Materials Data on BaCa2I6 by Materials Project
BaCa2I6 is zeta iron carbide-derived structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ba2+ is bonded to six I1- atoms to form distorted BaI6 pentagonal pyramids that share corners with four equivalent CaI6 octahedra, edges with two equivalent CaI6 octahedra, and edges with two equivalent BaI6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 41–62°. There are a spread of Ba–I bond distances ranging from 3.41–3.64 Å. Ca2+ is bonded to six I1- atoms to form CaI6 octahedra that share corners with six equivalent CaI6 octahedra, corners with two equivalent BaI6 pentagonal pyramids, an edgeedge with one CaI6 octahedra, and an edgeedge with one BaI6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 43–57°. There are a spread of Ca–I bond distances ranging from 3.04–3.26 Å. There are three inequivalent I1- sites. In the first I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Ba2+ and one Ca2+ atom. In the second I1- site, I1- is bonded in a distorted trigonal planar geometry to one Ba2+ and two equivalent Ca2+ atoms. In the third I1- site, I1- is bonded in a distorted T-shaped geometry to three equivalent Ca2+ atoms.