DOE OSTI2020
Sr3YI9 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 I1- atoms to form distorted SrI7 pentagonal bipyramids that share corners with two equivalent YI7 pentagonal bipyramids and an edgeedge with one SrI7 pentagonal bipyramid. There are a spread of Sr–I bond distances ranging from 3.31–3.55 Å. In the second Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight I1- atoms. There are a spread of Sr–I bond distances ranging from 3.27–3.70 Å. In the third Sr2+ site, Sr2+ is bonded to seven I1- atoms to form distorted SrI7 pentagonal bipyramids that share corners with two equivalent YI7 pentagonal bipyramids, an edgeedge with one SrI7 pentagonal bipyramid, and edges with two equivalent YI7 pentagonal bipyramids. There are a spread of Sr–I bond distances ranging from 3.31–3.57 Å. In the fourth Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight I1- atoms. There are a spread of Sr–I bond distances ranging from 3.30–3.82 Å. In the fifth Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight I1- atoms. There are a spread of Sr–I bond distances ranging from 3.26–3.69 Å. In the sixth Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven I1- atoms. There are a spread of Sr–I bond distances ranging from 3.28–3.73 Å. There are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight I1- atoms. There are a spread of Y–I bond distances ranging from 3.05–3.46 Å. In the second Y3+ site, Y3+ is bonded to seven I1- atoms to form distorted YI7 pentagonal bipyramids that share corners with four SrI7 pentagonal bipyramids and edges with two equivalent SrI7 pentagonal bipyramids. There are a spread of Y–I bond distances ranging from 3.10–3.44 Å. There are eighteen inequivalent I1- sites. In the first I1- site, I1- is bonded to three Sr2+ and one Y3+ atom to form a mixture of distorted corner and edge-sharing ISr3Y tetrahedra. In the second I1- site, I1- is bonded to three Sr2+ and one Y3+ atom to form a mixture of distorted corner and edge-sharing ISr3Y tetrahedra. In the third I1- site, I1- is bonded to three Sr2+ and one Y3+ atom to form a mixture of distorted corner and edge-sharing ISr3Y tetrahedra. In the fourth I1- site, I1- is bonded in a distorted trigonal non-coplanar geometry to two Sr2+ and one Y3+ atom. In the fifth I1- site, I1- is bonded in a distorted trigonal planar geometry to two Sr2+ and one Y3+ atom. In the sixth I1- site, I1- is bonded in a 3-coordinate geometry to two Sr2+ and one Y3+ atom. In the seventh I1- site, I1- is bonded in a 3-coordinate geometry to two Sr2+ and one Y3+ atom. In the eighth I1- site, I1- is bonded in a 3-coordinate geometry to two Sr2+ and one Y3+ atom. In the ninth I1- site, I1- is bonded in a distorted trigonal non-coplanar geometry to two Sr2+ and one Y3+ atom. In the tenth I1- site, I1- is bonded to three Sr2+ and one Y3+ atom to form a mixture of distorted corner and edge-sharing ISr3Y tetrahedra. In the eleventh I1- site, I1- is bonded to three Sr2+ and one Y3+ atom to form a mixture of distorted corner and edge-sharing ISr3Y tetrahedra. In the twelfth I1- site, I1- is bonded to three Sr2+ and one Y3+ atom to form a mixture of distorted corner and edge-sharing ISr3Y tetrahedra. In the thirteenth I1- site, I1- is bonded in a distorted trigonal non-coplanar geometry to three Sr2+ atoms. In the fourteenth I1- site, I1- is bonded in a trigonal planar geometry to three Sr2+ atoms. In the fifteenth I1- site, I1- is bonded in a 2-coordinate geometry to three Sr2+ atoms. In the sixteenth I1- site, I1- is bonded in a 3-coordinate geometry to two Sr2+ and one Y3+ atom. In the seventeenth I1- site, I1- is bonded in a distorted trigonal planar geometry to two Sr2+ and one Y3+ atom. In the eighteenth I1- site, I1- is bonded in a trigonal non-coplanar geometry to two Sr2+ and one Y3+ atom.