Materials Data on SrCa2I6 by Materials Project
SrCa2I6 is zeta iron carbide-derived structured and crystallizes in the trigonal P321 space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to six I1- atoms to form SrI6 octahedra that share corners with six equivalent CaI6 octahedra and edges with three equivalent CaI6 octahedra. The corner-sharing octahedra tilt angles range from 53–55°. There are three shorter (3.28 Å) and three longer (3.29 Å) Sr–I bond lengths. In the second Sr2+ site, Sr2+ is bonded to six equivalent I1- atoms to form SrI6 octahedra that share corners with six equivalent CaI6 octahedra and edges with three equivalent CaI6 octahedra. The corner-sharing octahedral tilt angles are 58°. All Sr–I bond lengths are 3.29 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six I1- atoms to form CaI6 octahedra that share corners with four equivalent SrI6 octahedra, corners with six equivalent CaI6 octahedra, and an edgeedge with one SrI6 octahedra. The corner-sharing octahedra tilt angles range from 46–55°. There are a spread of Ca–I bond distances ranging from 3.17–3.19 Å. In the second Ca2+ site, Ca2+ is bonded to six I1- atoms to form CaI6 octahedra that share corners with two equivalent SrI6 octahedra, corners with six equivalent CaI6 octahedra, and edges with two equivalent SrI6 octahedra. The corner-sharing octahedra tilt angles range from 46–58°. There are a spread of Ca–I bond distances ranging from 3.16–3.19 Å. There are three inequivalent I1- sites. In the first I1- site, I1- is bonded in a distorted trigonal planar geometry to one Sr2+ and two Ca2+ atoms. In the second I1- site, I1- is bonded in a distorted trigonal planar geometry to one Sr2+ and two Ca2+ atoms. In the third I1- site, I1- is bonded in a distorted trigonal planar geometry to one Sr2+ and two Ca2+ atoms.