DOE OSTI2020
BaYI5 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 5-coordinate geometry to eight I1- atoms. There are a spread of Ba–I bond distances ranging from 3.45–4.28 Å. In the second Ba2+ site, Ba2+ is bonded to seven I1- atoms to form distorted BaI7 hexagonal pyramids that share corners with six YI6 octahedra and an edgeedge with one YI6 octahedra. The corner-sharing octahedra tilt angles range from 48–67°. There are a spread of Ba–I bond distances ranging from 3.51–3.91 Å. There are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to six I1- atoms to form YI6 octahedra that share corners with three equivalent BaI7 hexagonal pyramids, corners with two equivalent YI6 octahedra, and an edgeedge with one BaI7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 61–67°. There are a spread of Y–I bond distances ranging from 3.00–3.25 Å. In the second Y3+ site, Y3+ is bonded to six I1- atoms to form YI6 octahedra that share corners with three equivalent BaI7 hexagonal pyramids and corners with two equivalent YI6 octahedra. The corner-sharing octahedra tilt angles range from 61–67°. There are a spread of Y–I bond distances ranging from 2.96–3.15 Å. There are ten inequivalent I1- sites. In the first I1- site, I1- is bonded in a 2-coordinate geometry to two Ba2+ and one Y3+ atom. In the second I1- site, I1- is bonded in a 2-coordinate geometry to two Ba2+ and one Y3+ atom. In the third I1- site, I1- is bonded in a distorted bent 120 degrees geometry to one Ba2+ and two Y3+ atoms. In the fourth I1- site, I1- is bonded in a distorted T-shaped geometry to two Ba2+ and one Y3+ atom. In the fifth I1- site, I1- is bonded in a trigonal planar geometry to two Ba2+ and one Y3+ atom. In the sixth I1- site, I1- is bonded in a 3-coordinate geometry to two Ba2+ and one Y3+ atom. In the seventh I1- site, I1- is bonded in a distorted bent 150 degrees geometry to one Ba2+ and one Y3+ atom. In the eighth I1- site, I1- is bonded in a distorted trigonal planar geometry to one Ba2+ and two Y3+ atoms. In the ninth I1- site, I1- is bonded in a distorted bent 120 degrees geometry to one Ba2+ and one Y3+ atom. In the tenth I1- site, I1- is bonded in a distorted bent 120 degrees geometry to one Ba2+ and one Y3+ atom.