pentagonal bipyramids, and edges with three SrBr7 pentagonal bipyramids. There are a spread of Sr–Br bond distances ranging from 3.09–3.30 Å. In the second Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Sr–Br bond distances ranging from 3.05–3.37 Å. In the third Sr2+ site, Sr2+ is bonded to seven Br1- atoms to form distorted SrBr7 pentagonal bipyramids that share corners with two equivalent SrBr7 pentagonal bipyramids, corners with two equivalent LaBr7 pentagonal bipyramids, an edgeedge with one SrBr7 pentagonal bipyramid, and edges with two equivalent LaBr7 pentagonal bipyramids. There are a spread of Sr–Br bond distances ranging from 3.08–3.29 Å. In the fourth Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Sr–Br bond distances ranging from 3.08–3.52 Å. In the fifth Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Sr–Br bond distances ranging from 3.06–3.39 Å. In the sixth Sr2+ site, Sr2+ is bonded to seven Br1- atoms to form distorted SrBr7 pentagonal bipyramids that share corners with four SrBr7 pentagonal bipyramids, an edgeedge with one LaBr7 pentagonal bipyramid, and edges with two equivalent SrBr7 pentagonal bipyramids. There are a spread of Sr–Br bond distances ranging from 3.06–3.38 Å. There are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of La–Br bond distances ranging from 2.96–3.24 Å. In the second La3+ site, La3+ is bonded to seven Br1- atoms to form distorted LaBr7 pentagonal bipyramids that share corners with four SrBr7 pentagonal bipyramids and edges with three SrBr7 pentagonal bipyramids. There are a spread of La–Br bond distances ranging from 3.00–3.18 Å. There are eighteen inequivalent Br1- sites. In the first Br1- site, Br1- is bonded to three Sr2+ and one La3+ atom to form a mixture of distorted corner and edge-sharing BrSr3La tetrahedra. In the second Br1- site, Br1- is bonded to three Sr2+ and one La3+ atom to form a mixture of distorted corner and edge-sharing BrSr3La tetrahedra. In the third Br1- site, Br1- is bonded to three Sr2+ and one La3+ atom to form a mixture of distorted corner and edge-sharing BrSr3La tetrahedra. In the fourth Br1- site, Br1- is bonded in a distorted trigonal non-coplanar geometry to two Sr2+ and one La3+ atom. In the fifth Br1- site, Br1- is bonded in a trigonal planar geometry to two Sr2+ and one La3+ atom. In the sixth Br1- site, Br1- is bonded in a distorted trigonal non-coplanar geometry to two Sr2+ and one La3+ atom. In the seventh Br1- site, Br1- is bonded in a 3-coordinate geometry to two Sr2+ and one La3+ atom. In the eighth Br1- site, Br1- is bonded in a distorted trigonal planar geometry to two Sr2+ and one La3+ atom. In the ninth Br1- site, Br1- is bonded in a distorted trigonal non-coplanar geometry to two Sr2+ and one La3+ atom. In the tenth Br1- site, Br1- is bonded to three Sr2+ and one La3+ atom to form a mixture of distorted corner and edge-sharing BrSr3La tetrahedra. In the eleventh Br1- site, Br1- is bonded to three Sr2+ and one La3+ atom to form a mixture of distorted corner and edge-sharing BrSr3La tetrahedra. In the twelfth Br1- site, Br1- is bonded to three Sr2+ and one La3+ atom to form a mixture of distorted corner and edge-sharing BrSr3La tetrahedra. In the thirteenth Br1- site, Br1- is bonded in a distorted trigonal non-coplanar geometry to three Sr2+ atoms. In the fourteenth Br1- site, Br1- is bonded in a trigonal planar geometry to three Sr2+ atoms. In the fifteenth Br1- site, Br1- is bonded in a 2-coordinate geometry to three Sr2+ atoms. In the sixteenth Br1- site, Br1- is bonded in a 3-coordinate geometry to two Sr2+ and one La3+ atom. In the seventeenth Br1- site, Br1- is bonded in a distorted trigonal planar geometry to two Sr2+ and one La3+ atom. In the eighteenth Br1- site, Br1- is bonded in a trigonal non-coplanar geometry to two Sr2+ and one La3+ atom.